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<li class="toctree-l1"><a class="reference internal" href="chapter1.html">1. Introduction to DNS and BIND 9</a></li>
<li class="toctree-l1"><a class="reference internal" href="chapter2.html">2. Resource Requirements</a></li>
<li class="toctree-l1"><a class="reference internal" href="chapter3.html">3. Configurations and Zone Files</a></li>
<li class="toctree-l1"><a class="reference internal" href="chapter4.html">4. Name Server Operations</a></li>
<li class="toctree-l1"><a class="reference internal" href="chapter5.html">5. DNSSEC</a></li>
<li class="toctree-l1"><a class="reference internal" href="chapter6.html">6. Advanced Configurations</a></li>
<li class="toctree-l1"><a class="reference internal" href="chapter7.html">7. Security Configurations</a></li>
<li class="toctree-l1 current"><a class="current reference internal" href="#">8. Configuration Reference</a><ul>
<li class="toctree-l2"><a class="reference internal" href="#configuration-file-named-conf">8.1. Configuration File (named.conf)</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#comment-syntax">8.1.1. Comment Syntax</a><ul>
<li class="toctree-l4"><a class="reference internal" href="#syntax">8.1.1.1. Syntax</a></li>
<li class="toctree-l4"><a class="reference internal" href="#definition-and-usage">8.1.1.2. Definition and Usage</a></li>
</ul>
</li>
<li class="toctree-l3"><a class="reference internal" href="#configuration-layout-styles">8.1.2. Configuration Layout Styles</a></li>
<li class="toctree-l3"><a class="reference internal" href="#include-directive">8.1.3. <code class="docutils literal notranslate"><span class="pre">include</span></code> Directive</a><ul>
<li class="toctree-l4"><a class="reference internal" href="#include-directive-definition-and-usage">8.1.3.1. <code class="docutils literal notranslate"><span class="pre">include</span></code> Directive Definition and Usage</a></li>
</ul>
</li>
<li class="toctree-l3"><a class="reference internal" href="#address-match-lists">8.1.4. Address Match Lists</a><ul>
<li class="toctree-l4"><a class="reference internal" href="#id3">8.1.4.1. Syntax</a></li>
<li class="toctree-l4"><a class="reference internal" href="#id4">8.1.4.2. Definition and Usage</a></li>
</ul>
</li>
<li class="toctree-l3"><a class="reference internal" href="#glossary-of-terms-used">8.1.5. Glossary of Terms Used</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="#blocks">8.2. Blocks</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#acl-block-grammar">8.2.1. <code class="xref any docutils literal notranslate"><span class="pre">acl</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#acl-block-definition-and-usage">8.2.2. <code class="xref any docutils literal notranslate"><span class="pre">acl</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#controls-block-grammar">8.2.3. <code class="xref any docutils literal notranslate"><span class="pre">controls</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#controls-block-definition-and-usage">8.2.4. <code class="xref any docutils literal notranslate"><span class="pre">controls</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#key-block-grammar">8.2.5. <code class="docutils literal notranslate"><span class="pre">key</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#key-block-definition-and-usage">8.2.6. <code class="docutils literal notranslate"><span class="pre">key</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#logging-block-grammar">8.2.7. <code class="xref any docutils literal notranslate"><span class="pre">logging</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#logging-block-definition-and-usage">8.2.8. <code class="xref any docutils literal notranslate"><span class="pre">logging</span></code> Block Definition and Usage</a><ul>
<li class="toctree-l4"><a class="reference internal" href="#the-channel-phrase">8.2.8.1. The <code class="xref any docutils literal notranslate"><span class="pre">channel</span></code> Phrase</a></li>
<li class="toctree-l4"><a class="reference internal" href="#the-category-phrase">8.2.8.2. The <code class="xref any docutils literal notranslate"><span class="pre">category</span></code> Phrase</a></li>
<li class="toctree-l4"><a class="reference internal" href="#the-query-errors-category">8.2.8.3. The <code class="docutils literal notranslate"><span class="pre">query-errors</span></code> Category</a></li>
</ul>
</li>
<li class="toctree-l3"><a class="reference internal" href="#parental-agents-block-grammar">8.2.9. <code class="xref any docutils literal notranslate"><span class="pre">parental-agents</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#parental-agents-block-definition-and-usage">8.2.10. <code class="xref any docutils literal notranslate"><span class="pre">parental-agents</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#primaries-block-grammar">8.2.11. <code class="xref any docutils literal notranslate"><span class="pre">primaries</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#primaries-block-definition-and-usage">8.2.12. <code class="xref any docutils literal notranslate"><span class="pre">primaries</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#options-block-grammar">8.2.13. <code class="docutils literal notranslate"><span class="pre">options</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#options-block-definition-and-usage">8.2.14. <code class="docutils literal notranslate"><span class="pre">options</span></code> Block Definition and Usage</a><ul>
<li class="toctree-l4"><a class="reference internal" href="#boolean-options">8.2.14.1. Boolean Options</a></li>
<li class="toctree-l4"><a class="reference internal" href="#forwarding">8.2.14.2. Forwarding</a></li>
<li class="toctree-l4"><a class="reference internal" href="#dual-stack-servers">8.2.14.3. Dual-stack Servers</a></li>
<li class="toctree-l4"><a class="reference internal" href="#access-control">8.2.14.4. Access Control</a></li>
<li class="toctree-l4"><a class="reference internal" href="#interfaces">8.2.14.5. Interfaces</a></li>
<li class="toctree-l4"><a class="reference internal" href="#query-address">8.2.14.6. Query Address</a></li>
<li class="toctree-l4"><a class="reference internal" href="#zone-transfers">8.2.14.7. Zone Transfers</a></li>
<li class="toctree-l4"><a class="reference internal" href="#operating-system-resource-limits">8.2.14.8. Operating System Resource Limits</a></li>
<li class="toctree-l4"><a class="reference internal" href="#server-resource-limits">8.2.14.9. Server Resource Limits</a></li>
<li class="toctree-l4"><a class="reference internal" href="#periodic-task-intervals">8.2.14.10. Periodic Task Intervals</a></li>
<li class="toctree-l4"><a class="reference internal" href="#the-sortlist-statement">8.2.14.11. The <code class="xref any docutils literal notranslate"><span class="pre">sortlist</span></code> Statement</a></li>
<li class="toctree-l4"><a class="reference internal" href="#rrset-ordering">8.2.14.12. RRset Ordering</a></li>
<li class="toctree-l4"><a class="reference internal" href="#tuning">8.2.14.13. Tuning</a></li>
<li class="toctree-l4"><a class="reference internal" href="#built-in-server-information-zones">8.2.14.14. Built-in Server Information Zones</a></li>
<li class="toctree-l4"><a class="reference internal" href="#built-in-empty-zones">8.2.14.15. Built-in Empty Zones</a></li>
<li class="toctree-l4"><a class="reference internal" href="#content-filtering">8.2.14.16. Content Filtering</a></li>
<li class="toctree-l4"><a class="reference internal" href="#response-policy-zone-rpz-rewriting">8.2.14.17. Response Policy Zone (RPZ) Rewriting</a></li>
<li class="toctree-l4"><a class="reference internal" href="#response-rate-limiting">8.2.14.18. Response Rate Limiting</a></li>
<li class="toctree-l4"><a class="reference internal" href="#nxdomain-redirection">8.2.14.19. NXDOMAIN Redirection</a></li>
</ul>
</li>
<li class="toctree-l3"><a class="reference internal" href="#server-block-grammar">8.2.15. <code class="docutils literal notranslate"><span class="pre">server</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#server-block-definition-and-usage">8.2.16. <code class="docutils literal notranslate"><span class="pre">server</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#statistics-channels-block-grammar">8.2.17. <code class="xref any docutils literal notranslate"><span class="pre">statistics-channels</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#statistics-channels-block-definition-and-usage">8.2.18. <code class="xref any docutils literal notranslate"><span class="pre">statistics-channels</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#tls-block-grammar">8.2.19. <code class="xref any docutils literal notranslate"><span class="pre">tls</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#tls-block-definition-and-usage">8.2.20. <code class="xref any docutils literal notranslate"><span class="pre">tls</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#http-block-grammar">8.2.21. <code class="xref any docutils literal notranslate"><span class="pre">http</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#http-block-definition-and-usage">8.2.22. <code class="xref any docutils literal notranslate"><span class="pre">http</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#trust-anchors-block-grammar">8.2.23. <code class="xref any docutils literal notranslate"><span class="pre">trust-anchors</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#trust-anchors-block-definition-and-usage">8.2.24. <code class="xref any docutils literal notranslate"><span class="pre">trust-anchors</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#dnssec-policy-block-grammar">8.2.25. <code class="xref any docutils literal notranslate"><span class="pre">dnssec-policy</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#dnssec-policy-block-definition-and-usage">8.2.26. <code class="xref any docutils literal notranslate"><span class="pre">dnssec-policy</span></code> Block Definition and Usage</a><ul>
<li class="toctree-l4"><a class="reference internal" href="#automated-ksk-rollovers">8.2.26.1. Automated KSK Rollovers</a></li>
</ul>
</li>
<li class="toctree-l3"><a class="reference internal" href="#managed-keys-block-grammar">8.2.27. <code class="xref any docutils literal notranslate"><span class="pre">managed-keys</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#managed-keys-block-definition-and-usage">8.2.28. <code class="xref any docutils literal notranslate"><span class="pre">managed-keys</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#trusted-keys-block-grammar">8.2.29. <code class="xref any docutils literal notranslate"><span class="pre">trusted-keys</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#trusted-keys-block-definition-and-usage">8.2.30. <code class="xref any docutils literal notranslate"><span class="pre">trusted-keys</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#view-block-grammar">8.2.31. <code class="xref any docutils literal notranslate"><span class="pre">view</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#view-block-definition-and-usage">8.2.32. <code class="xref any docutils literal notranslate"><span class="pre">view</span></code> Block Definition and Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="#zone-block-grammar">8.2.33. <code class="xref any docutils literal notranslate"><span class="pre">zone</span></code> Block Grammar</a></li>
<li class="toctree-l3"><a class="reference internal" href="#zone-block-definition-and-usage">8.2.34. <code class="xref any docutils literal notranslate"><span class="pre">zone</span></code> Block Definition and Usage</a><ul>
<li class="toctree-l4"><a class="reference internal" href="#zone-types">8.2.34.1. Zone Types</a></li>
<li class="toctree-l4"><a class="reference internal" href="#class">8.2.34.2. Class</a></li>
<li class="toctree-l4"><a class="reference internal" href="#zone-options">8.2.34.3. Zone Options</a></li>
<li class="toctree-l4"><a class="reference internal" href="#dynamic-update-policies">8.2.34.4. Dynamic Update Policies</a></li>
<li class="toctree-l4"><a class="reference internal" href="#multiple-views">8.2.34.5. Multiple Views</a></li>
</ul>
</li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="#statements">8.3. Statements</a></li>
<li class="toctree-l2"><a class="reference internal" href="#statements-by-tag">8.4. Statements by Tag</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#dnssec-tag-statements">8.4.1. DNSSEC Tag Statements</a></li>
<li class="toctree-l3"><a class="reference internal" href="#logging-tag-statements">8.4.2. Logging Tag Statements</a></li>
<li class="toctree-l3"><a class="reference internal" href="#query-tag-statements">8.4.3. Query Tag Statements</a></li>
<li class="toctree-l3"><a class="reference internal" href="#security-tag-statements">8.4.4. Security Tag Statements</a></li>
<li class="toctree-l3"><a class="reference internal" href="#server-tag-statements">8.4.5. Server Tag Statements</a></li>
<li class="toctree-l3"><a class="reference internal" href="#transfer-tag-statements">8.4.6. Transfer Tag Statements</a></li>
<li class="toctree-l3"><a class="reference internal" href="#view-tag-statements">8.4.7. View Tag Statements</a></li>
<li class="toctree-l3"><a class="reference internal" href="#zone-tag-statements">8.4.8. Zone Tag Statements</a></li>
<li class="toctree-l3"><a class="reference internal" href="#deprecated-tag-statements">8.4.9. Deprecated Tag Statements</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="#bind-9-statistics">8.5. BIND 9 Statistics</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#the-statistics-file">8.5.1. The Statistics File</a></li>
<li class="toctree-l3"><a class="reference internal" href="#statistics-counters">8.5.2. Statistics Counters</a><ul>
<li class="toctree-l4"><a class="reference internal" href="#name-server-statistics-counters">8.5.2.1. Name Server Statistics Counters</a></li>
<li class="toctree-l4"><a class="reference internal" href="#zone-maintenance-statistics-counters">8.5.2.2. Zone Maintenance Statistics Counters</a></li>
<li class="toctree-l4"><a class="reference internal" href="#resolver-statistics-counters">8.5.2.3. Resolver Statistics Counters</a></li>
<li class="toctree-l4"><a class="reference internal" href="#socket-i-o-statistics-counters">8.5.2.4. Socket I/O Statistics Counters</a></li>
</ul>
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<li class="toctree-l1"><a class="reference internal" href="chapter9.html">9. Troubleshooting</a></li>
<li class="toctree-l1"><a class="reference internal" href="chapter10.html">10. Building BIND 9</a></li>
</ul>
<p class="caption" role="heading"><span class="caption-text">Appendices</span></p>
<ul>
<li class="toctree-l1"><a class="reference internal" href="notes.html">Release Notes</a></li>
<li class="toctree-l1"><a class="reference internal" href="changelog.html">Changelog</a></li>
<li class="toctree-l1"><a class="reference internal" href="dnssec-guide.html">DNSSEC Guide</a></li>
<li class="toctree-l1"><a class="reference internal" href="history.html">A Brief History of the DNS and BIND</a></li>
<li class="toctree-l1"><a class="reference internal" href="general.html">General DNS Reference Information</a></li>
<li class="toctree-l1"><a class="reference internal" href="manpages.html">Manual Pages</a></li>
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<section id="configuration-reference">
<span id="reference"></span><h1><span class="section-number">8. </span>Configuration Reference<a class="headerlink" href="#configuration-reference" title="Link to this heading"></a></h1>
<p>The operational functionality of BIND 9 is defined using the file
<strong>named.conf</strong>, which is typically located in /etc or /usr/local/etc/namedb,
depending on the operating system or distribution. A further file <strong>rndc.conf</strong>
will be present if <strong>rndc</strong> is being run from a remote host, but is not required
if rndc is being run from <strong>localhost</strong> (the same system as BIND 9 is running
on).</p>
<section id="configuration-file-named-conf">
<span id="named-conf"></span><h2><span class="section-number">8.1. </span>Configuration File (named.conf)<a class="headerlink" href="#configuration-file-named-conf" title="Link to this heading"></a></h2>
<p>The file <code class="file docutils literal notranslate"><span class="pre">named.conf</span></code> may contain three types of entities:</p>
<dl class="glossary">
<dt id="term-Comment">Comment<a class="headerlink" href="#term-Comment" title="Link to this term"></a></dt><dd><p><a class="reference internal" href="#comment-syntax"><span class="std std-ref">Multiple comment formats are supported</span></a>.</p>
</dd>
<dt id="term-Block">Block<a class="headerlink" href="#term-Block" title="Link to this term"></a></dt><dd><p><a class="reference internal" href="#configuration-blocks"><span class="std std-ref">Blocks</span></a> are containers for <a class="reference internal" href="#term-Statement"><span class="xref std std-term">statements</span></a> which either have common functionality - for example,
the definition of a cryptographic key in a <a class="reference internal" href="#namedconf-statement-key" title="namedconf-statement-key"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">key</span></code></a> block - or which
define the scope of the statement - for example, a statement which appears
in a <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> block has scope only for that zone.</p>
<p>Blocks are organized hierarchically within <code class="file docutils literal notranslate"><span class="pre">named.conf</span></code> and may have a
number of different properties:</p>
<ul class="simple">
<li><p>Certain blocks cannot be nested inside other blocks and thus may be
regarded as the <em>topmost-level</em> blocks: for example, the
<a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> block and the <a class="reference internal" href="#namedconf-statement-logging" title="namedconf-statement-logging"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">logging</span></code></a> block.</p></li>
<li><p>Certain blocks can appear multiple times, in which case they have
an associated name to disambiguate them: for example, the
<a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> block (<code class="docutils literal notranslate"><span class="pre">zone</span> <span class="pre">example.com</span> <span class="pre">{</span> <span class="pre">...</span> <span class="pre">};</span></code>) or the
<a class="reference internal" href="#namedconf-statement-key" title="namedconf-statement-key"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">key</span></code></a> block (<code class="docutils literal notranslate"><span class="pre">key</span> <span class="pre">mykey</span> <span class="pre">{</span> <span class="pre">...</span> <span class="pre">};</span></code>).</p></li>
<li><p>Certain blocks may be “nested” within other blocks. For example, the
<a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> block may appear within a
<a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> block.</p></li>
</ul>
<p>The description of each block in this manual lists its permissible locations.</p>
</dd>
<dt id="term-Statement">Statement<a class="headerlink" href="#term-Statement" title="Link to this term"></a></dt><dd><ul class="simple">
<li><p>Statements define and control specific BIND behaviors.</p></li>
<li><p>Statements may have a single parameter (a <strong>Value</strong>) or multiple parameters
(<strong>Argument/Value</strong> pairs). For example, the <a class="reference internal" href="#namedconf-statement-recursion" title="namedconf-statement-recursion"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursion</span></code></a> statement takes a
single value parameter - in this case, the string <code class="docutils literal notranslate"><span class="pre">yes</span></code> or <code class="docutils literal notranslate"><span class="pre">no</span></code>
(<code class="docutils literal notranslate"><span class="pre">recursion</span> <span class="pre">yes;</span></code>) - while the <a class="reference internal" href="#namedconf-statement-port" title="namedconf-statement-port"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">port</span></code></a> statement takes a numeric value
defining the DNS port number (<code class="docutils literal notranslate"><span class="pre">port</span> <span class="pre">53;</span></code>). More complex statements take one or
more argument/value pairs. The <a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a> statement may take a number
of such argument/value pairs, such as <code class="docutils literal notranslate"><span class="pre">also-notify</span> <span class="pre">port</span> <span class="pre">5353;</span></code>,
where <code class="docutils literal notranslate"><span class="pre">port</span></code> is the argument and <code class="docutils literal notranslate"><span class="pre">5353</span></code> is the corresponding value.</p></li>
<li><p>Statements can appear in a single <a class="reference internal" href="#term-Block"><span class="xref std std-term">block</span></a> - for
example, an <a class="reference internal" href="#namedconf-statement-algorithm" title="namedconf-statement-algorithm"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">algorithm</span></code></a> statement can appear only in a
<a class="reference internal" href="#namedconf-statement-key" title="namedconf-statement-key"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">key</span></code></a> block - or in multiple blocks - for example, an
<a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a> statement can appear in an <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>
block where it has global (server-wide) scope, in a <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a>
block where it has scope only for the specific zone (and overrides
any global statement), or even in a <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> block where it has
scope for only that view (and overrides any global statement).</p></li>
</ul>
</dd>
</dl>
<p>The file <code class="file docutils literal notranslate"><span class="pre">named.conf</span></code> may further contain one or more instances of the
<a class="reference internal" href="#include-grammar"><span class="std std-ref">include</span></a> <strong>Directive</strong>. This directive is provided for
administrative convenience in assembling a complete <code class="file docutils literal notranslate"><span class="pre">named.conf</span></code> file and plays
no subsequent role in BIND 9 operational characteristics or functionality.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Over a period of many years the BIND ARM acquired a bewildering array of
terminology. Many of the terms used described similar concepts and served
only to add a layer of complexity, possibly confusion, and perhaps mystique
to BIND 9 configuration. The ARM now uses only the terms <strong>Block</strong>,
<strong>Statement</strong>, <strong>Argument</strong>, <strong>Value</strong>, and <strong>Directive</strong> to describe all
entities used in BIND 9 configuration.</p>
</div>
<section id="comment-syntax">
<span id="id1"></span><h3><span class="section-number">8.1.1. </span>Comment Syntax<a class="headerlink" href="#comment-syntax" title="Link to this heading"></a></h3>
<p>The BIND 9 comment syntax allows comments to appear anywhere that
whitespace may appear in a BIND configuration file. To appeal to
programmers of all kinds, they can be written in the C, C++, or
shell/Perl style.</p>
<section id="syntax">
<h4><span class="section-number">8.1.1.1. </span>Syntax<a class="headerlink" href="#syntax" title="Link to this heading"></a></h4>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>/* This is a BIND comment as in C */
</pre></div>
</div>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>// This is a BIND comment as in C++
</pre></div>
</div>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span># This is a BIND comment as in common Unix shells
# and Perl
</pre></div>
</div>
</section>
<section id="definition-and-usage">
<h4><span class="section-number">8.1.1.2. </span>Definition and Usage<a class="headerlink" href="#definition-and-usage" title="Link to this heading"></a></h4>
<p>Comments can be inserted anywhere that whitespace may appear in a BIND
configuration file.</p>
<p>C-style comments start with the two characters /* (slash, star) and end
with */ (star, slash). Because they are completely delimited with these
characters, they can be used to comment only a portion of a line or to
span multiple lines.</p>
<p>C-style comments cannot be nested. For example, the following is not
valid because the entire comment ends with the first */:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>/* This is the start of a comment.
This is still part of the comment.
/* This is an incorrect attempt at nesting a comment. */
This is no longer in any comment. */
</pre></div>
</div>
<p>C++-style comments start with the two characters // (slash, slash) and
continue to the end of the physical line. They cannot be continued
across multiple physical lines; to have one logical comment span
multiple lines, each line must use the // pair. For example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>// This is the start of a comment. The next line
// is a new comment, even though it is logically
// part of the previous comment.
</pre></div>
</div>
<p>Shell-style (or Perl-style) comments start with the
character <code class="docutils literal notranslate"><span class="pre">#</span></code> (number/pound sign) and continue to the end of the physical
line, as in C++ comments. For example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span># This is the start of a comment. The next line
# is a new comment, even though it is logically
# part of the previous comment.
</pre></div>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The semicolon (<code class="docutils literal notranslate"><span class="pre">;</span></code>) character cannot start a comment, unlike
in a zone file. The semicolon indicates the end of a
configuration statement.</p>
</div>
</section>
</section>
<section id="configuration-layout-styles">
<h3><span class="section-number">8.1.2. </span>Configuration Layout Styles<a class="headerlink" href="#configuration-layout-styles" title="Link to this heading"></a></h3>
<p>BIND is very picky about opening and closing brackets/braces, semicolons, and
all the other separators defined in the formal syntaxes in later sections.
There are many layout styles that can assist in minimizing errors, as shown in
the following examples:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>// dense single-line style
zone "example.com" in{type secondary; file "secondary.example.com"; primaries {10.0.0.1;};};
// single-statement-per-line style
zone "example.com" in{
type secondary;
file "secondary.example.com";
primaries {10.0.0.1;};
};
// spot the difference
zone "example.com" in{
type secondary;
file "sec.secondary.com";
primaries {10.0.0.1;}; };
</pre></div>
</div>
</section>
<section id="include-directive">
<span id="include-grammar"></span><h3><span class="section-number">8.1.3. </span><code class="docutils literal notranslate"><span class="pre">include</span></code> Directive<a class="headerlink" href="#include-directive" title="Link to this heading"></a></h3>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>include filename;
</pre></div>
</div>
<section id="include-directive-definition-and-usage">
<span id="include-statement"></span><h4><span class="section-number">8.1.3.1. </span><code class="docutils literal notranslate"><span class="pre">include</span></code> Directive Definition and Usage<a class="headerlink" href="#include-directive-definition-and-usage" title="Link to this heading"></a></h4>
<p>The include directive inserts the specified file (or files if a valid <a class="reference external" href="https://man7.org/linux/man-pages/man7/glob.7.html">glob
expression</a> is detected) at the point where the include directive is
encountered. The include directive facilitates the administration of
configuration files by permitting the reading or writing of some things but not
others. For example, the statement could include private keys that are readable
only by the name server.</p>
</section>
</section>
<section id="address-match-lists">
<span id="id2"></span><h3><span class="section-number">8.1.4. </span>Address Match Lists<a class="headerlink" href="#address-match-lists" title="Link to this heading"></a></h3>
<section id="id3">
<h4><span class="section-number">8.1.4.1. </span>Syntax<a class="headerlink" href="#id3" title="Link to this heading"></a></h4>
<p>An address match list is a list of semicolon-separated <a class="reference internal" href="#term-address_match_element"><span class="xref std std-term">address_match_element</span></a> s.</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
</pre></div>
</div>
<p>Each element is then defined as:</p>
<dl class="glossary">
<dt id="term-address_match_element"><code class="docutils literal notranslate"><span class="pre">address_match_element</span></code><a class="headerlink" href="#term-address_match_element" title="Link to this term"></a></dt><dd><div class="highlight-default notranslate"><div class="highlight"><pre><span></span>[ ! ] ( <ip_address> | <netprefix> | key <server_key> | <acl_name> | { address_match_list } )
</pre></div>
</div>
</dd>
</dl>
</section>
<section id="id4">
<h4><span class="section-number">8.1.4.2. </span>Definition and Usage<a class="headerlink" href="#id4" title="Link to this heading"></a></h4>
<p>Address match lists are primarily used to determine access control for
various server operations. They are also used in the <a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> and
<a class="reference internal" href="#namedconf-statement-sortlist" title="namedconf-statement-sortlist"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sortlist</span></code></a> statements. The elements which constitute an address match
list can be any of the following:</p>
<ul class="simple">
<li><p><a class="reference internal" href="#term-ip_address"><span class="xref std std-term">ip_address</span></a>: an IP address (IPv4 or IPv6)</p></li>
<li><p><a class="reference internal" href="#term-netprefix"><span class="xref std std-term">netprefix</span></a>: an IP prefix (in <code class="docutils literal notranslate"><span class="pre">/</span></code> notation)</p></li>
<li><p><a class="reference internal" href="#term-server_key"><span class="xref std std-term">server_key</span></a>: a key ID, as defined by the <code class="docutils literal notranslate"><span class="pre">key</span></code> statement</p></li>
<li><p><a class="reference internal" href="#term-acl_name"><span class="xref std std-term">acl_name</span></a>: the name of an address match list defined with the <a class="reference internal" href="#namedconf-statement-acl" title="namedconf-statement-acl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">acl</span></code></a> statement</p></li>
<li><p>a nested address match list enclosed in braces</p></li>
</ul>
<p>Elements can be negated with a leading exclamation mark (<code class="docutils literal notranslate"><span class="pre">!</span></code>), and the
match list names “any”, “none”, “localhost”, and “localnets” are
predefined. More information on those names can be found in the
description of the <a class="reference internal" href="#namedconf-statement-acl" title="namedconf-statement-acl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">acl</span></code></a> statement.</p>
<p>The addition of the key clause made the name of this syntactic element
something of a misnomer, since security keys can be used to validate
access without regard to a host or network address. Nonetheless, the
term “address match list” is still used throughout the documentation.</p>
<p>When a given IP address or prefix is compared to an address match list,
the comparison takes place in approximately O(1) time. However, key
comparisons require that the list of keys be traversed until a matching
key is found, and therefore may be somewhat slower.</p>
<p>The interpretation of a match depends on whether the list is being used
for access control, defining <a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> ports, or in a <a class="reference internal" href="#namedconf-statement-sortlist" title="namedconf-statement-sortlist"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sortlist</span></code></a>,
and whether the element was negated.</p>
<p>When used as an access control list, a non-negated match allows access
and a negated match denies access. If there is no match, access is
denied. The clauses <a class="reference internal" href="#namedconf-statement-allow-notify" title="namedconf-statement-allow-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-notify</span></code></a>, <a class="reference internal" href="#namedconf-statement-allow-recursion" title="namedconf-statement-allow-recursion"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-recursion</span></code></a>,
<a class="reference internal" href="#namedconf-statement-allow-recursion-on" title="namedconf-statement-allow-recursion-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-recursion-on</span></code></a>, <a class="reference internal" href="#namedconf-statement-allow-query" title="namedconf-statement-allow-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query</span></code></a>, <a class="reference internal" href="#namedconf-statement-allow-query-on" title="namedconf-statement-allow-query-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-on</span></code></a>,
<a class="reference internal" href="#namedconf-statement-allow-query-cache" title="namedconf-statement-allow-query-cache"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-cache</span></code></a>, <a class="reference internal" href="#namedconf-statement-allow-query-cache-on" title="namedconf-statement-allow-query-cache-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-cache-on</span></code></a>, <a class="reference internal" href="#namedconf-statement-allow-transfer" title="namedconf-statement-allow-transfer"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-transfer</span></code></a>,
<a class="reference internal" href="#namedconf-statement-allow-update" title="namedconf-statement-allow-update"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-update</span></code></a>, <a class="reference internal" href="#namedconf-statement-allow-update-forwarding" title="namedconf-statement-allow-update-forwarding"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-update-forwarding</span></code></a>, <a class="reference internal" href="#namedconf-statement-blackhole" title="namedconf-statement-blackhole"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">blackhole</span></code></a>, and
<a class="reference internal" href="#namedconf-statement-keep-response-order" title="namedconf-statement-keep-response-order"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">keep-response-order</span></code></a> all use address match lists. Similarly, the
<a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> option causes the server to refuse queries on any of
the machine’s addresses which do not match the list.</p>
<p>Order of insertion is significant. If more than one element in an ACL is
found to match a given IP address or prefix, preference is given to
the one that came <em>first</em> in the ACL definition. Because of this
first-match behavior, an element that defines a subset of another
element in the list should come before the broader element, regardless
of whether either is negated. For example, in <code class="docutils literal notranslate"><span class="pre">1.2.3/24;</span> <span class="pre">!</span> <span class="pre">1.2.3.13;</span></code>
the 1.2.3.13 element is completely useless because the algorithm
matches any lookup for 1.2.3.13 to the 1.2.3/24 element. Using
<code class="docutils literal notranslate"><span class="pre">!</span> <span class="pre">1.2.3.13;</span> <span class="pre">1.2.3/24</span></code> fixes that problem by blocking 1.2.3.13
via the negation, but all other 1.2.3.* hosts pass through.</p>
</section>
</section>
<section id="glossary-of-terms-used">
<h3><span class="section-number">8.1.5. </span>Glossary of Terms Used<a class="headerlink" href="#glossary-of-terms-used" title="Link to this heading"></a></h3>
<p>Following is a list of terms used throughout the BIND configuration
file documentation:</p>
<dl class="glossary">
<dt id="term-acl_name"><code class="docutils literal notranslate"><span class="pre">acl_name</span></code><a class="headerlink" href="#term-acl_name" title="Link to this term"></a></dt><dd><p>The name of an <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> as defined by the <a class="reference internal" href="#namedconf-statement-acl" title="namedconf-statement-acl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">acl</span></code></a> statement.</p>
</dd>
<dt id="term-address_match_list"><code class="docutils literal notranslate"><span class="pre">address_match_list</span></code><a class="headerlink" href="#term-address_match_list" title="Link to this term"></a></dt><dd><p>See <a class="reference internal" href="#address-match-lists"><span class="std std-ref">Address Match Lists</span></a>.</p>
</dd>
<dt id="term-boolean"><code class="docutils literal notranslate"><span class="pre">boolean</span></code><a class="headerlink" href="#term-boolean" title="Link to this term"></a></dt><dd><p>Either <code class="docutils literal notranslate"><span class="pre">yes</span></code> or <code class="docutils literal notranslate"><span class="pre">no</span></code>. The words <code class="docutils literal notranslate"><span class="pre">true</span></code> and <code class="docutils literal notranslate"><span class="pre">false</span></code> are also accepted, as are the numbers <code class="docutils literal notranslate"><span class="pre">1</span></code> and <code class="docutils literal notranslate"><span class="pre">0</span></code>.</p>
</dd>
<dt id="term-domain_name"><code class="docutils literal notranslate"><span class="pre">domain_name</span></code><a class="headerlink" href="#term-domain_name" title="Link to this term"></a></dt><dd><p>A quoted string which is used as a DNS name; for example: <code class="docutils literal notranslate"><span class="pre">my.test.domain</span></code>.</p>
</dd>
<dt id="term-duration"><code class="docutils literal notranslate"><span class="pre">duration</span></code><a class="headerlink" href="#term-duration" title="Link to this term"></a></dt><dd><p>A duration in BIND 9 can be written in three ways: as a single number
representing seconds, as a string of numbers with TTL-style
time-unit suffixes, or in ISO 6801 duration format.</p>
<p>Allowed TTL time-unit suffixes are: “W” (week), “D” (day), “H” (hour),
“M” (minute), and “S” (second). Examples: “1W” (1 week), “3d12h”
(3 days, 12 hours).</p>
<p>ISO 8601 duration format consists of the letter “P”, followed by an
optional series of numbers with unit suffixes “Y” (year), “M” (month),
“W” (week), and “D” (day); this may optionally be followed by the
letter “T”, and another series of numbers with unit suffixes
“H” (hour), “M” (minute), and “S” (second). Examples: “P3M10D”
(3 months, 10 days), “P2WT12H” (2 weeks, 12 hours), “pt15m”
(15 minutes). For more information on ISO 8601 duration format,
see <span class="target" id="index-0"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc3339.html"><strong>RFC 3339</strong></a>, appendix A.</p>
<p>Both TTL-style and ISO 8601 duration formats are case-insensitive.</p>
</dd>
<dt id="term-fixedpoint"><code class="docutils literal notranslate"><span class="pre">fixedpoint</span></code><a class="headerlink" href="#term-fixedpoint" title="Link to this term"></a></dt><dd><p>A non-negative real number that can be specified to the nearest one-hundredth. Up to five digits can be specified before a decimal point, and up to two digits after, so the maximum value is 99999.99. Acceptable values might be further limited by the contexts in which they are used.</p>
</dd>
<dt id="term-integer"><code class="docutils literal notranslate"><span class="pre">integer</span></code><a class="headerlink" href="#term-integer" title="Link to this term"></a></dt><dd><p>A non-negative 32-bit integer (i.e., a number between 0 and 4294967295, inclusive). Its acceptable value might be further limited by the context in which it is used.</p>
</dd>
<dt id="term-ip_address"><code class="docutils literal notranslate"><span class="pre">ip_address</span></code><a class="headerlink" href="#term-ip_address" title="Link to this term"></a></dt><dd><p>An <a class="reference internal" href="#term-ipv4_address"><span class="xref std std-term">ipv4_address</span></a> or <a class="reference internal" href="#term-ipv6_address"><span class="xref std std-term">ipv6_address</span></a>.</p>
</dd>
<dt id="term-ipv4_address"><code class="docutils literal notranslate"><span class="pre">ipv4_address</span></code><a class="headerlink" href="#term-ipv4_address" title="Link to this term"></a></dt><dd><p>An IPv4 address with exactly four integer elements valued 0 through 255
and separated by dots (<code class="docutils literal notranslate"><span class="pre">.</span></code>), such as <code class="docutils literal notranslate"><span class="pre">192.168.1.1</span></code> (a
“dotted-decimal” notation with all four elements present).</p>
</dd>
<dt id="term-ipv6_address"><code class="docutils literal notranslate"><span class="pre">ipv6_address</span></code><a class="headerlink" href="#term-ipv6_address" title="Link to this term"></a></dt><dd><p>An IPv6 address, such as <code class="docutils literal notranslate"><span class="pre">2001:db8::1234</span></code>. IPv6-scoped addresses that have ambiguity on their scope zones must be disambiguated by an appropriate zone ID with the percent character (<code class="docutils literal notranslate"><span class="pre">%</span></code>) as a delimiter. It is strongly recommended to use string zone names rather than numeric identifiers, to be robust against system configuration changes. However, since there is no standard mapping for such names and identifier values, only interface names as link identifiers are supported, assuming one-to-one mapping between interfaces and links. For example, a link-local address <code class="docutils literal notranslate"><span class="pre">fe80::1</span></code> on the link attached to the interface <code class="docutils literal notranslate"><span class="pre">ne0</span></code> can be specified as <code class="docutils literal notranslate"><span class="pre">fe80::1%ne0</span></code>. Note that on most systems link-local addresses always have ambiguity and need to be disambiguated.</p>
</dd>
<dt id="term-netprefix"><code class="docutils literal notranslate"><span class="pre">netprefix</span></code><a class="headerlink" href="#term-netprefix" title="Link to this term"></a></dt><dd><p>An IP network specified as an <a class="reference internal" href="#term-ip_address"><span class="xref std std-term">ip_address</span></a>, followed by a slash (<code class="docutils literal notranslate"><span class="pre">/</span></code>) and then the number of bits in the netmask. Trailing zeros in an <a class="reference internal" href="#term-ip_address"><span class="xref std std-term">ip_address</span></a> may be omitted. For example, <code class="docutils literal notranslate"><span class="pre">127/8</span></code> is the network <code class="docutils literal notranslate"><span class="pre">127.0.0.0</span></code> with netmask <code class="docutils literal notranslate"><span class="pre">255.0.0.0</span></code> and <code class="docutils literal notranslate"><span class="pre">1.2.3.0/28</span></code> is network <code class="docutils literal notranslate"><span class="pre">1.2.3.0</span></code> with netmask <code class="docutils literal notranslate"><span class="pre">255.255.255.240</span></code>.
When specifying a prefix involving an IPv6-scoped address, the scope may be omitted. In that case, the prefix matches packets from any scope.</p>
</dd>
<dt id="term-percentage"><code class="docutils literal notranslate"><span class="pre">percentage</span></code><a class="headerlink" href="#term-percentage" title="Link to this term"></a></dt><dd><p>An integer value followed by <code class="docutils literal notranslate"><span class="pre">%</span></code> to represent percent.</p>
</dd>
<dt id="term-port"><code class="docutils literal notranslate"><span class="pre">port</span></code><a class="headerlink" href="#term-port" title="Link to this term"></a></dt><dd><p>An IP port <a class="reference internal" href="#term-integer"><span class="xref std std-term">integer</span></a>. It is limited to 0 through 65535, with values below 1024 typically restricted to use by processes running as root. In some cases, an asterisk (<code class="docutils literal notranslate"><span class="pre">*</span></code>) character can be used as a placeholder to select a random high-numbered port.</p>
</dd>
<dt id="term-portrange"><code class="docutils literal notranslate"><span class="pre">portrange</span></code><a class="headerlink" href="#term-portrange" title="Link to this term"></a></dt><dd><p>A list of a <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a> or a port range. A port range is specified in the form of <code class="docutils literal notranslate"><span class="pre">range</span></code> followed by two <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a> s, <code class="docutils literal notranslate"><span class="pre">port_low</span></code> and <code class="docutils literal notranslate"><span class="pre">port_high</span></code>, which represents port numbers from <code class="docutils literal notranslate"><span class="pre">port_low</span></code> through <code class="docutils literal notranslate"><span class="pre">port_high</span></code>, inclusive. <code class="docutils literal notranslate"><span class="pre">port_low</span></code> must not be larger than <code class="docutils literal notranslate"><span class="pre">port_high</span></code>. For example, <code class="docutils literal notranslate"><span class="pre">range</span> <span class="pre">1024</span> <span class="pre">65535</span></code> represents ports from 1024 through 65535. The asterisk (<code class="docutils literal notranslate"><span class="pre">*</span></code>) character is not allowed as a valid <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a> or as a port range boundary.</p>
</dd>
<dt id="term-remote-servers"><code class="docutils literal notranslate"><span class="pre">remote-servers</span></code><a class="headerlink" href="#term-remote-servers" title="Link to this term"></a></dt><dd><p>A named list of one or more <a class="reference internal" href="#term-ip_address"><span class="xref std std-term">ip_address</span></a> es with optional <a class="reference internal" href="#term-tls_id"><span class="xref std std-term">tls_id</span></a>, <a class="reference internal" href="#term-server_key"><span class="xref std std-term">server_key</span></a>, and/or <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a>. A <code class="docutils literal notranslate"><span class="pre">remote-servers</span></code> list may include other <code class="docutils literal notranslate"><span class="pre">remote-servers</span></code> lists. See <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> block.</p>
</dd>
<dt id="term-server_key"><code class="docutils literal notranslate"><span class="pre">server_key</span></code><a class="headerlink" href="#term-server_key" title="Link to this term"></a></dt><dd><p>A <a class="reference internal" href="#term-domain_name"><span class="xref std std-term">domain_name</span></a> representing the name of a shared key, to be used for
<a class="reference internal" href="chapter7.html#tsig"><span class="std std-ref">transaction security</span></a>. Keys are defined using
<a class="reference internal" href="#namedconf-statement-key" title="namedconf-statement-key"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">key</span></code></a> blocks.</p>
</dd>
<dt id="term-size"><code class="docutils literal notranslate"><span class="pre">size</span></code><a class="headerlink" href="#term-size" title="Link to this term"></a></dt><dt id="term-sizeval"><code class="docutils literal notranslate"><span class="pre">sizeval</span></code><a class="headerlink" href="#term-sizeval" title="Link to this term"></a></dt><dd><p>A 64-bit unsigned integer. Integers may take values 0 <= value <= 18446744073709551615, though certain parameters (such as <a class="reference internal" href="#namedconf-statement-max-journal-size" title="namedconf-statement-max-journal-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-journal-size</span></code></a>) may use a more limited range within these extremes. In most cases, setting a value to 0 does not literally mean zero; it means “undefined” or “as big as possible,” depending on the context. See the explanations of particular parameters that use <code class="docutils literal notranslate"><span class="pre">size</span></code> for details on how they interpret its use. Numeric values can optionally be followed by a scaling factor: <code class="docutils literal notranslate"><span class="pre">K</span></code> or <code class="docutils literal notranslate"><span class="pre">k</span></code> for kilobytes, <code class="docutils literal notranslate"><span class="pre">M</span></code> or <code class="docutils literal notranslate"><span class="pre">m</span></code> for megabytes, and <code class="docutils literal notranslate"><span class="pre">G</span></code> or <code class="docutils literal notranslate"><span class="pre">g</span></code> for gigabytes, which scale by 1024, 1024*1024, and 1024*1024*1024 respectively.</p>
<p>Some statements also accept the keywords <code class="docutils literal notranslate"><span class="pre">unlimited</span></code> or <code class="docutils literal notranslate"><span class="pre">default</span></code>:
<code class="docutils literal notranslate"><span class="pre">unlimited</span></code> generally means “as big as possible,” and is usually the best way to safely set a very large number.
<code class="docutils literal notranslate"><span class="pre">default</span></code> uses the limit that was in force when the server was started.</p>
</dd>
<dt id="term-tls_id"><code class="docutils literal notranslate"><span class="pre">tls_id</span></code><a class="headerlink" href="#term-tls_id" title="Link to this term"></a></dt><dd><p>A named TLS configuration object which defines a TLS key and certificate. See <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> block.</p>
</dd>
</dl>
</section>
</section>
<section id="blocks">
<span id="configuration-blocks"></span><span id="configuration-file-grammar"></span><h2><span class="section-number">8.2. </span>Blocks<a class="headerlink" href="#blocks" title="Link to this heading"></a></h2>
<p>A BIND 9 configuration consists of blocks, statements, and comments.</p>
<p>The following blocks are supported:</p>
<blockquote>
<div><dl class="simple">
<dt><a class="reference internal" href="#namedconf-statement-acl" title="namedconf-statement-acl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">acl</span></code></a></dt><dd><p>Defines a named IP address matching list, for access control and other uses.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-controls" title="namedconf-statement-controls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">controls</span></code></a></dt><dd><p>Declares control channels to be used by the <a class="reference internal" href="manpages.html#std-iscman-rndc"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">rndc</span></code></a> utility.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a></dt><dd><p>Describes a DNSSEC key and signing policy for zones. See <a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> for details.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-key" title="namedconf-statement-key"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">key</span></code></a></dt><dd><p>Specifies key information for use in authentication and authorization using TSIG.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-logging" title="namedconf-statement-logging"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">logging</span></code></a></dt><dd><p>Specifies what information the server logs and where the log messages are sent.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">masters</span></code></dt><dd><p>Synonym for <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a></dt><dd><p>Controls global server configuration options and sets defaults for other statements.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-parental-agents" title="namedconf-statement-parental-agents"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parental-agents</span></code></a></dt><dd><p>Defines a named list of servers for inclusion in primary and secondary zones’ <a class="reference internal" href="#namedconf-statement-parental-agents" title="namedconf-statement-parental-agents"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parental-agents</span></code></a> lists.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a></dt><dd><p>Defines a named list of servers for inclusion in stub and secondary zones’ <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> or <a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a> lists. (Note: this is a synonym for the original keyword <code class="docutils literal notranslate"><span class="pre">masters</span></code>, which can still be used, but is no longer the preferred terminology.)</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">server</span></code></a></dt><dd><p>Sets certain configuration options on a per-server basis.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-statistics-channels" title="namedconf-statement-statistics-channels"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">statistics-channels</span></code></a></dt><dd><p>Declares communication channels to get access to <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> statistics.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a></dt><dd><p>Specifies configuration information for a TLS connection, including a <a class="reference internal" href="#namedconf-statement-key-file" title="namedconf-statement-key-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">key-file</span></code></a>, <a class="reference internal" href="#namedconf-statement-cert-file" title="namedconf-statement-cert-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">cert-file</span></code></a>, <a class="reference internal" href="#namedconf-statement-ca-file" title="namedconf-statement-ca-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ca-file</span></code></a>, <a class="reference internal" href="#namedconf-statement-dhparam-file" title="namedconf-statement-dhparam-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dhparam-file</span></code></a>, <a class="reference internal" href="#namedconf-statement-remote-hostname" title="namedconf-statement-remote-hostname"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">remote-hostname</span></code></a>, <a class="reference internal" href="#namedconf-statement-ciphers" title="namedconf-statement-ciphers"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ciphers</span></code></a>, <a class="reference internal" href="#namedconf-statement-protocols" title="namedconf-statement-protocols"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">protocols</span></code></a>, <a class="reference internal" href="#namedconf-statement-prefer-server-ciphers" title="namedconf-statement-prefer-server-ciphers"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">prefer-server-ciphers</span></code></a>, and <a class="reference internal" href="#namedconf-statement-session-tickets" title="namedconf-statement-session-tickets"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">session-tickets</span></code></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http</span></code></a></dt><dd><p>Specifies configuration information for an HTTP connection, including <a class="reference internal" href="#namedconf-statement-endpoints" title="namedconf-statement-endpoints"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">endpoints</span></code></a>, <a class="reference internal" href="#namedconf-statement-listener-clients" title="namedconf-statement-listener-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listener-clients</span></code></a>, and <a class="reference internal" href="#namedconf-statement-streams-per-connection" title="namedconf-statement-streams-per-connection"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">streams-per-connection</span></code></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a></dt><dd><p>Defines DNSSEC trust anchors: if used with the <code class="docutils literal notranslate"><span class="pre">initial-key</span></code> or <code class="docutils literal notranslate"><span class="pre">initial-ds</span></code> keyword, trust anchors are kept up-to-date using <span class="target" id="index-1"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc5011.html"><strong>RFC 5011</strong></a> trust anchor maintenance; if used with <code class="docutils literal notranslate"><span class="pre">static-key</span></code> or <code class="docutils literal notranslate"><span class="pre">static-ds</span></code>, keys are permanent.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-managed-keys" title="namedconf-statement-managed-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">managed-keys</span></code></a></dt><dd><p>Is identical to <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>; this option is deprecated in favor of <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> with the <code class="docutils literal notranslate"><span class="pre">initial-key</span></code> keyword, and may be removed in a future release.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-trusted-keys" title="namedconf-statement-trusted-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trusted-keys</span></code></a></dt><dd><p>Defines permanent trusted DNSSEC keys; this option is deprecated in favor of <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> with the <code class="docutils literal notranslate"><span class="pre">static-key</span></code> keyword, and may be removed in a future release.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a></dt><dd><p>Defines a view.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a></dt><dd><p>Defines a zone.</p>
</dd>
</dl>
</div></blockquote>
<p>The <a class="reference internal" href="#namedconf-statement-logging" title="namedconf-statement-logging"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">logging</span></code></a> and <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> statements may only occur once per
configuration.</p>
<section id="acl-block-grammar">
<h3><span class="section-number">8.2.1. </span><a class="reference internal" href="#namedconf-statement-acl" title="namedconf-statement-acl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">acl</span></code></a> Block Grammar<a class="headerlink" href="#acl-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-acl">
<span class="sig-name descname"><span class="pre">acl</span></span><a class="headerlink" href="#namedconf-statement-acl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">acl</span> <span class="pre"><string></span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>topmost</p>
<p><strong>Tags: </strong>server</p>
<p><p>Assigns a symbolic name to an address match list.</p>
</p>
</dd></dl>
</section>
<section id="acl-block-definition-and-usage">
<h3><span class="section-number">8.2.2. </span><a class="reference internal" href="#namedconf-statement-acl" title="namedconf-statement-acl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">acl</span></code></a> Block Definition and Usage<a class="headerlink" href="#acl-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-acl" title="namedconf-statement-acl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">acl</span></code></a> statement assigns a symbolic name to an address match list.
It gets its name from one of the primary uses of address match lists: Access
Control Lists (ACLs).</p>
<p>The following ACLs are built-in:</p>
<blockquote>
<div><dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">any</span></code></dt><dd><p>Matches all hosts.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">none</span></code></dt><dd><p>Matches no hosts.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">localhost</span></code></dt><dd><p>Matches the IPv4 and IPv6 addresses of all network interfaces on the system. When addresses are added or removed, the <code class="docutils literal notranslate"><span class="pre">localhost</span></code> ACL element is updated to reflect the changes.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">localnets</span></code></dt><dd><p>Matches any host on an IPv4 or IPv6 network for which the system has an interface. When addresses are added or removed, the <code class="docutils literal notranslate"><span class="pre">localnets</span></code> ACL element is updated to reflect the changes. Some systems do not provide a way to determine the prefix lengths of local IPv6 addresses; in such cases, <code class="docutils literal notranslate"><span class="pre">localnets</span></code> only matches the local IPv6 addresses, just like <code class="docutils literal notranslate"><span class="pre">localhost</span></code>.</p>
</dd>
</dl>
</div></blockquote>
</section>
<section id="controls-block-grammar">
<h3><span class="section-number">8.2.3. </span><a class="reference internal" href="#namedconf-statement-controls" title="namedconf-statement-controls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">controls</span></code></a> Block Grammar<a class="headerlink" href="#controls-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-controls">
<span class="sig-name descname"><span class="pre">controls</span></span><a class="headerlink" href="#namedconf-statement-controls" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">controls</span> <span class="p">{</span>
<span class="n">inet</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">)</span> <span class="p">[</span> <span class="n">port</span> <span class="p">(</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">)</span> <span class="p">]</span> <span class="n">allow</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">}</span> <span class="p">[</span> <span class="n">keys</span> <span class="p">{</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">}</span> <span class="p">]</span> <span class="p">[</span> <span class="n">read</span><span class="o">-</span><span class="n">only</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">];</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
<span class="n">unix</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span> <span class="n">perm</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="n">owner</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="n">group</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">[</span> <span class="n">keys</span> <span class="p">{</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">}</span> <span class="p">]</span> <span class="p">[</span> <span class="n">read</span><span class="o">-</span><span class="n">only</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">];</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
<span class="p">};</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>topmost</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies control channels to be used to manage the name server.</p>
</p>
</dd></dl>
</section>
<section id="controls-block-definition-and-usage">
<h3><span class="section-number">8.2.4. </span><a class="reference internal" href="#namedconf-statement-controls" title="namedconf-statement-controls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">controls</span></code></a> Block Definition and Usage<a class="headerlink" href="#controls-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-controls" title="namedconf-statement-controls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">controls</span></code></a> statement declares control channels to be used by
system administrators to manage the operation of the name server. These
control channels are used by the <a class="reference internal" href="manpages.html#std-iscman-rndc"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">rndc</span></code></a> utility to send commands to
and retrieve non-DNS results from a name server.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-unix">
<span class="sig-name descname"><span class="pre">unix</span></span><a class="headerlink" href="#namedconf-statement-unix" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">unix</span> <span class="pre"><quoted_string></span> <span class="pre">perm</span> <span class="pre"><integer></span> <span class="pre">owner</span> <span class="pre"><integer></span> <span class="pre">group</span> <span class="pre"><integer></span> <span class="pre">[</span> <span class="pre">keys</span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">read-only</span> <span class="pre"><boolean></span> <span class="pre">];</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>controls</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies a Unix domain socket as a control channel.</p>
</p>
<p>A <a class="reference internal" href="#namedconf-statement-unix" title="namedconf-statement-unix"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">unix</span></code></a> control channel is a Unix domain socket listening at the
specified path in the file system. Access to the socket is specified by
the <code class="docutils literal notranslate"><span class="pre">perm</span></code>, <code class="docutils literal notranslate"><span class="pre">owner</span></code>, and <code class="docutils literal notranslate"><span class="pre">group</span></code> clauses. Note that on some platforms
(SunOS and Solaris), the permissions (<code class="docutils literal notranslate"><span class="pre">perm</span></code>) are applied to the parent
directory as the permissions on the socket itself are ignored.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-inet">
<span class="sig-name descname"><span class="pre">inet</span></span><a class="headerlink" href="#namedconf-statement-inet" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar controls: </strong><code class="docutils literal notranslate"><span class="pre">inet</span> <span class="pre">(</span> <span class="pre"><ipv4_address></span> <span class="pre">|</span> <span class="pre"><ipv6_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">)</span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre">(</span> <span class="pre"><integer></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">)</span> <span class="pre">]</span> <span class="pre">allow</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">[</span> <span class="pre">keys</span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">read-only</span> <span class="pre"><boolean></span> <span class="pre">];</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Grammar statistics-channels: </strong><code class="docutils literal notranslate"><span class="pre">inet</span> <span class="pre">(</span> <span class="pre"><ipv4_address></span> <span class="pre">|</span> <span class="pre"><ipv6_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">)</span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre">(</span> <span class="pre"><integer></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">)</span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">allow</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">];</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>controls, statistics-channels</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies a TCP socket as a control channel.</p>
</p>
<p>An <a class="reference internal" href="#namedconf-statement-inet" title="namedconf-statement-inet"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">inet</span></code></a> control channel is a TCP socket listening at the specified
<a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a> on the specified <a class="reference internal" href="#term-ip_address"><span class="xref std std-term">ip_address</span></a>, which can be an IPv4 or IPv6
address. An <a class="reference internal" href="#term-ip_address"><span class="xref std std-term">ip_address</span></a> of <code class="docutils literal notranslate"><span class="pre">*</span></code> (asterisk) is interpreted as the IPv4
wildcard address; connections are accepted on any of the system’s
IPv4 addresses. To listen on the IPv6 wildcard address, use an
<a class="reference internal" href="#term-ip_address"><span class="xref std std-term">ip_address</span></a> of <code class="docutils literal notranslate"><span class="pre">::</span></code>. If <a class="reference internal" href="manpages.html#std-iscman-rndc"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">rndc</span></code></a> is only used on the local host,
using the loopback address (<code class="docutils literal notranslate"><span class="pre">127.0.0.1</span></code> or <code class="docutils literal notranslate"><span class="pre">::1</span></code>) is recommended for
maximum security.</p>
<p>If no port is specified, port 953 is used. The asterisk <code class="docutils literal notranslate"><span class="pre">*</span></code> cannot
be used for <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a>.</p>
<p>The ability to issue commands over the control channel is restricted by
the <code class="docutils literal notranslate"><span class="pre">allow</span></code> and <a class="reference internal" href="#namedconf-statement-keys" title="namedconf-statement-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">keys</span></code></a> clauses.</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">allow</span></code></dt><dd><p>Connections to the control channel
are permitted based on the <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a>. This is for simple IP
address-based filtering only; any <a class="reference internal" href="#term-server_key"><span class="xref std std-term">server_key</span></a> elements of the
<a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> are ignored.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-keys" title="namedconf-statement-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">keys</span></code></a></dt><dd><p>The primary authorization mechanism of the command channel is the
list of <a class="reference internal" href="#term-server_key"><span class="xref std std-term">server_key</span></a> s. Each listed
<a class="reference internal" href="#namedconf-statement-key" title="namedconf-statement-key"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">key</span></code></a> is authorized to execute commands over the control
channel. See <a class="reference internal" href="chapter4.html#admin-tools"><span class="std std-ref">Administrative Tools</span></a> for information about
configuring keys in <a class="reference internal" href="manpages.html#std-iscman-rndc"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">rndc</span></code></a>.</p>
</dd>
</dl>
</dd></dl>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">read-only</span></code></dt><dd><p>If the <code class="docutils literal notranslate"><span class="pre">read-only</span></code> argument is <code class="docutils literal notranslate"><span class="pre">on</span></code>, the control channel is limited
to the following set of read-only commands: <code class="docutils literal notranslate"><span class="pre">nta</span> <span class="pre">-dump</span></code>, <a class="reference internal" href="#namedconf-statement-null" title="namedconf-statement-null"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">null</span></code></a>,
<code class="docutils literal notranslate"><span class="pre">status</span></code>, <code class="docutils literal notranslate"><span class="pre">showzone</span></code>, <code class="docutils literal notranslate"><span class="pre">testgen</span></code>, and <code class="docutils literal notranslate"><span class="pre">zonestatus</span></code>. By default,
<code class="docutils literal notranslate"><span class="pre">read-only</span></code> is not enabled and the control channel allows read-write
access.</p>
</dd>
</dl>
<p>If no <a class="reference internal" href="#namedconf-statement-controls" title="namedconf-statement-controls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">controls</span></code></a> statement is present, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> sets up a default
control channel listening on the loopback address 127.0.0.1 and its IPv6
counterpart, ::1. In this case, and also when the <a class="reference internal" href="#namedconf-statement-controls" title="namedconf-statement-controls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">controls</span></code></a> statement
is present but does not have a <a class="reference internal" href="#namedconf-statement-keys" title="namedconf-statement-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">keys</span></code></a> clause, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> attempts
to load the command channel key from the file <code class="docutils literal notranslate"><span class="pre">/etc/bind/rndc.key</span></code>.
To create an <code class="docutils literal notranslate"><span class="pre">rndc.key</span></code> file, run <a class="reference internal" href="manpages.html#cmdoption-rndc-confgen-a"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc-confgen</span> <span class="pre">-a</span></code></a>.</p>
<p>To disable the command channel, use an empty <a class="reference internal" href="#namedconf-statement-controls" title="namedconf-statement-controls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">controls</span></code></a> statement:
<code class="docutils literal notranslate"><span class="pre">controls</span> <span class="pre">{</span> <span class="pre">};</span></code>.</p>
</section>
<section id="key-block-grammar">
<h3><span class="section-number">8.2.5. </span><code class="docutils literal notranslate"><span class="pre">key</span></code> Block Grammar<a class="headerlink" href="#key-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-key">
<span class="sig-name descname"><span class="pre">key</span></span><a class="headerlink" href="#namedconf-statement-key" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">key</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">{</span>
<span class="n">algorithm</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="n">secret</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="p">};</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>topmost, view</p>
<p><strong>Tags: </strong>security</p>
<p><p>Defines a shared secret key for use with <a class="reference internal" href="chapter7.html#tsig"><span class="std std-ref">TSIG</span></a> or the command channel.</p>
</p>
</dd></dl>
</section>
<section id="key-block-definition-and-usage">
<h3><span class="section-number">8.2.6. </span><code class="docutils literal notranslate"><span class="pre">key</span></code> Block Definition and Usage<a class="headerlink" href="#key-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <code class="docutils literal notranslate"><span class="pre">key</span></code> statement defines a shared secret key for use with TSIG (see
<a class="reference internal" href="chapter7.html#tsig"><span class="std std-ref">TSIG</span></a>) or the command channel (see <a class="reference internal" href="#namedconf-statement-controls" title="namedconf-statement-controls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">controls</span></code></a>).</p>
<p>The <code class="docutils literal notranslate"><span class="pre">key</span></code> statement can occur at the top level of the configuration
file or inside a <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statement. Keys defined in top-level <code class="docutils literal notranslate"><span class="pre">key</span></code>
statements can be used in all views. Keys intended for use in a
<a class="reference internal" href="#namedconf-statement-controls" title="namedconf-statement-controls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">controls</span></code></a> statement must be defined at the top level.</p>
<p>The <a class="reference internal" href="#term-server_key"><span class="xref std std-term">server_key</span></a>, also known as the key name, is a domain name that uniquely
identifies the key. It can be used in a <a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">server</span></code></a> statement to cause
requests sent to that server to be signed with this key, or in address
match lists to verify that incoming requests have been signed with a key
matching this name, algorithm, and secret.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-algorithm">
<span class="sig-name descname"><span class="pre">algorithm</span></span><a class="headerlink" href="#namedconf-statement-algorithm" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">algorithm</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>key, view.key</p>
<p><strong>Tags: </strong>security</p>
<p><p>Defines the algorithm to be used in a key clause.</p>
</p>
<p>The <code class="docutils literal notranslate"><span class="pre">algorithm_id</span></code> is a string that specifies a security/authentication
algorithm. The <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> server supports <code class="docutils literal notranslate"><span class="pre">hmac-md5</span></code>, <code class="docutils literal notranslate"><span class="pre">hmac-sha1</span></code>,
<code class="docutils literal notranslate"><span class="pre">hmac-sha224</span></code>, <code class="docutils literal notranslate"><span class="pre">hmac-sha256</span></code>, <code class="docutils literal notranslate"><span class="pre">hmac-sha384</span></code>, and <code class="docutils literal notranslate"><span class="pre">hmac-sha512</span></code>
TSIG authentication. Truncated hashes are supported by appending the
minimum number of required bits preceded by a dash, e.g.,
<code class="docutils literal notranslate"><span class="pre">hmac-sha1-80</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-secret">
<span class="sig-name descname"><span class="pre">secret</span></span><a class="headerlink" href="#namedconf-statement-secret" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">secret</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>key, view.key</p>
<p><strong>Tags: </strong>security</p>
<p><p>Defines a Base64-encoded string to be used as the secret by the algorithm.</p>
</p>
<p>The <code class="docutils literal notranslate"><span class="pre">secret_string</span></code> is the secret to be used by the
algorithm, and is treated as a Base64-encoded string.</p>
</dd></dl>
</section>
<section id="logging-block-grammar">
<h3><span class="section-number">8.2.7. </span><a class="reference internal" href="#namedconf-statement-logging" title="namedconf-statement-logging"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">logging</span></code></a> Block Grammar<a class="headerlink" href="#logging-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-logging">
<span class="sig-name descname"><span class="pre">logging</span></span><a class="headerlink" href="#namedconf-statement-logging" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">logging</span> <span class="p">{</span>
<span class="n">category</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">{</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
<span class="n">channel</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">{</span>
<span class="n">buffered</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span> <span class="p">[</span> <span class="n">versions</span> <span class="p">(</span> <span class="n">unlimited</span> <span class="o">|</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">)</span> <span class="p">]</span> <span class="p">[</span> <span class="n">size</span> <span class="o"><</span><span class="n">size</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">suffix</span> <span class="p">(</span> <span class="n">increment</span> <span class="o">|</span> <span class="n">timestamp</span> <span class="p">)</span> <span class="p">];</span>
<span class="n">null</span><span class="p">;</span>
<span class="nb">print</span><span class="o">-</span><span class="n">category</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="nb">print</span><span class="o">-</span><span class="n">severity</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="nb">print</span><span class="o">-</span><span class="n">time</span> <span class="p">(</span> <span class="n">iso8601</span> <span class="o">|</span> <span class="n">iso8601</span><span class="o">-</span><span class="n">utc</span> <span class="o">|</span> <span class="n">local</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span>
<span class="n">severity</span> <span class="o"><</span><span class="n">log_severity</span><span class="o">></span><span class="p">;</span>
<span class="n">stderr</span><span class="p">;</span>
<span class="n">syslog</span> <span class="p">[</span> <span class="o"><</span><span class="n">syslog_facility</span><span class="o">></span> <span class="p">];</span>
<span class="p">};</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>topmost</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Configures logging options for the name server.</p>
</p>
</dd></dl>
</section>
<section id="logging-block-definition-and-usage">
<h3><span class="section-number">8.2.8. </span><a class="reference internal" href="#namedconf-statement-logging" title="namedconf-statement-logging"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">logging</span></code></a> Block Definition and Usage<a class="headerlink" href="#logging-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-logging" title="namedconf-statement-logging"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">logging</span></code></a> statement configures a wide variety of logging options
for the name server. Its <a class="reference internal" href="#namedconf-statement-channel" title="namedconf-statement-channel"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">channel</span></code></a> phrase associates output methods,
format options, and severity levels with a name that can then be used
with the <a class="reference internal" href="#namedconf-statement-category" title="namedconf-statement-category"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">category</span></code></a> phrase to select how various classes of messages
are logged.</p>
<p>Only one <a class="reference internal" href="#namedconf-statement-logging" title="namedconf-statement-logging"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">logging</span></code></a> statement is used to define as many channels and
categories as desired. If there is no <a class="reference internal" href="#namedconf-statement-logging" title="namedconf-statement-logging"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">logging</span></code></a> statement, the
logging configuration is:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">logging</span> <span class="p">{</span>
<span class="n">category</span> <span class="n">default</span> <span class="p">{</span> <span class="n">default_syslog</span><span class="p">;</span> <span class="n">default_debug</span><span class="p">;</span> <span class="p">};</span>
<span class="n">category</span> <span class="n">unmatched</span> <span class="p">{</span> <span class="n">null</span><span class="p">;</span> <span class="p">};</span>
<span class="p">};</span>
</pre></div>
</div>
<p>If <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is started with the <a class="reference internal" href="manpages.html#cmdoption-named-L"><code class="xref std std-option docutils literal notranslate"><span class="pre">-L</span></code></a> option, it logs to the specified
file at startup, instead of using syslog. In this case the logging
configuration is:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">logging</span> <span class="p">{</span>
<span class="n">category</span> <span class="n">default</span> <span class="p">{</span> <span class="n">default_logfile</span><span class="p">;</span> <span class="n">default_debug</span><span class="p">;</span> <span class="p">};</span>
<span class="n">category</span> <span class="n">unmatched</span> <span class="p">{</span> <span class="n">null</span><span class="p">;</span> <span class="p">};</span>
<span class="p">};</span>
</pre></div>
</div>
<p>The logging configuration is only established when the entire
configuration file has been parsed. When the server starts up, all
logging messages regarding syntax errors in the configuration file go to
the default channels, or to standard error if the <a class="reference internal" href="manpages.html#cmdoption-named-g"><code class="xref std std-option docutils literal notranslate"><span class="pre">-g</span></code></a> option was
specified.</p>
<section id="the-channel-phrase">
<h4><span class="section-number">8.2.8.1. </span>The <a class="reference internal" href="#namedconf-statement-channel" title="namedconf-statement-channel"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">channel</span></code></a> Phrase<a class="headerlink" href="#the-channel-phrase" title="Link to this heading"></a></h4>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-channel">
<span class="sig-name descname"><span class="pre">channel</span></span><a class="headerlink" href="#namedconf-statement-channel" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">channel</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">{</span>
<span class="n">buffered</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span> <span class="p">[</span> <span class="n">versions</span> <span class="p">(</span> <span class="n">unlimited</span> <span class="o">|</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">)</span> <span class="p">]</span> <span class="p">[</span> <span class="n">size</span> <span class="o"><</span><span class="n">size</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">suffix</span> <span class="p">(</span> <span class="n">increment</span> <span class="o">|</span> <span class="n">timestamp</span> <span class="p">)</span> <span class="p">];</span>
<span class="n">null</span><span class="p">;</span>
<span class="nb">print</span><span class="o">-</span><span class="n">category</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="nb">print</span><span class="o">-</span><span class="n">severity</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="nb">print</span><span class="o">-</span><span class="n">time</span> <span class="p">(</span> <span class="n">iso8601</span> <span class="o">|</span> <span class="n">iso8601</span><span class="o">-</span><span class="n">utc</span> <span class="o">|</span> <span class="n">local</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span>
<span class="n">severity</span> <span class="o"><</span><span class="n">log_severity</span><span class="o">></span><span class="p">;</span>
<span class="n">stderr</span><span class="p">;</span>
<span class="n">syslog</span> <span class="p">[</span> <span class="o"><</span><span class="n">syslog_facility</span><span class="o">></span> <span class="p">];</span>
<span class="p">};</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>logging</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Defines a stream of data that can be independently logged.</p>
</p>
</dd></dl>
<p>All log output goes to one or more <code class="docutils literal notranslate"><span class="pre">channels</span></code>; there is no limit to
the number of channels that can be created.</p>
<p>Every channel definition must include a destination clause that says
whether messages selected for the channel go to a file, go to a particular
syslog facility, go to the standard error stream, or are discarded. The definition can
optionally also limit the message severity level that is accepted
by the channel (the default is <code class="docutils literal notranslate"><span class="pre">info</span></code>), and whether to include a
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>-generated time stamp, the category name, and/or the severity level
(the default is not to include any).</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-null">
<span class="sig-name descname"><span class="pre">null</span></span><a class="headerlink" href="#namedconf-statement-null" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">null;</span></code></p>
<p><strong>Blocks: </strong>logging.channel</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Causes all messages sent to the logging channel to be discarded.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-null" title="namedconf-statement-null"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">null</span></code></a> destination clause causes all messages sent to the channel
to be discarded; in that case, other options for the channel are
meaningless.</p>
</dd></dl>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">file</span></code></dt><dd><p>The <code class="docutils literal notranslate"><span class="pre">file</span></code> destination clause directs the channel to a disk file. It
can include additional arguments to specify how large the file is
allowed to become before it is rolled to a backup file (<code class="docutils literal notranslate"><span class="pre">size</span></code>), how
many backup versions of the file are saved each time this happens
(<code class="docutils literal notranslate"><span class="pre">versions</span></code>), and the format to use for naming backup versions
(<code class="docutils literal notranslate"><span class="pre">suffix</span></code>).</p>
<p>The <code class="docutils literal notranslate"><span class="pre">size</span></code> option is used to limit log file growth. If the file ever
exceeds the specified size, then <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> stops writing to the file
unless it has a <code class="docutils literal notranslate"><span class="pre">versions</span></code> option associated with it. If backup
versions are kept, the files are rolled as described below. If there is
no <code class="docutils literal notranslate"><span class="pre">versions</span></code> option, no more data is written to the log until
some out-of-band mechanism removes or truncates the log to less than the
maximum size. The default behavior is not to limit the size of the file.</p>
<p>File rolling only occurs when the file exceeds the size specified with
the <code class="docutils literal notranslate"><span class="pre">size</span></code> option. No backup versions are kept by default; any
existing log file is simply appended. The <code class="docutils literal notranslate"><span class="pre">versions</span></code> option specifies
how many backup versions of the file should be kept. If set to
<code class="docutils literal notranslate"><span class="pre">unlimited</span></code>, there is no limit.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">suffix</span></code> option can be set to either <code class="docutils literal notranslate"><span class="pre">increment</span></code> or
<code class="docutils literal notranslate"><span class="pre">timestamp</span></code>. If set to <code class="docutils literal notranslate"><span class="pre">timestamp</span></code>, then when a log file is rolled,
it is saved with the current timestamp as a file suffix. If set to
<code class="docutils literal notranslate"><span class="pre">increment</span></code>, then backup files are saved with incrementing numbers as
suffixes; older files are renamed when rolling. For example, if
<code class="docutils literal notranslate"><span class="pre">versions</span></code> is set to 3 and <code class="docutils literal notranslate"><span class="pre">suffix</span></code> to <code class="docutils literal notranslate"><span class="pre">increment</span></code>, then when
<code class="docutils literal notranslate"><span class="pre">filename.log</span></code> reaches the size specified by <code class="docutils literal notranslate"><span class="pre">size</span></code>,
<code class="docutils literal notranslate"><span class="pre">filename.log.1</span></code> is renamed to <code class="docutils literal notranslate"><span class="pre">filename.log.2</span></code>, <code class="docutils literal notranslate"><span class="pre">filename.log.0</span></code>
is renamed to <code class="docutils literal notranslate"><span class="pre">filename.log.1</span></code>, and <code class="docutils literal notranslate"><span class="pre">filename.log</span></code> is renamed to
<code class="docutils literal notranslate"><span class="pre">filename.log.0</span></code>, whereupon a new <code class="docutils literal notranslate"><span class="pre">filename.log</span></code> is opened.</p>
<p>Here is an example using the <code class="docutils literal notranslate"><span class="pre">size</span></code>, <code class="docutils literal notranslate"><span class="pre">versions</span></code>, and <code class="docutils literal notranslate"><span class="pre">suffix</span></code> options:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">channel</span> <span class="n">an_example_channel</span> <span class="p">{</span>
<span class="n">file</span> <span class="s2">"example.log"</span> <span class="n">versions</span> <span class="mi">3</span> <span class="n">size</span> <span class="mi">20</span><span class="n">m</span> <span class="n">suffix</span> <span class="n">increment</span><span class="p">;</span>
<span class="nb">print</span><span class="o">-</span><span class="n">time</span> <span class="n">yes</span><span class="p">;</span>
<span class="nb">print</span><span class="o">-</span><span class="n">category</span> <span class="n">yes</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
</dd>
</dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-syslog">
<span class="sig-name descname"><span class="pre">syslog</span></span><a class="headerlink" href="#namedconf-statement-syslog" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">syslog</span> <span class="pre">[</span> <span class="pre"><syslog_facility></span> <span class="pre">];</span></code></p>
<p><strong>Blocks: </strong>logging.channel</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Directs the logging channel to the system log.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">syslog</span></code></a> destination clause directs the channel to the system log.
Its argument is a syslog facility as described in the <a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">syslog</span></code></a> man
page. Known facilities are <code class="docutils literal notranslate"><span class="pre">kern</span></code>, <code class="docutils literal notranslate"><span class="pre">user</span></code>, <code class="docutils literal notranslate"><span class="pre">mail</span></code>, <code class="docutils literal notranslate"><span class="pre">daemon</span></code>,
<code class="docutils literal notranslate"><span class="pre">auth</span></code>, <a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">syslog</span></code></a>, <code class="docutils literal notranslate"><span class="pre">lpr</span></code>, <code class="docutils literal notranslate"><span class="pre">news</span></code>, <code class="docutils literal notranslate"><span class="pre">uucp</span></code>, <code class="docutils literal notranslate"><span class="pre">cron</span></code>,
<code class="docutils literal notranslate"><span class="pre">authpriv</span></code>, <code class="docutils literal notranslate"><span class="pre">ftp</span></code>, <code class="docutils literal notranslate"><span class="pre">local0</span></code>, <code class="docutils literal notranslate"><span class="pre">local1</span></code>, <code class="docutils literal notranslate"><span class="pre">local2</span></code>, <code class="docutils literal notranslate"><span class="pre">local3</span></code>,
<code class="docutils literal notranslate"><span class="pre">local4</span></code>, <code class="docutils literal notranslate"><span class="pre">local5</span></code>, <code class="docutils literal notranslate"><span class="pre">local6</span></code>, and <code class="docutils literal notranslate"><span class="pre">local7</span></code>; however, not all
facilities are supported on all operating systems. How <a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">syslog</span></code></a>
handles messages sent to this facility is described in the
<code class="docutils literal notranslate"><span class="pre">syslog.conf</span></code> man page. On a system which uses a very old
version of <a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">syslog</span></code></a>, which only uses two arguments to the <code class="docutils literal notranslate"><span class="pre">openlog()</span></code>
function, this clause is silently ignored.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-severity">
<span class="sig-name descname"><span class="pre">severity</span></span><a class="headerlink" href="#namedconf-statement-severity" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">severity</span> <span class="pre"><log_severity>;</span></code></p>
<p><strong>Blocks: </strong>logging.channel</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Defines the priority level of log messages.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-severity" title="namedconf-statement-severity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">severity</span></code></a> clause works like <a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">syslog</span></code></a>’s “priorities,” except
that they can also be used when writing straight to a file rather
than using <a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">syslog</span></code></a>. Messages which are not at least of the severity
level given are not selected for the channel; messages of higher
severity levels are accepted.</p>
<p>When using <a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">syslog</span></code></a>, the <code class="docutils literal notranslate"><span class="pre">syslog.conf</span></code> priorities
also determine what eventually passes through. For example, defining a
channel facility and severity as <code class="docutils literal notranslate"><span class="pre">daemon</span></code> and <code class="docutils literal notranslate"><span class="pre">debug</span></code>, but only
logging <code class="docutils literal notranslate"><span class="pre">daemon.warning</span></code> via <code class="docutils literal notranslate"><span class="pre">syslog.conf</span></code>, causes messages of
severity <code class="docutils literal notranslate"><span class="pre">info</span></code> and <code class="docutils literal notranslate"><span class="pre">notice</span></code> to be dropped. If the situation were
reversed, with <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> writing messages of only <code class="docutils literal notranslate"><span class="pre">warning</span></code> or higher,
then <code class="docutils literal notranslate"><span class="pre">syslogd</span></code> would print all messages it received from the channel.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-stderr">
<span class="sig-name descname"><span class="pre">stderr</span></span><a class="headerlink" href="#namedconf-statement-stderr" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">stderr;</span></code></p>
<p><strong>Blocks: </strong>logging.channel</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Directs the logging channel output to the server’s standard error stream.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-stderr" title="namedconf-statement-stderr"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">stderr</span></code></a> destination clause directs the channel to the server’s
standard error stream. This is intended for use when the server is
running as a foreground process, as when debugging a
configuration, for example.</p>
</dd></dl>
<p>The server can supply extensive debugging information when it is in
debugging mode. If the server’s global debug level is greater than zero,
debugging mode is active. The global debug level is set either
by starting the <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> server with the <a class="reference internal" href="manpages.html#cmdoption-named-d"><code class="xref std std-option docutils literal notranslate"><span class="pre">-d</span></code></a> flag followed by a
positive integer, or by running <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-trace"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">trace</span></code></a>. The global debug level
can be set to zero, and debugging mode turned off, by running <code class="docutils literal notranslate"><span class="pre">rndc</span>
<span class="pre">notrace</span></code>. All debugging messages in the server have a debug level;
higher debug levels give more detailed output. Channels that specify a
specific debug severity, for example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">channel</span> <span class="n">specific_debug_level</span> <span class="p">{</span>
<span class="n">file</span> <span class="s2">"foo"</span><span class="p">;</span>
<span class="n">severity</span> <span class="n">debug</span> <span class="mi">3</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
<p>get debugging output of level 3 or less any time the server is in
debugging mode, regardless of the global debugging level. Channels with
<code class="docutils literal notranslate"><span class="pre">dynamic</span></code> severity use the server’s global debug level to determine
what messages to print.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-print-time">
<span class="sig-name descname"><span class="pre">print-time</span></span><a class="headerlink" href="#namedconf-statement-print-time" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">print-time</span> <span class="pre">(</span> <span class="pre">iso8601</span> <span class="pre">|</span> <span class="pre">iso8601-utc</span> <span class="pre">|</span> <span class="pre">local</span> <span class="pre">|</span> <span class="pre"><boolean></span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>logging.channel</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Specifies the time format for log messages.</p>
</p>
<p><a class="reference internal" href="#namedconf-statement-print-time" title="namedconf-statement-print-time"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">print-time</span></code></a> can be set to <code class="docutils literal notranslate"><span class="pre">yes</span></code>, <code class="docutils literal notranslate"><span class="pre">no</span></code>, or a time format
specifier, which may be one of <code class="docutils literal notranslate"><span class="pre">local</span></code>, <code class="docutils literal notranslate"><span class="pre">iso8601</span></code>, or
<code class="docutils literal notranslate"><span class="pre">iso8601-utc</span></code>. If set to <code class="docutils literal notranslate"><span class="pre">no</span></code>, the date and time are not
logged. If set to <code class="docutils literal notranslate"><span class="pre">yes</span></code> or <code class="docutils literal notranslate"><span class="pre">local</span></code>, the date and time are logged in
a human-readable format, using the local time zone. If set to
<code class="docutils literal notranslate"><span class="pre">iso8601</span></code>, the local time is logged in ISO 8601 format. If set to
<code class="docutils literal notranslate"><span class="pre">iso8601-utc</span></code>, the date and time are logged in ISO 8601 format,
with time zone set to UTC. The default is <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
<p><a class="reference internal" href="#namedconf-statement-print-time" title="namedconf-statement-print-time"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">print-time</span></code></a> may be specified for a <a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">syslog</span></code></a> channel, but it is
usually pointless since <a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">syslog</span></code></a> also logs the date and time.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-print-category">
<span class="sig-name descname"><span class="pre">print-category</span></span><a class="headerlink" href="#namedconf-statement-print-category" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">print-category</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>logging.channel</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Includes the category in log messages.</p>
</p>
<p>If <a class="reference internal" href="#namedconf-statement-print-category" title="namedconf-statement-print-category"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">print-category</span></code></a> is requested, then the category of the message
is logged as well.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-print-severity">
<span class="sig-name descname"><span class="pre">print-severity</span></span><a class="headerlink" href="#namedconf-statement-print-severity" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">print-severity</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>logging.channel</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Includes the severity in log messages.</p>
</p>
<p>If <a class="reference internal" href="#namedconf-statement-print-severity" title="namedconf-statement-print-severity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">print-severity</span></code></a> is on, then the
severity level of the message is logged. The <code class="docutils literal notranslate"><span class="pre">print-</span></code> options may
be used in any combination, and are always printed in the following
order: time, category, severity.</p>
</dd></dl>
<p>Here is an example where all three <code class="docutils literal notranslate"><span class="pre">print-</span></code> options are on:</p>
<p><code class="docutils literal notranslate"><span class="pre">28-Feb-2000</span> <span class="pre">15:05:32.863</span> <span class="pre">general:</span> <span class="pre">notice:</span> <span class="pre">running</span></code></p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-buffered">
<span class="sig-name descname"><span class="pre">buffered</span></span><a class="headerlink" href="#namedconf-statement-buffered" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">buffered</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>logging.channel</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Controls flushing of log messages.</p>
</p>
<p>If <a class="reference internal" href="#namedconf-statement-buffered" title="namedconf-statement-buffered"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">buffered</span></code></a> has been turned on, the output to files is not
flushed after each log entry. By default all log messages are flushed.</p>
</dd></dl>
<p>There are four predefined channels that are used for <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>’s default
logging, as follows. If <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is started with the <a class="reference internal" href="manpages.html#cmdoption-named-L"><code class="xref std std-option docutils literal notranslate"><span class="pre">-L</span></code></a> option, then a fifth
channel, <code class="docutils literal notranslate"><span class="pre">default_logfile</span></code>, is added. How they are used is described in
<a class="reference internal" href="#namedconf-statement-category" title="namedconf-statement-category"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">category</span></code></a>.</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">channel</span> <span class="n">default_syslog</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">send</span> <span class="n">to</span> <span class="n">syslog</span><span class="s1">'s daemon facility</span>
<span class="n">syslog</span> <span class="n">daemon</span><span class="p">;</span>
<span class="o">//</span> <span class="n">only</span> <span class="n">send</span> <span class="n">priority</span> <span class="n">info</span> <span class="ow">and</span> <span class="n">higher</span>
<span class="n">severity</span> <span class="n">info</span><span class="p">;</span>
<span class="p">};</span>
<span class="n">channel</span> <span class="n">default_debug</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">write</span> <span class="n">to</span> <span class="n">named</span><span class="o">.</span><span class="n">run</span> <span class="ow">in</span> <span class="n">the</span> <span class="n">working</span> <span class="n">directory</span>
<span class="o">//</span> <span class="n">Note</span><span class="p">:</span> <span class="n">stderr</span> <span class="ow">is</span> <span class="n">used</span> <span class="n">instead</span> <span class="n">of</span> <span class="s2">"named.run"</span> <span class="k">if</span>
<span class="o">//</span> <span class="n">the</span> <span class="n">server</span> <span class="ow">is</span> <span class="n">started</span> <span class="k">with</span> <span class="n">the</span> <span class="s1">'-g'</span> <span class="n">option</span><span class="o">.</span>
<span class="n">file</span> <span class="s2">"named.run"</span><span class="p">;</span>
<span class="o">//</span> <span class="n">log</span> <span class="n">at</span> <span class="n">the</span> <span class="n">server</span><span class="s1">'s current debug level</span>
<span class="n">severity</span> <span class="n">dynamic</span><span class="p">;</span>
<span class="p">};</span>
<span class="n">channel</span> <span class="n">default_stderr</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">writes</span> <span class="n">to</span> <span class="n">stderr</span>
<span class="n">stderr</span><span class="p">;</span>
<span class="o">//</span> <span class="n">only</span> <span class="n">send</span> <span class="n">priority</span> <span class="n">info</span> <span class="ow">and</span> <span class="n">higher</span>
<span class="n">severity</span> <span class="n">info</span><span class="p">;</span>
<span class="p">};</span>
<span class="n">channel</span> <span class="n">null</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">toss</span> <span class="n">anything</span> <span class="n">sent</span> <span class="n">to</span> <span class="n">this</span> <span class="n">channel</span>
<span class="n">null</span><span class="p">;</span>
<span class="p">};</span>
<span class="n">channel</span> <span class="n">default_logfile</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">this</span> <span class="n">channel</span> <span class="ow">is</span> <span class="n">only</span> <span class="n">present</span> <span class="k">if</span> <span class="n">named</span> <span class="ow">is</span>
<span class="o">//</span> <span class="n">started</span> <span class="k">with</span> <span class="n">the</span> <span class="o">-</span><span class="n">L</span> <span class="n">option</span><span class="p">,</span> <span class="n">whose</span> <span class="n">argument</span>
<span class="o">//</span> <span class="n">provides</span> <span class="n">the</span> <span class="n">file</span> <span class="n">name</span>
<span class="n">file</span> <span class="s2">"..."</span><span class="p">;</span>
<span class="o">//</span> <span class="n">log</span> <span class="n">at</span> <span class="n">the</span> <span class="n">server</span><span class="s1">'s current debug level</span>
<span class="n">severity</span> <span class="n">dynamic</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
<p>The <code class="docutils literal notranslate"><span class="pre">default_debug</span></code> channel has the special property that it only
produces output when the server’s debug level is non-zero. It normally
writes to a file called <code class="docutils literal notranslate"><span class="pre">named.run</span></code> in the server’s working directory.</p>
<p>For security reasons, when the <a class="reference internal" href="manpages.html#cmdoption-named-u"><code class="xref std std-option docutils literal notranslate"><span class="pre">-u</span></code></a> command-line option is used, the
<code class="docutils literal notranslate"><span class="pre">named.run</span></code> file is created only after <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> has changed to the
new UID, and any debug output generated while <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is starting -
and still running as root - is discarded. To capture this
output, run the server with the <a class="reference internal" href="manpages.html#cmdoption-named-L"><code class="xref std std-option docutils literal notranslate"><span class="pre">-L</span></code></a> option to specify a
default logfile, or the <a class="reference internal" href="manpages.html#cmdoption-named-g"><code class="xref std std-option docutils literal notranslate"><span class="pre">-g</span></code></a> option to log to standard error which can
be redirected to a file.</p>
<p>Once a channel is defined, it cannot be redefined. The
built-in channels cannot be altered directly, but the default logging
can be modified by pointing categories at defined channels.</p>
</section>
<section id="the-category-phrase">
<h4><span class="section-number">8.2.8.2. </span>The <a class="reference internal" href="#namedconf-statement-category" title="namedconf-statement-category"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">category</span></code></a> Phrase<a class="headerlink" href="#the-category-phrase" title="Link to this heading"></a></h4>
<p>There are many categories, so desired logs can be sent anywhere
while unwanted logs are ignored. If
a list of channels is not specified for a category, log messages in that
category are sent to the <code class="docutils literal notranslate"><span class="pre">default</span></code> category instead. If no
default category is specified, the following “default default” is used:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">category</span> <span class="n">default</span> <span class="p">{</span> <span class="n">default_syslog</span><span class="p">;</span> <span class="n">default_debug</span><span class="p">;</span> <span class="p">};</span>
</pre></div>
</div>
<p>If <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is started with the <a class="reference internal" href="manpages.html#cmdoption-named-L"><code class="xref std std-option docutils literal notranslate"><span class="pre">-L</span></code></a> option, the default category
is:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">category</span> <span class="n">default</span> <span class="p">{</span> <span class="n">default_logfile</span><span class="p">;</span> <span class="n">default_debug</span><span class="p">;</span> <span class="p">};</span>
</pre></div>
</div>
<p>As an example, let’s say a user wants to log security events to a file, but
also wants to keep the default logging behavior. They would specify the
following:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">channel</span> <span class="n">my_security_channel</span> <span class="p">{</span>
<span class="n">file</span> <span class="s2">"my_security_file"</span><span class="p">;</span>
<span class="n">severity</span> <span class="n">info</span><span class="p">;</span>
<span class="p">};</span>
<span class="n">category</span> <span class="n">security</span> <span class="p">{</span>
<span class="n">my_security_channel</span><span class="p">;</span>
<span class="n">default_syslog</span><span class="p">;</span>
<span class="n">default_debug</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
<p>To discard all messages in a category, specify the <a class="reference internal" href="#namedconf-statement-null" title="namedconf-statement-null"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">null</span></code></a> channel:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">category</span> <span class="n">xfer</span><span class="o">-</span><span class="n">out</span> <span class="p">{</span> <span class="n">null</span><span class="p">;</span> <span class="p">};</span>
<span class="n">category</span> <span class="n">notify</span> <span class="p">{</span> <span class="n">null</span><span class="p">;</span> <span class="p">};</span>
</pre></div>
</div>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-category">
<span class="sig-name descname"><span class="pre">category</span></span><a class="headerlink" href="#namedconf-statement-category" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">category</span> <span class="pre"><string></span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>logging</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Specifies the type of data logged to a particular channel.</p>
</p>
</dd></dl>
<p>The following are the available categories and brief descriptions of the
types of log information they contain. More categories may be added in
future BIND releases.</p>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">client</span></code></dt><dd><p>Processing of client requests.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">cname</span></code></dt><dd><p>Name servers that are skipped for being a CNAME rather than A/AAAA records.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">config</span></code></dt><dd><p>Configuration file parsing and processing.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">database</span></code></dt><dd><p>Messages relating to the databases used internally by the name server to store zone and cache data.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">default</span></code></dt><dd><p>Logging options for those categories where no specific configuration has been defined.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">delegation-only</span></code></dt><dd><p>Queries that have been forced to NXDOMAIN as the result of a delegation-only zone or a <a class="reference internal" href="#namedconf-statement-delegation-only" title="namedconf-statement-delegation-only"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">delegation-only</span></code></a> in a forward, hint, or stub zone declaration.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">dispatch</span></code></dt><dd><p>Dispatching of incoming packets to the server modules where they are to be processed.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">dnssec</span></code></dt><dd><p>DNSSEC and TSIG protocol processing.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">dnstap</span></code></dt><dd><p>The <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> DNS traffic capture system.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">edns-disabled</span></code></dt><dd><p>Log queries that have been forced to use plain DNS due to timeouts. This is often due to the remote servers not being <span class="target" id="index-2"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1034.html"><strong>RFC 1034</strong></a>-compliant (not always returning FORMERR or similar to EDNS queries and other extensions to the DNS when they are not understood). In other words, this is targeted at servers that fail to respond to DNS queries that they don’t understand.</p>
<p>Note: the log message can also be due to packet loss. Before reporting servers for non-<span class="target" id="index-3"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1034.html"><strong>RFC 1034</strong></a> compliance they should be re-tested to determine the nature of the non-compliance. This testing should prevent or reduce the number of false-positive reports.</p>
<p>Note: eventually <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> will have to stop treating such timeouts as due to <span class="target" id="index-4"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1034.html"><strong>RFC 1034</strong></a> non-compliance and start treating it as plain packet loss. Falsely classifying packet loss as due to <span class="target" id="index-5"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1034.html"><strong>RFC 1034</strong></a> non-compliance impacts DNSSEC validation, which requires EDNS for the DNSSEC records to be returned.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">general</span></code></dt><dd><p>A catch-all for many things that still are not classified into categories.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">lame-servers</span></code></dt><dd><p>Misconfigurations in remote servers, discovered by BIND 9 when trying to query those servers during resolution.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">network</span></code></dt><dd><p>Network operations.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">notify</span></code></dt><dd><p>The NOTIFY protocol.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">nsid</span></code></dt><dd><p>NSID options received from upstream servers.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">queries</span></code></dt><dd><p>A location where queries should be logged.</p>
<p>At startup, specifying the category <code class="docutils literal notranslate"><span class="pre">queries</span></code> also enables query logging unless the <a class="reference internal" href="#namedconf-statement-querylog" title="namedconf-statement-querylog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">querylog</span></code></a> option has been specified.</p>
<p>The query log entry first reports a client object identifier in @0x<hexadecimal-number> format. Next, it reports the client’s IP address and port number, and the query name, class, and type. Next, it reports whether the Recursion Desired flag was set (+ if set, - if not set), whether the query was signed (S), whether EDNS was in use along with the EDNS version number (E(#)), whether TCP was used (T), whether DO (DNSSEC Ok) was set (D), whether CD (Checking Disabled) was set (C), whether a valid DNS Server COOKIE was received (V), and whether a DNS COOKIE option without a valid Server COOKIE was present (K). After this, the destination address the query was sent to is reported. Finally, if any CLIENT-SUBNET option was present in the client query, it is included in square brackets in the format [ECS address/source/scope].</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>client @0x7f91b8005490 127.0.0.1#62536 (www.example.com): query: www.example.com IN AAAA +E(0)K (127.0.0.1)
client @0x7f91b4007400 ::1#62537 (www.example.net): query: www.example.net IN AAAA +E(0)K (::1)
</pre></div>
</div>
<p>The first part of this log message, showing the client address/port number and query name, is repeated in all subsequent log messages related to the same query.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">query-errors</span></code></dt><dd><p>Information about queries that resulted in some failure.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">rate-limit</span></code></dt><dd><p>Start, periodic, and final notices of the rate limiting of a stream of responses that are logged at <code class="docutils literal notranslate"><span class="pre">info</span></code> severity in this category. These messages include a hash value of the domain name of the response and the name itself, except when there is insufficient memory to record the name for the final notice. The final notice is normally delayed until about one minute after rate limiting stops. A lack of memory can hurry the final notice, which is indicated by an initial asterisk (*). Various internal events are logged at debug level 1 and higher.</p>
<p>Rate limiting of individual requests is logged in the <code class="docutils literal notranslate"><span class="pre">query-errors</span></code> category.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">resolver</span></code></dt><dd><p>DNS resolution, such as the recursive lookups performed on behalf of clients by a caching name server.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">rpz</span></code></dt><dd><p>Information about errors in response policy zone files, rewritten responses, and, at the highest <code class="docutils literal notranslate"><span class="pre">debug</span></code> levels, mere rewriting attempts.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">rpz-passthru</span></code></dt><dd><p>Information about RPZ PASSTHRU policy activity. This category allows pre-approved policy activity to be logged into a dedicated channel.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">security</span></code></dt><dd><p>Approval and denial of requests.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">serve-stale</span></code></dt><dd><p>Indication of whether a stale answer is used following a resolver failure.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">spill</span></code></dt><dd><p>Queries that have been terminated, either by dropping or responding with SERVFAIL, as a result of a fetchlimit quota being exceeded.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">sslkeylog</span></code></dt><dd><p>TLS pre-master secrets (for debugging purposes).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">trust-anchor-telemetry</span></code></dt><dd><p><a class="reference internal" href="#namedconf-statement-trust-anchor-telemetry" title="namedconf-statement-trust-anchor-telemetry"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchor-telemetry</span></code></a> requests received by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">unmatched</span></code></dt><dd><p>Messages that <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> was unable to determine the class of, or for which there was no matching <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>. A one-line summary is also logged to the <code class="docutils literal notranslate"><span class="pre">client</span></code> category. This category is best sent to a file or stderr; by default it is sent to the <a class="reference internal" href="#namedconf-statement-null" title="namedconf-statement-null"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">null</span></code></a> channel.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">update</span></code></dt><dd><p>Dynamic updates.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">update-security</span></code></dt><dd><p>Approval and denial of update requests.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">xfer-in</span></code></dt><dd><p>Zone transfers the server is receiving.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">xfer-out</span></code></dt><dd><p>Zone transfers the server is sending.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">zoneload</span></code></dt><dd><p>Loading of zones and creation of automatic empty zones.</p>
</dd>
</dl>
</section>
<section id="the-query-errors-category">
<span id="query-errors"></span><h4><span class="section-number">8.2.8.3. </span>The <code class="docutils literal notranslate"><span class="pre">query-errors</span></code> Category<a class="headerlink" href="#the-query-errors-category" title="Link to this heading"></a></h4>
<p>The <code class="docutils literal notranslate"><span class="pre">query-errors</span></code> category is used to indicate why and how specific queries
resulted in responses which indicate an error. Normally, these messages are
logged at <code class="docutils literal notranslate"><span class="pre">debug</span></code> logging levels; note, however, that if query logging is
active, some are logged at <code class="docutils literal notranslate"><span class="pre">info</span></code>. The logging levels are described below:</p>
<p>At <code class="docutils literal notranslate"><span class="pre">debug</span></code> level 1 or higher - or at <code class="docutils literal notranslate"><span class="pre">info</span></code> when query logging is
active - each response with the rcode of SERVFAIL is logged as follows:</p>
<p><code class="docutils literal notranslate"><span class="pre">client</span> <span class="pre">127.0.0.1#61502:</span> <span class="pre">query</span> <span class="pre">failed</span> <span class="pre">(SERVFAIL)</span> <span class="pre">for</span> <span class="pre">www.example.com/IN/AAAA</span> <span class="pre">at</span> <span class="pre">query.c:3880</span></code></p>
<p>This means an error resulting in SERVFAIL was detected at line 3880 of source
file <code class="docutils literal notranslate"><span class="pre">query.c</span></code>. Log messages of this level are particularly helpful in identifying
the cause of SERVFAIL for an authoritative server.</p>
<p>At <code class="docutils literal notranslate"><span class="pre">debug</span></code> level 2 or higher, detailed context information about recursive
resolutions that resulted in SERVFAIL is logged. The log message looks
like this:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">fetch</span> <span class="n">completed</span> <span class="n">at</span> <span class="n">resolver</span><span class="o">.</span><span class="n">c</span><span class="p">:</span><span class="mi">2970</span> <span class="k">for</span> <span class="n">www</span><span class="o">.</span><span class="n">example</span><span class="o">.</span><span class="n">com</span><span class="o">/</span><span class="n">A</span>
<span class="ow">in</span> <span class="mf">10.000183</span><span class="p">:</span> <span class="n">timed</span> <span class="n">out</span><span class="o">/</span><span class="n">success</span> <span class="p">[</span><span class="n">domain</span><span class="p">:</span><span class="n">example</span><span class="o">.</span><span class="n">com</span><span class="p">,</span>
<span class="n">referral</span><span class="p">:</span><span class="mi">2</span><span class="p">,</span><span class="n">restart</span><span class="p">:</span><span class="mi">7</span><span class="p">,</span><span class="n">qrysent</span><span class="p">:</span><span class="mi">8</span><span class="p">,</span><span class="n">timeout</span><span class="p">:</span><span class="mi">5</span><span class="p">,</span><span class="n">lame</span><span class="p">:</span><span class="mi">0</span><span class="p">,</span><span class="n">quota</span><span class="p">:</span><span class="mi">0</span><span class="p">,</span><span class="n">neterr</span><span class="p">:</span><span class="mi">0</span><span class="p">,</span>
<span class="n">badresp</span><span class="p">:</span><span class="mi">1</span><span class="p">,</span><span class="n">adberr</span><span class="p">:</span><span class="mi">0</span><span class="p">,</span><span class="n">findfail</span><span class="p">:</span><span class="mi">0</span><span class="p">,</span><span class="n">valfail</span><span class="p">:</span><span class="mi">0</span><span class="p">]</span>
</pre></div>
</div>
<p>The first part before the colon shows that a recursive resolution for
AAAA records of www.example.com completed in 10.000183 seconds, and the
final result that led to the SERVFAIL was determined at line 2970 of
source file <code class="docutils literal notranslate"><span class="pre">resolver.c</span></code>.</p>
<p>The next part shows the detected final result and the latest result of
DNSSEC validation. The latter is always “success” when no validation attempt
was made. In this example, this query probably resulted in SERVFAIL because all
name servers are down or unreachable, leading to a timeout in 10 seconds.
DNSSEC validation was probably not attempted.</p>
<p>The last part, enclosed in square brackets, shows statistics collected for this
particular resolution attempt. The <code class="docutils literal notranslate"><span class="pre">domain</span></code> field shows the deepest zone that
the resolver reached; it is the zone where the error was finally detected. The
meaning of the other fields is summarized in the following list.</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">referral</span></code></dt><dd><p>The number of referrals the resolver received throughout the resolution process. In the above <code class="docutils literal notranslate"><span class="pre">example.com</span></code> there are two.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">restart</span></code></dt><dd><p>The number of cycles that the resolver tried remote servers at the <code class="docutils literal notranslate"><span class="pre">domain</span></code> zone. In each cycle, the resolver sends one query (possibly resending it, depending on the response) to each known name server of the <code class="docutils literal notranslate"><span class="pre">domain</span></code> zone.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">qrysent</span></code></dt><dd><p>The number of queries the resolver sent at the <code class="docutils literal notranslate"><span class="pre">domain</span></code> zone.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">timeout</span></code></dt><dd><p>The number of timeouts the resolver received since the last response.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">lame</span></code></dt><dd><p>The number of lame servers the resolver detected at the <code class="docutils literal notranslate"><span class="pre">domain</span></code> zone. A server is detected to be lame either by an invalid response or as a result of lookup in BIND 9’s address database (ADB), where lame servers are cached.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">quota</span></code></dt><dd><p>The number of times the resolver was unable to send a query because it had exceeded the permissible fetch quota for a server.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">neterr</span></code></dt><dd><p>The number of erroneous results that the resolver encountered in sending queries at the <code class="docutils literal notranslate"><span class="pre">domain</span></code> zone. One common case is when the remote server is unreachable and the resolver receives an “ICMP unreachable” error message.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">badresp</span></code></dt><dd><p>The number of unexpected responses (other than <code class="docutils literal notranslate"><span class="pre">lame</span></code>) to queries sent by the resolver at the <code class="docutils literal notranslate"><span class="pre">domain</span></code> zone.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">adberr</span></code></dt><dd><p>Failures in finding remote server addresses of the``domain`` zone in the ADB. One common case of this is that the remote server’s name does not have any address records.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">findfail</span></code></dt><dd><p>Failures to resolve remote server addresses. This is a total number of failures throughout the resolution process.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">valfail</span></code></dt><dd><p>Failures of DNSSEC validation. Validation failures are counted throughout the resolution process (not limited to the <code class="docutils literal notranslate"><span class="pre">domain</span></code> zone), but should only happen in <code class="docutils literal notranslate"><span class="pre">domain</span></code>.</p>
</dd>
</dl>
<p>At <code class="docutils literal notranslate"><span class="pre">debug</span></code> level 3 or higher, the same messages as those at
<code class="docutils literal notranslate"><span class="pre">debug</span></code> level 1 are logged for errors other than
SERVFAIL. Note that negative responses such as NXDOMAIN are not errors, and are
not logged at this debug level.</p>
<p>At <code class="docutils literal notranslate"><span class="pre">debug</span></code> level 4 or higher, the detailed context information logged at
<code class="docutils literal notranslate"><span class="pre">debug</span></code> level 2 is logged for errors other than SERVFAIL and for negative
responses such as NXDOMAIN.</p>
</section>
</section>
<section id="parental-agents-block-grammar">
<h3><span class="section-number">8.2.9. </span><a class="reference internal" href="#namedconf-statement-parental-agents" title="namedconf-statement-parental-agents"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parental-agents</span></code></a> Block Grammar<a class="headerlink" href="#parental-agents-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-parental-agents">
<span class="sig-name descname"><span class="pre">parental-agents</span></span><a class="headerlink" href="#namedconf-statement-parental-agents" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar zone (primary, secondary): </strong><code class="docutils literal notranslate"><span class="pre">parental-agents</span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span>  <span class="pre">{</span> <span class="pre">(</span> <span class="pre"><remote-servers></span> <span class="pre">|</span> <span class="pre"><ipv4_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">|</span> <span class="pre"><ipv6_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">)</span> <span class="pre">[</span> <span class="pre">key</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">tls</span> <span class="pre"><string></span> <span class="pre">];</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Grammar topmost: </strong><code class="docutils literal notranslate"><span class="pre">parental-agents</span> <span class="pre"><string></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span>  <span class="pre">{</span> <span class="pre">(</span> <span class="pre"><remote-servers></span> <span class="pre">|</span> <span class="pre"><ipv4_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">|</span> <span class="pre"><ipv6_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">)</span> <span class="pre">[</span> <span class="pre">key</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">tls</span> <span class="pre"><string></span> <span class="pre">];</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>topmost, zone (primary, secondary)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Defines a list of delegation agents to be used by primary and secondary zones.</p>
</p>
</dd></dl>
</section>
<section id="parental-agents-block-definition-and-usage">
<h3><span class="section-number">8.2.10. </span><a class="reference internal" href="#namedconf-statement-parental-agents" title="namedconf-statement-parental-agents"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parental-agents</span></code></a> Block Definition and Usage<a class="headerlink" href="#parental-agents-block-definition-and-usage" title="Link to this heading"></a></h3>
<p><a class="reference internal" href="#namedconf-statement-parental-agents" title="namedconf-statement-parental-agents"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parental-agents</span></code></a> lists allow for a common set of parental agents to be
easily used by multiple primary and secondary zones. A “parental agent” is a
trusted DNS server that is queried to check whether DS records for a given zones
are up-to-date.</p>
</section>
<section id="primaries-block-grammar">
<h3><span class="section-number">8.2.11. </span><a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> Block Grammar<a class="headerlink" href="#primaries-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-primaries">
<span class="sig-name descname"><span class="pre">primaries</span></span><a class="headerlink" href="#namedconf-statement-primaries" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar zone (mirror, redirect, secondary, stub): </strong><code class="docutils literal notranslate"><span class="pre">primaries</span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span>  <span class="pre">{</span> <span class="pre">(</span> <span class="pre"><remote-servers></span> <span class="pre">|</span> <span class="pre"><ipv4_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">|</span> <span class="pre"><ipv6_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">)</span> <span class="pre">[</span> <span class="pre">key</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">tls</span> <span class="pre"><string></span> <span class="pre">];</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Grammar topmost: </strong><code class="docutils literal notranslate"><span class="pre">primaries</span> <span class="pre"><string></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span>  <span class="pre">{</span> <span class="pre">(</span> <span class="pre"><remote-servers></span> <span class="pre">|</span> <span class="pre"><ipv4_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">|</span> <span class="pre"><ipv6_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">)</span> <span class="pre">[</span> <span class="pre">key</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">tls</span> <span class="pre"><string></span> <span class="pre">];</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>topmost, zone (mirror, redirect, secondary, stub)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Defines one or more primary servers for a zone.</p>
</p>
</dd></dl>
</section>
<section id="primaries-block-definition-and-usage">
<h3><span class="section-number">8.2.12. </span><a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> Block Definition and Usage<a class="headerlink" href="#primaries-block-definition-and-usage" title="Link to this heading"></a></h3>
<p><a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> lists allow for a common set of primary servers to be easily
used by multiple stub and secondary zones in their <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> or
<a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a> lists. (Note: <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> is a synonym for the original
keyword <code class="docutils literal notranslate"><span class="pre">masters</span></code>, which can still be used, but is no longer the
preferred terminology.)</p>
<p>To force the zone transfer requests to be sent over TLS, use <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> keyword,
e.g. <code class="docutils literal notranslate"><span class="pre">primaries</span> <span class="pre">{</span> <span class="pre">192.0.2.1</span> <span class="pre">tls</span> <span class="pre">tls-configuration-name;</span> <span class="pre">};</span></code>,
where <code class="docutils literal notranslate"><span class="pre">tls-configuration-name</span></code> refers to a previously defined
<a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span> <span class="pre">statement</span></code></a>.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Please note that TLS connections to primaries are <strong>not
authenticated</strong> unless <a class="reference internal" href="#namedconf-statement-remote-hostname" title="namedconf-statement-remote-hostname"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">remote-hostname</span></code></a> or <a class="reference internal" href="#namedconf-statement-ca-file" title="namedconf-statement-ca-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ca-file</span></code></a> are specified
within the <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span> <span class="pre">statement</span></code></a> in use (see information on
<a class="reference internal" href="#strict-tls"><span class="std std-ref">Strict TLS</span></a> and <a class="reference internal" href="#mutual-tls"><span class="std std-ref">Mutual TLS</span></a>
for more details). <strong>Not authenticated mode</strong> (<a class="reference internal" href="#opportunistic-tls"><span class="std std-ref">Opportunistic
TLS</span></a>) provides protection from passive
observers but does not protect from man-in-the-middle attacks on
zone transfers.</p>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Please note that this version of BIND 9 does not support dynamic update
forwarding (see <a class="reference internal" href="#namedconf-statement-allow-update-forwarding" title="namedconf-statement-allow-update-forwarding"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-update-forwarding</span></code></a>) in conjunction with zone
transfers over TLS (XoT). This includes when the <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> keyword is used with
<a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a>, e.g. <code class="docutils literal notranslate"><span class="pre">primaries</span> <span class="pre">{</span> <span class="pre">192.0.2.1</span> <span class="pre">tls</span> <span class="pre">tls-configuration-name;</span> <span class="pre">};</span></code>.</p>
</div>
</section>
<section id="options-block-grammar">
<h3><span class="section-number">8.2.13. </span><code class="docutils literal notranslate"><span class="pre">options</span></code> Block Grammar<a class="headerlink" href="#options-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-options">
<span class="sig-name descname"><span class="pre">options</span></span><a class="headerlink" href="#namedconf-statement-options" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span>options {
allow-new-zones <boolean>;
allow-notify { <address_match_element>; ... };
allow-query { <address_match_element>; ... };
allow-query-cache { <address_match_element>; ... };
allow-query-cache-on { <address_match_element>; ... };
allow-query-on { <address_match_element>; ... };
allow-recursion { <address_match_element>; ... };
allow-recursion-on { <address_match_element>; ... };
allow-transfer [ port <integer> ] [ transport <string> ] { <address_match_element>; ... };
allow-update { <address_match_element>; ... };
allow-update-forwarding { <address_match_element>; ... };
also-notify [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... };
alt-transfer-source ( <ipv4_address> | * ); // deprecated
alt-transfer-source-v6 ( <ipv6_address> | * ); // deprecated
answer-cookie <boolean>;
attach-cache <string>;
auth-nxdomain <boolean>;
auto-dnssec ( allow | maintain | off ); // deprecated
automatic-interface-scan <boolean>;
avoid-v4-udp-ports { <portrange>; ... }; // deprecated
avoid-v6-udp-ports { <portrange>; ... }; // deprecated
bindkeys-file <quoted_string>;
blackhole { <address_match_element>; ... };
catalog-zones { zone <string> [ default-primaries [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... } ] [ zone-directory <quoted_string> ] [ in-memory <boolean> ] [ min-update-interval <duration> ]; ... };
check-dup-records ( fail | warn | ignore );
check-integrity <boolean>;
check-mx ( fail | warn | ignore );
check-mx-cname ( fail | warn | ignore );
check-names ( primary | master | secondary | slave | response ) ( fail | warn | ignore ); // may occur multiple times
check-sibling <boolean>;
check-spf ( warn | ignore );
check-srv-cname ( fail | warn | ignore );
check-wildcard <boolean>;
clients-per-query <integer>;
cookie-algorithm ( aes | siphash24 );
cookie-secret <string>; // may occur multiple times
coresize ( default | unlimited | <sizeval> ); // deprecated
datasize ( default | unlimited | <sizeval> ); // deprecated
deny-answer-addresses { <address_match_element>; ... } [ except-from { <string>; ... } ];
deny-answer-aliases { <string>; ... } [ except-from { <string>; ... } ];
dialup ( notify | notify-passive | passive | refresh | <boolean> ); // deprecated
directory <quoted_string>;
disable-algorithms <string> { <string>; ... }; // may occur multiple times
disable-ds-digests <string> { <string>; ... }; // may occur multiple times
disable-empty-zone <string>; // may occur multiple times
dns64 <netprefix> {
break-dnssec <boolean>;
clients { <address_match_element>; ... };
exclude { <address_match_element>; ... };
mapped { <address_match_element>; ... };
recursive-only <boolean>;
suffix <ipv6_address>;
}; // may occur multiple times
dns64-contact <string>;
dns64-server <string>;
dnskey-sig-validity <integer>;
dnsrps-enable <boolean>;
dnsrps-options { <unspecified-text> };
dnssec-accept-expired <boolean>;
dnssec-dnskey-kskonly <boolean>;
dnssec-loadkeys-interval <integer>;
dnssec-must-be-secure <string> <boolean>; // may occur multiple times, deprecated
dnssec-policy <string>;
dnssec-secure-to-insecure <boolean>;
dnssec-update-mode ( maintain | no-resign );
dnssec-validation ( yes | no | auto );
dnstap { ( all | auth | client | forwarder | resolver | update ) [ ( query | response ) ]; ... };
dnstap-identity ( <quoted_string> | none | hostname );
dnstap-output ( file | unix ) <quoted_string> [ size ( unlimited | <size> ) ] [ versions ( unlimited | <integer> ) ] [ suffix ( increment | timestamp ) ];
dnstap-version ( <quoted_string> | none );
dscp <integer>; // obsolete
dual-stack-servers [ port <integer> ] { ( <quoted_string> [ port <integer> ] | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ); ... };
dump-file <quoted_string>;
edns-udp-size <integer>;
empty-contact <string>;
empty-server <string>;
empty-zones-enable <boolean>;
fetch-quota-params <integer> <fixedpoint> <fixedpoint> <fixedpoint>;
fetches-per-server <integer> [ ( drop | fail ) ];
fetches-per-zone <integer> [ ( drop | fail ) ];
files ( default | unlimited | <sizeval> ); // deprecated
flush-zones-on-shutdown <boolean>;
forward ( first | only );
forwarders [ port <integer> ] { ( <ipv4_address> | <ipv6_address> ) [ port <integer> ]; ... };
fstrm-set-buffer-hint <integer>;
fstrm-set-flush-timeout <integer>;
fstrm-set-input-queue-size <integer>;
fstrm-set-output-notify-threshold <integer>;
fstrm-set-output-queue-model ( mpsc | spsc );
fstrm-set-output-queue-size <integer>;
fstrm-set-reopen-interval <duration>;
geoip-directory ( <quoted_string> | none );
glue-cache <boolean>; // deprecated
heartbeat-interval <integer>; // deprecated
hostname ( <quoted_string> | none );
http-listener-clients <integer>;
http-port <integer>;
http-streams-per-connection <integer>;
https-port <integer>;
interface-interval <duration>;
ipv4only-contact <string>;
ipv4only-enable <boolean>;
ipv4only-server <string>;
ixfr-from-differences ( primary | master | secondary | slave | <boolean> );
keep-response-order { <address_match_element>; ... };
key-directory <quoted_string>;
lame-ttl <duration>;
listen-on [ port <integer> ] [ tls <string> ] [ http <string> ] { <address_match_element>; ... }; // may occur multiple times
listen-on-v6 [ port <integer> ] [ tls <string> ] [ http <string> ] { <address_match_element>; ... }; // may occur multiple times
lmdb-mapsize <sizeval>;
lock-file ( <quoted_string> | none );
managed-keys-directory <quoted_string>;
masterfile-format ( raw | text );
masterfile-style ( full | relative );
match-mapped-addresses <boolean>;
max-cache-size ( default | unlimited | <sizeval> | <percentage> );
max-cache-ttl <duration>;
max-clients-per-query <integer>;
max-ixfr-ratio ( unlimited | <percentage> );
max-journal-size ( default | unlimited | <sizeval> );
max-ncache-ttl <duration>;
max-query-count <integer>;
max-query-restarts <integer>;
max-records <integer>;
max-records-per-type <integer>;
max-recursion-depth <integer>;
max-recursion-queries <integer>;
max-refresh-time <integer>;
max-retry-time <integer>;
max-rsa-exponent-size <integer>;
max-stale-ttl <duration>;
max-transfer-idle-in <integer>;
max-transfer-idle-out <integer>;
max-transfer-time-in <integer>;
max-transfer-time-out <integer>;
max-types-per-name <integer>;
max-udp-size <integer>;
max-zone-ttl ( unlimited | <duration> );
memstatistics <boolean>;
memstatistics-file <quoted_string>;
message-compression <boolean>;
min-cache-ttl <duration>;
min-ncache-ttl <duration>;
min-refresh-time <integer>;
min-retry-time <integer>;
minimal-any <boolean>;
minimal-responses ( no-auth | no-auth-recursive | <boolean> );
multi-master <boolean>;
new-zones-directory <quoted_string>;
no-case-compress { <address_match_element>; ... };
nocookie-udp-size <integer>;
notify ( explicit | master-only | primary-only | <boolean> );
notify-delay <integer>;
notify-rate <integer>;
notify-source ( <ipv4_address> | * );
notify-source-v6 ( <ipv6_address> | * );
notify-to-soa <boolean>;
nsec3-test-zone <boolean>; // test only
nta-lifetime <duration>;
nta-recheck <duration>;
nxdomain-redirect <string>;
parental-source ( <ipv4_address> | * );
parental-source-v6 ( <ipv6_address> | * );
pid-file ( <quoted_string> | none );
port <integer>;
preferred-glue <string>;
prefetch <integer> [ <integer> ];
provide-ixfr <boolean>;
qname-minimization ( strict | relaxed | disabled | off );
query-source [ address ] ( <ipv4_address> | * );
query-source-v6 [ address ] ( <ipv6_address> | * );
querylog <boolean>;
random-device ( <quoted_string> | none ); // obsolete
rate-limit {
all-per-second <integer>;
errors-per-second <integer>;
exempt-clients { <address_match_element>; ... };
ipv4-prefix-length <integer>;
ipv6-prefix-length <integer>;
log-only <boolean>;
max-table-size <integer>;
min-table-size <integer>;
nodata-per-second <integer>;
nxdomains-per-second <integer>;
qps-scale <integer>;
referrals-per-second <integer>;
responses-per-second <integer>;
slip <integer>;
window <integer>;
};
recursing-file <quoted_string>;
recursion <boolean>;
recursive-clients <integer>;
request-expire <boolean>;
request-ixfr <boolean>;
request-nsid <boolean>;
require-server-cookie <boolean>;
reserved-sockets <integer>; // deprecated
resolver-nonbackoff-tries <integer>; // deprecated
resolver-query-timeout <integer>;
resolver-retry-interval <integer>; // deprecated
response-padding { <address_match_element>; ... } block-size <integer>;
response-policy { zone <string> [ add-soa <boolean> ] [ log <boolean> ] [ max-policy-ttl <duration> ] [ min-update-interval <duration> ] [ policy ( cname | disabled | drop | given | no-op | nodata | nxdomain | passthru | tcp-only <quoted_string> ) ] [ recursive-only <boolean> ] [ nsip-enable <boolean> ] [ nsdname-enable <boolean> ]; ... } [ add-soa <boolean> ] [ break-dnssec <boolean> ] [ max-policy-ttl <duration> ] [ min-update-interval <duration> ] [ min-ns-dots <integer> ] [ nsip-wait-recurse <boolean> ] [ nsdname-wait-recurse <boolean> ] [ qname-wait-recurse <boolean> ] [ recursive-only <boolean> ] [ nsip-enable <boolean> ] [ nsdname-enable <boolean> ] [ dnsrps-enable <boolean> ] [ dnsrps-options { <unspecified-text> } ];
reuseport <boolean>;
root-delegation-only [ exclude { <string>; ... } ]; // deprecated
root-key-sentinel <boolean>;
rrset-order { [ class <string> ] [ type <string> ] [ name <quoted_string> ] <string> <string>; ... };
secroots-file <quoted_string>;
send-cookie <boolean>;
serial-query-rate <integer>;
serial-update-method ( date | increment | unixtime );
server-id ( <quoted_string> | none | hostname );
servfail-ttl <duration>;
session-keyalg <string>;
session-keyfile ( <quoted_string> | none );
session-keyname <string>;
sig-signing-nodes <integer>;
sig-signing-signatures <integer>;
sig-signing-type <integer>;
sig-validity-interval <integer> [ <integer> ];
sortlist { <address_match_element>; ... };
stacksize ( default | unlimited | <sizeval> ); // deprecated
stale-answer-client-timeout ( disabled | off | <integer> );
stale-answer-enable <boolean>;
stale-answer-ttl <duration>;
stale-cache-enable <boolean>;
stale-refresh-time <duration>;
startup-notify-rate <integer>;
statistics-file <quoted_string>;
suppress-initial-notify <boolean>; // obsolete
synth-from-dnssec <boolean>;
tcp-advertised-timeout <integer>;
tcp-clients <integer>;
tcp-idle-timeout <integer>;
tcp-initial-timeout <integer>;
tcp-keepalive-timeout <integer>;
tcp-listen-queue <integer>;
tcp-receive-buffer <integer>;
tcp-send-buffer <integer>;
tkey-dhkey <quoted_string> <integer>; // deprecated
tkey-domain <quoted_string>;
tkey-gssapi-credential <quoted_string>;
tkey-gssapi-keytab <quoted_string>;
tls-port <integer>;
transfer-format ( many-answers | one-answer );
transfer-message-size <integer>;
transfer-source ( <ipv4_address> | * );
transfer-source-v6 ( <ipv6_address> | * );
transfers-in <integer>;
transfers-out <integer>;
transfers-per-ns <integer>;
trust-anchor-telemetry <boolean>;
try-tcp-refresh <boolean>;
udp-receive-buffer <integer>;
udp-send-buffer <integer>;
update-check-ksk <boolean>;
update-quota <integer>;
use-alt-transfer-source <boolean>; // deprecated
use-v4-udp-ports { <portrange>; ... }; // deprecated
use-v6-udp-ports { <portrange>; ... }; // deprecated
v6-bias <integer>;
validate-except { <string>; ... };
version ( <quoted_string> | none );
zero-no-soa-ttl <boolean>;
zero-no-soa-ttl-cache <boolean>;
zone-statistics ( full | terse | none | <boolean> );
};
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>topmost</p>
<p><strong>Tags: </strong>server</p>
<p><p>Defines global options to be used by BIND 9.</p>
</p>
</dd></dl>
<p>This is the grammar of the <code class="docutils literal notranslate"><span class="pre">options</span></code> statement in the <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>
file:</p>
</section>
<section id="options-block-definition-and-usage">
<h3><span class="section-number">8.2.14. </span><code class="docutils literal notranslate"><span class="pre">options</span></code> Block Definition and Usage<a class="headerlink" href="#options-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <code class="docutils literal notranslate"><span class="pre">options</span></code> statement sets up global options to be used by BIND.
This statement may appear only once in a configuration file. If there is
no <code class="docutils literal notranslate"><span class="pre">options</span></code> statement, an options block with each option set to its
default is used.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-attach-cache">
<span class="sig-name descname"><span class="pre">attach-cache</span></span><a class="headerlink" href="#namedconf-statement-attach-cache" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">attach-cache</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>view</p>
<p><p>Allows multiple views to share a single cache database.</p>
</p>
<p>This option allows multiple views to share a single cache database. Each view has
its own cache database by default, but if multiple views have the
same operational policy for name resolution and caching, those views
can share a single cache to save memory, and possibly improve
resolution efficiency, by using this option.</p>
<p>The <a class="reference internal" href="#namedconf-statement-attach-cache" title="namedconf-statement-attach-cache"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">attach-cache</span></code></a> option may also be specified in <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>
statements, in which case it overrides the global <a class="reference internal" href="#namedconf-statement-attach-cache" title="namedconf-statement-attach-cache"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">attach-cache</span></code></a>
option.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">cache_name</span></code> specifies the cache to be shared. When the <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
server configures views which are supposed to share a cache, it
creates a cache with the specified name for the first view of these
sharing views. The rest of the views simply refer to the
already-created cache.</p>
<p>One common configuration to share a cache is to allow all views
to share a single cache. This can be done by specifying
<a class="reference internal" href="#namedconf-statement-attach-cache" title="namedconf-statement-attach-cache"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">attach-cache</span></code></a> as a global option with an arbitrary name.</p>
<p>Another possible operation is to allow a subset of all views to share
a cache while the others retain their own caches. For example, if
there are three views A, B, and C, and only A and B should share a
cache, specify the <a class="reference internal" href="#namedconf-statement-attach-cache" title="namedconf-statement-attach-cache"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">attach-cache</span></code></a> option as a view of A (or B)’s
option, referring to the other view name:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">view</span> <span class="s2">"A"</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">this</span> <span class="n">view</span> <span class="n">has</span> <span class="n">its</span> <span class="n">own</span> <span class="n">cache</span>
<span class="o">...</span>
<span class="p">};</span>
<span class="n">view</span> <span class="s2">"B"</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">this</span> <span class="n">view</span> <span class="n">refers</span> <span class="n">to</span> <span class="n">A</span><span class="s1">'s cache</span>
<span class="n">attach</span><span class="o">-</span><span class="n">cache</span> <span class="s2">"A"</span><span class="p">;</span>
<span class="p">};</span>
<span class="n">view</span> <span class="s2">"C"</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">this</span> <span class="n">view</span> <span class="n">has</span> <span class="n">its</span> <span class="n">own</span> <span class="n">cache</span>
<span class="o">...</span>
<span class="p">};</span>
</pre></div>
</div>
<p>Views that share a cache must have the same policy on configurable
parameters that may affect caching. The current implementation
requires the following configurable options be consistent among these
views: <a class="reference internal" href="#namedconf-statement-check-names" title="namedconf-statement-check-names"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-names</span></code></a>, <a class="reference internal" href="#namedconf-statement-dnssec-accept-expired" title="namedconf-statement-dnssec-accept-expired"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-accept-expired</span></code></a>,
<a class="reference internal" href="#namedconf-statement-dnssec-validation" title="namedconf-statement-dnssec-validation"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-validation</span></code></a>, <a class="reference internal" href="#namedconf-statement-max-cache-ttl" title="namedconf-statement-max-cache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-cache-ttl</span></code></a>, <a class="reference internal" href="#namedconf-statement-max-ncache-ttl" title="namedconf-statement-max-ncache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-ncache-ttl</span></code></a>,
<a class="reference internal" href="#namedconf-statement-max-stale-ttl" title="namedconf-statement-max-stale-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-stale-ttl</span></code></a>, <a class="reference internal" href="#namedconf-statement-max-cache-size" title="namedconf-statement-max-cache-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-cache-size</span></code></a>, <a class="reference internal" href="#namedconf-statement-min-cache-ttl" title="namedconf-statement-min-cache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">min-cache-ttl</span></code></a>,
<a class="reference internal" href="#namedconf-statement-min-ncache-ttl" title="namedconf-statement-min-ncache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">min-ncache-ttl</span></code></a>, and <a class="reference internal" href="#namedconf-statement-zero-no-soa-ttl" title="namedconf-statement-zero-no-soa-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zero-no-soa-ttl</span></code></a>.</p>
<p>Note that there may be other parameters that may cause confusion if
they are inconsistent for different views that share a single cache.
For example, if these views define different sets of forwarders that
can return different answers for the same question, sharing the
answer does not make sense or could even be harmful. It is the
administrator’s responsibility to ensure that configuration differences in
different views do not cause disruption with a shared cache.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-directory">
<span class="sig-name descname"><span class="pre">directory</span></span><a class="headerlink" href="#namedconf-statement-directory" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">directory</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the server’s working directory.</p>
</p>
<p>This sets the working directory of the server. Any non-absolute pathnames in
the configuration file are taken as relative to this directory.
The default location for most server output files (e.g.,
<code class="docutils literal notranslate"><span class="pre">named.run</span></code>) is this directory. If a directory is not specified,
the working directory defaults to <code class="docutils literal notranslate"><span class="pre">"."</span></code>, the directory from
which the server was started. The directory specified should be an
absolute path, and <em>must</em> be writable by the effective user ID of the
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> process.</p>
<p>The option takes effect only at the time that the configuration
option is parsed; if other files are being included before or after specifying the
new <a class="reference internal" href="#namedconf-statement-directory" title="namedconf-statement-directory"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">directory</span></code></a>, the <a class="reference internal" href="#namedconf-statement-directory" title="namedconf-statement-directory"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">directory</span></code></a> option must be listed
before any other directive (like <code class="docutils literal notranslate"><span class="pre">include</span></code>) that can work with relative
files. The safest way to include files is to use absolute file names.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnstap">
<span class="sig-name descname"><span class="pre">dnstap</span></span><a class="headerlink" href="#namedconf-statement-dnstap" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnstap</span> <span class="pre">{</span> <span class="pre">(</span> <span class="pre">all</span> <span class="pre">|</span> <span class="pre">auth</span> <span class="pre">|</span> <span class="pre">client</span> <span class="pre">|</span> <span class="pre">forwarder</span> <span class="pre">|</span> <span class="pre">resolver</span> <span class="pre">|</span> <span class="pre">update</span> <span class="pre">)</span> <span class="pre">[</span> <span class="pre">(</span> <span class="pre">query</span> <span class="pre">|</span> <span class="pre">response</span> <span class="pre">)</span> <span class="pre">];</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Enables logging of <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages.</p>
</p>
<p><a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> is a fast, flexible method for capturing and logging DNS
traffic. Developed by Robert Edmonds at Farsight Security, Inc., and
supported by multiple DNS implementations, <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> uses
<code class="docutils literal notranslate"><span class="pre">libfstrm</span></code> (a lightweight high-speed framing library; see
<a class="reference external" href="https://github.com/farsightsec/fstrm">https://github.com/farsightsec/fstrm</a>) to send event payloads which
are encoded using Protocol Buffers (<code class="docutils literal notranslate"><span class="pre">libprotobuf-c</span></code>, a mechanism
for serializing structured data developed by Google, Inc.; see
<a class="reference external" href="https://protobuf.dev">https://protobuf.dev</a>).</p>
<p>To enable <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> at compile time, the <code class="docutils literal notranslate"><span class="pre">fstrm</span></code> and
<code class="docutils literal notranslate"><span class="pre">protobuf-c</span></code> libraries must be available, and BIND must be
configured with <code class="docutils literal notranslate"><span class="pre">--enable-dnstap</span></code>.</p>
<p>The <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> option is a bracketed list of message types to be
logged. These may be set differently for each view. Supported types
are <code class="docutils literal notranslate"><span class="pre">client</span></code>, <code class="docutils literal notranslate"><span class="pre">auth</span></code>, <code class="docutils literal notranslate"><span class="pre">resolver</span></code>, <code class="docutils literal notranslate"><span class="pre">forwarder</span></code>, and
<code class="docutils literal notranslate"><span class="pre">update</span></code>. Specifying type <code class="docutils literal notranslate"><span class="pre">all</span></code> causes all <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a>
messages to be logged, regardless of type.</p>
<p>Each type may take an additional argument to indicate whether to log
<code class="docutils literal notranslate"><span class="pre">query</span></code> messages or <code class="docutils literal notranslate"><span class="pre">response</span></code> messages; if not specified, both
queries and responses are logged.</p>
<p>Example: To log all authoritative queries and responses, recursive
client responses, and upstream queries sent by the resolver, use:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">dnstap</span> <span class="p">{</span>
<span class="n">auth</span><span class="p">;</span>
<span class="n">client</span> <span class="n">response</span><span class="p">;</span>
<span class="n">resolver</span> <span class="n">query</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>In the default configuration, the dnstap output for
recursive resolver traffic does not include the IP addresses used
by server-side sockets. This is caused by the fact that unless the
<a class="reference internal" href="#query-address"><span class="std std-ref">query source address</span></a> is explicitly set,
these sockets are bound to wildcard IP addresses and determining
the specific IP address used by each of them requires issuing a
system call (i.e. incurring a performance penalty).</p>
</div>
<p>Logged <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages can be parsed using the <a class="reference internal" href="manpages.html#std-iscman-dnstap-read"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">dnstap-read</span></code></a>
utility (see <a class="reference internal" href="manpages.html#man-dnstap-read"><span class="std std-ref">dnstap-read - print dnstap data in human-readable form</span></a> for details).</p>
<p>For more information on <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a>, see <a class="reference external" href="http://dnstap.info">http://dnstap.info</a>.</p>
<p>The fstrm library has a number of tunables that are exposed in
<a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>, and can be modified if necessary to improve
performance or prevent loss of data. These are:</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-fstrm-set-buffer-hint">
<span class="sig-name descname"><span class="pre">fstrm-set-buffer-hint</span></span><a class="headerlink" href="#namedconf-statement-fstrm-set-buffer-hint" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">fstrm-set-buffer-hint</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Sets the number of accumulated bytes in the output buffer before forcing a buffer flush.</p>
</p>
<p>The threshold number of bytes to
accumulate in the output buffer before forcing a buffer flush. The
minimum is 1024, the maximum is 65536, and the default is 8192.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-fstrm-set-flush-timeout">
<span class="sig-name descname"><span class="pre">fstrm-set-flush-timeout</span></span><a class="headerlink" href="#namedconf-statement-fstrm-set-flush-timeout" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">fstrm-set-flush-timeout</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Sets the number of seconds that unflushed data remains in the output buffer.</p>
</p>
<p>The number of seconds to allow
unflushed data to remain in the output buffer. The minimum is 1
second, the maximum is 600 seconds (10 minutes), and the default
is 1 second.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-fstrm-set-output-notify-threshold">
<span class="sig-name descname"><span class="pre">fstrm-set-output-notify-threshold</span></span><a class="headerlink" href="#namedconf-statement-fstrm-set-output-notify-threshold" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">fstrm-set-output-notify-threshold</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Sets the number of outstanding queue entries allowed on an input queue before waking the I/O thread.</p>
</p>
<p>The number of outstanding
queue entries to allow on an input queue before waking the I/O
thread. The minimum is 1 and the default is 32.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-fstrm-set-output-queue-model">
<span class="sig-name descname"><span class="pre">fstrm-set-output-queue-model</span></span><a class="headerlink" href="#namedconf-statement-fstrm-set-output-queue-model" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">fstrm-set-output-queue-model</span> <span class="pre">(</span> <span class="pre">mpsc</span> <span class="pre">|</span> <span class="pre">spsc</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Sets the queuing semantics to use for queue objects.</p>
</p>
<p>The queuing semantics
to use for queue objects. The default is <code class="docutils literal notranslate"><span class="pre">mpsc</span></code> (multiple
producer, single consumer); the other option is <code class="docutils literal notranslate"><span class="pre">spsc</span></code> (single
producer, single consumer).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-fstrm-set-input-queue-size">
<span class="sig-name descname"><span class="pre">fstrm-set-input-queue-size</span></span><a class="headerlink" href="#namedconf-statement-fstrm-set-input-queue-size" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">fstrm-set-input-queue-size</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Sets the number of queue entries to allocate for each input queue.</p>
</p>
<p>The number of queue entries to
allocate for each input queue. This value must be a power of 2.
The minimum is 2, the maximum is 16384, and the default is 512.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-fstrm-set-output-queue-size">
<span class="sig-name descname"><span class="pre">fstrm-set-output-queue-size</span></span><a class="headerlink" href="#namedconf-statement-fstrm-set-output-queue-size" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">fstrm-set-output-queue-size</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Sets the number of queue entries allocated for each output queue.</p>
</p>
<p>The number of queue entries to
allocate for each output queue. The minimum is 2, the maximum is
system-dependent and based on <code class="docutils literal notranslate"><span class="pre">IOV_MAX</span></code>, and the default is 64.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-fstrm-set-reopen-interval">
<span class="sig-name descname"><span class="pre">fstrm-set-reopen-interval</span></span><a class="headerlink" href="#namedconf-statement-fstrm-set-reopen-interval" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">fstrm-set-reopen-interval</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Sets the number of seconds to wait between attempts to reopen a closed output stream.</p>
</p>
<p>The number of seconds to wait
between attempts to reopen a closed output stream. The minimum is
1 second, the maximum is 600 seconds (10 minutes), and the default
is 5 seconds. For convenience, TTL-style time-unit suffixes may be
used to specify the value.</p>
</dd></dl>
<p>Note that all of the above minimum, maximum, and default values are
set by the <code class="docutils literal notranslate"><span class="pre">libfstrm</span></code> library, and may be subject to change in
future versions of the library. See the <code class="docutils literal notranslate"><span class="pre">libfstrm</span></code> documentation
for more information.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnstap-output">
<span class="sig-name descname"><span class="pre">dnstap-output</span></span><a class="headerlink" href="#namedconf-statement-dnstap-output" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnstap-output</span> <span class="pre">(</span> <span class="pre">file</span> <span class="pre">|</span> <span class="pre">unix</span> <span class="pre">)</span> <span class="pre"><quoted_string></span> <span class="pre">[</span> <span class="pre">size</span> <span class="pre">(</span> <span class="pre">unlimited</span> <span class="pre">|</span> <span class="pre"><size></span> <span class="pre">)</span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">versions</span> <span class="pre">(</span> <span class="pre">unlimited</span> <span class="pre">|</span> <span class="pre"><integer></span> <span class="pre">)</span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">suffix</span> <span class="pre">(</span> <span class="pre">increment</span> <span class="pre">|</span> <span class="pre">timestamp</span> <span class="pre">)</span> <span class="pre">];</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Configures the path to which the <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> frame stream is sent.</p>
</p>
<p>This configures the path to which the <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> frame stream is sent
if <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> is enabled at compile time and active.</p>
<p>The first argument is either <code class="docutils literal notranslate"><span class="pre">file</span></code> or <code class="docutils literal notranslate"><span class="pre">unix</span></code>, indicating whether
the destination is a file or a Unix domain socket. The second
argument is the path of the file or socket. (Note: when using a
socket, <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages are only sent if another process such
as <code class="docutils literal notranslate"><span class="pre">fstrm_capture</span></code> (provided with <code class="docutils literal notranslate"><span class="pre">libfstrm</span></code>) is listening on the
socket.)</p>
<p>If the first argument is <code class="docutils literal notranslate"><span class="pre">file</span></code>, then up to three additional
options can be added: <code class="docutils literal notranslate"><span class="pre">size</span></code> indicates the size to which a
<a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> log file can grow before being rolled to a new file;
<code class="docutils literal notranslate"><span class="pre">versions</span></code> specifies the number of rolled log files to retain; and
<code class="docutils literal notranslate"><span class="pre">suffix</span></code> indicates whether to retain rolled log files with an
incrementing counter as the suffix (<code class="docutils literal notranslate"><span class="pre">increment</span></code>) or with the
current timestamp (<code class="docutils literal notranslate"><span class="pre">timestamp</span></code>). These are similar to the <code class="docutils literal notranslate"><span class="pre">size</span></code>,
<code class="docutils literal notranslate"><span class="pre">versions</span></code>, and <code class="docutils literal notranslate"><span class="pre">suffix</span></code> options in a <a class="reference internal" href="#namedconf-statement-logging" title="namedconf-statement-logging"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">logging</span></code></a> channel. The
default is to allow <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> log files to grow to any size without
rolling.</p>
<p><a class="reference internal" href="#namedconf-statement-dnstap-output" title="namedconf-statement-dnstap-output"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap-output</span></code></a> can only be set globally in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>. Currently,
it can only be set once while <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is running; once set, it
cannot be changed by <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-reload"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">reload</span></code></a> or <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-reconfig"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">reconfig</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnstap-identity">
<span class="sig-name descname"><span class="pre">dnstap-identity</span></span><a class="headerlink" href="#namedconf-statement-dnstap-identity" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnstap-identity</span> <span class="pre">(</span> <span class="pre"><quoted_string></span> <span class="pre">|</span> <span class="pre">none</span> <span class="pre">|</span> <span class="pre">hostname</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Specifies an <code class="docutils literal notranslate"><span class="pre">identity</span></code> string to send in <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages.</p>
</p>
<p>This specifies an <code class="docutils literal notranslate"><span class="pre">identity</span></code> string to send in <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages. If
set to <a class="reference internal" href="#namedconf-statement-hostname" title="namedconf-statement-hostname"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">hostname</span></code></a>, which is the default, the server’s hostname
is sent. If set to <code class="docutils literal notranslate"><span class="pre">none</span></code>, no identity string is sent.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnstap-version">
<span class="sig-name descname"><span class="pre">dnstap-version</span></span><a class="headerlink" href="#namedconf-statement-dnstap-version" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnstap-version</span> <span class="pre">(</span> <span class="pre"><quoted_string></span> <span class="pre">|</span> <span class="pre">none</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Specifies a <a class="reference internal" href="#namedconf-statement-version" title="namedconf-statement-version"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">version</span></code></a> string to send in <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages.</p>
</p>
<p>This specifies a <a class="reference internal" href="#namedconf-statement-version" title="namedconf-statement-version"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">version</span></code></a> string to send in <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages. The
default is the version number of the BIND release. If set to
<code class="docutils literal notranslate"><span class="pre">none</span></code>, no version string is sent.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-geoip-directory">
<span class="sig-name descname"><span class="pre">geoip-directory</span></span><a class="headerlink" href="#namedconf-statement-geoip-directory" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">geoip-directory</span> <span class="pre">(</span> <span class="pre"><quoted_string></span> <span class="pre">|</span> <span class="pre">none</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the directory containing GeoIP database files.</p>
</p>
<p>When <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is compiled using the MaxMind GeoIP2 geolocation API, this
specifies the directory containing GeoIP database files. By default, the
option is set based on the prefix used to build the <code class="docutils literal notranslate"><span class="pre">libmaxminddb</span></code> module;
for example, if the library is installed in <code class="docutils literal notranslate"><span class="pre">/usr/local/lib</span></code>, then the
default <a class="reference internal" href="#namedconf-statement-geoip-directory" title="namedconf-statement-geoip-directory"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">geoip-directory</span></code></a> is <code class="docutils literal notranslate"><span class="pre">/usr/local/share/GeoIP</span></code>. See <a class="reference internal" href="#namedconf-statement-acl" title="namedconf-statement-acl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">acl</span></code></a>
for details about <code class="docutils literal notranslate"><span class="pre">geoip</span></code> ACLs.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-key-directory">
<span class="sig-name descname"><span class="pre">key-directory</span></span><a class="headerlink" href="#namedconf-statement-key-directory" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">key-directory</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Indicates the directory where public and private DNSSEC key files are found.</p>
</p>
<p>This is the directory where the public and private DNSSEC key files should be
found when performing a dynamic update of secure zones, if different
than the current working directory. (Note that this option has no
effect on the paths for files containing non-DNSSEC keys such as
<code class="docutils literal notranslate"><span class="pre">bind.keys</span></code>, <code class="docutils literal notranslate"><span class="pre">rndc.key</span></code>, or <code class="docutils literal notranslate"><span class="pre">session.key</span></code>.)</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-lmdb-mapsize">
<span class="sig-name descname"><span class="pre">lmdb-mapsize</span></span><a class="headerlink" href="#namedconf-statement-lmdb-mapsize" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">lmdb-mapsize</span> <span class="pre"><sizeval>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets a maximum size for the memory map of the new-zone database in LMDB database format.</p>
</p>
<p>When <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is built with liblmdb, this option sets a maximum size
for the memory map of the new-zone database (NZD) in LMDB database
format. This database is used to store configuration information for
zones added using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-addzone"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">addzone</span></code></a>. Note that this is not the NZD
database file size, but the largest size that the database may grow
to.</p>
<p>Because the database file is memory-mapped, its size is limited by
the address space of the <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> process. The default of 32 megabytes
was chosen to be usable with 32-bit <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> builds. The largest
permitted value is 1 terabyte. Given typical zone configurations
without elaborate ACLs, a 32 MB NZD file ought to be able to hold
configurations of about 100,000 zones.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-managed-keys-directory">
<span class="sig-name descname"><span class="pre">managed-keys-directory</span></span><a class="headerlink" href="#namedconf-statement-managed-keys-directory" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">managed-keys-directory</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the directory in which to store the files that track managed DNSSEC keys.</p>
</p>
<p>This specifies the directory in which to store the files that track managed DNSSEC
keys (i.e., those configured using the <code class="docutils literal notranslate"><span class="pre">initial-key</span></code> or <code class="docutils literal notranslate"><span class="pre">initial-ds</span></code>
keywords in a <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> statement). By default, this is the working
directory. The directory <em>must</em> be writable by the effective user ID of the
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> process.</p>
<p>If <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is not configured to use views, managed keys for
the server are tracked in a single file called
<code class="docutils literal notranslate"><span class="pre">managed-keys.bind</span></code>. Otherwise, managed keys are tracked in
separate files, one file per view; each file name is the view
name (or, if it contains characters that are incompatible with use as
a file name, the SHA256 hash of the view name), followed by the
extension <code class="docutils literal notranslate"><span class="pre">.mkeys</span></code>.</p>
<p>(Note: in earlier releases, file names for views always used the
SHA256 hash of the view name. To ensure compatibility after upgrading,
if a file using the old name format is found to exist, it is
used instead of the new format.)</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-ixfr-ratio">
<span class="sig-name descname"><span class="pre">max-ixfr-ratio</span></span><a class="headerlink" href="#namedconf-statement-max-ixfr-ratio" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-ixfr-ratio</span> <span class="pre">(</span> <span class="pre">unlimited</span> <span class="pre">|</span> <span class="pre"><percentage></span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Sets the maximum size for IXFR responses to zone transfer requests.</p>
</p>
<p>This sets the size threshold (expressed as a percentage of the size
of the full zone) beyond which <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> chooses to use an AXFR
response rather than IXFR when answering zone transfer requests. See
<a class="reference internal" href="chapter6.html#incremental-zone-transfers"><span class="std std-ref">Incremental Zone Transfers (IXFR)</span></a>.</p>
<p>The minimum value is <code class="docutils literal notranslate"><span class="pre">1%</span></code>. The keyword <code class="docutils literal notranslate"><span class="pre">unlimited</span></code> disables ratio
checking and allows IXFRs of any size. The default is <code class="docutils literal notranslate"><span class="pre">100%</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-new-zones-directory">
<span class="sig-name descname"><span class="pre">new-zones-directory</span></span><a class="headerlink" href="#namedconf-statement-new-zones-directory" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">new-zones-directory</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Specifies the directory where configuration parameters are stored for zones added by <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-addzone"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">addzone</span></code></a>.</p>
</p>
<p>This specifies the directory in which to store the configuration
parameters for zones added via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-addzone"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">addzone</span></code></a>. By default, this is
the working directory. If set to a relative path, it is relative
to the working directory. The directory <em>must</em> be writable by the
effective user ID of the <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> process.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-qname-minimization">
<span class="sig-name descname"><span class="pre">qname-minimization</span></span><a class="headerlink" href="#namedconf-statement-qname-minimization" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">qname-minimization</span> <span class="pre">(</span> <span class="pre">strict</span> <span class="pre">|</span> <span class="pre">relaxed</span> <span class="pre">|</span> <span class="pre">disabled</span> <span class="pre">|</span> <span class="pre">off</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls QNAME minimization behavior in the BIND 9 resolver.</p>
</p>
<p>When this is set to <code class="docutils literal notranslate"><span class="pre">strict</span></code>, BIND follows the QNAME minimization
algorithm to the letter, as specified in <span class="target" id="index-6"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc7816.html"><strong>RFC 7816</strong></a>.</p>
<p>Setting this option to <code class="docutils literal notranslate"><span class="pre">relaxed</span></code> causes BIND to fall back to
normal (non-minimized) query mode when it receives either NXDOMAIN
or other unexpected responses (e.g., SERVFAIL, improper zone
cut, REFUSED) to a minimized query.</p>
<p>In <code class="docutils literal notranslate"><span class="pre">relaxed</span></code> mode <code class="docutils literal notranslate"><span class="pre">named</span></code> makes NS queries for <code class="docutils literal notranslate"><span class="pre"><domain></span></code> as it
walks down the tree.</p>
<p><code class="docutils literal notranslate"><span class="pre">disabled</span></code> disables QNAME minimization completely.
<code class="docutils literal notranslate"><span class="pre">off</span></code> is a synonym for <code class="docutils literal notranslate"><span class="pre">disabled</span></code>.</p>
<p>The current default is <code class="docutils literal notranslate"><span class="pre">relaxed</span></code>, but it may be changed to
<code class="docutils literal notranslate"><span class="pre">strict</span></code> in a future release.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tkey-gssapi-keytab">
<span class="sig-name descname"><span class="pre">tkey-gssapi-keytab</span></span><a class="headerlink" href="#namedconf-statement-tkey-gssapi-keytab" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tkey-gssapi-keytab</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>security</p>
<p><p>Sets the KRB5 keytab file to use for GSS-TSIG updates.</p>
</p>
<p>This is the KRB5 keytab file to use for GSS-TSIG updates. If this option is
set and <code class="docutils literal notranslate"><span class="pre">tkey-gssapi-credential</span></code> is not set, updates are
allowed with any key matching a principal in the specified keytab.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tkey-gssapi-credential">
<span class="sig-name descname"><span class="pre">tkey-gssapi-credential</span></span><a class="headerlink" href="#namedconf-statement-tkey-gssapi-credential" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tkey-gssapi-credential</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>security</p>
<p><p>Sets the security credential for authentication keys requested by the GSS-TSIG protocol.</p>
</p>
<p>This is the security credential with which the server should authenticate
keys requested by the GSS-TSIG protocol. Currently only Kerberos 5
authentication is available; the credential is a Kerberos
principal which the server can acquire through the default system key
file, normally <code class="docutils literal notranslate"><span class="pre">/etc/krb5.keytab</span></code>. The location of the keytab file can be
overridden using the <a class="reference internal" href="#namedconf-statement-tkey-gssapi-keytab" title="namedconf-statement-tkey-gssapi-keytab"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tkey-gssapi-keytab</span></code></a> option. Normally this
principal is of the form <code class="docutils literal notranslate"><span class="pre">DNS/server.domain</span></code>. To use
GSS-TSIG, <a class="reference internal" href="#namedconf-statement-tkey-domain" title="namedconf-statement-tkey-domain"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tkey-domain</span></code></a> must also be set if a specific keytab is
not set with <a class="reference internal" href="#namedconf-statement-tkey-gssapi-keytab" title="namedconf-statement-tkey-gssapi-keytab"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tkey-gssapi-keytab</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tkey-domain">
<span class="sig-name descname"><span class="pre">tkey-domain</span></span><a class="headerlink" href="#namedconf-statement-tkey-domain" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tkey-domain</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>security</p>
<p><p>Sets the domain appended to the names of all shared keys generated with <code class="docutils literal notranslate"><span class="pre">TKEY</span></code>.</p>
</p>
<p>This domain is appended to the names of all shared keys generated with
<code class="docutils literal notranslate"><span class="pre">TKEY</span></code>. When a client requests a <code class="docutils literal notranslate"><span class="pre">TKEY</span></code> exchange, it may or may
not specify the desired name for the key. If present, the name of the
shared key is <code class="docutils literal notranslate"><span class="pre">client-specified</span> <span class="pre">part</span></code> + <a class="reference internal" href="#namedconf-statement-tkey-domain" title="namedconf-statement-tkey-domain"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tkey-domain</span></code></a>.
Otherwise, the name of the shared key is <code class="docutils literal notranslate"><span class="pre">random</span> <span class="pre">hex</span> <span class="pre">digits</span></code>
+ <a class="reference internal" href="#namedconf-statement-tkey-domain" title="namedconf-statement-tkey-domain"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tkey-domain</span></code></a>. In most cases, the <code class="docutils literal notranslate"><span class="pre">domainname</span></code>
should be the server’s domain name, or an otherwise nonexistent
subdomain like <code class="docutils literal notranslate"><span class="pre">_tkey.domainname</span></code>. If using GSS-TSIG,
this variable must be defined, unless a specific keytab
is specified using <a class="reference internal" href="#namedconf-statement-tkey-gssapi-keytab" title="namedconf-statement-tkey-gssapi-keytab"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tkey-gssapi-keytab</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tkey-dhkey">
<span class="sig-name descname"><span class="pre">tkey-dhkey</span></span><a class="headerlink" href="#namedconf-statement-tkey-dhkey" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tkey-dhkey</span> <span class="pre"><quoted_string></span> <span class="pre"><integer>;</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Sets the Diffie-Hellman key used by the server to generate shared keys.</p>
</p>
<p>This is the Diffie-Hellman key used by the server to generate shared keys
with clients using the Diffie-Hellman mode of <code class="docutils literal notranslate"><span class="pre">TKEY</span></code>. The server
must be able to load the public and private keys from files in the
working directory. In most cases, the <code class="docutils literal notranslate"><span class="pre">key_name</span></code> should be the
server’s host name.</p>
<p>This option is deprecated, and will be rendered non-operational in a
future release.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dump-file">
<span class="sig-name descname"><span class="pre">dump-file</span></span><a class="headerlink" href="#namedconf-statement-dump-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dump-file</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Indicates the pathname of the file where the server dumps the database after <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-dumpdb"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">dumpdb</span></code></a>.</p>
</p>
<p>This is the pathname of the file the server dumps the database to, when
instructed to do so with <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-dumpdb"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">dumpdb</span></code></a>. If not specified, the
default is <code class="docutils literal notranslate"><span class="pre">named_dump.db</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-memstatistics-file">
<span class="sig-name descname"><span class="pre">memstatistics-file</span></span><a class="headerlink" href="#namedconf-statement-memstatistics-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">memstatistics-file</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Sets the pathname of the file where the server writes memory usage statistics on exit.</p>
</p>
<p>This is the pathname of the file the server writes memory usage statistics to
on exit. If not specified, the default is <code class="docutils literal notranslate"><span class="pre">named.memstats</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-lock-file">
<span class="sig-name descname"><span class="pre">lock-file</span></span><a class="headerlink" href="#namedconf-statement-lock-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">lock-file</span> <span class="pre">(</span> <span class="pre"><quoted_string></span> <span class="pre">|</span> <span class="pre">none</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the pathname of the file on which <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> attempts to acquire a file lock when starting for the first time.</p>
</p>
<p>This is the pathname of a file on which <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> attempts to acquire a
file lock when starting for the first time; if unsuccessful, the
server terminates, under the assumption that another server
is already running. If not specified, the default is
<code class="docutils literal notranslate"><span class="pre">none</span></code>.</p>
<p>Specifying <code class="docutils literal notranslate"><span class="pre">lock-file</span> <span class="pre">none</span></code> disables the use of a lock file.
<a class="reference internal" href="#namedconf-statement-lock-file" title="namedconf-statement-lock-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">lock-file</span></code></a> is ignored if <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> was run using the <a class="reference internal" href="manpages.html#cmdoption-named-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></code></a>
option, which overrides it. Changes to <a class="reference internal" href="#namedconf-statement-lock-file" title="namedconf-statement-lock-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">lock-file</span></code></a> are ignored if
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is being reloaded or reconfigured; it is only effective
when the server is first started.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-pid-file">
<span class="sig-name descname"><span class="pre">pid-file</span></span><a class="headerlink" href="#namedconf-statement-pid-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">pid-file</span> <span class="pre">(</span> <span class="pre"><quoted_string></span> <span class="pre">|</span> <span class="pre">none</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the pathname of the file where the server writes its process ID.</p>
</p>
<p>This is the pathname of the file the server writes its process ID in. If not
specified, the default is <code class="docutils literal notranslate"><span class="pre">/run/named.pid</span></code>. The PID file
is used by programs that send signals to the running name
server. Specifying <code class="docutils literal notranslate"><span class="pre">pid-file</span> <span class="pre">none</span></code> disables the use of a PID file;
no file is written and any existing one is removed. Note
that <code class="docutils literal notranslate"><span class="pre">none</span></code> is a keyword, not a filename, and therefore is not
enclosed in double quotes.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-recursing-file">
<span class="sig-name descname"><span class="pre">recursing-file</span></span><a class="headerlink" href="#namedconf-statement-recursing-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">recursing-file</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the pathname of the file where the server dumps queries that are currently recursing via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-recursing"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">recursing</span></code></a>.</p>
</p>
<p>This is the pathname of the file where the server dumps the queries that are
currently recursing, when instructed to do so with <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-recursing"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">recursing</span></code></a>.
If not specified, the default is <code class="docutils literal notranslate"><span class="pre">named.recursing</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-statistics-file">
<span class="sig-name descname"><span class="pre">statistics-file</span></span><a class="headerlink" href="#namedconf-statement-statistics-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">statistics-file</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging, server</p>
<p><p>Specifies the pathname of the file where the server appends statistics, when using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-stats"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">stats</span></code></a>.</p>
</p>
<p>This is the pathname of the file the server appends statistics to, when
instructed to do so using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-stats"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">stats</span></code></a>. If not specified, the
default is <code class="docutils literal notranslate"><span class="pre">named.stats</span></code> in the server’s current directory. The
format of the file is described in <a class="reference internal" href="#statsfile"><span class="std std-ref">The Statistics File</span></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-bindkeys-file">
<span class="sig-name descname"><span class="pre">bindkeys-file</span></span><a class="headerlink" href="#namedconf-statement-bindkeys-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">bindkeys-file</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the pathname of a file to override the built-in trusted keys provided by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
</p>
<p>This is the pathname of a file to override the built-in trusted keys provided
by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>. See the discussion of <a class="reference internal" href="#namedconf-statement-dnssec-validation" title="namedconf-statement-dnssec-validation"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-validation</span></code></a> for
details. If not specified, the default is <code class="docutils literal notranslate"><span class="pre">/etc/bind/bind.keys</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-secroots-file">
<span class="sig-name descname"><span class="pre">secroots-file</span></span><a class="headerlink" href="#namedconf-statement-secroots-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">secroots-file</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the pathname of the file where the server dumps security roots, when using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-secroots"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">secroots</span></code></a>.</p>
</p>
<p>This is the pathname of the file the server dumps security roots to, when
instructed to do so with <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-secroots"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">secroots</span></code></a>. If not specified, the
default is <code class="docutils literal notranslate"><span class="pre">named.secroots</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-session-keyfile">
<span class="sig-name descname"><span class="pre">session-keyfile</span></span><a class="headerlink" href="#namedconf-statement-session-keyfile" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">session-keyfile</span> <span class="pre">(</span> <span class="pre"><quoted_string></span> <span class="pre">|</span> <span class="pre">none</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>security</p>
<p><p>Specifies the pathname of the file where a TSIG session key is written, when generated by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> for use by <code class="docutils literal notranslate"><span class="pre">nsupdate</span> <span class="pre">-l</span></code>.</p>
</p>
<p>This is the pathname of the file into which to write a TSIG session key
generated by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> for use by <code class="docutils literal notranslate"><span class="pre">nsupdate</span> <span class="pre">-l</span></code>. If not specified,
the default is <code class="docutils literal notranslate"><span class="pre">/run/session.key</span></code>. (See <a class="reference internal" href="#dynamic-update-policies"><span class="std std-ref">Dynamic Update Policies</span></a>,
and in particular the discussion of the <a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> statement’s
<code class="docutils literal notranslate"><span class="pre">local</span></code> option, for more information about this feature.)</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-session-keyname">
<span class="sig-name descname"><span class="pre">session-keyname</span></span><a class="headerlink" href="#namedconf-statement-session-keyname" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">session-keyname</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>security</p>
<p><p>Specifies the key name for the TSIG session key.</p>
</p>
<p>This is the key name to use for the TSIG session key. If not specified, the
default is <code class="docutils literal notranslate"><span class="pre">local-ddns</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-session-keyalg">
<span class="sig-name descname"><span class="pre">session-keyalg</span></span><a class="headerlink" href="#namedconf-statement-session-keyalg" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">session-keyalg</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>security</p>
<p><p>Specifies the algorithm to use for the TSIG session key.</p>
</p>
<p>This is the algorithm to use for the TSIG session key. Valid values are
hmac-sha1, hmac-sha224, hmac-sha256, hmac-sha384, hmac-sha512, and
hmac-md5. If not specified, the default is hmac-sha256.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-port">
<span class="sig-name descname"><span class="pre">port</span></span><a class="headerlink" href="#namedconf-statement-port" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">port</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Specifies the UDP/TCP port number the server uses to receive and send DNS protocol traffic.</p>
</p>
<p>This is the UDP/TCP port number the server uses to receive and send DNS
protocol traffic. The default is 53. This option is mainly intended
for server testing; a server using a port other than 53 is not
able to communicate with the global DNS.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tls-port">
<span class="sig-name descname"><span class="pre">tls-port</span></span><a class="headerlink" href="#namedconf-statement-tls-port" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tls-port</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Specifies the TCP port number the server uses to receive and send DNS-over-TLS protocol traffic.</p>
</p>
<p>This is the TCP port number the server uses to receive and send
DNS-over-TLS protocol traffic. The default is 853.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-https-port">
<span class="sig-name descname"><span class="pre">https-port</span></span><a class="headerlink" href="#namedconf-statement-https-port" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">https-port</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Specifies the TCP port number the server uses to receive and send DNS-over-HTTPS protocol traffic.</p>
</p>
<p>This is the TCP port number the server uses to receive and send
DNS-over-HTTPS protocol traffic. The default is 443.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-http-port">
<span class="sig-name descname"><span class="pre">http-port</span></span><a class="headerlink" href="#namedconf-statement-http-port" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">http-port</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Specifies the TCP port number the server uses to receive and send unencrypted DNS traffic via HTTP.</p>
</p>
<p>This is the TCP port number the server uses to receive and send
unencrypted DNS traffic via HTTP (a configuration that may be useful
when encryption is handled by third-party software or by a reverse
proxy).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-http-listener-clients">
<span class="sig-name descname"><span class="pre">http-listener-clients</span></span><a class="headerlink" href="#namedconf-statement-http-listener-clients" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">http-listener-clients</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Limits the number of active concurrent connections on a per-listener basis.</p>
</p>
<p>This sets a hard limit on the number of active concurrent connections
on a per-listener basis. The default value is 300; setting it to 0
removes the quota.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-http-streams-per-connection">
<span class="sig-name descname"><span class="pre">http-streams-per-connection</span></span><a class="headerlink" href="#namedconf-statement-http-streams-per-connection" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">http-streams-per-connection</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Limits the number of active concurrent HTTP/2 streams on a per-connection basis.</p>
</p>
<p>This sets a hard limit on the number of active concurrent HTTP/2
streams on a per-connection basis. The default value is 100;
setting it to 0 removes the limit. Once the limit is exceeded, the
server finishes the HTTP session.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dscp">
<span class="sig-name descname"><span class="pre">dscp</span></span><a class="headerlink" href="#namedconf-statement-dscp" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dscp</span> <span class="pre"><integer>;</span> <span class="pre">//</span> <span class="pre">obsolete</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Sets the Differentiated Services Code Point (DSCP) value (obsolete).</p>
</p>
<p>This option used to set the global Differentiated Services Code Point
(DSCP) value to classify outgoing DNS traffic. It is now obsolete and
has no effect.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-preferred-glue">
<span class="sig-name descname"><span class="pre">preferred-glue</span></span><a class="headerlink" href="#namedconf-statement-preferred-glue" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">preferred-glue</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls the order of glue records in an A or AAAA response.</p>
</p>
<p>If specified, the listed type (A or AAAA) is emitted before
other glue in the additional section of a query response. The default
is to prefer A records when responding to queries that arrived via
IPv4 and AAAA when responding to queries that arrived via IPv6.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-root-delegation-only">
<span class="sig-name descname"><span class="pre">root-delegation-only</span></span><a class="headerlink" href="#namedconf-statement-root-delegation-only" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">root-delegation-only</span> <span class="pre">[</span> <span class="pre">exclude</span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">];</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Turns on enforcement of delegation-only in top-level domains (TLDs) and root zones with an optional exclude list.</p>
</p>
<p>This turns on enforcement of delegation-only in top-level domains (TLDs)
and root zones with an
optional exclude list.</p>
<p>DS queries are expected to be made to and be answered by delegation-only
zones. Such queries and responses are treated as an exception to
delegation-only processing and are not converted to NXDOMAIN
responses, provided a CNAME is not discovered at the query name.</p>
<p>If a delegation-only zone server also serves a child zone, it is not
always possible to determine whether an answer comes from the
delegation-only zone or the child zone. SOA NS and DNSKEY records are
apex-only records and a matching response that contains these records
or DS is treated as coming from a child zone. RRSIG records are also
examined to see whether they are signed by a child zone, and the
authority section is examined to see if there is evidence that
the answer is from the child zone. Answers that are determined to be
from a child zone are not converted to NXDOMAIN responses. Despite
all these checks, there is still a possibility of false negatives when
a child zone is being served.</p>
<p>Similarly, false positives can arise from empty nodes (no records at
the name) in the delegation-only zone when the query type is not <code class="docutils literal notranslate"><span class="pre">ANY</span></code>.</p>
<p>Note that some TLDs are not delegation-only; e.g., “DE”, “LV”, “US”, and
“MUSEUM”. This list is not exhaustive.</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">options</span> <span class="p">{</span>
<span class="n">root</span><span class="o">-</span><span class="n">delegation</span><span class="o">-</span><span class="n">only</span> <span class="n">exclude</span> <span class="p">{</span> <span class="s2">"de"</span><span class="p">;</span> <span class="s2">"lv"</span><span class="p">;</span> <span class="s2">"us"</span><span class="p">;</span> <span class="s2">"museum"</span><span class="p">;</span> <span class="p">};</span>
<span class="p">};</span>
</pre></div>
</div>
<p>This option is deprecated, and will be rendered non-operational in a
future release.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-disable-algorithms">
<span class="sig-name descname"><span class="pre">disable-algorithms</span></span><a class="headerlink" href="#namedconf-statement-disable-algorithms" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">disable-algorithms</span> <span class="pre"><string></span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Disables DNSSEC algorithms from a specified zone.</p>
</p>
<p>This disables the specified DNSSEC algorithms at and below the specified
name. Multiple <a class="reference internal" href="#namedconf-statement-disable-algorithms" title="namedconf-statement-disable-algorithms"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">disable-algorithms</span></code></a> statements are allowed. Only
the best-match <a class="reference internal" href="#namedconf-statement-disable-algorithms" title="namedconf-statement-disable-algorithms"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">disable-algorithms</span></code></a> clause is used to
determine the algorithms.</p>
<p>If all supported algorithms are disabled, the zones covered by the
<a class="reference internal" href="#namedconf-statement-disable-algorithms" title="namedconf-statement-disable-algorithms"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">disable-algorithms</span></code></a> setting are treated as insecure.</p>
<p>Configured trust anchors in <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> (or <a class="reference internal" href="#namedconf-statement-managed-keys" title="namedconf-statement-managed-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">managed-keys</span></code></a> or
<a class="reference internal" href="#namedconf-statement-trusted-keys" title="namedconf-statement-trusted-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trusted-keys</span></code></a>) that match a disabled algorithm are ignored and treated
as if they were not configured.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-disable-ds-digests">
<span class="sig-name descname"><span class="pre">disable-ds-digests</span></span><a class="headerlink" href="#namedconf-statement-disable-ds-digests" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">disable-ds-digests</span> <span class="pre"><string></span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>dnssec, zone</p>
<p><p>Disables DS digest types from a specified zone.</p>
</p>
<p>This disables the specified DS digest types at and below the specified
name. Multiple <a class="reference internal" href="#namedconf-statement-disable-ds-digests" title="namedconf-statement-disable-ds-digests"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">disable-ds-digests</span></code></a> statements are allowed. Only
the best-match <a class="reference internal" href="#namedconf-statement-disable-ds-digests" title="namedconf-statement-disable-ds-digests"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">disable-ds-digests</span></code></a> clause is used to
determine the digest types.</p>
<p>If all supported digest types are disabled, the zones covered by
<a class="reference internal" href="#namedconf-statement-disable-ds-digests" title="namedconf-statement-disable-ds-digests"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">disable-ds-digests</span></code></a> are treated as insecure.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnssec-must-be-secure">
<span class="sig-name descname"><span class="pre">dnssec-must-be-secure</span></span><a class="headerlink" href="#namedconf-statement-dnssec-must-be-secure" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnssec-must-be-secure</span> <span class="pre"><string></span> <span class="pre"><boolean>;</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times,</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Defines hierarchies that must or may not be secure (signed and validated).</p>
</p>
<p>This option is deprecated and will be removed in a future release.</p>
<p>This specifies hierarchies which must be or may not be secure (signed and
validated). If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, then <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> only accepts answers if
they are secure. If <code class="docutils literal notranslate"><span class="pre">no</span></code>, then normal DNSSEC validation applies,
allowing insecure answers to be accepted. The specified domain
must be defined as a trust anchor, for instance in a <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>
statement, or <code class="docutils literal notranslate"><span class="pre">dnssec-validation</span> <span class="pre">auto</span></code> must be active.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dns64">
<span class="sig-name descname"><span class="pre">dns64</span></span><a class="headerlink" href="#namedconf-statement-dns64" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">dns64</span> <span class="o"><</span><span class="n">netprefix</span><span class="o">></span> <span class="p">{</span>
<span class="k">break</span><span class="o">-</span><span class="n">dnssec</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">clients</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">exclude</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">mapped</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">recursive</span><span class="o">-</span><span class="n">only</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">suffix</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span><span class="p">;</span>
<span class="p">};</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Instructs <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to return mapped IPv4 addresses to AAAA queries when there are no AAAA records.</p>
</p>
<p>This directive instructs <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to return mapped IPv4 addresses to
AAAA queries when there are no AAAA records. It is intended to be
used in conjunction with a NAT64. Each <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> defines one DNS64
prefix. Multiple DNS64 prefixes can be defined.</p>
<p>Compatible IPv6 prefixes have lengths of 32, 40, 48, 56, 64, and 96, per
<span class="target" id="index-7"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc6052.html"><strong>RFC 6052</strong></a>. Bits 64..71 inclusive must be zero, with the most significant bit
of the prefix in position 0.</p>
<p>In addition, a reverse IP6.ARPA zone is created for the prefix
to provide a mapping from the IP6.ARPA names to the corresponding
IN-ADDR.ARPA names using synthesized CNAMEs.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dns64-server">
<span class="sig-name descname"><span class="pre">dns64-server</span></span><a class="headerlink" href="#namedconf-statement-dns64-server" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dns64-server</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the name of the server for <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> zones.</p>
</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dns64-contact">
<span class="sig-name descname"><span class="pre">dns64-contact</span></span><a class="headerlink" href="#namedconf-statement-dns64-contact" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dns64-contact</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the name of the contact for <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> zones.</p>
</p>
<p><a class="reference internal" href="#namedconf-statement-dns64-server" title="namedconf-statement-dns64-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64-server</span></code></a> and
<a class="reference internal" href="#namedconf-statement-dns64-contact" title="namedconf-statement-dns64-contact"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64-contact</span></code></a> can be used to specify the name of the server and
contact for the zones. These can be set at the view/options
level but not on a per-prefix basis.</p>
<p><a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> will also cause IPV4ONLY.ARPA to be created if not
explicitly disabled using <a class="reference internal" href="#namedconf-statement-ipv4only-enable" title="namedconf-statement-ipv4only-enable"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ipv4only-enable</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-clients">
<span class="sig-name descname"><span class="pre">clients</span></span><a class="headerlink" href="#namedconf-statement-clients" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">clients</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options.dns64, view.dns64</p>
<p><strong>Tags: </strong>query</p>
<p><p>Specifies an access control list (ACL) of clients that are affected by a given <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> directive.</p>
</p>
<p>Each <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> supports an optional <a class="reference internal" href="#namedconf-statement-clients" title="namedconf-statement-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">clients</span></code></a> ACL that determines
which clients are affected by this directive. If not defined, it
defaults to <code class="docutils literal notranslate"><span class="pre">any;</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-mapped">
<span class="sig-name descname"><span class="pre">mapped</span></span><a class="headerlink" href="#namedconf-statement-mapped" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">mapped</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options.dns64, view.dns64</p>
<p><strong>Tags: </strong>query</p>
<p><p>Specifies an access control list (ACL) of IPv4 addresses that are to be mapped to the corresponding A RRset in <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p>
<p>Each <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> block supports an optional <a class="reference internal" href="#namedconf-statement-mapped" title="namedconf-statement-mapped"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">mapped</span></code></a> ACL that selects which
IPv4 addresses are to be mapped in the corresponding A RRset. If not
defined, it defaults to <code class="docutils literal notranslate"><span class="pre">any;</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-exclude">
<span class="sig-name descname"><span class="pre">exclude</span></span><a class="headerlink" href="#namedconf-statement-exclude" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">exclude</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options.dns64, view.dns64</p>
<p><strong>Tags: </strong>query</p>
<p><p>Allows a list of IPv6 addresses to be ignored if they appear in a domain name’s AAAA records in <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p>
<p>Normally, DNS64 does not apply to a domain name that owns one or more
AAAA records; these records are simply returned. The optional
<a class="reference internal" href="#namedconf-statement-exclude" title="namedconf-statement-exclude"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">exclude</span></code></a> ACL allows specification of a list of IPv6 addresses that
are ignored if they appear in a domain name’s AAAA records;
DNS64 is applied to any A records the domain name owns. If not
defined, <a class="reference internal" href="#namedconf-statement-exclude" title="namedconf-statement-exclude"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">exclude</span></code></a> defaults to ::ffff:0.0.0.0/96.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-suffix">
<span class="sig-name descname"><span class="pre">suffix</span></span><a class="headerlink" href="#namedconf-statement-suffix" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">suffix</span> <span class="pre"><ipv6_address>;</span></code></p>
<p><strong>Blocks: </strong>options.dns64, view.dns64</p>
<p><strong>Tags: </strong>query</p>
<p><p>Defines trailing bits for mapped IPv4 address bits in <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p>
<p>An optional <a class="reference internal" href="#namedconf-statement-suffix" title="namedconf-statement-suffix"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">suffix</span></code></a> can also be defined to set the bits trailing
the mapped IPv4 address bits. By default these bits are set to
<code class="docutils literal notranslate"><span class="pre">::</span></code>. The bits matching the prefix and mapped IPv4 address must be
zero.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-recursive-only">
<span class="sig-name descname"><span class="pre">recursive-only</span></span><a class="headerlink" href="#namedconf-statement-recursive-only" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">recursive-only</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options.dns64, view.dns64</p>
<p><strong>Tags: </strong>query</p>
<p><p>Toggles whether <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> synthesis occurs only for recursive queries.</p>
</p>
<p>If <a class="reference internal" href="#namedconf-statement-recursive-only" title="namedconf-statement-recursive-only"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursive-only</span></code></a> is set to <code class="docutils literal notranslate"><span class="pre">yes</span></code>, the DNS64 synthesis only
happens for recursive queries. The default is <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-break-dnssec">
<span class="sig-name descname"><span class="pre">break-dnssec</span></span><a class="headerlink" href="#namedconf-statement-break-dnssec" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">break-dnssec</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options.dns64, view.dns64</p>
<p><strong>Tags: </strong>query</p>
<p><p>Enables <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> synthesis even if the validated result would cause a DNSSEC validation failure.</p>
</p>
<p>If <a class="reference internal" href="#namedconf-statement-break-dnssec" title="namedconf-statement-break-dnssec"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">break-dnssec</span></code></a> is set to <code class="docutils literal notranslate"><span class="pre">yes</span></code>, the DNS64 synthesis happens
even if the result, if validated, would cause a DNSSEC validation
failure. If this option is set to <code class="docutils literal notranslate"><span class="pre">no</span></code> (the default), the DO is set
on the incoming query, and there are RRSIGs on the applicable
records, then synthesis does not happen.</p>
</dd></dl>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>acl rfc1918 { 10/8; 192.168/16; 172.16/12; };
dns64 64:FF9B::/96 {
clients { any; };
mapped { !rfc1918; any; };
exclude { 64:FF9B::/96; ::ffff:0000:0000/96; };
suffix ::;
};
</pre></div>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-ipv4only-enable">
<span class="sig-name descname"><span class="pre">ipv4only-enable</span></span><a class="headerlink" href="#namedconf-statement-ipv4only-enable" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">ipv4only-enable</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Enables automatic IPv4 zones if a <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> block is configured.</p>
</p>
<p>This enables or disables automatic zones <code class="docutils literal notranslate"><span class="pre">ipv4only.arpa</span></code>,
<code class="docutils literal notranslate"><span class="pre">170.0.0.192.in-addr.arpa</span></code>, and <code class="docutils literal notranslate"><span class="pre">171.0.0.192.in-addr.arpa</span></code>.</p>
<p>By default these zones are loaded if <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> is configured.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-ipv4only-server">
<span class="sig-name descname"><span class="pre">ipv4only-server</span></span><a class="headerlink" href="#namedconf-statement-ipv4only-server" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">ipv4only-server</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Specifies the name of the server for the IPV4ONLY.ARPA zone created by <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-ipv4only-contact">
<span class="sig-name descname"><span class="pre">ipv4only-contact</span></span><a class="headerlink" href="#namedconf-statement-ipv4only-contact" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">ipv4only-contact</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the contact for the IPV4ONLY.ARPA zone created by <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p>
<p><a class="reference internal" href="#namedconf-statement-ipv4only-server" title="namedconf-statement-ipv4only-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ipv4only-server</span></code></a> and <a class="reference internal" href="#namedconf-statement-ipv4only-contact" title="namedconf-statement-ipv4only-contact"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ipv4only-contact</span></code></a> can be used to specify the name
of the server and contact for the IPV4ONLY.ARPA zone created by
<a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnssec-loadkeys-interval">
<span class="sig-name descname"><span class="pre">dnssec-loadkeys-interval</span></span><a class="headerlink" href="#namedconf-statement-dnssec-loadkeys-interval" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnssec-loadkeys-interval</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Sets the frequency of automatic checks of the DNSSEC key repository.</p>
</p>
<p>When a zone is configured with <code class="docutils literal notranslate"><span class="pre">auto-dnssec</span> <span class="pre">maintain;</span></code>, its key
repository must be checked periodically to see if any new keys have
been added or any existing keys’ timing metadata has been updated
(see <a class="reference internal" href="manpages.html#man-dnssec-keygen"><span class="std std-ref">dnssec-keygen: DNSSEC key generation tool</span></a> and <a class="reference internal" href="manpages.html#man-dnssec-settime"><span class="std std-ref">dnssec-settime: set the key timing metadata for a DNSSEC key</span></a>).
The <a class="reference internal" href="#namedconf-statement-dnssec-loadkeys-interval" title="namedconf-statement-dnssec-loadkeys-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-loadkeys-interval</span></code></a> option
sets the frequency of automatic repository checks, in minutes. The
default is <code class="docutils literal notranslate"><span class="pre">60</span></code> (1 hour), the minimum is <code class="docutils literal notranslate"><span class="pre">1</span></code> (1 minute), and
the maximum is <code class="docutils literal notranslate"><span class="pre">1440</span></code> (24 hours); any higher value is silently
reduced.</p>
</dd></dl>
<p><a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a></p>
<blockquote>
<div><p>This specifies which key and signing policy (KASP) should be used for this
zone. This is a string referring to a <a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> block.
The default is <code class="docutils literal notranslate"><span class="pre">none</span></code>.</p>
</div></blockquote>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnssec-update-mode">
<span class="sig-name descname"><span class="pre">dnssec-update-mode</span></span><a class="headerlink" href="#namedconf-statement-dnssec-update-mode" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnssec-update-mode</span> <span class="pre">(</span> <span class="pre">maintain</span> <span class="pre">|</span> <span class="pre">no-resign</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Controls the scheduled maintenance of DNSSEC signatures.</p>
</p>
<p>If this option is set to its default value of <code class="docutils literal notranslate"><span class="pre">maintain</span></code> in a zone
of <a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span> <span class="pre">primary</span></code></a> which is DNSSEC-signed and configured to allow
dynamic updates (see <a class="reference internal" href="#dynamic-update-policies"><span class="std std-ref">Dynamic Update Policies</span></a>), and if <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> has access
to the private signing key(s) for the zone, then <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
automatically signs all new or changed records and maintains signatures
for the zone by regenerating RRSIG records whenever they approach
their expiration date.</p>
<p>If the option is changed to <code class="docutils literal notranslate"><span class="pre">no-resign</span></code>, then <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> signs
all new or changed records, but scheduled maintenance of signatures
is disabled.</p>
<p>With either of these settings, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> rejects updates to a
DNSSEC-signed zone when the signing keys are inactive or unavailable
to <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>. (A planned third option, <code class="docutils literal notranslate"><span class="pre">external</span></code>, will disable all
automatic signing and allow DNSSEC data to be submitted into a zone
via dynamic update; this is not yet implemented.)</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-nta-lifetime">
<span class="sig-name descname"><span class="pre">nta-lifetime</span></span><a class="headerlink" href="#namedconf-statement-nta-lifetime" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">nta-lifetime</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the lifetime, in seconds, for negative trust anchors added via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-nta"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">nta</span></code></a>.</p>
</p>
<p>This specifies the default lifetime, in seconds, for
negative trust anchors added via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-nta"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">nta</span></code></a>.</p>
<p>A negative trust anchor selectively disables DNSSEC validation for
zones that are known to be failing because of misconfiguration, rather
than an attack. When data to be validated is at or below an active
NTA (and above any other configured trust anchors), <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
aborts the DNSSEC validation process and treats the data as insecure
rather than bogus. This continues until the NTA’s lifetime has
elapsed. NTAs persist across <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> restarts.</p>
<p>For convenience, TTL-style time-unit suffixes can be used to specify the NTA
lifetime in seconds, minutes, or hours. It also accepts ISO 8601 duration
formats.</p>
<p><a class="reference internal" href="#namedconf-statement-nta-lifetime" title="namedconf-statement-nta-lifetime"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">nta-lifetime</span></code></a> defaults to one hour; it cannot exceed one week.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-nta-recheck">
<span class="sig-name descname"><span class="pre">nta-recheck</span></span><a class="headerlink" href="#namedconf-statement-nta-recheck" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">nta-recheck</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the time interval for checking whether negative trust anchors added via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-nta"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">nta</span></code></a> are still necessary.</p>
</p>
<p>This specifies how often to check whether negative trust anchors added via
<a class="reference internal" href="manpages.html#cmdoption-rndc-arg-nta"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">nta</span></code></a> are still necessary.</p>
<p>A negative trust anchor is normally used when a domain has stopped
validating due to operator error; it temporarily disables DNSSEC
validation for that domain. In the interest of ensuring that DNSSEC
validation is turned back on as soon as possible, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
periodically sends a query to the domain, ignoring negative trust
anchors, to find out whether it can now be validated. If so, the
negative trust anchor is allowed to expire early.</p>
<p>Validity checks can be disabled for an individual NTA by using
<a class="reference internal" href="manpages.html#cmdoption-rndc-arg-nta"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">nta</span> <span class="pre">-f</span></code></a>, or for all NTAs by setting <a class="reference internal" href="#namedconf-statement-nta-recheck" title="namedconf-statement-nta-recheck"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">nta-recheck</span></code></a> to zero.</p>
<p>For convenience, TTL-style time-unit suffixes can be used to specify the NTA
recheck interval in seconds, minutes, or hours. It also accepts ISO 8601
duration formats.</p>
<p>The default is five minutes. It cannot be longer than <a class="reference internal" href="#namedconf-statement-nta-lifetime" title="namedconf-statement-nta-lifetime"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">nta-lifetime</span></code></a>, which
cannot be longer than a week.</p>
</dd></dl>
<dl>
<dt><a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-zone-ttl</span></code></a></dt><dd><dl class="field-list simple">
<dt class="field-odd">tags<span class="colon">:</span></dt>
<dd class="field-odd"><p>deprecated</p>
</dd>
<dt class="field-even">short<span class="colon">:</span></dt>
<dd class="field-even"><p>Specifies a maximum permissible time-to-live (TTL) value, in seconds.</p>
</dd>
</dl>
<p>This should now be configured as part of <a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a>.
Use of this option in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>, <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>
and <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> blocks has no effect on any zone for which
a <a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> has also been configured.</p>
<p><a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-zone-ttl</span></code></a> specifies a maximum permissible TTL value in seconds.
For convenience, TTL-style time-unit suffixes may be used to specify the
maximum value. When a zone file is loaded, any record encountered with a
TTL higher than <a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-zone-ttl</span></code></a> causes the zone to be rejected.</p>
<p>This is needed in DNSSEC-maintained zones because when rolling to a new
DNSKEY, the old key needs to remain available until RRSIG records
have expired from caches. The <a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-zone-ttl</span></code></a> option guarantees that
the largest TTL in the zone is no higher than the set value.</p>
<p>When used in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>, <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> and
<a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> blocks, setting <a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-zone-ttl</span></code></a> to zero
is equivalent to “unlimited”.</p>
</dd>
</dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-stale-answer-ttl">
<span class="sig-name descname"><span class="pre">stale-answer-ttl</span></span><a class="headerlink" href="#namedconf-statement-stale-answer-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">stale-answer-ttl</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Specifies the time to live (TTL) to be returned on stale answers, in seconds.</p>
</p>
<p>This specifies the TTL to be returned on stale answers. The default is 30
seconds. The minimum allowed is 1 second; a value of 0 is updated silently
to 1 second.</p>
<p>For stale answers to be returned, they must be enabled, either in the
configuration file using <a class="reference internal" href="#namedconf-statement-stale-answer-enable" title="namedconf-statement-stale-answer-enable"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">stale-answer-enable</span></code></a> or via
<a class="reference internal" href="manpages.html#cmdoption-rndc-arg-serve-stale"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">serve-stale</span> <span class="pre">on</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-serial-update-method">
<span class="sig-name descname"><span class="pre">serial-update-method</span></span><a class="headerlink" href="#namedconf-statement-serial-update-method" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">serial-update-method</span> <span class="pre">(</span> <span class="pre">date</span> <span class="pre">|</span> <span class="pre">increment</span> <span class="pre">|</span> <span class="pre">unixtime</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Specifies the update method to be used for the zone serial number in the SOA record.</p>
</p>
<p>Zones configured for dynamic DNS may use this option to set the
update method to be used for the zone serial number in the SOA
record.</p>
<p>With the default setting of <code class="docutils literal notranslate"><span class="pre">serial-update-method</span> <span class="pre">increment;</span></code>, the
SOA serial number is incremented by one each time the zone is
updated.</p>
<p>When set to <code class="docutils literal notranslate"><span class="pre">serial-update-method</span> <span class="pre">unixtime;</span></code>, the SOA serial number
is set to the number of seconds since the Unix epoch, unless the
serial number is already greater than or equal to that value, in
which case it is simply incremented by one.</p>
<p>When set to <code class="docutils literal notranslate"><span class="pre">serial-update-method</span> <span class="pre">date;</span></code>, the new SOA serial number
is the current date in the form “YYYYMMDD”, followed by two
zeroes, unless the existing serial number is already greater than or
equal to that value, in which case it is incremented by one.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-zone-statistics">
<span class="sig-name descname"><span class="pre">zone-statistics</span></span><a class="headerlink" href="#namedconf-statement-zone-statistics" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">zone-statistics</span> <span class="pre">(</span> <span class="pre">full</span> <span class="pre">|</span> <span class="pre">terse</span> <span class="pre">|</span> <span class="pre">none</span> <span class="pre">|</span> <span class="pre"><boolean></span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, redirect, secondary, static-stub, stub)</p>
<p><strong>Tags: </strong>zone, logging</p>
<p><p>Controls the level of statistics gathered for all zones.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">full</span></code>, the server collects statistical data on all zones,
unless specifically turned off on a per-zone basis by specifying
<code class="docutils literal notranslate"><span class="pre">zone-statistics</span> <span class="pre">terse</span></code> or <code class="docutils literal notranslate"><span class="pre">zone-statistics</span> <span class="pre">none</span></code> in the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a>
statement. The statistical data includes, for example, DNSSEC signing
operations and the number of authoritative answers per query type. The
default is <code class="docutils literal notranslate"><span class="pre">terse</span></code>, providing minimal statistics on zones
(including name and current serial number, but not query type
counters).</p>
<p>These statistics may be accessed via the <code class="docutils literal notranslate"><span class="pre">statistics-channel</span></code> or
using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-stats"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">stats</span></code></a>, which dumps them to the file listed in the
<a class="reference internal" href="#namedconf-statement-statistics-file" title="namedconf-statement-statistics-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">statistics-file</span></code></a>. See also <a class="reference internal" href="#statsfile"><span class="std std-ref">The Statistics File</span></a>.</p>
<p>For backward compatibility with earlier versions of BIND 9, the
<a class="reference internal" href="#namedconf-statement-zone-statistics" title="namedconf-statement-zone-statistics"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone-statistics</span></code></a> option can also accept <code class="docutils literal notranslate"><span class="pre">yes</span></code> or <code class="docutils literal notranslate"><span class="pre">no</span></code>; <code class="docutils literal notranslate"><span class="pre">yes</span></code>
has the same meaning as <code class="docutils literal notranslate"><span class="pre">full</span></code>. As of BIND 9.10, <code class="docutils literal notranslate"><span class="pre">no</span></code> has the
same meaning as <code class="docutils literal notranslate"><span class="pre">none</span></code>; previously, it was the same as <code class="docutils literal notranslate"><span class="pre">terse</span></code>.</p>
</dd></dl>
<section id="boolean-options">
<span id="id5"></span><h4><span class="section-number">8.2.14.1. </span>Boolean Options<a class="headerlink" href="#boolean-options" title="Link to this heading"></a></h4>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-automatic-interface-scan">
<span class="sig-name descname"><span class="pre">automatic-interface-scan</span></span><a class="headerlink" href="#namedconf-statement-automatic-interface-scan" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">automatic-interface-scan</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Controls the automatic rescanning of network interfaces when addresses are added or removed.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code> and supported by the operating system, this automatically rescans
network interfaces when the interface addresses are added or removed. The
default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>. This configuration option does not affect the time-based
<a class="reference internal" href="#namedconf-statement-interface-interval" title="namedconf-statement-interface-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">interface-interval</span></code></a> option; it is recommended to set the time-based
<a class="reference internal" href="#namedconf-statement-interface-interval" title="namedconf-statement-interface-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">interface-interval</span></code></a> to 0 when the operator confirms that automatic
interface scanning is supported by the operating system.</p>
<p>The <a class="reference internal" href="#namedconf-statement-automatic-interface-scan" title="namedconf-statement-automatic-interface-scan"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">automatic-interface-scan</span></code></a> implementation uses routing sockets for the
network interface discovery; therefore, the operating system must
support the routing sockets for this feature to work.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-allow-new-zones">
<span class="sig-name descname"><span class="pre">allow-new-zones</span></span><a class="headerlink" href="#namedconf-statement-allow-new-zones" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">allow-new-zones</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, zone</p>
<p><p>Controls the ability to add zones at runtime via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-addzone"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">addzone</span></code></a>.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, then zones can be added at runtime via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-addzone"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">addzone</span></code></a>.
The default is <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
<p>Newly added zones’ configuration parameters are stored so that they
can persist after the server is restarted. The configuration
information is saved in a file called <code class="docutils literal notranslate"><span class="pre">viewname.nzf</span></code> (or, if
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is compiled with liblmdb, in an LMDB database file called
<code class="docutils literal notranslate"><span class="pre">viewname.nzd</span></code>). “viewname” is the name of the view, unless the view
name contains characters that are incompatible with use as a file
name, in which case a cryptographic hash of the view name is used
instead.</p>
<p>Configurations for zones added at runtime are stored either in
a new-zone file (NZF) or a new-zone database (NZD), depending on
whether <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> was linked with liblmdb at compile time. See
<a class="reference internal" href="manpages.html#man-rndc"><span class="std std-ref">rndc - name server control utility</span></a> for further details about <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-addzone"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">addzone</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-auth-nxdomain">
<span class="sig-name descname"><span class="pre">auth-nxdomain</span></span><a class="headerlink" href="#namedconf-statement-auth-nxdomain" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">auth-nxdomain</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls whether BIND, acting as a resolver, provides authoritative NXDOMAIN (domain does not exist) answers.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, then the <code class="docutils literal notranslate"><span class="pre">AA</span></code> bit is always set on NXDOMAIN responses,
even if the server is not actually authoritative. The default is
<code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-memstatistics">
<span class="sig-name descname"><span class="pre">memstatistics</span></span><a class="headerlink" href="#namedconf-statement-memstatistics" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">memstatistics</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server, logging</p>
<p><p>Controls whether memory statistics are written to the file specified by <a class="reference internal" href="#namedconf-statement-memstatistics-file" title="namedconf-statement-memstatistics-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">memstatistics-file</span></code></a> at exit.</p>
</p>
<p>This writes memory statistics to the file specified by
<a class="reference internal" href="#namedconf-statement-memstatistics-file" title="namedconf-statement-memstatistics-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">memstatistics-file</span></code></a> at exit. The default is <code class="docutils literal notranslate"><span class="pre">no</span></code> unless <a class="reference internal" href="manpages.html#cmdoption-named-m"><code class="xref std std-option docutils literal notranslate"><span class="pre">-m</span>
<span class="pre">record</span></code></a> is specified on the command line, in which case it is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dialup">
<span class="sig-name descname"><span class="pre">dialup</span></span><a class="headerlink" href="#namedconf-statement-dialup" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dialup</span> <span class="pre">(</span> <span class="pre">notify</span> <span class="pre">|</span> <span class="pre">notify-passive</span> <span class="pre">|</span> <span class="pre">passive</span> <span class="pre">|</span> <span class="pre">refresh</span> <span class="pre">|</span> <span class="pre"><boolean></span> <span class="pre">);</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary, stub)</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Concentrates zone maintenance so that all transfers take place once every <a class="reference internal" href="#namedconf-statement-heartbeat-interval" title="namedconf-statement-heartbeat-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">heartbeat-interval</span></code></a>, ideally during a single call.</p>
</p>
<p>This option is deprecated and will be removed in a future release.</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, then the server treats all zones as if they are doing
zone transfers across a dial-on-demand dialup link, which can be
brought up by traffic originating from this server. Although this setting has
different effects according to zone type, it concentrates the zone
maintenance so that everything happens quickly, once every
<a class="reference internal" href="#namedconf-statement-heartbeat-interval" title="namedconf-statement-heartbeat-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">heartbeat-interval</span></code></a>, ideally during a single call. It also
suppresses some normal zone maintenance traffic. The default
is <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
<p>If specified in the <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> and
<a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statements, the <a class="reference internal" href="#namedconf-statement-dialup" title="namedconf-statement-dialup"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dialup</span></code></a> option overrides the global <a class="reference internal" href="#namedconf-statement-dialup" title="namedconf-statement-dialup"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dialup</span></code></a>
option.</p>
<p>If the zone is a primary zone, the server sends out a NOTIFY
request to all the secondaries (default). This should trigger the zone
serial number check in the secondary (providing it supports NOTIFY),
allowing the secondary to verify the zone while the connection is active.
The set of servers to which NOTIFY is sent can be controlled by
<a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify</span></code></a> and <a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a>.</p>
<p>If the zone is a secondary or stub zone, the server suppresses
the regular “zone up to date” (refresh) queries and only performs them
when the <a class="reference internal" href="#namedconf-statement-heartbeat-interval" title="namedconf-statement-heartbeat-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">heartbeat-interval</span></code></a> expires, in addition to sending NOTIFY
requests.</p>
<p>Finer control can be achieved by using <a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify</span></code></a>, which only sends
NOTIFY messages; <code class="docutils literal notranslate"><span class="pre">notify-passive</span></code>, which sends NOTIFY messages and
suppresses the normal refresh queries; <code class="docutils literal notranslate"><span class="pre">refresh</span></code>, which suppresses
normal refresh processing and sends refresh queries when the
<a class="reference internal" href="#namedconf-statement-heartbeat-interval" title="namedconf-statement-heartbeat-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">heartbeat-interval</span></code></a> expires; and <code class="docutils literal notranslate"><span class="pre">passive</span></code>, which disables
normal refresh processing.</p>
<table class="docutils align-default">
<tbody>
<tr class="row-odd"><td><p>dialup mode</p></td>
<td><p>normal refresh</p></td>
<td><p>heart-beat
refresh</p></td>
<td><p>heart-beat
notify</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">no</span></code>
(default)</p></td>
<td><p>yes</p></td>
<td><p>no</p></td>
<td><p>no</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">yes</span></code></p></td>
<td><p>no</p></td>
<td><p>yes</p></td>
<td><p>yes</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">notify</span></code></p></td>
<td><p>yes</p></td>
<td><p>no</p></td>
<td><p>yes</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">refresh</span></code></p></td>
<td><p>no</p></td>
<td><p>yes</p></td>
<td><p>no</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">passive</span></code></p></td>
<td><p>no</p></td>
<td><p>no</p></td>
<td><p>no</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">notify-passive</span></code></p></td>
<td><p>no</p></td>
<td><p>no</p></td>
<td><p>yes</p></td>
</tr>
</tbody>
</table>
<p>Note that normal NOTIFY processing is not affected by <a class="reference internal" href="#namedconf-statement-dialup" title="namedconf-statement-dialup"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dialup</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-flush-zones-on-shutdown">
<span class="sig-name descname"><span class="pre">flush-zones-on-shutdown</span></span><a class="headerlink" href="#namedconf-statement-flush-zones-on-shutdown" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">flush-zones-on-shutdown</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Controls whether pending zone writes are flushed when the name server exits.</p>
</p>
<p>When the name server exits upon receiving SIGTERM, flush or do not
flush any pending zone writes. The default is
<code class="docutils literal notranslate"><span class="pre">flush-zones-on-shutdown</span> <span class="pre">no</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-root-key-sentinel">
<span class="sig-name descname"><span class="pre">root-key-sentinel</span></span><a class="headerlink" href="#namedconf-statement-root-key-sentinel" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">root-key-sentinel</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Controls whether BIND 9 responds to root key sentinel probes.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, the server responds to root key sentinel probes as described in
<span class="target" id="index-8"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc8509.html"><strong>RFC 8509</strong></a>:. The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-reuseport">
<span class="sig-name descname"><span class="pre">reuseport</span></span><a class="headerlink" href="#namedconf-statement-reuseport" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">reuseport</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Enables kernel load-balancing of sockets.</p>
</p>
<p>This option enables kernel load-balancing of sockets on systems which support
it, including Linux (SO_REUSEPORT) and FreeBSD (SO_REUSEPORT_LB). This
instructs the kernel to distribute incoming socket connections among the
networking threads based on a hashing scheme. For more information, see the
receive network flow classification options (<code class="docutils literal notranslate"><span class="pre">rx-flow-hash</span></code>) section in the
<code class="docutils literal notranslate"><span class="pre">ethtool</span></code> manual page. The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
<p>Enabling <a class="reference internal" href="#namedconf-statement-reuseport" title="namedconf-statement-reuseport"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">reuseport</span></code></a> significantly increases general throughput when
incoming traffic is distributed uniformly onto the threads by the
operating system. However, in cases where a worker thread is busy with a
long-lasting operation, such as processing a Response Policy Zone (RPZ) or
Catalog Zone update or an unusually large zone transfer, incoming traffic
that hashes onto that thread may be delayed. On servers where these events
occur frequently, it may be preferable to disable socket load-balancing so
that other threads can pick up the traffic that would have been sent to the
busy thread.</p>
<p>Note: this option can only be set when <code class="docutils literal notranslate"><span class="pre">named</span></code> first starts.
Changes will not take effect during reconfiguration; the server
must be restarted.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-message-compression">
<span class="sig-name descname"><span class="pre">message-compression</span></span><a class="headerlink" href="#namedconf-statement-message-compression" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">message-compression</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls whether DNS name compression is used in responses to regular queries.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, DNS name compression is used in responses to regular
queries (not including AXFR or IXFR, which always use compression).
Setting this option to <code class="docutils literal notranslate"><span class="pre">no</span></code> reduces CPU usage on servers and may
improve throughput. However, it increases response size, which may
cause more queries to be processed using TCP; a server with
compression disabled is out of compliance with <span class="target" id="index-9"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1123.html"><strong>RFC 1123</strong></a> Section
6.1.3.2. The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-minimal-responses">
<span class="sig-name descname"><span class="pre">minimal-responses</span></span><a class="headerlink" href="#namedconf-statement-minimal-responses" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">minimal-responses</span> <span class="pre">(</span> <span class="pre">no-auth</span> <span class="pre">|</span> <span class="pre">no-auth-recursive</span> <span class="pre">|</span> <span class="pre"><boolean></span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls whether the server only adds records to the authority and additional data sections when they are required (e.g. delegations, negative responses). This improves server performance.</p>
</p>
<p>This option controls the addition of records to the authority and
additional sections of responses. Such records may be included in
responses to be helpful to clients; for example, MX records may
have associated address records included in the additional section,
obviating the need for a separate address lookup. However, adding
these records to responses is not mandatory and requires additional
database lookups, causing extra latency when marshalling responses.</p>
<p>Responses to DNSKEY, DS, CDNSKEY, and CDS requests will never have
optional additional records added. Responses to NS requests will
always have additional section processing.</p>
<p><a class="reference internal" href="#namedconf-statement-minimal-responses" title="namedconf-statement-minimal-responses"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">minimal-responses</span></code></a> takes one of four values:</p>
<ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">no</span></code>: the server is as complete as possible when generating
responses.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">yes</span></code>: the server only adds records to the authority and additional
sections when such records are required by the DNS protocol (for
example, when returning delegations or negative responses). This
provides the best server performance but may result in more client
queries.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">no-auth</span></code>: the server omits records from the authority section except
when they are required, but it may still add records to the
additional section.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">no-auth-recursive</span></code>: the same as <code class="docutils literal notranslate"><span class="pre">no-auth</span></code> when recursion is requested
in the query (RD=1), or the same as <code class="docutils literal notranslate"><span class="pre">no</span></code> if recursion is not requested.</p></li>
</ul>
<p><code class="docutils literal notranslate"><span class="pre">no-auth</span></code> and <code class="docutils literal notranslate"><span class="pre">no-auth-recursive</span></code> are useful when answering stub
clients, which usually ignore the authority section.
<code class="docutils literal notranslate"><span class="pre">no-auth-recursive</span></code> is meant for use in mixed-mode servers that
handle both authoritative and recursive queries.</p>
<p>The default is <code class="docutils literal notranslate"><span class="pre">no-auth-recursive</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-glue-cache">
<span class="sig-name descname"><span class="pre">glue-cache</span></span><a class="headerlink" href="#namedconf-statement-glue-cache" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">glue-cache</span> <span class="pre"><boolean>;</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Deprecated.</p>
</p>
<p>When set to <code class="docutils literal notranslate"><span class="pre">yes</span></code>, a cache is used to improve query performance
when adding address-type (A and AAAA) glue records to the additional
section of DNS response messages that delegate to a child zone.</p>
<p>The glue cache uses memory proportional to the number of delegations
in the zone. The default setting is <code class="docutils literal notranslate"><span class="pre">yes</span></code>, which improves
performance at the cost of increased memory usage for the zone. To avoid
this, set it to <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>This option is deprecated and its use is discouraged. The
glue cache will be permanently <em>enabled</em> in a future release.</p>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-minimal-any">
<span class="sig-name descname"><span class="pre">minimal-any</span></span><a class="headerlink" href="#namedconf-statement-minimal-any" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">minimal-any</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls whether the server replies with only one of the RRsets for a query name, when generating a positive response to a query of type ANY over UDP.</p>
</p>
<p>If set to <code class="docutils literal notranslate"><span class="pre">yes</span></code>, the server replies with only one of
the RRsets for the query name, and its covering RRSIGs if any,
when generating a positive response to a query of type ANY over UDP,
instead of replying with all known RRsets for the name. Similarly, a
query for type RRSIG is answered with the RRSIG records covering
only one type. This can reduce the impact of some kinds of attack
traffic, without harming legitimate clients. (Note, however, that the
RRset returned is the first one found in the database; it is not
necessarily the smallest available RRset.) Additionally,
<a class="reference internal" href="#namedconf-statement-minimal-responses" title="namedconf-statement-minimal-responses"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">minimal-responses</span></code></a> is turned on for these queries, so no
unnecessary records are added to the authority or additional
sections. The default is <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-notify">
<span class="sig-name descname"><span class="pre">notify</span></span><a class="headerlink" href="#namedconf-statement-notify" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">notify</span> <span class="pre">(</span> <span class="pre">explicit</span> <span class="pre">|</span> <span class="pre">master-only</span> <span class="pre">|</span> <span class="pre">primary-only</span> <span class="pre">|</span> <span class="pre"><boolean></span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Controls whether <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages are sent on zone changes.</p>
</p>
<p>If set to <code class="docutils literal notranslate"><span class="pre">yes</span></code> (the default), DNS NOTIFY messages are sent when a
zone the server is authoritative for changes; see <a class="reference internal" href="chapter6.html#notify"><span class="std std-ref">using notify</span></a>.
The messages are sent to the servers listed in the zone’s NS records
(except the primary server identified in the SOA MNAME field), and to
any servers listed in the <a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a> option.</p>
<p>If set to <code class="docutils literal notranslate"><span class="pre">primary-only</span></code> (or the older keyword <code class="docutils literal notranslate"><span class="pre">master-only</span></code>),
notifies are only sent for primary zones. If set to <code class="docutils literal notranslate"><span class="pre">explicit</span></code>,
notifies are sent only to servers explicitly listed using
<a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a>. If set to <code class="docutils literal notranslate"><span class="pre">no</span></code>, no notifies are sent.</p>
<p>The <a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify</span></code></a> option may also be specified in the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a>
statement, in which case it overrides the <code class="docutils literal notranslate"><span class="pre">options</span> <span class="pre">notify</span></code>
statement. It would only be necessary to turn off this option if it
caused secondary zones to crash.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-notify-to-soa">
<span class="sig-name descname"><span class="pre">notify-to-soa</span></span><a class="headerlink" href="#namedconf-statement-notify-to-soa" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">notify-to-soa</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Controls whether the name servers in the NS RRset are checked against the SOA MNAME.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, do not check the name servers in the NS RRset against the
SOA MNAME. Normally a NOTIFY message is not sent to the SOA MNAME
(SOA ORIGIN), as it is supposed to contain the name of the ultimate
primary server. Sometimes, however, a secondary server is listed as the SOA MNAME in
hidden primary configurations; in that case, the
ultimate primary should be set to still send NOTIFY messages to all the name servers
listed in the NS RRset.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-recursion">
<span class="sig-name descname"><span class="pre">recursion</span></span><a class="headerlink" href="#namedconf-statement-recursion" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">recursion</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Defines whether recursion and caching are allowed.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, and a DNS query requests recursion, then the server
attempts to do all the work required to answer the query. If recursion
is off and the server does not already know the answer, it
returns a referral response. The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>. Note that setting
<code class="docutils literal notranslate"><span class="pre">recursion</span> <span class="pre">no</span></code> does not prevent clients from getting data from the
server’s cache; it only prevents new data from being cached as an
effect of client queries. Caching may still occur as an effect of the
server’s internal operation, such as NOTIFY address lookups.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-request-nsid">
<span class="sig-name descname"><span class="pre">request-nsid</span></span><a class="headerlink" href="#namedconf-statement-request-nsid" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">request-nsid</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, server, view, view.server</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls whether an empty EDNS(0) NSID (Name Server Identifier) option is sent with all queries to authoritative name servers during iterative resolution.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, then an empty EDNS(0) NSID (Name Server Identifier)
option is sent with all queries to authoritative name servers during
iterative resolution. If the authoritative server returns an NSID
option in its response, then its contents are logged in the <code class="docutils literal notranslate"><span class="pre">nsid</span></code>
category at level <code class="docutils literal notranslate"><span class="pre">info</span></code>. The default is <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-require-server-cookie">
<span class="sig-name descname"><span class="pre">require-server-cookie</span></span><a class="headerlink" href="#namedconf-statement-require-server-cookie" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">require-server-cookie</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls whether a valid server cookie is required before sending a full response to a UDP request.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, require a valid server cookie before sending a full response to a UDP
request from a cookie-aware client. BADCOOKIE is sent if there is a
bad or nonexistent server cookie.</p>
<p>The default is <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
<p>Users wishing to test that DNS COOKIE clients correctly handle
BADCOOKIE, or who are getting a lot of forged DNS requests with DNS COOKIES
present, should set this to <code class="docutils literal notranslate"><span class="pre">yes</span></code>. Setting this to <code class="docutils literal notranslate"><span class="pre">yes</span></code> results in a reduced amplification effect
in a reflection attack, as the BADCOOKIE response is smaller than a full
response, while also requiring a legitimate client to follow up with a second
query with the new, valid, cookie.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-answer-cookie">
<span class="sig-name descname"><span class="pre">answer-cookie</span></span><a class="headerlink" href="#namedconf-statement-answer-cookie" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">answer-cookie</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls whether COOKIE EDNS replies are sent in response to client queries.</p>
</p>
<p>When set to the default value of <code class="docutils literal notranslate"><span class="pre">yes</span></code>, COOKIE EDNS options are
sent when applicable in replies to client queries. If set to <code class="docutils literal notranslate"><span class="pre">no</span></code>,
COOKIE EDNS options are not sent in replies. This can only be set
at the global options level, not per-view.</p>
<p><code class="docutils literal notranslate"><span class="pre">answer-cookie</span> <span class="pre">no</span></code> is intended as a temporary measure, for use when
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> shares an IP address with other servers that do not yet
support DNS COOKIE. A mismatch between servers on the same address is
not expected to cause operational problems, but the option to disable
COOKIE responses so that all servers have the same behavior is
provided out of an abundance of caution. DNS COOKIE is an important
security mechanism, and should not be disabled unless absolutely
necessary.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-send-cookie">
<span class="sig-name descname"><span class="pre">send-cookie</span></span><a class="headerlink" href="#namedconf-statement-send-cookie" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">send-cookie</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, server, view, view.server</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls whether a COOKIE EDNS option is sent along with a query.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, then a COOKIE EDNS option is sent along with the query.
If the resolver has previously communicated with the server, the COOKIE
returned in the previous transaction is sent. This is used by the
server to determine whether the resolver has talked to it before. A
resolver sending the correct COOKIE is assumed not to be an off-path
attacker sending a spoofed-source query; the query is therefore
unlikely to be part of a reflection/amplification attack, so
resolvers sending a correct COOKIE option are not subject to response
rate limiting (RRL). Resolvers which do not send a correct COOKIE
option may be limited to receiving smaller responses via the
<a class="reference internal" href="#namedconf-statement-nocookie-udp-size" title="namedconf-statement-nocookie-udp-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">nocookie-udp-size</span></code></a> option.</p>
<p>The <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> server may determine that COOKIE is not supported by the
remote server and not add a COOKIE EDNS option to requests.</p>
<p>The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-stale-answer-enable">
<span class="sig-name descname"><span class="pre">stale-answer-enable</span></span><a class="headerlink" href="#namedconf-statement-stale-answer-enable" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">stale-answer-enable</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Enables the returning of “stale” cached answers when the name servers for a zone are not answering.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, enable the returning of “stale” cached answers when the name
servers for a zone are not answering and the <a class="reference internal" href="#namedconf-statement-stale-cache-enable" title="namedconf-statement-stale-cache-enable"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">stale-cache-enable</span></code></a> option is
also enabled. The default is not to return stale answers.</p>
<p>Stale answers can also be enabled or disabled at runtime via
<a class="reference internal" href="manpages.html#cmdoption-rndc-arg-serve-stale"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">serve-stale</span> <span class="pre">on</span></code></a> or <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-serve-stale"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">serve-stale</span> <span class="pre">off</span></code></a>; these override
the configured setting. <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-serve-stale"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">serve-stale</span> <span class="pre">reset</span></code></a> restores the
setting to the one specified in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>. Note that if stale
answers have been disabled by <a class="reference internal" href="manpages.html#std-iscman-rndc"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">rndc</span></code></a>, they cannot be
re-enabled by reloading or reconfiguring <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>; they must be
re-enabled with <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-serve-stale"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">serve-stale</span> <span class="pre">on</span></code></a>, or the server must be
restarted.</p>
<p>Information about stale answers is logged under the <code class="docutils literal notranslate"><span class="pre">serve-stale</span></code>
log category.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-stale-answer-client-timeout">
<span class="sig-name descname"><span class="pre">stale-answer-client-timeout</span></span><a class="headerlink" href="#namedconf-statement-stale-answer-client-timeout" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">stale-answer-client-timeout</span> <span class="pre">(</span> <span class="pre">disabled</span> <span class="pre">|</span> <span class="pre">off</span> <span class="pre">|</span> <span class="pre"><integer></span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Defines the amount of time (in milliseconds) that <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> waits before attempting to answer a query with a stale RRset from cache.</p>
</p>
<p>This option defines the amount of time (in milliseconds) that <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
waits before attempting to answer the query with a stale RRset from cache.
If a stale answer is found, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> continues the ongoing fetches,
attempting to refresh the RRset in cache until the
<a class="reference internal" href="#namedconf-statement-resolver-query-timeout" title="namedconf-statement-resolver-query-timeout"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">resolver-query-timeout</span></code></a> interval is reached.</p>
<p>This option is off by default, which is equivalent to setting it to
<code class="docutils literal notranslate"><span class="pre">off</span></code> or <code class="docutils literal notranslate"><span class="pre">disabled</span></code>. It also has no effect if <a class="reference internal" href="#namedconf-statement-stale-answer-enable" title="namedconf-statement-stale-answer-enable"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">stale-answer-enable</span></code></a>
is disabled.</p>
<p>The maximum value for this option is <a class="reference internal" href="#namedconf-statement-resolver-query-timeout" title="namedconf-statement-resolver-query-timeout"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">resolver-query-timeout</span></code></a> minus
one second. The minimum value, <code class="docutils literal notranslate"><span class="pre">0</span></code>, causes a cached (stale) RRset to be
immediately returned if it is available while still attempting to
refresh the data in cache. <span class="target" id="index-10"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc8767.html"><strong>RFC 8767</strong></a> recommends a value of <code class="docutils literal notranslate"><span class="pre">1800</span></code>
(milliseconds).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-stale-cache-enable">
<span class="sig-name descname"><span class="pre">stale-cache-enable</span></span><a class="headerlink" href="#namedconf-statement-stale-cache-enable" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">stale-cache-enable</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Enables the retention of “stale” cached answers.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, enable the retaining of “stale” cached answers. Default <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-stale-refresh-time">
<span class="sig-name descname"><span class="pre">stale-refresh-time</span></span><a class="headerlink" href="#namedconf-statement-stale-refresh-time" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">stale-refresh-time</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Sets the time window for the return of “stale” cached answers before the next attempt to contact, if the name servers for a given zone are not responding.</p>
</p>
<p>If the name servers for a given zone are not answering, this sets the time
window for which <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> will promptly return “stale” cached answers for
that RRSet being requested before a new attempt in contacting the servers
is made. For convenience, TTL-style time-unit suffixes may be used to
specify the value. It also accepts ISO 8601 duration formats.</p>
<p>The default <a class="reference internal" href="#namedconf-statement-stale-refresh-time" title="namedconf-statement-stale-refresh-time"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">stale-refresh-time</span></code></a> is 30 seconds, as <span class="target" id="index-11"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc8767.html"><strong>RFC 8767</strong></a> recommends
that attempts to refresh to be done no more frequently than every 30
seconds. A value of zero disables the feature, meaning that normal
resolution will take place first, if that fails only then <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> will
return “stale” cached answers.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-nocookie-udp-size">
<span class="sig-name descname"><span class="pre">nocookie-udp-size</span></span><a class="headerlink" href="#namedconf-statement-nocookie-udp-size" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">nocookie-udp-size</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Sets the maximum size of UDP responses that are sent to queries without a valid server COOKIE.</p>
</p>
<p>This sets the maximum size of UDP responses that are sent to queries
without a valid server COOKIE. A value below 128 is silently
raised to 128. The default value is 4096, but the <a class="reference internal" href="#namedconf-statement-max-udp-size" title="namedconf-statement-max-udp-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-udp-size</span></code></a>
option may further limit the response size as the default for
<a class="reference internal" href="#namedconf-statement-max-udp-size" title="namedconf-statement-max-udp-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-udp-size</span></code></a> is 1232.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-cookie-algorithm">
<span class="sig-name descname"><span class="pre">cookie-algorithm</span></span><a class="headerlink" href="#namedconf-statement-cookie-algorithm" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">cookie-algorithm</span> <span class="pre">(</span> <span class="pre">aes</span> <span class="pre">|</span> <span class="pre">siphash24</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the algorithm to be used when generating a server cookie.</p>
</p>
<p>This sets the algorithm to be used when generating the server cookie; the options are
“aes” or “siphash24”. The default is “siphash24”. The “aes” option remains for legacy
purposes.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-cookie-secret">
<span class="sig-name descname"><span class="pre">cookie-secret</span></span><a class="headerlink" href="#namedconf-statement-cookie-secret" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">cookie-secret</span> <span class="pre"><string>;</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies a shared secret used for generating and verifying EDNS COOKIE options within an anycast cluster.</p>
</p>
<p>If set, this is a shared secret used for generating and verifying
EDNS COOKIE options within an anycast cluster. If not set, the system
generates a random secret at startup. The shared secret is
encoded as a hex string and needs to be 128 bits for either “siphash24”
or “aes”.</p>
<p>If there are multiple secrets specified, the first one listed in
<a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a> is used to generate new server cookies. The others
are only used to verify returned cookies.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-response-padding">
<span class="sig-name descname"><span class="pre">response-padding</span></span><a class="headerlink" href="#namedconf-statement-response-padding" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">response-padding</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">block-size</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Adds an EDNS Padding option to encrypted messages, to reduce the chance of guessing the contents based on size.</p>
</p>
<p>The EDNS Padding option is intended to improve confidentiality when
DNS queries are sent over an encrypted channel, by reducing the
variability in packet sizes. If a query:</p>
<ol class="arabic simple">
<li><p>contains an EDNS Padding option,</p></li>
<li><p>includes a valid server cookie or uses TCP,</p></li>
<li><p>is not signed using TSIG or SIG(0), and</p></li>
<li><p>is from a client whose address matches the specified ACL,</p></li>
</ol>
<p>then the response is padded with an EDNS Padding option to a multiple
of <code class="docutils literal notranslate"><span class="pre">block-size</span></code> bytes. If these conditions are not met, the
response is not padded.</p>
<p>If <code class="docutils literal notranslate"><span class="pre">block-size</span></code> is 0 or the ACL is <code class="docutils literal notranslate"><span class="pre">none;</span></code>, this feature is
disabled and no padding occurs; this is the default. If
<code class="docutils literal notranslate"><span class="pre">block-size</span></code> is greater than 512, a warning is logged and the value
is truncated to 512. Block sizes are ordinarily expected to be powers
of two (for instance, 128), but this is not mandatory.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-trust-anchor-telemetry">
<span class="sig-name descname"><span class="pre">trust-anchor-telemetry</span></span><a class="headerlink" href="#namedconf-statement-trust-anchor-telemetry" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">trust-anchor-telemetry</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Instructs <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to send specially formed queries once per day to domains for which trust anchors have been configured.</p>
</p>
<p>This causes <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to send specially formed queries once per day to
domains for which trust anchors have been configured via, e.g.,
<a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> or <code class="docutils literal notranslate"><span class="pre">dnssec-validation</span> <span class="pre">auto</span></code>.</p>
<p>The query name used for these queries has the form
<code class="docutils literal notranslate"><span class="pre">_ta-xxxx(-xxxx)(...).<domain></span></code>, where each “xxxx” is a group of four
hexadecimal digits representing the key ID of a trusted DNSSEC key.
The key IDs for each domain are sorted smallest to largest prior to
encoding. The query type is NULL.</p>
<p>By monitoring these queries, zone operators are able to see which
resolvers have been updated to trust a new key; this may help them
decide when it is safe to remove an old one.</p>
<p>The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-provide-ixfr">
<span class="sig-name descname"><span class="pre">provide-ixfr</span></span><a class="headerlink" href="#namedconf-statement-provide-ixfr" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">provide-ixfr</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, server, view, view.server</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Controls whether a primary responds to an incremental zone request (IXFR) or only responds with a full zone transfer (AXFR).</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-provide-ixfr" title="namedconf-statement-provide-ixfr"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">provide-ixfr</span></code></a> clause determines whether the local server, acting
as primary, responds with an incremental zone transfer when the given
remote server, a secondary, requests it. If set to <code class="docutils literal notranslate"><span class="pre">yes</span></code>, incremental
transfer is provided whenever possible. If set to <code class="docutils literal notranslate"><span class="pre">no</span></code>, all
transfers to the remote server are non-incremental.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-request-ixfr">
<span class="sig-name descname"><span class="pre">request-ixfr</span></span><a class="headerlink" href="#namedconf-statement-request-ixfr" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">request-ixfr</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, server, view, zone (mirror, secondary), view.server</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Controls whether a secondary requests an incremental zone transfer (IXFR) or a full zone transfer (AXFR).</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-request-ixfr" title="namedconf-statement-request-ixfr"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">request-ixfr</span></code></a> statement determines whether the local server, acting
as a secondary, requests incremental zone transfers from the given
remote server, a primary.</p>
<p>IXFR requests to servers that do not support IXFR automatically
fall back to AXFR. Therefore, there is no need to manually list which
servers support IXFR and which ones do not; the global default of
<code class="docutils literal notranslate"><span class="pre">yes</span></code> should always work. The purpose of the <a class="reference internal" href="#namedconf-statement-provide-ixfr" title="namedconf-statement-provide-ixfr"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">provide-ixfr</span></code></a> and
<a class="reference internal" href="#namedconf-statement-request-ixfr" title="namedconf-statement-request-ixfr"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">request-ixfr</span></code></a> statements is to make it possible to disable the use of
IXFR even when both primary and secondary claim to support it: for example, if
one of the servers is buggy and crashes or corrupts data when IXFR is
used.</p>
<p>It may also be set in the zone block; if set there, it overrides the global
or view setting for that zone. It may also be set in the
<a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">server</span></code></a> block.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-request-expire">
<span class="sig-name descname"><span class="pre">request-expire</span></span><a class="headerlink" href="#namedconf-statement-request-expire" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">request-expire</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, server, view, zone (mirror, secondary), view.server</p>
<p><strong>Tags: </strong>transfer, query</p>
<p><p>Specifies whether the local server requests the EDNS EXPIRE value, when acting as a secondary.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-request-expire" title="namedconf-statement-request-expire"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">request-expire</span></code></a> statement determines whether the local server, when
acting as a secondary, requests the EDNS EXPIRE value. The EDNS EXPIRE
value indicates the remaining time before the zone data expires and
needs to be refreshed. This is used when a secondary server transfers
a zone from another secondary server; when transferring from the
primary, the expiration timer is set from the EXPIRE field of the SOA
record instead. The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-match-mapped-addresses">
<span class="sig-name descname"><span class="pre">match-mapped-addresses</span></span><a class="headerlink" href="#namedconf-statement-match-mapped-addresses" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">match-mapped-addresses</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Allows IPv4-mapped IPv6 addresses to match address-match list entries for corresponding IPv4 addresses.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, then an IPv4-mapped IPv6 address matches any
address-match list entries that match the corresponding IPv4 address.</p>
<p>This option was introduced to work around a kernel quirk in some
operating systems that causes IPv4 TCP connections, such as zone
transfers, to be accepted on an IPv6 socket using mapped addresses.
This caused address-match lists designed for IPv4 to fail to match.
However, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> now solves this problem internally. The use of
this option is discouraged.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-ixfr-from-differences">
<span class="sig-name descname"><span class="pre">ixfr-from-differences</span></span><a class="headerlink" href="#namedconf-statement-ixfr-from-differences" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar zone (mirror, primary, secondary): </strong><code class="docutils literal notranslate"><span class="pre">ixfr-from-differences</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Grammar options, view: </strong><code class="docutils literal notranslate"><span class="pre">ixfr-from-differences</span> <span class="pre">(</span> <span class="pre">primary</span> <span class="pre">|</span> <span class="pre">master</span> <span class="pre">|</span> <span class="pre">secondary</span> <span class="pre">|</span> <span class="pre">slave</span> <span class="pre">|</span> <span class="pre"><boolean></span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Controls how IXFR transfers are calculated.</p>
</p>
<p>When <code class="docutils literal notranslate"><span class="pre">yes</span></code> and the server loads a new version of a primary zone from
its zone file or receives a new version of a secondary file via zone
transfer, it compares the new version to the previous one and
calculates a set of differences. The differences are then logged in
the zone’s journal file so that the changes can be transmitted to
downstream secondaries as an incremental zone transfer.</p>
<p>By allowing incremental zone transfers to be used for non-dynamic
zones, this option saves bandwidth at the expense of increased CPU
and memory consumption at the primary server. In particular, if the new
version of a zone is completely different from the previous one, the
set of differences is of a size comparable to the combined size
of the old and new zone versions, and the server needs to
temporarily allocate memory to hold this complete difference set.</p>
<p><a class="reference internal" href="#namedconf-statement-ixfr-from-differences" title="namedconf-statement-ixfr-from-differences"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ixfr-from-differences</span></code></a> also accepts <code class="docutils literal notranslate"><span class="pre">primary</span></code>
and <code class="docutils literal notranslate"><span class="pre">secondary</span></code> at the view and options levels,
which causes <a class="reference internal" href="#namedconf-statement-ixfr-from-differences" title="namedconf-statement-ixfr-from-differences"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ixfr-from-differences</span></code></a> to be enabled for all primary
or secondary zones, respectively. It is off for all zones by default.</p>
<p>Note: if inline signing is enabled for a zone, the user-provided
<a class="reference internal" href="#namedconf-statement-ixfr-from-differences" title="namedconf-statement-ixfr-from-differences"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ixfr-from-differences</span></code></a> setting is ignored for that zone.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-multi-master">
<span class="sig-name descname"><span class="pre">multi-master</span></span><a class="headerlink" href="#namedconf-statement-multi-master" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">multi-master</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, secondary, stub)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Controls whether serial number mismatch errors are logged.</p>
</p>
<p>This should be set when there are multiple primary servers for a zone and the
addresses refer to different machines. If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> does not
log when the serial number on the primary is less than what <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
currently has. The default is <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-auto-dnssec">
<span class="sig-name descname"><span class="pre">auto-dnssec</span></span><a class="headerlink" href="#namedconf-statement-auto-dnssec" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">auto-dnssec</span> <span class="pre">(</span> <span class="pre">allow</span> <span class="pre">|</span> <span class="pre">maintain</span> <span class="pre">|</span> <span class="pre">off</span> <span class="pre">);</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Permits varying levels of automatic DNSSEC key management.</p>
</p>
<p>Zones configured for dynamic DNS may use this option to allow varying
levels of automatic DNSSEC key management. There are three possible
settings:</p>
<p><code class="docutils literal notranslate"><span class="pre">auto-dnssec</span> <span class="pre">allow;</span></code> permits keys to be updated and the zone fully
re-signed whenever the user issues the command <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-sign"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">sign</span> <span class="pre">zonename</span></code></a>.</p>
<p><code class="docutils literal notranslate"><span class="pre">auto-dnssec</span> <span class="pre">maintain;</span></code> includes the above, but also
automatically adjusts the zone’s DNSSEC keys on a schedule, according
to the keys’ timing metadata (see <a class="reference internal" href="manpages.html#man-dnssec-keygen"><span class="std std-ref">dnssec-keygen: DNSSEC key generation tool</span></a> and
<a class="reference internal" href="manpages.html#man-dnssec-settime"><span class="std std-ref">dnssec-settime: set the key timing metadata for a DNSSEC key</span></a>). The command <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-sign"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">sign</span> <span class="pre">zonename</span></code></a>
causes <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to load keys from the key repository and sign the
zone with all keys that are active. <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-loadkeys"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">loadkeys</span> <span class="pre">zonename</span></code></a>
causes <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to load keys from the key repository and schedule
key maintenance events to occur in the future, but it does not sign
the full zone immediately. Note: once keys have been loaded for a
zone the first time, the repository is searched for changes
periodically, regardless of whether <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-loadkeys"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">loadkeys</span></code></a> is used. The
recheck interval is defined by <a class="reference internal" href="#namedconf-statement-dnssec-loadkeys-interval" title="namedconf-statement-dnssec-loadkeys-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-loadkeys-interval</span></code></a>.</p>
<p><code class="docutils literal notranslate"><span class="pre">auto-dnssec</span> <span class="pre">off;</span></code> does not allow for DNSSEC key management.
This is the default setting.</p>
<p>This option may only be activated at the zone level; if configured
at the view or options level, it must be set to <code class="docutils literal notranslate"><span class="pre">off</span></code>.</p>
<p>The DNSSEC records are written to the zone’s filename set in <a class="reference internal" href="#namedconf-statement-file" title="namedconf-statement-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">file</span></code></a>,
unless <a class="reference internal" href="#namedconf-statement-inline-signing" title="namedconf-statement-inline-signing"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">inline-signing</span></code></a> is enabled.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnssec-validation">
<span class="sig-name descname"><span class="pre">dnssec-validation</span></span><a class="headerlink" href="#namedconf-statement-dnssec-validation" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnssec-validation</span> <span class="pre">(</span> <span class="pre">yes</span> <span class="pre">|</span> <span class="pre">no</span> <span class="pre">|</span> <span class="pre">auto</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Enables DNSSEC validation in <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
</p>
<p>This option enables DNSSEC validation in <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
<p>If set to <code class="docutils literal notranslate"><span class="pre">auto</span></code>, DNSSEC validation is enabled and a default trust
anchor for the DNS root zone is used. This trust anchor is provided
as part of BIND and is kept up-to-date using <a class="reference internal" href="chapter5.html#rfc5011-support"><span class="std std-ref">Dynamic Trust Anchor Management</span></a> key
management.</p>
<p>If set to <code class="docutils literal notranslate"><span class="pre">yes</span></code>, DNSSEC validation is enabled, but a trust anchor must be
manually configured using a <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> statement (or the
<a class="reference internal" href="#namedconf-statement-managed-keys" title="namedconf-statement-managed-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">managed-keys</span></code></a> or <a class="reference internal" href="#namedconf-statement-trusted-keys" title="namedconf-statement-trusted-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trusted-keys</span></code></a> statements, both deprecated). If
there is no configured trust anchor, validation does not take place.</p>
<p>If set to <code class="docutils literal notranslate"><span class="pre">no</span></code>, DNSSEC validation is disabled.</p>
<p>The default is <code class="docutils literal notranslate"><span class="pre">auto</span></code>, unless BIND is built with
<code class="docutils literal notranslate"><span class="pre">configure</span> <span class="pre">--disable-auto-validation</span></code>, in which case the default is
<code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
<p>The default root trust anchor is stored in the file <code class="docutils literal notranslate"><span class="pre">bind.keys</span></code>.
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> loads that key at startup if <a class="reference internal" href="#namedconf-statement-dnssec-validation" title="namedconf-statement-dnssec-validation"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-validation</span></code></a> is
set to <code class="docutils literal notranslate"><span class="pre">auto</span></code>. A copy of the file is installed along with BIND 9,
and is current as of the release date. If the root key expires, a new
copy of <code class="docutils literal notranslate"><span class="pre">bind.keys</span></code> can be downloaded from
<a class="reference external" href="https://www.isc.org/bind-keys">https://www.isc.org/bind-keys</a>.</p>
<p>(To prevent problems if <code class="docutils literal notranslate"><span class="pre">bind.keys</span></code> is not found, the current trust
anchor is also compiled in <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>. Relying on this is not
recommended, however, as it requires <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to be recompiled with
a new key when the root key expires.)</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p><a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> loads <em>only</em> the root key from <code class="docutils literal notranslate"><span class="pre">bind.keys</span></code>. The file
cannot be used to store keys for other zones. The root key in
<code class="docutils literal notranslate"><span class="pre">bind.keys</span></code> is ignored if <code class="docutils literal notranslate"><span class="pre">dnssec-validation</span> <span class="pre">auto</span></code> is not in
use.</p>
<p>Whenever the resolver sends out queries to an EDNS-compliant
server, it always sets the DO bit indicating it can support DNSSEC
responses, even if <a class="reference internal" href="#namedconf-statement-dnssec-validation" title="namedconf-statement-dnssec-validation"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-validation</span></code></a> is off.</p>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-validate-except">
<span class="sig-name descname"><span class="pre">validate-except</span></span><a class="headerlink" href="#namedconf-statement-validate-except" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">validate-except</span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies a list of domain names at and beneath which DNSSEC validation should not be performed.</p>
</p>
<p>This specifies a list of domain names at and beneath which DNSSEC
validation should <em>not</em> be performed, regardless of the presence of a
trust anchor at or above those names. This may be used, for example,
when configuring a top-level domain intended only for local use, so
that the lack of a secure delegation for that domain in the root zone
does not cause validation failures. (This is similar to setting a
negative trust anchor except that it is a permanent configuration,
whereas negative trust anchors expire and are removed after a set
period of time.)</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnssec-accept-expired">
<span class="sig-name descname"><span class="pre">dnssec-accept-expired</span></span><a class="headerlink" href="#namedconf-statement-dnssec-accept-expired" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnssec-accept-expired</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Instructs BIND 9 to accept expired DNSSEC signatures when validating.</p>
</p>
<p>This accepts expired signatures when verifying DNSSEC signatures. The
default is <code class="docutils literal notranslate"><span class="pre">no</span></code>. Setting this option to <code class="docutils literal notranslate"><span class="pre">yes</span></code> leaves <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
vulnerable to replay attacks.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-querylog">
<span class="sig-name descname"><span class="pre">querylog</span></span><a class="headerlink" href="#namedconf-statement-querylog" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">querylog</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>logging, server</p>
<p><p>Specifies whether query logging should be active when <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> first starts.</p>
</p>
<p>Query logging provides a complete log of all incoming queries and all query
errors. This provides more insight into the server’s activity, but with a
cost to performance which may be significant on heavily loaded servers.</p>
<p>The <a class="reference internal" href="#namedconf-statement-querylog" title="namedconf-statement-querylog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">querylog</span></code></a> option specifies whether query logging should be active when
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> first starts. If <a class="reference internal" href="#namedconf-statement-querylog" title="namedconf-statement-querylog"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">querylog</span></code></a> is not specified, then query logging
is determined by the presence of the logging category <code class="docutils literal notranslate"><span class="pre">queries</span></code>. Please
note that <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-reconfig"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">reconfig</span></code></a> and <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-reload"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">reload</span></code></a> have no effect on
this option, so it cannot be changed once the server is running. However,
query logging can be activated at runtime using the command <code class="docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">querylog</span>
<span class="pre">on</span></code>, or deactivated with <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-querylog"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">querylog</span> <span class="pre">off</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-check-names">
<span class="sig-name descname"><span class="pre">check-names</span></span><a class="headerlink" href="#namedconf-statement-check-names" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar zone (hint, mirror, primary, secondary, stub): </strong><code class="docutils literal notranslate"><span class="pre">check-names</span> <span class="pre">(</span> <span class="pre">fail</span> <span class="pre">|</span> <span class="pre">warn</span> <span class="pre">|</span> <span class="pre">ignore</span> <span class="pre">);</span></code></p>
<p><strong>Grammar options, view: </strong><code class="docutils literal notranslate"><span class="pre">check-names</span> <span class="pre">(</span> <span class="pre">primary</span> <span class="pre">|</span> <span class="pre">master</span> <span class="pre">|</span> <span class="pre">secondary</span> <span class="pre">|</span> <span class="pre">slave</span> <span class="pre">|</span> <span class="pre">response</span> <span class="pre">)</span> <span class="pre">(</span> <span class="pre">fail</span> <span class="pre">|</span> <span class="pre">warn</span> <span class="pre">|</span> <span class="pre">ignore</span> <span class="pre">);</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (hint, mirror, primary, secondary, stub)</p>
<p><strong>Tags: </strong>query, server</p>
<p><p>Restricts the character set and syntax of certain domain names in primary files and/or DNS responses received from the network.</p>
</p>
<p>This option is used to restrict the character set and syntax of
certain domain names in primary files and/or DNS responses received
from the network. The default varies according to usage area. For
<a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span> <span class="pre">primary</span></code></a> zones the default is <code class="docutils literal notranslate"><span class="pre">fail</span></code>. For <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span> <span class="pre">secondary</span></code></a> zones the
default is <code class="docutils literal notranslate"><span class="pre">warn</span></code>. For answers received from the network
(<code class="docutils literal notranslate"><span class="pre">response</span></code>), the default is <code class="docutils literal notranslate"><span class="pre">ignore</span></code>.</p>
<p>The rules for legal hostnames and mail domains are derived from
<span class="target" id="index-12"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc952.html"><strong>RFC 952</strong></a> and <span class="target" id="index-13"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc821.html"><strong>RFC 821</strong></a> as modified by <span class="target" id="index-14"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1123.html"><strong>RFC 1123</strong></a>.</p>
<p><a class="reference internal" href="#namedconf-statement-check-names" title="namedconf-statement-check-names"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-names</span></code></a> applies to the owner names of A, AAAA, and MX records.
It also applies to the domain names in the RDATA of NS, SOA, MX, and
SRV records. It further applies to the RDATA of PTR records where the
owner name indicates that it is a reverse lookup of a hostname (the
owner name ends in IN-ADDR.ARPA, IP6.ARPA, or IP6.INT).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-check-dup-records">
<span class="sig-name descname"><span class="pre">check-dup-records</span></span><a class="headerlink" href="#namedconf-statement-check-dup-records" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">check-dup-records</span> <span class="pre">(</span> <span class="pre">fail</span> <span class="pre">|</span> <span class="pre">warn</span> <span class="pre">|</span> <span class="pre">ignore</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary)</p>
<p><strong>Tags: </strong>dnssec, query</p>
<p><p>Checks primary zones for records that are treated as different by DNSSEC but are semantically equal in plain DNS.</p>
</p>
<p>This checks primary zones for records that are treated as different by
DNSSEC but are semantically equal in plain DNS. The default is to
<code class="docutils literal notranslate"><span class="pre">warn</span></code>. Other possible values are <code class="docutils literal notranslate"><span class="pre">fail</span></code> and <code class="docutils literal notranslate"><span class="pre">ignore</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-check-mx">
<span class="sig-name descname"><span class="pre">check-mx</span></span><a class="headerlink" href="#namedconf-statement-check-mx" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">check-mx</span> <span class="pre">(</span> <span class="pre">fail</span> <span class="pre">|</span> <span class="pre">warn</span> <span class="pre">|</span> <span class="pre">ignore</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Checks whether an MX record appears to refer to an IP address.</p>
</p>
<p>This checks whether the MX record appears to refer to an IP address. The
default is to <code class="docutils literal notranslate"><span class="pre">warn</span></code>. Other possible values are <code class="docutils literal notranslate"><span class="pre">fail</span></code> and
<code class="docutils literal notranslate"><span class="pre">ignore</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-check-wildcard">
<span class="sig-name descname"><span class="pre">check-wildcard</span></span><a class="headerlink" href="#namedconf-statement-check-wildcard" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">check-wildcard</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Checks for non-terminal wildcards.</p>
</p>
<p>This option is used to check for non-terminal wildcards. The use of
non-terminal wildcards is almost always as a result of a lack of
understanding of the wildcard-matching algorithm (<span class="target" id="index-15"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1034.html"><strong>RFC 1034</strong></a>). This option
affects primary zones. The default (<code class="docutils literal notranslate"><span class="pre">yes</span></code>) is to check for
non-terminal wildcards and issue a warning.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-check-integrity">
<span class="sig-name descname"><span class="pre">check-integrity</span></span><a class="headerlink" href="#namedconf-statement-check-integrity" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">check-integrity</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Performs post-load zone integrity checks on primary zones.</p>
</p>
<p>This performs post-load zone integrity checks on primary zones. It checks
that MX and SRV records refer to address (A or AAAA) records and that
glue address records exist for delegated zones. For MX and SRV
records, only in-zone hostnames are checked (for out-of-zone hostnames,
use <a class="reference internal" href="manpages.html#std-iscman-named-checkzone"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named-checkzone</span></code></a>). For NS records, only names below top-of-zone
are checked (for out-of-zone names and glue consistency checks, use
<a class="reference internal" href="manpages.html#std-iscman-named-checkzone"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named-checkzone</span></code></a>). The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
<p>The use of the SPF record to publish Sender Policy Framework is
deprecated, as the migration from using TXT records to SPF records was
abandoned. Enabling this option also checks that a TXT Sender Policy
Framework record exists (starts with “v=spf1”) if there is an SPF
record. Warnings are emitted if the TXT record does not exist; they can
be suppressed with <a class="reference internal" href="#namedconf-statement-check-spf" title="namedconf-statement-check-spf"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-spf</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-check-mx-cname">
<span class="sig-name descname"><span class="pre">check-mx-cname</span></span><a class="headerlink" href="#namedconf-statement-check-mx-cname" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">check-mx-cname</span> <span class="pre">(</span> <span class="pre">fail</span> <span class="pre">|</span> <span class="pre">warn</span> <span class="pre">|</span> <span class="pre">ignore</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Sets the response to MX records that refer to CNAMEs.</p>
</p>
<p>If <a class="reference internal" href="#namedconf-statement-check-integrity" title="namedconf-statement-check-integrity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-integrity</span></code></a> is set, then fail, warn, or ignore MX records
that refer to CNAMEs. The default is to <code class="docutils literal notranslate"><span class="pre">warn</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-check-srv-cname">
<span class="sig-name descname"><span class="pre">check-srv-cname</span></span><a class="headerlink" href="#namedconf-statement-check-srv-cname" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">check-srv-cname</span> <span class="pre">(</span> <span class="pre">fail</span> <span class="pre">|</span> <span class="pre">warn</span> <span class="pre">|</span> <span class="pre">ignore</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Sets the response to SRV records that refer to CNAMEs.</p>
</p>
<p>If <a class="reference internal" href="#namedconf-statement-check-integrity" title="namedconf-statement-check-integrity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-integrity</span></code></a> is set, then fail, warn, or ignore SRV records
that refer to CNAMEs. The default is to <code class="docutils literal notranslate"><span class="pre">warn</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-check-sibling">
<span class="sig-name descname"><span class="pre">check-sibling</span></span><a class="headerlink" href="#namedconf-statement-check-sibling" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">check-sibling</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Specifies whether to check for sibling glue when performing integrity checks.</p>
</p>
<p>When performing integrity checks, also check that sibling glue
exists. The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-check-spf">
<span class="sig-name descname"><span class="pre">check-spf</span></span><a class="headerlink" href="#namedconf-statement-check-spf" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">check-spf</span> <span class="pre">(</span> <span class="pre">warn</span> <span class="pre">|</span> <span class="pre">ignore</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Specifies whether to check for a TXT Sender Policy Framework record, if an SPF record is present.</p>
</p>
<p>If <a class="reference internal" href="#namedconf-statement-check-integrity" title="namedconf-statement-check-integrity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-integrity</span></code></a> is set, check that there is a TXT Sender
Policy Framework record present (starts with “v=spf1”) if there is an
SPF record present. The default is <code class="docutils literal notranslate"><span class="pre">warn</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-zero-no-soa-ttl">
<span class="sig-name descname"><span class="pre">zero-no-soa-ttl</span></span><a class="headerlink" href="#namedconf-statement-zero-no-soa-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">zero-no-soa-ttl</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>zone, query, server</p>
<p><p>Specifies whether to set the time to live (TTL) of the SOA record to zero, when returning authoritative negative responses to SOA queries.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, when returning authoritative negative responses to SOA queries, set
the TTL of the SOA record returned in the authority section to zero.
The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-zero-no-soa-ttl-cache">
<span class="sig-name descname"><span class="pre">zero-no-soa-ttl-cache</span></span><a class="headerlink" href="#namedconf-statement-zero-no-soa-ttl-cache" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">zero-no-soa-ttl-cache</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>zone, query, server</p>
<p><p>Sets the time to live (TTL) to zero when caching a negative response to an SOA query.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, when caching a negative response to an SOA query set the TTL to zero.
The default is <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-update-check-ksk">
<span class="sig-name descname"><span class="pre">update-check-ksk</span></span><a class="headerlink" href="#namedconf-statement-update-check-ksk" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">update-check-ksk</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>zone, dnssec</p>
<p><p>Specifies whether to check the KSK bit to determine how a key should be used, when generating RRSIGs for a secure zone.</p>
</p>
<p>When set to the default value of <code class="docutils literal notranslate"><span class="pre">yes</span></code>, check the KSK bit in each
key to determine how the key should be used when generating RRSIGs
for a secure zone.</p>
<p>Ordinarily, zone-signing keys (that is, keys without the KSK bit set)
are used to sign the entire zone, while key-signing keys (keys with
the KSK bit set) are only used to sign the DNSKEY RRset at the zone
apex. However, if this option is set to <code class="docutils literal notranslate"><span class="pre">no</span></code>, then the KSK bit is
ignored; KSKs are treated as if they were ZSKs and are used to sign
the entire zone. This is similar to the <a class="reference internal" href="manpages.html#cmdoption-dnssec-signzone-z"><code class="xref std std-option docutils literal notranslate"><span class="pre">dnssec-signzone</span> <span class="pre">-z</span></code></a>
command-line option.</p>
<p>When this option is set to <code class="docutils literal notranslate"><span class="pre">yes</span></code>, there must be at least two active
keys for every algorithm represented in the DNSKEY RRset: at least
one KSK and one ZSK per algorithm. If there is any algorithm for
which this requirement is not met, this option is ignored for
that algorithm.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnssec-dnskey-kskonly">
<span class="sig-name descname"><span class="pre">dnssec-dnskey-kskonly</span></span><a class="headerlink" href="#namedconf-statement-dnssec-dnskey-kskonly" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnssec-dnskey-kskonly</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies that only key-signing keys are used to sign the DNSKEY, CDNSKEY, and CDS RRsets at a zone’s apex.</p>
</p>
<p>When this option and <a class="reference internal" href="#namedconf-statement-update-check-ksk" title="namedconf-statement-update-check-ksk"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-check-ksk</span></code></a> are both set to <code class="docutils literal notranslate"><span class="pre">yes</span></code>,
only key-signing keys (that is, keys with the KSK bit set) are
used to sign the DNSKEY, CDNSKEY, and CDS RRsets at the zone apex.
Zone-signing keys (keys without the KSK bit set) are used to sign
the remainder of the zone, but not the DNSKEY RRset. This is similar
to the <a class="reference internal" href="manpages.html#cmdoption-dnssec-signzone-x"><code class="xref std std-option docutils literal notranslate"><span class="pre">dnssec-signzone</span> <span class="pre">-x</span></code></a> command-line option.</p>
<p>The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>. If <a class="reference internal" href="#namedconf-statement-update-check-ksk" title="namedconf-statement-update-check-ksk"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-check-ksk</span></code></a> is set to <code class="docutils literal notranslate"><span class="pre">no</span></code>, this
option is ignored.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-try-tcp-refresh">
<span class="sig-name descname"><span class="pre">try-tcp-refresh</span></span><a class="headerlink" href="#namedconf-statement-try-tcp-refresh" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">try-tcp-refresh</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Specifies that BIND 9 should attempt to refresh a zone using TCP if UDP queries fail.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, try to refresh the zone using TCP if UDP queries fail. The default is
<code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnssec-secure-to-insecure">
<span class="sig-name descname"><span class="pre">dnssec-secure-to-insecure</span></span><a class="headerlink" href="#namedconf-statement-dnssec-secure-to-insecure" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnssec-secure-to-insecure</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Allows a dynamic zone to transition from secure to insecure by deleting all DNSKEY records.</p>
</p>
<p>This allows a dynamic zone to transition from secure to insecure (i.e.,
signed to unsigned) by deleting all of the DNSKEY records. The
default is <code class="docutils literal notranslate"><span class="pre">no</span></code>. If set to <code class="docutils literal notranslate"><span class="pre">yes</span></code>, and if the DNSKEY RRset at the
zone apex is deleted, all RRSIG and NSEC records are removed from
the zone as well.</p>
<p>If the zone uses NSEC3, it is also necessary to delete the
NSEC3PARAM RRset from the zone apex; this causes the removal of
all corresponding NSEC3 records. (It is expected that this
requirement will be eliminated in a future release.)</p>
<p>Note that if a zone has been configured with <code class="docutils literal notranslate"><span class="pre">auto-dnssec</span> <span class="pre">maintain</span></code>
and the private keys remain accessible in the key repository,
the zone will be automatically signed again the next time <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
is started.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-synth-from-dnssec">
<span class="sig-name descname"><span class="pre">synth-from-dnssec</span></span><a class="headerlink" href="#namedconf-statement-synth-from-dnssec" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">synth-from-dnssec</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Enables support for <span class="target" id="index-18"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc8198.html"><strong>RFC 8198</strong></a>, Aggressive Use of DNSSEC-Validated Cache.</p>
</p>
<p>This option enables support for <span class="target" id="index-17"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc8198.html"><strong>RFC 8198</strong></a>, Aggressive Use of
DNSSEC-Validated Cache. It allows the resolver to send a smaller number
of queries when resolving queries for DNSSEC-signed domains
by synthesizing answers from cached NSEC and other RRsets that
have been proved to be correct using DNSSEC.
The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>DNSSEC validation must be enabled for this option to be effective.
This initial implementation only covers synthesis of answers from
NSEC records; synthesis from NSEC3 is planned for the future. This
will also be controlled by <a class="reference internal" href="#namedconf-statement-synth-from-dnssec" title="namedconf-statement-synth-from-dnssec"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">synth-from-dnssec</span></code></a>.</p>
</div>
</dd></dl>
</section>
<section id="forwarding">
<h4><span class="section-number">8.2.14.2. </span>Forwarding<a class="headerlink" href="#forwarding" title="Link to this heading"></a></h4>
<p>The forwarding facility can be used to create a large site-wide cache on
a few servers, reducing traffic over links to external name servers. It
can also be used to allow queries by servers that do not have direct
access to the Internet, but wish to look up exterior names anyway.
Forwarding occurs only on those queries for which the server is not
authoritative and does not have the answer in its cache.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-forward">
<span class="sig-name descname"><span class="pre">forward</span></span><a class="headerlink" href="#namedconf-statement-forward" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">forward</span> <span class="pre">(</span> <span class="pre">first</span> <span class="pre">|</span> <span class="pre">only</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (forward, primary, secondary, static-stub, stub)</p>
<p><strong>Tags: </strong>query</p>
<p><p>Allows or disallows fallback to recursion if forwarding has failed; it is always used in conjunction with the <a class="reference internal" href="#namedconf-statement-forwarders" title="namedconf-statement-forwarders"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forwarders</span></code></a> statement.</p>
</p>
<p>This option is only meaningful if the forwarders list is not empty. A
value of <code class="docutils literal notranslate"><span class="pre">first</span></code> is the default and causes the server to query the
forwarders first; if that does not answer the question, the
server then looks for the answer itself. If <code class="docutils literal notranslate"><span class="pre">only</span></code> is
specified, the server only queries the forwarders.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-forwarders">
<span class="sig-name descname"><span class="pre">forwarders</span></span><a class="headerlink" href="#namedconf-statement-forwarders" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">forwarders</span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span>  <span class="pre">{</span> <span class="pre">(</span> <span class="pre"><ipv4_address></span> <span class="pre">|</span> <span class="pre"><ipv6_address></span> <span class="pre">)</span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">];</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (forward, primary, secondary, static-stub, stub)</p>
<p><strong>Tags: </strong>query</p>
<p><p>Defines one or more hosts to which queries are forwarded.</p>
</p>
<p>This specifies a list of IP addresses to which queries are forwarded. The
default is the empty list (no forwarding). Each address in the list can be
associated with an optional port number. A default port number can be set
for the entire list.</p>
</dd></dl>
<p>Forwarding can also be configured on a per-domain basis, allowing for
the global forwarding options to be overridden in a variety of ways.
Particular domains can be set to use different forwarders, or have a
different <code class="docutils literal notranslate"><span class="pre">forward</span> <span class="pre">only/first</span></code> behavior, or not forward at all; see
<a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a>.</p>
</section>
<section id="dual-stack-servers">
<span id="dual-stack"></span><h4><span class="section-number">8.2.14.3. </span>Dual-stack Servers<a class="headerlink" href="#dual-stack-servers" title="Link to this heading"></a></h4>
<p>Dual-stack servers are used as servers of last resort, to work around
problems in reachability due to the lack of support for either IPv4 or IPv6
on the host machine.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dual-stack-servers">
<span class="sig-name descname"><span class="pre">dual-stack-servers</span></span><a class="headerlink" href="#namedconf-statement-dual-stack-servers" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dual-stack-servers</span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">{</span> <span class="pre">(</span> <span class="pre"><quoted_string></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">|</span> <span class="pre"><ipv4_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">|</span> <span class="pre"><ipv6_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">);</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies host names or addresses of machines with access to both IPv4 and IPv6 transports.</p>
</p>
<p>This specifies host names or addresses of machines with access to both
IPv4 and IPv6 transports. If a hostname is used, the server must be
able to resolve the name using only the transport it has. If the
machine is dual-stacked, the <a class="reference internal" href="#namedconf-statement-dual-stack-servers" title="namedconf-statement-dual-stack-servers"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dual-stack-servers</span></code></a> parameter has no
effect unless access to a transport has been disabled on the command
line (e.g., <a class="reference internal" href="manpages.html#cmdoption-named-4"><code class="xref std std-option docutils literal notranslate"><span class="pre">named</span> <span class="pre">-4</span></code></a>).</p>
</dd></dl>
</section>
<section id="access-control">
<span id="id6"></span><h4><span class="section-number">8.2.14.4. </span>Access Control<a class="headerlink" href="#access-control" title="Link to this heading"></a></h4>
<p>Access to the server can be restricted based on the IP address of the
requesting system. See <a class="reference internal" href="#address-match-lists"><span class="std std-ref">Address Match Lists</span></a>
for details on how to specify IP address lists.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-allow-notify">
<span class="sig-name descname"><span class="pre">allow-notify</span></span><a class="headerlink" href="#namedconf-statement-allow-notify" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">allow-notify</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> that is allowed to send <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages for the zone, in addition to addresses defined in the <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> option for the zone.</p>
</p>
<p>This ACL specifies which hosts may send NOTIFY messages to inform
this server of changes to zones for which it is acting as a secondary
server. This is only applicable for secondary zones (i.e., <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span>
<span class="pre">secondary</span></code></a> or <code class="docutils literal notranslate"><span class="pre">slave</span></code>).</p>
<p>If this option is set in <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> or <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>, it is globally
applied to all secondary zones. If set in the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statement, the
global value is overridden.</p>
<p>If not specified, the default is to process NOTIFY messages only from
the configured <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> for the zone. <a class="reference internal" href="#namedconf-statement-allow-notify" title="namedconf-statement-allow-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-notify</span></code></a> can be used
to expand the list of permitted hosts, not to reduce it.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-allow-query">
<span class="sig-name descname"><span class="pre">allow-query</span></span><a class="headerlink" href="#namedconf-statement-allow-query" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">allow-query</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, redirect, secondary, static-stub, stub)</p>
<p><strong>Tags: </strong>query</p>
<p><p>Specifies which hosts (an IP address list) are allowed to send queries to this resolver.</p>
</p>
<p><a class="reference internal" href="#namedconf-statement-allow-query" title="namedconf-statement-allow-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query</span></code></a> may also be specified in the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statement, in
which case it overrides the <code class="docutils literal notranslate"><span class="pre">options</span> <span class="pre">allow-query</span></code> statement. If not
specified, the default is to allow queries from all hosts.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p><a class="reference internal" href="#namedconf-statement-allow-query-cache" title="namedconf-statement-allow-query-cache"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-cache</span></code></a> is used to specify access to the cache.</p>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-allow-query-on">
<span class="sig-name descname"><span class="pre">allow-query-on</span></span><a class="headerlink" href="#namedconf-statement-allow-query-on" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">allow-query-on</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, redirect, secondary, static-stub, stub)</p>
<p><strong>Tags: </strong>query</p>
<p><p>Specifies which local addresses (an IP address list) are allowed to send queries to this resolver. Used in multi-homed configurations.</p>
</p>
<p>This makes it possible, for instance, to allow queries on
internal-facing interfaces but disallow them on external-facing ones,
without necessarily knowing the internal network’s addresses.</p>
<p>Note that <a class="reference internal" href="#namedconf-statement-allow-query-on" title="namedconf-statement-allow-query-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-on</span></code></a> is only checked for queries that are
permitted by <a class="reference internal" href="#namedconf-statement-allow-query" title="namedconf-statement-allow-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query</span></code></a>. A query must be allowed by both ACLs,
or it is refused.</p>
<p><a class="reference internal" href="#namedconf-statement-allow-query-on" title="namedconf-statement-allow-query-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-on</span></code></a> may also be specified in the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statement,
in which case it overrides the <code class="docutils literal notranslate"><span class="pre">options</span> <span class="pre">allow-query-on</span></code> statement.</p>
<p>If not specified, the default is to allow queries on all addresses.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p><a class="reference internal" href="#namedconf-statement-allow-query-cache" title="namedconf-statement-allow-query-cache"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-cache</span></code></a> is used to specify access to the cache.</p>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-allow-query-cache">
<span class="sig-name descname"><span class="pre">allow-query-cache</span></span><a class="headerlink" href="#namedconf-statement-allow-query-cache" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">allow-query-cache</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Specifies which hosts (an IP address list) can access this server’s cache and thus effectively controls recursion.</p>
</p>
<p>Defines an <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> of IP address(es) which are allowed to
issue queries that access the local cache. Without access to the local
cache recursive queries are effectively useless so, in effect, this
statement (or its default) controls recursive behavior. This statement’s
default setting depends on:</p>
<ol class="arabic simple">
<li><p>If <a class="reference internal" href="#namedconf-statement-recursion" title="namedconf-statement-recursion"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursion</span> <span class="pre">no;</span></code></a> present, defaults to
<code class="docutils literal notranslate"><span class="pre">allow-query-cache</span> <span class="pre">{none;};</span></code>. No local cache access permitted.</p></li>
<li><p>If <a class="reference internal" href="#namedconf-statement-recursion" title="namedconf-statement-recursion"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursion</span> <span class="pre">yes;</span></code></a> (default) then, if
<a class="reference internal" href="#namedconf-statement-allow-recursion" title="namedconf-statement-allow-recursion"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-recursion</span></code></a> present, defaults to the value of
<a class="reference internal" href="#namedconf-statement-allow-recursion" title="namedconf-statement-allow-recursion"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-recursion</span></code></a>. Local cache access permitted to the same
<a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> as <a class="reference internal" href="#namedconf-statement-allow-recursion" title="namedconf-statement-allow-recursion"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-recursion</span></code></a>.</p></li>
<li><p>If <a class="reference internal" href="#namedconf-statement-recursion" title="namedconf-statement-recursion"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursion</span> <span class="pre">yes;</span></code></a> (default) then, if
<a class="reference internal" href="#namedconf-statement-allow-recursion" title="namedconf-statement-allow-recursion"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-recursion</span></code></a> is <strong>not</strong> present, defaults to
<code class="docutils literal notranslate"><span class="pre">allow-query-cache</span> <span class="pre">{localnets;</span> <span class="pre">localhost;};</span></code>. Local cache access permitted
to <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> localnets and localhost IP addresses only.</p></li>
</ol>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-allow-query-cache-on">
<span class="sig-name descname"><span class="pre">allow-query-cache-on</span></span><a class="headerlink" href="#namedconf-statement-allow-query-cache-on" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">allow-query-cache-on</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Specifies which hosts (an IP address list) can access this server’s cache. Used on servers with multiple interfaces.</p>
</p>
<p>This specifies which local addresses can send answers from the cache. If
<a class="reference internal" href="#namedconf-statement-allow-query-cache-on" title="namedconf-statement-allow-query-cache-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-cache-on</span></code></a> is not set, then <a class="reference internal" href="#namedconf-statement-allow-recursion-on" title="namedconf-statement-allow-recursion-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-recursion-on</span></code></a> is
used if set. Otherwise, the default is to allow cache responses to be
sent from any address. Note: both <a class="reference internal" href="#namedconf-statement-allow-query-cache" title="namedconf-statement-allow-query-cache"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-cache</span></code></a> and
<a class="reference internal" href="#namedconf-statement-allow-query-cache-on" title="namedconf-statement-allow-query-cache-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-cache-on</span></code></a> must be satisfied before a cache response
can be sent; a client that is blocked by one cannot be allowed by the
other.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-allow-recursion">
<span class="sig-name descname"><span class="pre">allow-recursion</span></span><a class="headerlink" href="#namedconf-statement-allow-recursion" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">allow-recursion</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of clients that are allowed to perform recursive queries.</p>
</p>
<p>This specifies which hosts are allowed to make recursive queries through
this server. BIND checks to see if the following parameters are set, in
order: <a class="reference internal" href="#namedconf-statement-allow-query-cache" title="namedconf-statement-allow-query-cache"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-cache</span></code></a> and <a class="reference internal" href="#namedconf-statement-allow-query" title="namedconf-statement-allow-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query</span></code></a>. If neither of those parameters
is set, the default (localnets; localhost;) is used.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-allow-recursion-on">
<span class="sig-name descname"><span class="pre">allow-recursion-on</span></span><a class="headerlink" href="#namedconf-statement-allow-recursion-on" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">allow-recursion-on</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query, server</p>
<p><p>Specifies which local addresses can accept recursive queries.</p>
</p>
<p>This specifies which local addresses can accept recursive queries. If
<a class="reference internal" href="#namedconf-statement-allow-recursion-on" title="namedconf-statement-allow-recursion-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-recursion-on</span></code></a> is not set, then <a class="reference internal" href="#namedconf-statement-allow-query-cache-on" title="namedconf-statement-allow-query-cache-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-cache-on</span></code></a> is
used if set; otherwise, the default is to allow recursive queries on
all addresses. Any client permitted to send recursive queries can
send them to any address on which <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is listening. Note: both
<a class="reference internal" href="#namedconf-statement-allow-recursion" title="namedconf-statement-allow-recursion"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-recursion</span></code></a> and <a class="reference internal" href="#namedconf-statement-allow-recursion-on" title="namedconf-statement-allow-recursion-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-recursion-on</span></code></a> must be satisfied
before recursion is allowed; a client that is blocked by one cannot
be allowed by the other.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-allow-update">
<span class="sig-name descname"><span class="pre">allow-update</span></span><a class="headerlink" href="#namedconf-statement-allow-update" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">allow-update</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts that are allowed to submit dynamic updates for primary zones.</p>
</p>
<p>A simple access control list.
When set in the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statement for a primary zone, this specifies which
hosts are allowed to submit dynamic DNS updates to that zone. The
default is to deny updates from all hosts.</p>
<p>Note that allowing updates based on the requestor’s IP address is
insecure; see <a class="reference internal" href="chapter7.html#dynamic-update-security"><span class="std std-ref">Dynamic Update Security</span></a> for details.</p>
<p>In general, this option should only be set at the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> level.
While a default value can be set at the <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> or <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> level
and inherited by zones, this could lead to some zones unintentionally
allowing updates.</p>
<p>Updates are written to the zone’s filename that is set in <a class="reference internal" href="#namedconf-statement-file" title="namedconf-statement-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">file</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-allow-update-forwarding">
<span class="sig-name descname"><span class="pre">allow-update-forwarding</span></span><a class="headerlink" href="#namedconf-statement-allow-update-forwarding" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">allow-update-forwarding</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts that are allowed to submit dynamic updates to a secondary server for transmission to a primary.</p>
</p>
<p>When set in the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statement for a secondary zone, this specifies which
hosts are allowed to submit dynamic DNS updates and have them be
forwarded to the primary. The default is <code class="docutils literal notranslate"><span class="pre">{</span> <span class="pre">none;</span> <span class="pre">}</span></code>, which means
that no update forwarding is performed.</p>
<p>To enable update forwarding, specify
<code class="docutils literal notranslate"><span class="pre">allow-update-forwarding</span> <span class="pre">{</span> <span class="pre">any;</span> <span class="pre">};</span></code> in the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statement.
Specifying values other than <code class="docutils literal notranslate"><span class="pre">{</span> <span class="pre">none;</span> <span class="pre">}</span></code> or <code class="docutils literal notranslate"><span class="pre">{</span> <span class="pre">any;</span> <span class="pre">}</span></code> is usually
counterproductive; the responsibility for update access control
should rest with the primary server, not the secondary.</p>
<p>Note that enabling the update forwarding feature on a secondary server
may expose primary servers to attacks if they rely on insecure
IP-address-based access control; see <a class="reference internal" href="chapter7.html#dynamic-update-security"><span class="std std-ref">Dynamic Update Security</span></a> for more details.</p>
<p>In general this option should only be set at the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> level.
While a default value can be set at the <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> or <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> level
and inherited by zones, this can lead to some zones unintentionally
forwarding updates.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-allow-transfer">
<span class="sig-name descname"><span class="pre">allow-transfer</span></span><a class="headerlink" href="#namedconf-statement-allow-transfer" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">allow-transfer</span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">transport</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts that are allowed to transfer the zone information from this server.</p>
</p>
<p>This specifies which hosts are allowed to receive zone transfers from the
server. <a class="reference internal" href="#namedconf-statement-allow-transfer" title="namedconf-statement-allow-transfer"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-transfer</span></code></a> may also be specified in the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a>
statement, in which case it overrides the <a class="reference internal" href="#namedconf-statement-allow-transfer" title="namedconf-statement-allow-transfer"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-transfer</span></code></a>
statement set in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> or <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>. If not specified, the
default is to allow transfers to all hosts.</p>
<p>The transport level limitations can also be specified. In particular,
zone transfers can be restricted to a specific port and/or DNS
transport protocol by using the options <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a> and <code class="docutils literal notranslate"><span class="pre">transport</span></code>.
Either option can be specified; if both are used, both constraints
must be satisfied in order for the transfer to be allowed. Zone
transfers are currently only possible via the TCP and TLS transports.</p>
<p>For example: <code class="docutils literal notranslate"><span class="pre">allow-transfer</span> <span class="pre">port</span> <span class="pre">853</span> <span class="pre">transport</span> <span class="pre">tls</span> <span class="pre">{</span> <span class="pre">any;</span> <span class="pre">};</span></code>
allows outgoing zone transfers to any host using the TLS transport
over port 853.</p>
</dd></dl>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Please note that incoming TLS connections are
<strong>not authenticated at the TLS level by default</strong>.
Please use <a class="reference internal" href="chapter7.html#tsig"><span class="std std-ref">TSIG</span></a> to authenticate requestors
or consider implementing <a class="reference internal" href="#mutual-tls"><span class="std std-ref">Mutual TLS</span></a>
authentication.</p>
</div>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-blackhole">
<span class="sig-name descname"><span class="pre">blackhole</span></span><a class="headerlink" href="#namedconf-statement-blackhole" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">blackhole</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>query</p>
<p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts to ignore. The server will neither respond to queries from nor send queries to these addresses.</p>
</p>
<p>This specifies a list of addresses which the server does not accept queries
from or use to resolve a query. Queries from these addresses are not
responded to. The default is <code class="docutils literal notranslate"><span class="pre">none</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-keep-response-order">
<span class="sig-name descname"><span class="pre">keep-response-order</span></span><a class="headerlink" href="#namedconf-statement-keep-response-order" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">keep-response-order</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of addresses which do not accept reordered answers within a single TCP stream.</p>
</p>
<p>This specifies a list of addresses to which the server sends responses
to TCP queries, in the same order in which they were received. This
disables the processing of TCP queries in parallel. The default is
<code class="docutils literal notranslate"><span class="pre">none</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-no-case-compress">
<span class="sig-name descname"><span class="pre">no-case-compress</span></span><a class="headerlink" href="#namedconf-statement-no-case-compress" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">no-case-compress</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies a list of addresses that require case-insensitive compression in responses.</p>
</p>
<p>This specifies a list of addresses which require responses to use
case-insensitive compression. This ACL can be used when <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
needs to work with clients that do not comply with the requirement in
<span class="target" id="index-19"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1034.html"><strong>RFC 1034</strong></a> to use case-insensitive name comparisons when checking for
matching domain names.</p>
<p>If left undefined, the ACL defaults to <code class="docutils literal notranslate"><span class="pre">none</span></code>: case-sensitive
compression is used for all clients. If the ACL is defined and
matches a client, case is ignored when compressing domain
names in DNS responses sent to that client.</p>
<p>This can result in slightly smaller responses; if a response contains
the names “example.com” and “example.COM”, case-insensitive
compression treats the second one as a duplicate. It also
ensures that the case of the query name exactly matches the case of
the owner names of returned records, rather than matches the case of
the records entered in the zone file. This allows responses to
exactly match the query, which is required by some clients due to
incorrect use of case-sensitive comparisons.</p>
<p>Case-insensitive compression is <em>always</em> used in AXFR and IXFR
responses, regardless of whether the client matches this ACL.</p>
<p>There are circumstances in which <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> does not preserve the case
of owner names of records: if a zone file defines records of
different types with the same name, but the capitalization of the
name is different (e.g., “www.example.com/A” and
“WWW.EXAMPLE.COM/AAAA”), then all responses for that name use
the <em>first</em> version of the name that was used in the zone file. This
limitation may be addressed in a future release. However, domain
names specified in the rdata of resource records (i.e., records of
type NS, MX, CNAME, etc.) always have their case preserved unless
the client matches this ACL.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-resolver-query-timeout">
<span class="sig-name descname"><span class="pre">resolver-query-timeout</span></span><a class="headerlink" href="#namedconf-statement-resolver-query-timeout" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">resolver-query-timeout</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Specifies the length of time, in milliseconds, that a resolver attempts to resolve a recursive query before failing.</p>
</p>
<p>This is the amount of time in milliseconds that the resolver spends
attempting to resolve a recursive query before failing. The default
and minimum is <code class="docutils literal notranslate"><span class="pre">10000</span></code> and the maximum is <code class="docutils literal notranslate"><span class="pre">30000</span></code>. Setting it to
<code class="docutils literal notranslate"><span class="pre">0</span></code> results in the default being used.</p>
<p>This value was originally specified in seconds. Values less than or
equal to 300 are treated as seconds and converted to
milliseconds before applying the above limits.</p>
</dd></dl>
</section>
<section id="interfaces">
<span id="id7"></span><h4><span class="section-number">8.2.14.5. </span>Interfaces<a class="headerlink" href="#interfaces" title="Link to this heading"></a></h4>
<p>The interfaces, ports, and protocols that the server can use to answer
queries may be specified using the <a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> and <a class="reference internal" href="#namedconf-statement-listen-on-v6" title="namedconf-statement-listen-on-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on-v6</span></code></a> options.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-listen-on">
<span class="sig-name descname"><span class="pre">listen-on</span></span><a class="headerlink" href="#namedconf-statement-listen-on" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">listen-on</span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">tls</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">http</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the IPv4 addresses on which a server listens for DNS queries.</p>
</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-listen-on-v6">
<span class="sig-name descname"><span class="pre">listen-on-v6</span></span><a class="headerlink" href="#namedconf-statement-listen-on-v6" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">listen-on-v6</span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">tls</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">http</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the IPv6 addresses on which a server listens for DNS queries.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> and <a class="reference internal" href="#namedconf-statement-listen-on-v6" title="namedconf-statement-listen-on-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on-v6</span></code></a> statements can each take an optional
port, TLS configuration identifier, and/or HTTP configuration identifier,
in addition to an <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a>.</p>
<p>The <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> in <a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> specifies the IPv4 addresses
on which the server will listen. (IPv6 addresses are ignored, with a
logged warning.) The server listens on all interfaces allowed by the
address match list. If no <a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> is specified, the default is
to listen for standard DNS queries on port 53 of all IPv4 interfaces.</p>
<p><a class="reference internal" href="#namedconf-statement-listen-on-v6" title="namedconf-statement-listen-on-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on-v6</span></code></a> takes an <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> of IPv6 addresses.
The server listens on all interfaces allowed by the address match list.
If no <a class="reference internal" href="#namedconf-statement-listen-on-v6" title="namedconf-statement-listen-on-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on-v6</span></code></a> is specified, the default is to listen for standard
DNS queries on port 53 of all IPv6 interfaces.</p>
<p>If a TLS configuration is specified, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> will listen for DNS-over-TLS
(DoT) connections, using the key and certificate specified in the
referenced <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> statement. If the name <code class="docutils literal notranslate"><span class="pre">ephemeral</span></code> is used,
an ephemeral key and certificate created for the currently running
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> process will be used.</p>
<p>If an HTTP configuration is specified, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> will listen for
DNS-over-HTTPS (DoH) connections using the HTTP endpoint specified in the
referenced <a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http</span></code></a> statement. If the name <code class="docutils literal notranslate"><span class="pre">default</span></code> is used, then
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> will listen for connections at the default endpoint,
<code class="docutils literal notranslate"><span class="pre">/dns-query</span></code>.</p>
<p>Use of an <a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http</span></code></a> specification requires <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> to be specified
as well. If an unencrypted connection is desired (for example,
on load-sharing servers behind a reverse proxy), <code class="docutils literal notranslate"><span class="pre">tls</span> <span class="pre">none</span></code> may be used.</p>
<p>If a port number is not specified, the default is 53 for standard DNS,
853 for DNS over TLS, 443 for DNS over HTTPS, and 80 for
DNS over HTTP (unencrypted). These defaults may be overridden using the
<a class="reference internal" href="#namedconf-statement-port" title="namedconf-statement-port"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">port</span></code></a>, <a class="reference internal" href="#namedconf-statement-tls-port" title="namedconf-statement-tls-port"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls-port</span></code></a>, <a class="reference internal" href="#namedconf-statement-https-port" title="namedconf-statement-https-port"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">https-port</span></code></a>, and <a class="reference internal" href="#namedconf-statement-http-port" title="namedconf-statement-http-port"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http-port</span></code></a> options.</p>
<p>Multiple <a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> statements are allowed. For example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>listen-on { 5.6.7.8; };
listen-on port 1234 { !1.2.3.4; 1.2/16; };
listen-on port 8853 tls ephemeral { 4.3.2.1; };
listen-on port 8453 tls ephemeral http myserver { 8.7.6.5; };
</pre></div>
</div>
<p>The first two lines instruct the name server to listen for standard DNS
queries on port 53 of the IP address 5.6.7.8 and on port 1234 of an address
on the machine in net 1.2 that is not 1.2.3.4. The third line instructs the
server to listen for DNS-over-TLS connections on port 8853 of the IP
address 4.3.2.1 using the ephemeral key and certifcate. The fourth line
enables DNS-over-HTTPS connections on port 8453 of address 8.7.6.5, using
the ephemeral key and certificate, and the HTTP endpoint or endpoints
configured in an <a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http</span></code></a> statement with the name <code class="docutils literal notranslate"><span class="pre">myserver</span></code>.</p>
<p>Multiple <a class="reference internal" href="#namedconf-statement-listen-on-v6" title="namedconf-statement-listen-on-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on-v6</span></code></a> options can be used. For example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>listen-on-v6 { any; };
listen-on-v6 port 1234 { !2001:db8::/32; any; };
listen-on port 8853 tls example-tls { 2001:db8::100; };
listen-on port 8453 tls example-tls http default { 2001:db8::100; };
listen-on port 8000 tls none http myserver { 2001:db8::100; };
</pre></div>
</div>
<p>The first two lines instruct the name server to listen for standard DNS
queries on port 53 of any IPv6 addresses, and on port 1234 of IPv6
addresses that are not in the prefix 2001:db8::/32. The third line
instructs the server to listen for for DNS-over-TLS connections on port
8853 of the address 2001:db8::100, using a TLS key and certificate specified
in the a <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> statement with the name <code class="docutils literal notranslate"><span class="pre">example-tls</span></code>. The fourth
instructs the server to listen for DNS-over-HTTPS connections, again using
<code class="docutils literal notranslate"><span class="pre">example-tls</span></code>, on the default HTTP endpoint. The fifth line, in which
the <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> parameter is set to <code class="docutils literal notranslate"><span class="pre">none</span></code>, instructs the server to listen
for <em>unencrypted</em> DNS queries over HTTP at the endpoint specified in
<code class="docutils literal notranslate"><span class="pre">myserver</span></code>..</p>
<p>To instruct the server not to listen on any IPv6 addresses, use:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">listen</span><span class="o">-</span><span class="n">on</span><span class="o">-</span><span class="n">v6</span> <span class="p">{</span> <span class="n">none</span><span class="p">;</span> <span class="p">};</span>
</pre></div>
</div>
</dd></dl>
</section>
<section id="query-address">
<span id="id8"></span><h4><span class="section-number">8.2.14.6. </span>Query Address<a class="headerlink" href="#query-address" title="Link to this heading"></a></h4>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-query-source">
<span class="sig-name descname"><span class="pre">query-source</span></span><a class="headerlink" href="#namedconf-statement-query-source" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">query-source</span> <span class="pre">[</span> <span class="pre">address</span> <span class="pre">]</span> <span class="pre">(</span> <span class="pre"><ipv4_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, server, view, view.server</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls the IPv4 address from which queries are issued.</p>
</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-query-source-v6">
<span class="sig-name descname"><span class="pre">query-source-v6</span></span><a class="headerlink" href="#namedconf-statement-query-source-v6" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">query-source-v6</span> <span class="pre">[</span> <span class="pre">address</span> <span class="pre">]</span> <span class="pre">(</span> <span class="pre"><ipv6_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, server, view, view.server</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls the IPv6 address from which queries are issued.</p>
</p>
<p>If the server does not know the answer to a question, it queries other
name servers. <a class="reference internal" href="#namedconf-statement-query-source" title="namedconf-statement-query-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">query-source</span></code></a> specifies the address and port used for
such queries. For queries sent over IPv6, there is a separate
<a class="reference internal" href="#namedconf-statement-query-source-v6" title="namedconf-statement-query-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">query-source-v6</span></code></a> option. If <code class="docutils literal notranslate"><span class="pre">address</span></code> is <code class="docutils literal notranslate"><span class="pre">*</span></code> (asterisk) or is
omitted, a wildcard IP address (<code class="docutils literal notranslate"><span class="pre">INADDR_ANY</span></code>) is used.</p>
<p>The defaults of the <a class="reference internal" href="#namedconf-statement-query-source" title="namedconf-statement-query-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">query-source</span></code></a> and <a class="reference internal" href="#namedconf-statement-query-source-v6" title="namedconf-statement-query-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">query-source-v6</span></code></a> options
are:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">query</span><span class="o">-</span><span class="n">source</span> <span class="n">address</span> <span class="o">*</span> <span class="n">port</span> <span class="o">*</span><span class="p">;</span>
<span class="n">query</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="n">address</span> <span class="o">*</span> <span class="n">port</span> <span class="o">*</span><span class="p">;</span>
</pre></div>
</div>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p><code class="docutils literal notranslate"><span class="pre">port</span></code> configuration is deprecated. A warning will be logged
when this parameter is used.</p>
</div>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>The address specified in the <a class="reference internal" href="#namedconf-statement-query-source" title="namedconf-statement-query-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">query-source</span></code></a> option is
used for both UDP and TCP queries, but the port applies only to UDP
queries. TCP queries always use a random unprivileged port.</p>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-use-v4-udp-ports">
<span class="sig-name descname"><span class="pre">use-v4-udp-ports</span></span><a class="headerlink" href="#namedconf-statement-use-v4-udp-ports" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">use-v4-udp-ports</span> <span class="pre">{</span> <span class="pre"><portrange>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Specifies a list of ports that are valid sources for UDP/IPv4 messages.</p>
</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-use-v6-udp-ports">
<span class="sig-name descname"><span class="pre">use-v6-udp-ports</span></span><a class="headerlink" href="#namedconf-statement-use-v6-udp-ports" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">use-v6-udp-ports</span> <span class="pre">{</span> <span class="pre"><portrange>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Specifies a list of ports that are valid sources for UDP/IPv6 messages.</p>
</p>
<p>These statements, which are deprecated and will be removed in a future
release, specify a list of IPv4 and IPv6 UDP ports that are used as
source ports for UDP messages.</p>
<p>If <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a> is <code class="docutils literal notranslate"><span class="pre">*</span></code> or is omitted, a random port number from a
pre-configured range is selected and used for each query. The
port range(s) are specified in the <a class="reference internal" href="#namedconf-statement-use-v4-udp-ports" title="namedconf-statement-use-v4-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-v4-udp-ports</span></code></a> (for IPv4)
and <a class="reference internal" href="#namedconf-statement-use-v6-udp-ports" title="namedconf-statement-use-v6-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-v6-udp-ports</span></code></a> (for IPv6) options.</p>
<p>If <a class="reference internal" href="#namedconf-statement-use-v4-udp-ports" title="namedconf-statement-use-v4-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-v4-udp-ports</span></code></a> or <a class="reference internal" href="#namedconf-statement-use-v6-udp-ports" title="namedconf-statement-use-v6-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-v6-udp-ports</span></code></a> is unspecified,
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> checks whether the operating system provides a programming
interface to retrieve the system’s default range for ephemeral ports. If
such an interface is available, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> uses the corresponding
system default range; otherwise, it uses its own defaults:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">use</span><span class="o">-</span><span class="n">v4</span><span class="o">-</span><span class="n">udp</span><span class="o">-</span><span class="n">ports</span> <span class="p">{</span> <span class="nb">range</span> <span class="mi">1024</span> <span class="mi">65535</span><span class="p">;</span> <span class="p">};</span>
<span class="n">use</span><span class="o">-</span><span class="n">v6</span><span class="o">-</span><span class="n">udp</span><span class="o">-</span><span class="n">ports</span> <span class="p">{</span> <span class="nb">range</span> <span class="mi">1024</span> <span class="mi">65535</span><span class="p">;</span> <span class="p">};</span>
</pre></div>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-avoid-v4-udp-ports">
<span class="sig-name descname"><span class="pre">avoid-v4-udp-ports</span></span><a class="headerlink" href="#namedconf-statement-avoid-v4-udp-ports" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">avoid-v4-udp-ports</span> <span class="pre">{</span> <span class="pre"><portrange>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Specifies the range(s) of ports to be excluded from use as sources for UDP/IPv4 messages.</p>
</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-avoid-v6-udp-ports">
<span class="sig-name descname"><span class="pre">avoid-v6-udp-ports</span></span><a class="headerlink" href="#namedconf-statement-avoid-v6-udp-ports" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">avoid-v6-udp-ports</span> <span class="pre">{</span> <span class="pre"><portrange>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Specifies the range(s) of ports to be excluded from use as sources for UDP/IPv6 messages.</p>
</p>
<p>These statements, which are deprecated and will be removed in a future
release, indicate ranges of port numbers to exclude from those specified
in the <a class="reference internal" href="#namedconf-statement-avoid-v4-udp-ports" title="namedconf-statement-avoid-v4-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">avoid-v4-udp-ports</span></code></a> and <a class="reference internal" href="#namedconf-statement-avoid-v6-udp-ports" title="namedconf-statement-avoid-v6-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">avoid-v6-udp-ports</span></code></a>
options, respectively.</p>
<p>The defaults of the <a class="reference internal" href="#namedconf-statement-avoid-v4-udp-ports" title="namedconf-statement-avoid-v4-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">avoid-v4-udp-ports</span></code></a> and <a class="reference internal" href="#namedconf-statement-avoid-v6-udp-ports" title="namedconf-statement-avoid-v6-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">avoid-v6-udp-ports</span></code></a>
options are:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">avoid</span><span class="o">-</span><span class="n">v4</span><span class="o">-</span><span class="n">udp</span><span class="o">-</span><span class="n">ports</span> <span class="p">{};</span>
<span class="n">avoid</span><span class="o">-</span><span class="n">v6</span><span class="o">-</span><span class="n">udp</span><span class="o">-</span><span class="n">ports</span> <span class="p">{};</span>
</pre></div>
</div>
<p>For example, with the following configuration:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">use</span><span class="o">-</span><span class="n">v6</span><span class="o">-</span><span class="n">udp</span><span class="o">-</span><span class="n">ports</span> <span class="p">{</span> <span class="nb">range</span> <span class="mi">32768</span> <span class="mi">65535</span><span class="p">;</span> <span class="p">};</span>
<span class="n">avoid</span><span class="o">-</span><span class="n">v6</span><span class="o">-</span><span class="n">udp</span><span class="o">-</span><span class="n">ports</span> <span class="p">{</span> <span class="mi">40000</span><span class="p">;</span> <span class="nb">range</span> <span class="mi">50000</span> <span class="mi">60000</span><span class="p">;</span> <span class="p">};</span>
</pre></div>
</div>
<p>UDP ports of IPv6 messages sent from <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> are in one of the
following ranges: 32768 to 39999, 40001 to 49999, or 60001 to 65535.</p>
<p><a class="reference internal" href="#namedconf-statement-avoid-v4-udp-ports" title="namedconf-statement-avoid-v4-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">avoid-v4-udp-ports</span></code></a> and <a class="reference internal" href="#namedconf-statement-avoid-v6-udp-ports" title="namedconf-statement-avoid-v6-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">avoid-v6-udp-ports</span></code></a> can be used to prevent
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> from choosing as its random source port a port that is blocked
by a firewall or that is used by other applications; if a
query went out with a source port blocked by a firewall, the answer
would not pass through the firewall and the name server would have to query
again. Note: the desired range can also be represented only with
<a class="reference internal" href="#namedconf-statement-use-v4-udp-ports" title="namedconf-statement-use-v4-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-v4-udp-ports</span></code></a> and <a class="reference internal" href="#namedconf-statement-use-v6-udp-ports" title="namedconf-statement-use-v6-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-v6-udp-ports</span></code></a>, and the <code class="docutils literal notranslate"><span class="pre">avoid-</span></code>
options are redundant in that sense; they are provided for backward
compatibility and to possibly simplify the port specification.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Make sure the ranges are sufficiently large for security. A
desirable size depends on several parameters, but we generally recommend
it contain at least 16384 ports (14 bits of entropy). Note also that the
system’s default range when used may be too small for this purpose, and
that the range may even be changed while <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is running; the new
range is automatically applied when <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is reloaded. Explicit
configuration of <a class="reference internal" href="#namedconf-statement-use-v4-udp-ports" title="namedconf-statement-use-v4-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-v4-udp-ports</span></code></a> and <a class="reference internal" href="#namedconf-statement-use-v6-udp-ports" title="namedconf-statement-use-v6-udp-ports"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-v6-udp-ports</span></code></a> is encouraged,
so that the ranges are sufficiently large and are reasonably
independent from the ranges used by other applications.</p>
</div>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>The operational configuration where <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> runs may prohibit
the use of some ports. For example, Unix systems do not allow
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>, if run without root privilege, to use ports less than 1024.
If such ports are included in the specified (or detected) set of query
ports, the corresponding query attempts will fail, resulting in
resolution failures or delay. It is therefore important to configure the
set of ports that can be safely used in the expected operational
environment.</p>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Specifying a single port is discouraged, as it removes a layer of
protection against spoofing errors.</p>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The configured <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a> must not be the same as the listening port.</p>
</div>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>See also <a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a>, <a class="reference internal" href="#namedconf-statement-notify-source" title="namedconf-statement-notify-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-source</span></code></a> and <a class="reference internal" href="#namedconf-statement-parental-source" title="namedconf-statement-parental-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parental-source</span></code></a>.</p>
</div>
</dd></dl>
</section>
<section id="zone-transfers">
<span id="id9"></span><h4><span class="section-number">8.2.14.7. </span>Zone Transfers<a class="headerlink" href="#zone-transfers" title="Link to this heading"></a></h4>
<p>BIND has mechanisms in place to facilitate zone transfers and set limits
on the amount of load that transfers place on the system. The following
options apply to zone transfers.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-also-notify">
<span class="sig-name descname"><span class="pre">also-notify</span></span><a class="headerlink" href="#namedconf-statement-also-notify" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">also-notify</span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span>  <span class="pre">{</span> <span class="pre">(</span> <span class="pre"><remote-servers></span> <span class="pre">|</span> <span class="pre"><ipv4_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">|</span> <span class="pre"><ipv6_address></span> <span class="pre">[</span> <span class="pre">port</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">)</span> <span class="pre">[</span> <span class="pre">key</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">tls</span> <span class="pre"><string></span> <span class="pre">];</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Defines one or more hosts that are sent <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages when zone changes occur.</p>
</p>
<p>This option defines a global list of IP addresses of name servers that are also
sent NOTIFY messages whenever a fresh copy of the zone is loaded, in
addition to the servers listed in the zone’s NS records. This helps
to ensure that copies of the zones quickly converge on stealth
servers. Optionally, a port may be specified with each
<a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a> address to send the notify messages to a port other
than the default of 53. An optional TSIG key can also be specified
with each address to cause the notify messages to be signed; this can
be useful when sending notifies to multiple views. In place of
explicit addresses, one or more named <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> lists can be used.</p>
<p>If an <a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a> list is given in a <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statement, it
overrides the <code class="docutils literal notranslate"><span class="pre">options</span> <span class="pre">also-notify</span></code> statement. When a
<code class="docutils literal notranslate"><span class="pre">zone</span> <span class="pre">notify</span></code> statement is set to <code class="docutils literal notranslate"><span class="pre">no</span></code>, the IP addresses in the
global <a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a> list are not sent NOTIFY messages for that
zone. The default is the empty list (no global notification list).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-transfer-time-in">
<span class="sig-name descname"><span class="pre">max-transfer-time-in</span></span><a class="headerlink" href="#namedconf-statement-max-transfer-time-in" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-transfer-time-in</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, secondary, stub)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Specifies the number of minutes after which inbound zone transfers are terminated.</p>
</p>
<p>Inbound zone transfers running longer than this many minutes are
terminated. The default is 120 minutes (2 hours). The maximum value
is 28 days (40320 minutes).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-transfer-idle-in">
<span class="sig-name descname"><span class="pre">max-transfer-idle-in</span></span><a class="headerlink" href="#namedconf-statement-max-transfer-idle-in" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-transfer-idle-in</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, secondary, stub)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Specifies the number of minutes after which inbound zone transfers making no progress are terminated.</p>
</p>
<p>Inbound zone transfers making no progress in this many minutes are
terminated. The default is 60 minutes (1 hour). The maximum value
is 28 days (40320 minutes).</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Inbound zone transfers are also affected by
<code class="docutils literal notranslate"><span class="pre">tcp-idle-timeout</span></code>; <code class="docutils literal notranslate"><span class="pre">max-transfer-idle-in</span></code> closes the
inbound zone transfer if there is no complete AXFR or no complete
IXFR chunk. <code class="docutils literal notranslate"><span class="pre">tcp-idle-timeout</span></code> closes the connection if
there is no progress on the TCP level.</p>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-transfer-time-out">
<span class="sig-name descname"><span class="pre">max-transfer-time-out</span></span><a class="headerlink" href="#namedconf-statement-max-transfer-time-out" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-transfer-time-out</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Specifies the number of minutes after which outbound zone transfers are terminated.</p>
</p>
<p>Outbound zone transfers running longer than this many minutes are
terminated. The default is 120 minutes (2 hours). The maximum value
is 28 days (40320 minutes).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-transfer-idle-out">
<span class="sig-name descname"><span class="pre">max-transfer-idle-out</span></span><a class="headerlink" href="#namedconf-statement-max-transfer-idle-out" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-transfer-idle-out</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Specifies the number of minutes after which outbound zone transfers making no progress are terminated.</p>
</p>
<p>Outbound zone transfers making no progress in this many minutes are
terminated. The default is 60 minutes (1 hour). The maximum value
is 28 days (40320 minutes).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-notify-rate">
<span class="sig-name descname"><span class="pre">notify-rate</span></span><a class="headerlink" href="#namedconf-statement-notify-rate" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">notify-rate</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>transfer, zone</p>
<p><p>Specifies the rate at which NOTIFY requests are sent during normal zone maintenance operations.</p>
</p>
<p>This specifies the rate at which NOTIFY requests are sent during normal zone
maintenance operations. (NOTIFY requests due to initial zone loading
are subject to a separate rate limit; see below.) The default is 20
per second. The lowest possible rate is one per second; when set to
zero, it is silently raised to one.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-startup-notify-rate">
<span class="sig-name descname"><span class="pre">startup-notify-rate</span></span><a class="headerlink" href="#namedconf-statement-startup-notify-rate" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">startup-notify-rate</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>transfer, zone</p>
<p><p>Specifies the rate at which NOTIFY requests are sent when the name server is first starting, or when new zones have been added.</p>
</p>
<p>This is the rate at which NOTIFY requests are sent when the name server
is first starting up, or when zones have been newly added to the
name server. The default is 20 per second. The lowest possible rate is
one per second; when set to zero, it is silently raised to one.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-serial-query-rate">
<span class="sig-name descname"><span class="pre">serial-query-rate</span></span><a class="headerlink" href="#namedconf-statement-serial-query-rate" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">serial-query-rate</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Defines an upper limit on the number of queries per second issued by the server, when querying the SOA RRs used for zone transfers.</p>
</p>
<p>Secondary servers periodically query primary servers to find out if
zone serial numbers have changed. Each such query uses a minute
amount of the secondary server’s network bandwidth. To limit the amount
of bandwidth used, BIND 9 limits the rate at which queries are sent.
The value of the <a class="reference internal" href="#namedconf-statement-serial-query-rate" title="namedconf-statement-serial-query-rate"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">serial-query-rate</span></code></a> option, an integer, is the
maximum number of queries sent per second. The default is 20 per
second. The lowest possible rate is one per second; when set to zero,
it is silently raised to one.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-transfer-format">
<span class="sig-name descname"><span class="pre">transfer-format</span></span><a class="headerlink" href="#namedconf-statement-transfer-format" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">transfer-format</span> <span class="pre">(</span> <span class="pre">many-answers</span> <span class="pre">|</span> <span class="pre">one-answer</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, server, view, view.server</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Controls whether multiple records can be packed into a message during zone transfers.</p>
</p>
<p>Zone transfers can be sent using two different formats,
<code class="docutils literal notranslate"><span class="pre">one-answer</span></code> and <code class="docutils literal notranslate"><span class="pre">many-answers</span></code>. The <a class="reference internal" href="#namedconf-statement-transfer-format" title="namedconf-statement-transfer-format"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-format</span></code></a> option
is used on the primary server to determine which format it sends.
<code class="docutils literal notranslate"><span class="pre">one-answer</span></code> uses one DNS message per resource record transferred.
<code class="docutils literal notranslate"><span class="pre">many-answers</span></code> packs as many resource records as possible into one
message. <code class="docutils literal notranslate"><span class="pre">many-answers</span></code> is more efficient; the default is <code class="docutils literal notranslate"><span class="pre">many-answers</span></code>.
<a class="reference internal" href="#namedconf-statement-transfer-format" title="namedconf-statement-transfer-format"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-format</span></code></a> may be overridden on a per-server basis by using
the <a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">server</span></code></a> block.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-transfer-message-size">
<span class="sig-name descname"><span class="pre">transfer-message-size</span></span><a class="headerlink" href="#namedconf-statement-transfer-message-size" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">transfer-message-size</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Limits the uncompressed size of DNS messages used in zone transfers over TCP.</p>
</p>
<p>This is an upper bound on the uncompressed size of DNS messages used
in zone transfers over TCP. If a message grows larger than this size,
additional messages are used to complete the zone transfer.
(Note, however, that this is a hint, not a hard limit; if a message
contains a single resource record whose RDATA does not fit within the
size limit, a larger message will be permitted so the record can be
transferred.)</p>
<p>Valid values are between 512 and 65535 octets; any values outside
that range are adjusted to the nearest value within it. The
default is <code class="docutils literal notranslate"><span class="pre">20480</span></code>, which was selected to improve message
compression; most DNS messages of this size will compress to less
than 16536 bytes. Larger messages cannot be compressed as
effectively, because 16536 is the largest permissible compression
offset pointer in a DNS message.</p>
<p>This option is mainly intended for server testing; there is rarely
any benefit in setting a value other than the default.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-transfers-in">
<span class="sig-name descname"><span class="pre">transfers-in</span></span><a class="headerlink" href="#namedconf-statement-transfers-in" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">transfers-in</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Limits the number of concurrent inbound zone transfers.</p>
</p>
<p>This is the maximum number of inbound zone transfers that can run
concurrently. The default value is <code class="docutils literal notranslate"><span class="pre">10</span></code>. Increasing
<a class="reference internal" href="#namedconf-statement-transfers-in" title="namedconf-statement-transfers-in"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfers-in</span></code></a> may speed up the convergence of secondary zones, but it
also may increase the load on the local system.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-transfers-out">
<span class="sig-name descname"><span class="pre">transfers-out</span></span><a class="headerlink" href="#namedconf-statement-transfers-out" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">transfers-out</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Limits the number of concurrent outbound zone transfers.</p>
</p>
<p>This is the maximum number of outbound zone transfers that can run
concurrently. Zone transfer requests in excess of the limit are
refused. The default value is <code class="docutils literal notranslate"><span class="pre">10</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-transfers-per-ns">
<span class="sig-name descname"><span class="pre">transfers-per-ns</span></span><a class="headerlink" href="#namedconf-statement-transfers-per-ns" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">transfers-per-ns</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Limits the number of concurrent inbound zone transfers from a remote server.</p>
</p>
<p>This is the maximum number of inbound zone transfers that can concurrently
transfer from a given remote name server. The default value is
<code class="docutils literal notranslate"><span class="pre">2</span></code>. Increasing <a class="reference internal" href="#namedconf-statement-transfers-per-ns" title="namedconf-statement-transfers-per-ns"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfers-per-ns</span></code></a> may speed up the convergence
of secondary zones, but it also may increase the load on the remote name
server. <a class="reference internal" href="#namedconf-statement-transfers-per-ns" title="namedconf-statement-transfers-per-ns"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfers-per-ns</span></code></a> may be overridden on a per-server basis
by using the <a class="reference internal" href="#namedconf-statement-transfers" title="namedconf-statement-transfers"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfers</span></code></a> phrase of the <a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">server</span></code></a> statement.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-transfer-source">
<span class="sig-name descname"><span class="pre">transfer-source</span></span><a class="headerlink" href="#namedconf-statement-transfer-source" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">transfer-source</span> <span class="pre">(</span> <span class="pre"><ipv4_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, server, view, zone (mirror, secondary, stub), view.server</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Defines which local IPv4 address(es) are bound to TCP connections used to fetch zones transferred inbound by the server.</p>
</p>
<p><a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a> determines which local address is bound to
IPv4 TCP connections used to fetch zones transferred inbound by the
server. It also determines the source IPv4 address, and optionally
the UDP port, used for the refresh queries and forwarded dynamic
updates. If not set, it defaults to a system-controlled value which
is usually the address of the interface “closest to” the remote
end. This address must appear in the remote end’s <a class="reference internal" href="#namedconf-statement-allow-transfer" title="namedconf-statement-allow-transfer"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-transfer</span></code></a>
option for the zone being transferred, if one is specified. This
statement sets the <a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a> for all zones, but can be
overridden on a per-view or per-zone basis by including a
<a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a> statement within the <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> or <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> block
in the configuration file.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p><code class="docutils literal notranslate"><span class="pre">port</span></code> configuration is deprecated. A warning will be logged
when this parameter is used.</p>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Specifying a single port is discouraged, as it removes a layer of
protection against spoofing errors.</p>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The configured <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a> must not be the same as the listening port.</p>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-transfer-source-v6">
<span class="sig-name descname"><span class="pre">transfer-source-v6</span></span><a class="headerlink" href="#namedconf-statement-transfer-source-v6" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">transfer-source-v6</span> <span class="pre">(</span> <span class="pre"><ipv6_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, server, view, zone (mirror, secondary, stub), view.server</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Defines which local IPv6 address(es) are bound to TCP connections used to fetch zones transferred inbound by the server.</p>
</p>
<p>This option is the same as <a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a>, except zone transfers
are performed using IPv6.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-alt-transfer-source">
<span class="sig-name descname"><span class="pre">alt-transfer-source</span></span><a class="headerlink" href="#namedconf-statement-alt-transfer-source" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">alt-transfer-source</span> <span class="pre">(</span> <span class="pre"><ipv4_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">);</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Defines alternate local IPv4 address(es) to be used by the server for inbound zone transfers, if the address(es) defined by <a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a> fail and <a class="reference internal" href="#namedconf-statement-use-alt-transfer-source" title="namedconf-statement-use-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-alt-transfer-source</span></code></a> is enabled.</p>
</p>
<p>This indicates an alternate transfer source if the one listed in <a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a>
fails and <a class="reference internal" href="#namedconf-statement-use-alt-transfer-source" title="namedconf-statement-use-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-alt-transfer-source</span></code></a> is set.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>To avoid using the alternate transfer source,
set <a class="reference internal" href="#namedconf-statement-use-alt-transfer-source" title="namedconf-statement-use-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-alt-transfer-source</span></code></a> appropriately and
do not depend upon getting an answer back to the first refresh
query.</p>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-alt-transfer-source-v6">
<span class="sig-name descname"><span class="pre">alt-transfer-source-v6</span></span><a class="headerlink" href="#namedconf-statement-alt-transfer-source-v6" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">alt-transfer-source-v6</span> <span class="pre">(</span> <span class="pre"><ipv6_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">);</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Defines alternate local IPv6 address(es) to be used by the server for inbound zone transfers.</p>
</p>
<p>This indicates an alternate transfer source if the one listed in
<a class="reference internal" href="#namedconf-statement-transfer-source-v6" title="namedconf-statement-transfer-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source-v6</span></code></a> fails and <a class="reference internal" href="#namedconf-statement-use-alt-transfer-source" title="namedconf-statement-use-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-alt-transfer-source</span></code></a> is set.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-use-alt-transfer-source">
<span class="sig-name descname"><span class="pre">use-alt-transfer-source</span></span><a class="headerlink" href="#namedconf-statement-use-alt-transfer-source" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">use-alt-transfer-source</span> <span class="pre"><boolean>;</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, secondary, stub)</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Indicates whether <a class="reference internal" href="#namedconf-statement-alt-transfer-source" title="namedconf-statement-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">alt-transfer-source</span></code></a> and <a class="reference internal" href="#namedconf-statement-alt-transfer-source-v6" title="namedconf-statement-alt-transfer-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">alt-transfer-source-v6</span></code></a> can be used.</p>
</p>
<p>This indicates whether the alternate transfer sources should be used. If views are specified,
this defaults to <code class="docutils literal notranslate"><span class="pre">no</span></code>; otherwise, it defaults to <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-notify-source">
<span class="sig-name descname"><span class="pre">notify-source</span></span><a class="headerlink" href="#namedconf-statement-notify-source" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">notify-source</span> <span class="pre">(</span> <span class="pre"><ipv4_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, server, view, zone (mirror, primary, secondary), view.server</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Defines the IPv4 address (and optional port) to be used for outgoing <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages.</p>
</p>
<p><a class="reference internal" href="#namedconf-statement-notify-source" title="namedconf-statement-notify-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-source</span></code></a> determines which local source address, and
optionally UDP port, is used to send NOTIFY messages. This
address must appear in the secondary server’s <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> zone clause or
in an <a class="reference internal" href="#namedconf-statement-allow-notify" title="namedconf-statement-allow-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-notify</span></code></a> clause. This statement sets the
<a class="reference internal" href="#namedconf-statement-notify-source" title="namedconf-statement-notify-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-source</span></code></a> for all zones, but can be overridden on a per-zone
or per-view basis by including a <a class="reference internal" href="#namedconf-statement-notify-source" title="namedconf-statement-notify-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-source</span></code></a> statement within
the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> or <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> block in the configuration file.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p><code class="docutils literal notranslate"><span class="pre">port</span></code> configuration is deprecated. A warning will be logged
when this parameter is used.</p>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Specifying a single port is discouraged, as it removes a layer of
protection against spoofing errors.</p>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The configured <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a> must not be the same as the listening port.</p>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-notify-source-v6">
<span class="sig-name descname"><span class="pre">notify-source-v6</span></span><a class="headerlink" href="#namedconf-statement-notify-source-v6" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">notify-source-v6</span> <span class="pre">(</span> <span class="pre"><ipv6_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, server, view, zone (mirror, primary, secondary), view.server</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Defines the IPv6 address (and optional port) to be used for outgoing <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages.</p>
</p>
<p>This option acts like <a class="reference internal" href="#namedconf-statement-notify-source" title="namedconf-statement-notify-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-source</span></code></a>, but applies to <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages sent to IPv6
addresses.</p>
</dd></dl>
</section>
<section id="operating-system-resource-limits">
<span id="resource-limits"></span><h4><span class="section-number">8.2.14.8. </span>Operating System Resource Limits<a class="headerlink" href="#operating-system-resource-limits" title="Link to this heading"></a></h4>
<p>The server’s usage of many system resources can be limited. Scaled
values are allowed when specifying resource limits. For example, <code class="docutils literal notranslate"><span class="pre">1G</span></code>
can be used instead of <code class="docutils literal notranslate"><span class="pre">1073741824</span></code> to specify a limit of one
gigabyte. <code class="docutils literal notranslate"><span class="pre">unlimited</span></code> requests unlimited use, or the maximum available
amount. <code class="docutils literal notranslate"><span class="pre">default</span></code> uses the limit that was in force when the server was
started. See the description of <a class="reference internal" href="#term-size"><span class="xref std std-term">size</span></a>.</p>
<p>The following options are deprecated in favor of setting the operating system
resource limits from the operating system and/or process supervisor. They should not
be used and will be rendered non-operational in a future release.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-coresize">
<span class="sig-name descname"><span class="pre">coresize</span></span><a class="headerlink" href="#namedconf-statement-coresize" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">coresize</span> <span class="pre">(</span> <span class="pre">default</span> <span class="pre">|</span> <span class="pre">unlimited</span> <span class="pre">|</span> <span class="pre"><sizeval></span> <span class="pre">);</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Sets the maximum size of a core dump.</p>
</p>
<p>This sets the maximum size of a core dump. The default is <code class="docutils literal notranslate"><span class="pre">default</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-datasize">
<span class="sig-name descname"><span class="pre">datasize</span></span><a class="headerlink" href="#namedconf-statement-datasize" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">datasize</span> <span class="pre">(</span> <span class="pre">default</span> <span class="pre">|</span> <span class="pre">unlimited</span> <span class="pre">|</span> <span class="pre"><sizeval></span> <span class="pre">);</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Sets the maximum amount of data memory that can be used by the server.</p>
</p>
<p>This sets the maximum amount of data memory the server may use. The default is
<code class="docutils literal notranslate"><span class="pre">default</span></code>. This is a hard limit on server memory usage; if the
server attempts to allocate memory in excess of this limit, the
allocation will fail, which may in turn leave the server unable to
perform DNS service. Therefore, this option is rarely useful as a way
to limit the amount of memory used by the server, but it can be
used to raise an operating system data size limit that is too small
by default. To limit the amount of memory used by the
server, use the <a class="reference internal" href="#namedconf-statement-max-cache-size" title="namedconf-statement-max-cache-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-cache-size</span></code></a> and <a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursive-clients</span></code></a> options
instead.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-files">
<span class="sig-name descname"><span class="pre">files</span></span><a class="headerlink" href="#namedconf-statement-files" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">files</span> <span class="pre">(</span> <span class="pre">default</span> <span class="pre">|</span> <span class="pre">unlimited</span> <span class="pre">|</span> <span class="pre"><sizeval></span> <span class="pre">);</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Sets the maximum number of files the server may have open concurrently.</p>
</p>
<p>This sets the maximum number of files the server may have open concurrently.
The default is <code class="docutils literal notranslate"><span class="pre">unlimited</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-stacksize">
<span class="sig-name descname"><span class="pre">stacksize</span></span><a class="headerlink" href="#namedconf-statement-stacksize" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">stacksize</span> <span class="pre">(</span> <span class="pre">default</span> <span class="pre">|</span> <span class="pre">unlimited</span> <span class="pre">|</span> <span class="pre"><sizeval></span> <span class="pre">);</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Sets the maximum amount of stack memory that can be used by the server.</p>
</p>
<p>This sets the maximum amount of stack memory the server may use. The default is
<code class="docutils literal notranslate"><span class="pre">default</span></code>.</p>
</dd></dl>
</section>
<section id="server-resource-limits">
<span id="id10"></span><h4><span class="section-number">8.2.14.9. </span>Server Resource Limits<a class="headerlink" href="#server-resource-limits" title="Link to this heading"></a></h4>
<p>The following options set limits on the server’s resource consumption
that are enforced internally by the server rather than by the operating
system.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-journal-size">
<span class="sig-name descname"><span class="pre">max-journal-size</span></span><a class="headerlink" href="#namedconf-statement-max-journal-size" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-journal-size</span> <span class="pre">(</span> <span class="pre">default</span> <span class="pre">|</span> <span class="pre">unlimited</span> <span class="pre">|</span> <span class="pre"><sizeval></span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Controls the size of journal files.</p>
</p>
<p>This sets a maximum size for each journal file (see <a class="reference internal" href="chapter6.html#journal"><span class="std std-ref">The Journal File</span></a>),
expressed in bytes or, if followed by an
optional unit suffix (‘k’, ‘m’, or ‘g’), in kilobytes, megabytes, or
gigabytes. When the journal file approaches the specified size, some
of the oldest transactions in the journal are automatically
removed. The largest permitted value is 2 gigabytes. Very small
values are rounded up to 4096 bytes. It is possible to specify <code class="docutils literal notranslate"><span class="pre">unlimited</span></code>,
which also means 2 gigabytes. If the limit is set to <code class="docutils literal notranslate"><span class="pre">default</span></code> or
left unset, the journal is allowed to grow up to twice as large
as the zone. (There is little benefit in storing larger journals.)</p>
<p>This option may also be set on a per-zone basis.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-records">
<span class="sig-name descname"><span class="pre">max-records</span></span><a class="headerlink" href="#namedconf-statement-max-records" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-records</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, redirect, secondary, static-stub, stub)</p>
<p><strong>Tags: </strong>zone, server</p>
<p><p>Sets the maximum number of records permitted in a zone.</p>
</p>
<p>This sets the maximum number of records permitted in a zone. The default is
zero, which means the maximum is unlimited.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-records-per-type">
<span class="sig-name descname"><span class="pre">max-records-per-type</span></span><a class="headerlink" href="#namedconf-statement-max-records-per-type" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-records-per-type</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, redirect, secondary, static-stub, stub)</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the maximum number of records that can be stored in an RRset.</p>
</p>
<p>This sets the maximum number of resource records that can be stored
in an RRset in a database. When configured in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>
or <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>, it controls the cache database; it also sets
the default value for zone databases, which can be overridden by setting
it at the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> level.</p>
<p>If set to a positive value, any attempt to cache, or to add to a zone
an RRset with more than the specified number of records, will result in
a failure. If set to 0, there is no cap on RRset size. The default is
100.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-types-per-name">
<span class="sig-name descname"><span class="pre">max-types-per-name</span></span><a class="headerlink" href="#namedconf-statement-max-types-per-name" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-types-per-name</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, redirect, secondary, static-stub, stub)</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the maximum number of RR types that can be stored for an owner name.</p>
</p>
<p>This sets the maximum number of resource record types that can be stored
for a single owner name in a database. When configured in
<a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> or <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>, it controls the cache
database and sets the default value for zone databases, which can be
overridden by setting it at the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> level.</p>
<p>An RR type and its corresponding signature are counted as two types. So,
for example, a signed node containing A and AAAA records has four types:
A, RRSIG(A), AAAA, and RRSIG(AAAA).</p>
<p>The behavior is slightly different for zone and cache databases:</p>
<p>In a zone, if <a class="reference internal" href="#namedconf-statement-max-types-per-name" title="namedconf-statement-max-types-per-name"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-types-per-name</span></code></a> is set to a positive number, any
attempt to add a new resource record set to a name that already has the
specified number of types will fail.</p>
<p>In a cache, if <a class="reference internal" href="#namedconf-statement-max-types-per-name" title="namedconf-statement-max-types-per-name"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-types-per-name</span></code></a> is set to a positive number, an
attempt to add a new resource record set to a name that already has the
specified number of types will temporarily succeed, so that the query can
be answered. However, the newly added RRset will immediately be purged.</p>
<p>Certain high-priority types, including SOA, CNAME, DNSKEY, and their
corresponding signatures, are always cached. If <a class="reference internal" href="#namedconf-statement-max-types-per-name" title="namedconf-statement-max-types-per-name"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-types-per-name</span></code></a>
is set to a very low value, then it may be ignored to allow high-priority
types to be cached.</p>
<p>When <a class="reference internal" href="#namedconf-statement-max-types-per-name" title="namedconf-statement-max-types-per-name"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-types-per-name</span></code></a> is set to 0, there is no cap on the number
of RR types. The default is 100.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-recursive-clients">
<span class="sig-name descname"><span class="pre">recursive-clients</span></span><a class="headerlink" href="#namedconf-statement-recursive-clients" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">recursive-clients</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>query</p>
<p><p>Specifies the maximum number of concurrent recursive queries the server can perform.</p>
</p>
<p>This sets the maximum number (a “hard quota”) of simultaneous recursive lookups
the server performs on behalf of clients. The default is
<code class="docutils literal notranslate"><span class="pre">1000</span></code>. Because each recursing client uses a fair bit of memory (on
the order of 20 kilobytes), the value of the <a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursive-clients</span></code></a>
option may have to be decreased on hosts with limited memory.</p>
<p><a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursive-clients</span></code></a> defines a “hard quota” limit for pending
recursive clients; when more clients than this are pending, new
incoming requests are not accepted, and for each incoming request
a previous pending request is dropped.</p>
<p>A “soft quota” is also set. When this lower quota is exceeded,
incoming requests are accepted, but for each one, a pending request
is dropped. If <a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursive-clients</span></code></a> is greater than 1000, the
soft quota is set to <a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursive-clients</span></code></a> minus 100; otherwise it is
set to 90% of <a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursive-clients</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tcp-clients">
<span class="sig-name descname"><span class="pre">tcp-clients</span></span><a class="headerlink" href="#namedconf-statement-tcp-clients" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tcp-clients</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the maximum number of simultaneous client TCP connections accepted by the server.</p>
</p>
<p>This is the maximum number of simultaneous client TCP connections that the
server accepts. The default is <code class="docutils literal notranslate"><span class="pre">150</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-clients-per-query">
<span class="sig-name descname"><span class="pre">clients-per-query</span></span><a class="headerlink" href="#namedconf-statement-clients-per-query" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">clients-per-query</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the initial minimum number of simultaneous recursive clients accepted by the server for any given query before the server drops additional clients.</p>
</p>
<p>This sets the initial value (minimum) number of simultaneous recursive clients
for any given query (<qname,qtype,qclass>) that the server accepts before
dropping additional clents. <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> attempts to self-tune this
value and changes are logged. The default value is 10.</p>
<p>The chosen value should reflect how many queries come in for a given name
in the time it takes to resolve that name.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-clients-per-query">
<span class="sig-name descname"><span class="pre">max-clients-per-query</span></span><a class="headerlink" href="#namedconf-statement-max-clients-per-query" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-clients-per-query</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the maximum number of simultaneous recursive clients accepted by the server for any given query before the server drops additional clients.</p>
</p>
<p>This sets the maximum number of simultaneous recursive clients for any
given query (<qname,qtype,qclass>) that the server accepts before
dropping additional clients.</p>
<p>If the number of queries exceeds <a class="reference internal" href="#namedconf-statement-clients-per-query" title="namedconf-statement-clients-per-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">clients-per-query</span></code></a>, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
assumes that it is dealing with a non-responsive zone and drops additional
queries. If it gets a response after dropping queries, it raises the estimate,
up to a limit of <a class="reference internal" href="#namedconf-statement-max-clients-per-query" title="namedconf-statement-max-clients-per-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-clients-per-query</span></code></a>. The estimate is then lowered
after 20 minutes if it has remained unchanged.</p>
<p>If <a class="reference internal" href="#namedconf-statement-max-clients-per-query" title="namedconf-statement-max-clients-per-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-clients-per-query</span></code></a> is set to zero, there is no upper bound, other
than that imposed by <a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursive-clients</span></code></a>. If <a class="reference internal" href="#namedconf-statement-clients-per-query" title="namedconf-statement-clients-per-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">clients-per-query</span></code></a> is
set to zero, <a class="reference internal" href="#namedconf-statement-max-clients-per-query" title="namedconf-statement-max-clients-per-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-clients-per-query</span></code></a> no longer applies and there is no
upper bound, other than that imposed by <a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursive-clients</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-fetches-per-zone">
<span class="sig-name descname"><span class="pre">fetches-per-zone</span></span><a class="headerlink" href="#namedconf-statement-fetches-per-zone" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">fetches-per-zone</span> <span class="pre"><integer></span> <span class="pre">[</span> <span class="pre">(</span> <span class="pre">drop</span> <span class="pre">|</span> <span class="pre">fail</span> <span class="pre">)</span> <span class="pre">];</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Sets the maximum number of simultaneous iterative queries allowed to any one domain before the server blocks new queries for data in or beneath that zone.</p>
</p>
<p>This sets the maximum number of simultaneous iterative queries to any one
domain that the server permits before blocking new queries for
data in or beneath that zone. This value should reflect how many
fetches would normally be sent to any one zone in the time it would
take to resolve them. It should be smaller than
<a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursive-clients</span></code></a>.</p>
<p>When many clients simultaneously query for the same name and type,
the clients are all attached to the same fetch, up to the
<a class="reference internal" href="#namedconf-statement-max-clients-per-query" title="namedconf-statement-max-clients-per-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-clients-per-query</span></code></a> limit, and only one iterative query is
sent. However, when clients are simultaneously querying for
<em>different</em> names or types, multiple queries are sent and
<a class="reference internal" href="#namedconf-statement-max-clients-per-query" title="namedconf-statement-max-clients-per-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-clients-per-query</span></code></a> is not effective as a limit.</p>
<p>Optionally, this value may be followed by the keyword <code class="docutils literal notranslate"><span class="pre">drop</span></code> or
<code class="docutils literal notranslate"><span class="pre">fail</span></code>, indicating whether queries which exceed the fetch quota for
a zone are dropped with no response, or answered with SERVFAIL.
The default is <code class="docutils literal notranslate"><span class="pre">drop</span></code>.</p>
<p>If <a class="reference internal" href="#namedconf-statement-fetches-per-zone" title="namedconf-statement-fetches-per-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-zone</span></code></a> is set to zero, there is no limit on the
number of fetches per query and no queries are dropped. The
default is zero.</p>
<p>The current list of active fetches can be dumped by running
<a class="reference internal" href="manpages.html#cmdoption-rndc-arg-recursing"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">recursing</span></code></a>. The list includes the number of active fetches
for each domain and the number of queries that have been passed
(allowed) or dropped (spilled) as a result of the <a class="reference internal" href="#namedconf-statement-fetches-per-zone" title="namedconf-statement-fetches-per-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-zone</span></code></a>
limit. (Note: these counters are not cumulative over time;
whenever the number of active fetches for a domain drops to zero,
the counter for that domain is deleted, and the next time a fetch
is sent to that domain, it is recreated with the counters set
to zero.)</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-fetches-per-server">
<span class="sig-name descname"><span class="pre">fetches-per-server</span></span><a class="headerlink" href="#namedconf-statement-fetches-per-server" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">fetches-per-server</span> <span class="pre"><integer></span> <span class="pre">[</span> <span class="pre">(</span> <span class="pre">drop</span> <span class="pre">|</span> <span class="pre">fail</span> <span class="pre">)</span> <span class="pre">];</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Sets the maximum number of simultaneous iterative queries allowed to be sent by a server to an upstream name server before the server blocks additional queries.</p>
</p>
<p>This sets the maximum number of simultaneous iterative queries that the server
allows to be sent to a single upstream name server before
blocking additional queries. This value should reflect how many
fetches would normally be sent to any one server in the time it would
take to resolve them. It should be smaller than
<a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursive-clients</span></code></a>.</p>
<p>Optionally, this value may be followed by the keyword <code class="docutils literal notranslate"><span class="pre">drop</span></code> or
<code class="docutils literal notranslate"><span class="pre">fail</span></code>, indicating whether queries are dropped with no
response or answered with SERVFAIL, when all of the servers
authoritative for a zone are found to have exceeded the per-server
quota. The default is <code class="docutils literal notranslate"><span class="pre">fail</span></code>.</p>
<p>If <a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-server</span></code></a> is set to zero, there is no limit on
the number of fetches per query and no queries are dropped. The
default is zero.</p>
<p>The <a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-server</span></code></a> quota is dynamically adjusted in response
to detected congestion. As queries are sent to a server and either are
answered or time out, an exponentially weighted moving average
is calculated of the ratio of timeouts to responses. If the current
average timeout ratio rises above a “high” threshold, then
<a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-server</span></code></a> is reduced for that server. If the timeout
ratio drops below a “low” threshold, then <a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-server</span></code></a> is
increased. The <a class="reference internal" href="#namedconf-statement-fetch-quota-params" title="namedconf-statement-fetch-quota-params"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetch-quota-params</span></code></a> options can be used to adjust
the parameters for this calculation.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-fetch-quota-params">
<span class="sig-name descname"><span class="pre">fetch-quota-params</span></span><a class="headerlink" href="#namedconf-statement-fetch-quota-params" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">fetch-quota-params</span> <span class="pre"><integer></span> <span class="pre"><fixedpoint></span> <span class="pre"><fixedpoint></span> <span class="pre"><fixedpoint>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Sets the parameters for dynamic resizing of the <a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-server</span></code></a> quota in response to detected congestion.</p>
</p>
<p>This sets the parameters to use for dynamic resizing of the
<a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-server</span></code></a> quota in response to detected congestion.</p>
<p>The first argument is an integer value indicating how frequently to
recalculate the moving average of the ratio of timeouts to responses
for each server. The default is 100, meaning that BIND recalculates the
average ratio after every 100 queries have either been answered or
timed out.</p>
<p>The remaining three arguments represent the “low” threshold
(defaulting to a timeout ratio of 0.1), the “high” threshold
(defaulting to a timeout ratio of 0.3), and the discount rate for the
moving average (defaulting to 0.7). A higher discount rate causes
recent events to weigh more heavily when calculating the moving
average; a lower discount rate causes past events to weigh more
heavily, smoothing out short-term blips in the timeout ratio. These
arguments are all fixed-point numbers with precision of 1/100; at
most two places after the decimal point are significant.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-reserved-sockets">
<span class="sig-name descname"><span class="pre">reserved-sockets</span></span><a class="headerlink" href="#namedconf-statement-reserved-sockets" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">reserved-sockets</span> <span class="pre"><integer>;</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Deprecated.</p>
</p>
<p>This option is deprecated and no longer has any effect.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-cache-size">
<span class="sig-name descname"><span class="pre">max-cache-size</span></span><a class="headerlink" href="#namedconf-statement-max-cache-size" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-cache-size</span> <span class="pre">(</span> <span class="pre">default</span> <span class="pre">|</span> <span class="pre">unlimited</span> <span class="pre">|</span> <span class="pre"><sizeval></span> <span class="pre">|</span> <span class="pre"><percentage></span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the maximum amount of memory to use for an individual cache database and its associated metadata.</p>
</p>
<p>This sets the maximum amount of memory to use for an individual cache
database and its associated metadata, in bytes or percentage of total
physical memory. By default, each view has its own separate cache,
which means the total amount of memory required for cache data is the
sum of the cache database sizes for all views (unless the
<a class="reference internal" href="#namedconf-statement-attach-cache" title="namedconf-statement-attach-cache"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">attach-cache</span></code></a> option is used).</p>
<p>When the amount of data in a cache database reaches the configured
limit, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> starts purging non-expired records (following an
LRU-based strategy).</p>
<p>The default size limit for each individual cache is:</p>
<blockquote>
<div><ul class="simple">
<li><p>90% of physical memory for views with <a class="reference internal" href="#namedconf-statement-recursion" title="namedconf-statement-recursion"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursion</span></code></a> set to
<code class="docutils literal notranslate"><span class="pre">yes</span></code> (the default), or</p></li>
<li><p>2 MB for views with <a class="reference internal" href="#namedconf-statement-recursion" title="namedconf-statement-recursion"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursion</span></code></a> set to <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p></li>
</ul>
</div></blockquote>
<p>Any positive value smaller than 2 MB is ignored and reset to 2 MB.
The keyword <code class="docutils literal notranslate"><span class="pre">unlimited</span></code>, or the value <code class="docutils literal notranslate"><span class="pre">0</span></code>, places no limit on the
cache size; records are then purged from the cache only when they
expire (according to their TTLs).</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>For configurations which define multiple views with separate
caches and recursion enabled, it is recommended to set
<a class="reference internal" href="#namedconf-statement-max-cache-size" title="namedconf-statement-max-cache-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-cache-size</span></code></a> appropriately for each view, as using the
default value of that option (90% of physical memory for each
individual cache) may lead to memory exhaustion over time.</p>
</div>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p><a class="reference internal" href="#namedconf-statement-max-cache-size" title="namedconf-statement-max-cache-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-cache-size</span></code></a> does not work reliably for a maximum
amount of memory of 100 MB or lower.</p>
</div>
<p>Upon startup and reconfiguration, caches with a limited size
preallocate a small amount of memory (less than 1% of
<a class="reference internal" href="#namedconf-statement-max-cache-size" title="namedconf-statement-max-cache-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-cache-size</span></code></a> for a given view). This preallocation serves as an
optimization to eliminate extra latency introduced by resizing
internal cache structures.</p>
<p>On systems where detection of the amount of physical memory is not
supported, percentage-based values fall back to <code class="docutils literal notranslate"><span class="pre">unlimited</span></code>. Note
that the amount of physical memory available is only detected on
startup, so <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> does not adjust the cache size limits if the
amount of physical memory is changed at runtime.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tcp-listen-queue">
<span class="sig-name descname"><span class="pre">tcp-listen-queue</span></span><a class="headerlink" href="#namedconf-statement-tcp-listen-queue" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tcp-listen-queue</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the listen-queue depth.</p>
</p>
<p>This sets the listen-queue depth. The default and minimum is 10. If the kernel
supports the accept filter “dataready”, this also controls how many
TCP connections are queued in kernel space waiting for some
data before being passed to accept. Non-zero values less than 10 are
silently raised. A value of 0 may also be used; on most platforms
this sets the listen-queue length to a system-defined default value.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tcp-initial-timeout">
<span class="sig-name descname"><span class="pre">tcp-initial-timeout</span></span><a class="headerlink" href="#namedconf-statement-tcp-initial-timeout" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tcp-initial-timeout</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Sets the amount of time (in milliseconds) that the server waits on a new TCP connection for the first message from the client.</p>
</p>
<p>This sets the amount of time (in units of 100 milliseconds) that the server waits on
a new TCP connection for the first message from the client. The
default is 300 (30 seconds), the minimum is 25 (2.5 seconds), and the
maximum is 1200 (two minutes). Values above the maximum or below the
minimum are adjusted with a logged warning. (Note: this value
must be greater than the expected round-trip delay time; otherwise, no
client will ever have enough time to submit a message.) This value
can be updated at runtime by using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-tcp-timeouts"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">tcp-timeouts</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tcp-idle-timeout">
<span class="sig-name descname"><span class="pre">tcp-idle-timeout</span></span><a class="headerlink" href="#namedconf-statement-tcp-idle-timeout" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tcp-idle-timeout</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>query</p>
<p><p>Sets the amount of time (in milliseconds) that the server waits on an idle TCP connection before closing it, if the EDNS TCP keepalive option is not in use.</p>
</p>
<p>This sets the amount of time (in units of 100 milliseconds) that the server waits on
an idle TCP connection before closing it, when the client is not using
the EDNS TCP keepalive option. The default is 300 (30 seconds), the
maximum is 1200 (two minutes), and the minimum is 1 (one-tenth of a
second). Values above the maximum or below the minimum are
adjusted with a logged warning. See <a class="reference internal" href="#namedconf-statement-tcp-keepalive-timeout" title="namedconf-statement-tcp-keepalive-timeout"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tcp-keepalive-timeout</span></code></a> for
clients using the EDNS TCP keepalive option. This value can be
updated at runtime by using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-tcp-timeouts"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">tcp-timeouts</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tcp-keepalive-timeout">
<span class="sig-name descname"><span class="pre">tcp-keepalive-timeout</span></span><a class="headerlink" href="#namedconf-statement-tcp-keepalive-timeout" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tcp-keepalive-timeout</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>query</p>
<p><p>Sets the amount of time (in milliseconds) that the server waits on an idle TCP connection before closing it, if the EDNS TCP keepalive option is in use.</p>
</p>
<p>This sets the amount of time (in units of 100 milliseconds) that the server waits on
an idle TCP connection before closing it, when the client is using the
EDNS TCP keepalive option. The default is 300 (30 seconds), the
maximum is 65535 (about 1.8 hours), and the minimum is 1 (one-tenth
of a second). Values above the maximum or below the minimum are
adjusted with a logged warning. This value may be greater than
<a class="reference internal" href="#namedconf-statement-tcp-idle-timeout" title="namedconf-statement-tcp-idle-timeout"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tcp-idle-timeout</span></code></a> because clients using the EDNS TCP keepalive
option are expected to use TCP connections for more than one message.
This value can be updated at runtime by using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-tcp-timeouts"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">tcp-timeouts</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tcp-advertised-timeout">
<span class="sig-name descname"><span class="pre">tcp-advertised-timeout</span></span><a class="headerlink" href="#namedconf-statement-tcp-advertised-timeout" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tcp-advertised-timeout</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>query</p>
<p><p>Sets the timeout value (in milliseconds) that the server sends in responses containing the EDNS TCP keepalive option.</p>
</p>
<p>This sets the timeout value (in units of 100 milliseconds) that the server sends
in responses containing the EDNS TCP keepalive option, which informs a
client of the amount of time it may keep the session open. The
default is 300 (30 seconds), the maximum is 65535 (about 1.8 hours),
and the minimum is 0, which signals that the clients must close TCP
connections immediately. Ordinarily this should be set to the same
value as <a class="reference internal" href="#namedconf-statement-tcp-keepalive-timeout" title="namedconf-statement-tcp-keepalive-timeout"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tcp-keepalive-timeout</span></code></a>. This value can be updated at
runtime by using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-tcp-timeouts"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">tcp-timeouts</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-update-quota">
<span class="sig-name descname"><span class="pre">update-quota</span></span><a class="headerlink" href="#namedconf-statement-update-quota" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">update-quota</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the maximum number of concurrent DNS UPDATE messages that can be processed by the server.</p>
</p>
<p>This is the maximum number of simultaneous DNS UPDATE messages that
the server will accept, for updating local authoritative zones or
forwarding to a primary server. The default is <code class="docutils literal notranslate"><span class="pre">100</span></code>.</p>
</dd></dl>
</section>
<section id="periodic-task-intervals">
<span id="intervals"></span><h4><span class="section-number">8.2.14.10. </span>Periodic Task Intervals<a class="headerlink" href="#periodic-task-intervals" title="Link to this heading"></a></h4>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-heartbeat-interval">
<span class="sig-name descname"><span class="pre">heartbeat-interval</span></span><a class="headerlink" href="#namedconf-statement-heartbeat-interval" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">heartbeat-interval</span> <span class="pre"><integer>;</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Sets the interval at which the server performs zone maintenance tasks for all zones marked as <a class="reference internal" href="#namedconf-statement-dialup" title="namedconf-statement-dialup"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dialup</span></code></a>.</p>
</p>
<p>The server performs zone maintenance tasks for all zones marked
as <a class="reference internal" href="#namedconf-statement-dialup" title="namedconf-statement-dialup"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dialup</span></code></a> whenever this interval expires. The default is 60
minutes. Reasonable values are up to 1 day (1440 minutes). The
maximum value is 28 days (40320 minutes). If set to 0, no zone
maintenance for these zones occurs.</p>
<p>This option is deprecated and will be removed in a future release.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-interface-interval">
<span class="sig-name descname"><span class="pre">interface-interval</span></span><a class="headerlink" href="#namedconf-statement-interface-interval" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">interface-interval</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the interval at which the server scans the network interface list.</p>
</p>
<p>The server scans the network interface list on every interval as specified by
<a class="reference internal" href="#namedconf-statement-interface-interval" title="namedconf-statement-interface-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">interface-interval</span></code></a>.</p>
<p>If set to 0, interface scanning only occurs when the configuration
file is loaded, or when <a class="reference internal" href="#namedconf-statement-automatic-interface-scan" title="namedconf-statement-automatic-interface-scan"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">automatic-interface-scan</span></code></a> is enabled and supported
by the operating system. After the scan, the server begins listening for
queries on any newly discovered interfaces (provided they are allowed by the
<a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> configuration), and stops listening on interfaces that have
gone away. For convenience, TTL-style time-unit suffixes may be used to
specify the value. It also accepts ISO 8601 duration formats.</p>
<p>The default is 60 minutes (1 hour); the maximum value is 28 days.</p>
</dd></dl>
</section>
<section id="the-sortlist-statement">
<h4><span class="section-number">8.2.14.11. </span>The <a class="reference internal" href="#namedconf-statement-sortlist" title="namedconf-statement-sortlist"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sortlist</span></code></a> Statement<a class="headerlink" href="#the-sortlist-statement" title="Link to this heading"></a></h4>
<p>The response to a DNS query may consist of multiple resource records
(RRs) forming a resource record set (RRset). The name server
normally returns the RRs within the RRset in an indeterminate order (but
see the <a class="reference internal" href="#namedconf-statement-rrset-order" title="namedconf-statement-rrset-order"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rrset-order</span></code></a> statement in <a class="reference internal" href="#rrset-ordering"><span class="std std-ref">RRset Ordering</span></a>). The client resolver code should
rearrange the RRs as appropriate: that is, using any addresses on the
local net in preference to other addresses. However, not all resolvers
can do this or are correctly configured. When a client is using a local
server, the sorting can be performed in the server, based on the
client’s address. This only requires configuring the name servers, not
all the clients.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-sortlist">
<span class="sig-name descname"><span class="pre">sortlist</span></span><a class="headerlink" href="#namedconf-statement-sortlist" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">sortlist</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls the ordering of RRs returned to the client, based on the client’s IP address.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-sortlist" title="namedconf-statement-sortlist"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sortlist</span></code></a> statement (see below) takes an <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> and
interprets it in a special way. Each top-level statement in the <a class="reference internal" href="#namedconf-statement-sortlist" title="namedconf-statement-sortlist"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sortlist</span></code></a>
must itself be an explicit <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> with one or two elements. The
first element (which may be an IP address, an IP prefix, an ACL name, or a nested
<a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a>) of each top-level list is checked against the source
address of the query until a match is found. When the addresses in the first
element overlap, the first rule to match is selected.</p>
<p>Once the source address of the query has been matched, if the top-level
statement contains only one element, the actual primitive element that
matched the source address is used to select the address in the response
to move to the beginning of the response. If the statement is a list of
two elements, then the second element is interpreted as a topology
preference list. Each top-level element is assigned a distance, and the
address in the response with the minimum distance is moved to the
beginning of the response.</p>
<p>In the following example, any queries received from any of the addresses
of the host itself get responses preferring addresses on any of the
locally connected networks. Next most preferred are addresses on the
192.168.1/24 network, and after that either the 192.168.2/24 or
192.168.3/24 network, with no preference shown between these two
networks. Queries received from a host on the 192.168.1/24 network
prefer other addresses on that network to the 192.168.2/24 and
192.168.3/24 networks. Queries received from a host on the 192.168.4/24
or the 192.168.5/24 network only prefer other addresses on their
directly connected networks.</p>
</dd></dl>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">sortlist</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">IF</span> <span class="n">the</span> <span class="n">local</span> <span class="n">host</span>
<span class="o">//</span> <span class="n">THEN</span> <span class="n">first</span> <span class="n">fit</span> <span class="n">on</span> <span class="n">the</span> <span class="n">following</span> <span class="n">nets</span>
<span class="p">{</span> <span class="n">localhost</span><span class="p">;</span>
<span class="p">{</span> <span class="n">localnets</span><span class="p">;</span>
<span class="mf">192.168.1</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span>
<span class="p">{</span> <span class="mf">192.168.2</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span> <span class="mf">192.168.3</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span> <span class="p">};</span> <span class="p">};</span> <span class="p">};</span>
<span class="o">//</span> <span class="n">IF</span> <span class="n">on</span> <span class="k">class</span> <span class="nc">C</span> <span class="mf">192.168.1</span> <span class="n">THEN</span> <span class="n">use</span> <span class="mf">.1</span><span class="p">,</span> <span class="ow">or</span> <span class="mf">.2</span> <span class="ow">or</span> <span class="mf">.3</span>
<span class="p">{</span> <span class="mf">192.168.1</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span>
<span class="p">{</span> <span class="mf">192.168.1</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span>
<span class="p">{</span> <span class="mf">192.168.2</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span> <span class="mf">192.168.3</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span> <span class="p">};</span> <span class="p">};</span> <span class="p">};</span>
<span class="o">//</span> <span class="n">IF</span> <span class="n">on</span> <span class="k">class</span> <span class="nc">C</span> <span class="mf">192.168.2</span> <span class="n">THEN</span> <span class="n">use</span> <span class="mf">.2</span><span class="p">,</span> <span class="ow">or</span> <span class="mf">.1</span> <span class="ow">or</span> <span class="mf">.3</span>
<span class="p">{</span> <span class="mf">192.168.2</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span>
<span class="p">{</span> <span class="mf">192.168.2</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span>
<span class="p">{</span> <span class="mf">192.168.1</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span> <span class="mf">192.168.3</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span> <span class="p">};</span> <span class="p">};</span> <span class="p">};</span>
<span class="o">//</span> <span class="n">IF</span> <span class="n">on</span> <span class="k">class</span> <span class="nc">C</span> <span class="mf">192.168.3</span> <span class="n">THEN</span> <span class="n">use</span> <span class="mf">.3</span><span class="p">,</span> <span class="ow">or</span> <span class="mf">.1</span> <span class="ow">or</span> <span class="mf">.2</span>
<span class="p">{</span> <span class="mf">192.168.3</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span>
<span class="p">{</span> <span class="mf">192.168.3</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span>
<span class="p">{</span> <span class="mf">192.168.1</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span> <span class="mf">192.168.2</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span> <span class="p">};</span> <span class="p">};</span> <span class="p">};</span>
<span class="o">//</span> <span class="n">IF</span> <span class="mf">.4</span> <span class="ow">or</span> <span class="mf">.5</span> <span class="n">THEN</span> <span class="n">prefer</span> <span class="n">that</span> <span class="n">net</span>
<span class="p">{</span> <span class="p">{</span> <span class="mf">192.168.4</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span> <span class="mf">192.168.5</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span> <span class="p">};</span>
<span class="p">};</span>
<span class="p">};</span>
</pre></div>
</div>
<p>The following example illlustrates reasonable behavior for the local host
and hosts on directly connected networks. Responses sent to queries from the
local host favor any of the directly connected networks. Responses
sent to queries from any other hosts on a directly connected network
prefer addresses on that same network. Responses to other queries
are not sorted.</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">sortlist</span> <span class="p">{</span>
<span class="p">{</span> <span class="n">localhost</span><span class="p">;</span> <span class="n">localnets</span><span class="p">;</span> <span class="p">};</span>
<span class="p">{</span> <span class="n">localnets</span><span class="p">;</span> <span class="p">};</span>
<span class="p">};</span>
</pre></div>
</div>
</section>
<section id="rrset-ordering">
<span id="id11"></span><h4><span class="section-number">8.2.14.12. </span>RRset Ordering<a class="headerlink" href="#rrset-ordering" title="Link to this heading"></a></h4>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>While alternating the order of records in a DNS response between
subsequent queries is a known load distribution technique, certain
caveats apply (mostly stemming from caching) which usually make it a
suboptimal choice for load balancing purposes when used on its own.</p>
</div>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-rrset-order">
<span class="sig-name descname"><span class="pre">rrset-order</span></span><a class="headerlink" href="#namedconf-statement-rrset-order" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">rrset-order</span> <span class="pre">{</span> <span class="pre">[</span> <span class="pre">class</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">type</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">name</span> <span class="pre"><quoted_string></span> <span class="pre">]</span> <span class="pre"><string></span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Defines the order in which equal RRs (RRsets) are returned.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-rrset-order" title="namedconf-statement-rrset-order"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rrset-order</span></code></a> statement permits configuration of the ordering of
the records in a multiple-record response. See also:
<a class="reference internal" href="#namedconf-statement-sortlist" title="namedconf-statement-sortlist"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sortlist</span></code></a>.</p>
<p>Each rule in an <a class="reference internal" href="#namedconf-statement-rrset-order" title="namedconf-statement-rrset-order"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rrset-order</span></code></a> statement is defined as follows:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>[class <class_name>] [type <type_name>] [name "<domain_name>"] order <ordering>
</pre></div>
</div>
<p>The default qualifiers for each rule are:</p>
<blockquote>
<div><ul class="simple">
<li><p>If no <code class="docutils literal notranslate"><span class="pre">class</span></code> is specified, the default is <code class="docutils literal notranslate"><span class="pre">ANY</span></code>.</p></li>
<li><p>If no <a class="reference internal" href="#namedconf-statement-type" title="namedconf-statement-type"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span></code></a> is specified, the default is <code class="docutils literal notranslate"><span class="pre">ANY</span></code>.</p></li>
<li><p>If no <code class="docutils literal notranslate"><span class="pre">name</span></code> is specified, the default is <code class="docutils literal notranslate"><span class="pre">*</span></code> (asterisk).</p></li>
</ul>
</div></blockquote>
<p><a class="reference internal" href="#term-domain_name"><span class="xref std std-term"><domain_name></span></a> only matches the name itself, not any of its
subdomains. To make a rule match all subdomains of a given name, a
wildcard name (<code class="docutils literal notranslate"><span class="pre">*.<domain_name></span></code>) must be used. Note that
<code class="docutils literal notranslate"><span class="pre">*.<domain_name></span></code> does <em>not</em> match <code class="docutils literal notranslate"><span class="pre"><domain_name></span></code> itself; to
specify RRset ordering for a name and all of its subdomains, two
separate rules must be defined: one for <code class="docutils literal notranslate"><span class="pre"><domain_name></span></code> and one for
<code class="docutils literal notranslate"><span class="pre">*.<domain_name></span></code>.</p>
<p>The legal values for <code class="docutils literal notranslate"><span class="pre"><ordering></span></code> are:</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">fixed</span></code></dt><dd><p>Records are returned in the order they are defined in the zone file.</p>
</dd>
</dl>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>The <code class="docutils literal notranslate"><span class="pre">fixed</span></code> option is only available if BIND is configured with
<code class="docutils literal notranslate"><span class="pre">--enable-fixed-rrset</span></code> at compile time.</p>
</div>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">random</span></code></dt><dd><p>Records are returned in a random order.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">cyclic</span></code></dt><dd><p>Records are returned in a cyclic round-robin order, rotating by one
record per query.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">none</span></code></dt><dd><p>Records are returned in the order they were retrieved from the
database. This order is indeterminate, but remains consistent as
long as the database is not modified.</p>
</dd>
</dl>
<p>The default RRset order used depends on whether any <a class="reference internal" href="#namedconf-statement-rrset-order" title="namedconf-statement-rrset-order"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rrset-order</span></code></a>
statements are present in the configuration file used by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>:</p>
<blockquote>
<div><ul class="simple">
<li><p>If no <a class="reference internal" href="#namedconf-statement-rrset-order" title="namedconf-statement-rrset-order"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rrset-order</span></code></a> statement is present in the configuration
file, the implicit default is to return all records in <code class="docutils literal notranslate"><span class="pre">random</span></code>
order.</p></li>
<li><p>If any <a class="reference internal" href="#namedconf-statement-rrset-order" title="namedconf-statement-rrset-order"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rrset-order</span></code></a> statements are present in the configuration
file, but no ordering rule specified in these statements matches a
given RRset, the default order for that RRset is <code class="docutils literal notranslate"><span class="pre">none</span></code>.</p></li>
</ul>
</div></blockquote>
<p>Note that if multiple <a class="reference internal" href="#namedconf-statement-rrset-order" title="namedconf-statement-rrset-order"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rrset-order</span></code></a> statements are present in the
configuration file (at both the <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> and <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> levels), they
are <em>not</em> combined; instead, the more-specific one (<a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>) replaces
the less-specific one (<a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>).</p>
<p>If multiple rules within a single <a class="reference internal" href="#namedconf-statement-rrset-order" title="namedconf-statement-rrset-order"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rrset-order</span></code></a> statement match a
given RRset, the first matching rule is applied.</p>
<p>Example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">rrset</span><span class="o">-</span><span class="n">order</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">A</span> <span class="n">name</span> <span class="s2">"foo.isc.org"</span> <span class="n">order</span> <span class="n">random</span><span class="p">;</span>
<span class="nb">type</span> <span class="n">AAAA</span> <span class="n">name</span> <span class="s2">"foo.isc.org"</span> <span class="n">order</span> <span class="n">cyclic</span><span class="p">;</span>
<span class="n">name</span> <span class="s2">"bar.isc.org"</span> <span class="n">order</span> <span class="n">fixed</span><span class="p">;</span>
<span class="n">name</span> <span class="s2">"*.bar.isc.org"</span> <span class="n">order</span> <span class="n">random</span><span class="p">;</span>
<span class="n">name</span> <span class="s2">"*.baz.isc.org"</span> <span class="n">order</span> <span class="n">cyclic</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
<p>With the above configuration, the following RRset ordering is used:</p>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>QNAME</p></th>
<th class="head"><p>QTYPE</p></th>
<th class="head"><p>RRset Order</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">foo.isc.org</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">A</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">random</span></code></p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">foo.isc.org</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">AAAA</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">cyclic</span></code></p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">foo.isc.org</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">TXT</span></code></p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">none</span></code></p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">sub.foo.isc.org</span></code></p></td>
<td><p>all</p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">none</span></code></p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">bar.isc.org</span></code></p></td>
<td><p>all</p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">fixed</span></code></p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">sub.bar.isc.org</span></code></p></td>
<td><p>all</p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">random</span></code></p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">baz.isc.org</span></code></p></td>
<td><p>all</p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">none</span></code></p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">sub.baz.isc.org</span></code></p></td>
<td><p>all</p></td>
<td><p><code class="docutils literal notranslate"><span class="pre">cyclic</span></code></p></td>
</tr>
</tbody>
</table>
</dd></dl>
</section>
<section id="tuning">
<span id="id12"></span><h4><span class="section-number">8.2.14.13. </span>Tuning<a class="headerlink" href="#tuning" title="Link to this heading"></a></h4>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-lame-ttl">
<span class="sig-name descname"><span class="pre">lame-ttl</span></span><a class="headerlink" href="#namedconf-statement-lame-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">lame-ttl</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the resolver’s lame cache.</p>
</p>
<p>This is always set to 0. More information is available in the
<a class="reference external" href="https://kb.isc.org/docs/cve-2021-25219">security advisory for CVE-2021-25219</a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-servfail-ttl">
<span class="sig-name descname"><span class="pre">servfail-ttl</span></span><a class="headerlink" href="#namedconf-statement-servfail-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">servfail-ttl</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the length of time (in seconds) that a SERVFAIL response is cached.</p>
</p>
<p>This sets the number of seconds to cache a SERVFAIL response due to DNSSEC
validation failure or other general server failure. If set to <code class="docutils literal notranslate"><span class="pre">0</span></code>,
SERVFAIL caching is disabled. The SERVFAIL cache is not consulted if
a query has the CD (Checking Disabled) bit set; this allows a query
that failed due to DNSSEC validation to be retried without waiting
for the SERVFAIL TTL to expire.</p>
<p>The maximum value is <code class="docutils literal notranslate"><span class="pre">30</span></code> seconds; any higher value is
silently reduced. The default is <code class="docutils literal notranslate"><span class="pre">1</span></code> second.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-min-ncache-ttl">
<span class="sig-name descname"><span class="pre">min-ncache-ttl</span></span><a class="headerlink" href="#namedconf-statement-min-ncache-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">min-ncache-ttl</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the minimum retention time (in seconds) for storage of negative answers in the server’s cache.</p>
</p>
<p>To reduce network traffic and increase performance, the server stores
negative answers. <a class="reference internal" href="#namedconf-statement-min-ncache-ttl" title="namedconf-statement-min-ncache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">min-ncache-ttl</span></code></a> is used to set a minimum
retention time for these answers in the server, in seconds. For
convenience, TTL-style time-unit suffixes may be used to specify the
value. It also accepts ISO 8601 duration formats.</p>
<p>The default <a class="reference internal" href="#namedconf-statement-min-ncache-ttl" title="namedconf-statement-min-ncache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">min-ncache-ttl</span></code></a> is <code class="docutils literal notranslate"><span class="pre">0</span></code> seconds. <a class="reference internal" href="#namedconf-statement-min-ncache-ttl" title="namedconf-statement-min-ncache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">min-ncache-ttl</span></code></a> cannot
exceed 90 seconds and is truncated to 90 seconds if set to a greater
value.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-min-cache-ttl">
<span class="sig-name descname"><span class="pre">min-cache-ttl</span></span><a class="headerlink" href="#namedconf-statement-min-cache-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">min-cache-ttl</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the minimum time (in seconds) that the server caches ordinary (positive) answers.</p>
</p>
<p>This sets the minimum time for which the server caches ordinary (positive)
answers, in seconds. For convenience, TTL-style time-unit suffixes may be used
to specify the value. It also accepts ISO 8601 duration formats.</p>
<p>The default <a class="reference internal" href="#namedconf-statement-min-cache-ttl" title="namedconf-statement-min-cache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">min-cache-ttl</span></code></a> is <code class="docutils literal notranslate"><span class="pre">0</span></code> seconds. <a class="reference internal" href="#namedconf-statement-min-cache-ttl" title="namedconf-statement-min-cache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">min-cache-ttl</span></code></a> cannot
exceed 90 seconds and is truncated to 90 seconds if set to a greater
value.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-ncache-ttl">
<span class="sig-name descname"><span class="pre">max-ncache-ttl</span></span><a class="headerlink" href="#namedconf-statement-max-ncache-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-ncache-ttl</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the maximum retention time (in seconds) for storage of negative answers in the server’s cache.</p>
</p>
<p>To reduce network traffic and increase performance, the server stores
negative answers. <a class="reference internal" href="#namedconf-statement-max-ncache-ttl" title="namedconf-statement-max-ncache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-ncache-ttl</span></code></a> is used to set a maximum retention time
for these answers in the server, in seconds. For convenience, TTL-style
time-unit suffixes may be used to specify the value. It also accepts ISO 8601
duration formats.</p>
<p>The default <a class="reference internal" href="#namedconf-statement-max-ncache-ttl" title="namedconf-statement-max-ncache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-ncache-ttl</span></code></a> is 10800 seconds (3 hours). <a class="reference internal" href="#namedconf-statement-max-ncache-ttl" title="namedconf-statement-max-ncache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-ncache-ttl</span></code></a>
cannot exceed 7 days and is silently truncated to 7 days if set to a
greater value.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-cache-ttl">
<span class="sig-name descname"><span class="pre">max-cache-ttl</span></span><a class="headerlink" href="#namedconf-statement-max-cache-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-cache-ttl</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the maximum time (in seconds) that the server caches ordinary (positive) answers.</p>
</p>
<p>This sets the maximum time for which the server caches ordinary (positive)
answers, in seconds. For convenience, TTL-style time-unit suffixes may be used
to specify the value. It also accepts ISO 8601 duration formats.</p>
<p>The default <a class="reference internal" href="#namedconf-statement-max-cache-ttl" title="namedconf-statement-max-cache-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-cache-ttl</span></code></a> is 604800 (one week). A value of zero may cause
all queries to return SERVFAIL, because of lost caches of intermediate RRsets
(such as NS and glue AAAA/A records) in the resolution process.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-stale-ttl">
<span class="sig-name descname"><span class="pre">max-stale-ttl</span></span><a class="headerlink" href="#namedconf-statement-max-stale-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-stale-ttl</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the maximum time that the server retains records past their normal expiry, to return them as stale records.</p>
</p>
<p>If retaining stale RRsets in cache is enabled, and returning of stale cached
answers is also enabled, <a class="reference internal" href="#namedconf-statement-max-stale-ttl" title="namedconf-statement-max-stale-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-stale-ttl</span></code></a> sets the maximum time for which
the server retains records past their normal expiry to return them as stale
records, when the servers for those records are not reachable. The default
is 1 day. The minimum allowed is 1 second; a value of 0 is updated silently
to 1 second.</p>
<p>For stale answers to be returned, the retaining of them in cache must be
enabled via the configuration option <a class="reference internal" href="#namedconf-statement-stale-cache-enable" title="namedconf-statement-stale-cache-enable"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">stale-cache-enable</span></code></a>, and returning
cached answers must be enabled, either in the configuration file using the
<a class="reference internal" href="#namedconf-statement-stale-answer-enable" title="namedconf-statement-stale-answer-enable"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">stale-answer-enable</span></code></a> option or by calling <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-serve-stale"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">serve-stale</span> <span class="pre">on</span></code></a>.</p>
<p>When <a class="reference internal" href="#namedconf-statement-stale-cache-enable" title="namedconf-statement-stale-cache-enable"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">stale-cache-enable</span></code></a> is set to <code class="docutils literal notranslate"><span class="pre">no</span></code>, setting the <a class="reference internal" href="#namedconf-statement-max-stale-ttl" title="namedconf-statement-max-stale-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-stale-ttl</span></code></a>
has no effect; the value of <a class="reference internal" href="#namedconf-statement-max-stale-ttl" title="namedconf-statement-max-stale-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-stale-ttl</span></code></a> will be <code class="docutils literal notranslate"><span class="pre">0</span></code> in such case.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-resolver-nonbackoff-tries">
<span class="sig-name descname"><span class="pre">resolver-nonbackoff-tries</span></span><a class="headerlink" href="#namedconf-statement-resolver-nonbackoff-tries" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">resolver-nonbackoff-tries</span> <span class="pre"><integer>;</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>deprecated.</p>
<p><p>Specifies the number of retries before exponential backoff.</p>
</p>
<p>This specifies how many retries occur before exponential backoff kicks in.
The default is <code class="docutils literal notranslate"><span class="pre">3</span></code>.</p>
<p>This option is deprecated and will be removed in a future release.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-resolver-retry-interval">
<span class="sig-name descname"><span class="pre">resolver-retry-interval</span></span><a class="headerlink" href="#namedconf-statement-resolver-retry-interval" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">resolver-retry-interval</span> <span class="pre"><integer>;</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Sets the base retry interval (in milliseconds).</p>
</p>
<p>This sets the base retry interval in milliseconds. The default is <code class="docutils literal notranslate"><span class="pre">800</span></code>.</p>
<p>This option is deprecated and will be removed in a future release.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-sig-validity-interval">
<span class="sig-name descname"><span class="pre">sig-validity-interval</span></span><a class="headerlink" href="#namedconf-statement-sig-validity-interval" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">sig-validity-interval</span> <span class="pre"><integer></span> <span class="pre">[</span> <span class="pre"><integer></span> <span class="pre">];</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the maximum number of days that RRSIGs generated by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> are valid.</p>
</p>
<p>This specifies the upper bound of the number of days that RRSIGs
generated by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> are valid; the default is <code class="docutils literal notranslate"><span class="pre">30</span></code> days,
with a maximum of 3660 days (10 years). The optional second value
specifies the minimum bound on those RRSIGs and also determines
how long before expiry <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> starts regenerating those RRSIGs.
The default value for the lower bound is 1/4 of the upper bound;
it is expressed in days if the upper bound is greater than 7,
and hours if it is less than or equal to 7 days.</p>
<p>When new RRSIGs are generated, the length of time is randomly
chosen between these two limits, to spread out the re-signing
load. When RRSIGs are re-generated, the upper bound is used, with
a small amount of jitter added. New RRSIGs are generated by a
number of processes, including the processing of UPDATE requests
(ref:<cite>dynamic_update</cite>), the addition and removal of records via
in-line signing, and the initial signing of a zone.</p>
<p>The signature inception time is unconditionally set to one hour
before the current time, to allow for a limited amount of clock skew.</p>
<p>The <a class="reference internal" href="#namedconf-statement-sig-validity-interval" title="namedconf-statement-sig-validity-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-validity-interval</span></code></a> can be overridden for DNSKEY records by
setting <a class="reference internal" href="#namedconf-statement-dnskey-sig-validity" title="namedconf-statement-dnskey-sig-validity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnskey-sig-validity</span></code></a>.</p>
<p>The <a class="reference internal" href="#namedconf-statement-sig-validity-interval" title="namedconf-statement-sig-validity-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-validity-interval</span></code></a> should be at least several multiples
of the SOA expire interval, to allow for reasonable interaction
between the various timer and expiry dates.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnskey-sig-validity">
<span class="sig-name descname"><span class="pre">dnskey-sig-validity</span></span><a class="headerlink" href="#namedconf-statement-dnskey-sig-validity" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnskey-sig-validity</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the number of days in the future when automatically generated DNSSEC signatures expire.</p>
</p>
<p>This specifies the number of days into the future when DNSSEC signatures
that are automatically generated for DNSKEY RRsets as a result of
dynamic updates (<a class="reference internal" href="chapter6.html#dynamic-update"><span class="std std-ref">Dynamic Update</span></a>) will expire.
If set to a non-zero value, this overrides the value set by
<a class="reference internal" href="#namedconf-statement-sig-validity-interval" title="namedconf-statement-sig-validity-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-validity-interval</span></code></a>. The default is zero, meaning
<a class="reference internal" href="#namedconf-statement-sig-validity-interval" title="namedconf-statement-sig-validity-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-validity-interval</span></code></a> is used. The maximum value is 3660 days (10
years), and higher values are rejected.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-sig-signing-nodes">
<span class="sig-name descname"><span class="pre">sig-signing-nodes</span></span><a class="headerlink" href="#namedconf-statement-sig-signing-nodes" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">sig-signing-nodes</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the maximum number of nodes to be examined in each quantum, when signing a zone with a new DNSKEY.</p>
</p>
<p>This specifies the maximum number of nodes to be examined in each quantum,
when signing a zone with a new DNSKEY. The default is <code class="docutils literal notranslate"><span class="pre">100</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-sig-signing-signatures">
<span class="sig-name descname"><span class="pre">sig-signing-signatures</span></span><a class="headerlink" href="#namedconf-statement-sig-signing-signatures" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">sig-signing-signatures</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the threshold for the number of signatures that terminates processing a quantum, when signing a zone with a new DNSKEY.</p>
</p>
<p>This specifies a threshold number of signatures that terminates
processing a quantum, when signing a zone with a new DNSKEY. The
default is <code class="docutils literal notranslate"><span class="pre">10</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-sig-signing-type">
<span class="sig-name descname"><span class="pre">sig-signing-type</span></span><a class="headerlink" href="#namedconf-statement-sig-signing-type" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">sig-signing-type</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies a private RDATA type to use when generating signing-state records.</p>
</p>
<p>This specifies a private RDATA type to be used when generating signing-state
records. The default is <code class="docutils literal notranslate"><span class="pre">65534</span></code>.</p>
<p>This parameter may be removed in a future version,
once there is a standard type.</p>
<p>Signing-state records are used internally by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to track
the current state of a zone-signing process, i.e., whether it is
still active or has been completed. The records can be inspected
using the command <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-signing"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">signing</span> <span class="pre">-list</span> <span class="pre">zone</span></code></a>. Once <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> has
finished signing a zone with a particular key, the signing-state
record associated with that key can be removed from the zone by
running <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-signing"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">signing</span> <span class="pre">-clear</span> <span class="pre">keyid/algorithm</span> <span class="pre">zone</span></code></a>. To clear all of
the completed signing-state records for a zone, use
<a class="reference internal" href="manpages.html#cmdoption-rndc-arg-signing"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">signing</span> <span class="pre">-clear</span> <span class="pre">all</span> <span class="pre">zone</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-min-refresh-time">
<span class="sig-name descname"><span class="pre">min-refresh-time</span></span><a class="headerlink" href="#namedconf-statement-min-refresh-time" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">min-refresh-time</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, secondary, stub)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Limits the zone refresh interval to no more often than the specified value, in seconds.</p>
</p>
<p>This option controls the server’s behavior on refreshing a zone
(querying for SOA changes). Usually, the SOA refresh values for
the zone are used; however, these values are set by the primary, giving
secondary server administrators little control over their contents.</p>
<p>This option allows the administrator to set a minimum
refresh time in seconds per-zone, per-view, or globally.
This option is valid for secondary and stub zones, and clamps the SOA
refresh time to the specified value.</p>
<p>The default is 300 seconds.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-refresh-time">
<span class="sig-name descname"><span class="pre">max-refresh-time</span></span><a class="headerlink" href="#namedconf-statement-max-refresh-time" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-refresh-time</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, secondary, stub)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Limits the zone refresh interval to no less often than the specified value, in seconds.</p>
</p>
<p>This option controls the server’s behavior on refreshing a zone
(querying for SOA changes). Usually, the SOA refresh values for
the zone are used; however, these values are set by the primary, giving
secondary server administrators little control over their contents.</p>
<p>This option allows the administrator to set a maximum
refresh time in seconds per-zone, per-view, or globally.
This option is valid for secondary and stub zones, and clamps the SOA
refresh time to the specified value.</p>
<p>The default is 2419200 seconds (4 weeks).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-min-retry-time">
<span class="sig-name descname"><span class="pre">min-retry-time</span></span><a class="headerlink" href="#namedconf-statement-min-retry-time" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">min-retry-time</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, secondary, stub)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Limits the zone refresh retry interval to no more often than the specified value, in seconds.</p>
</p>
<p>This option controls the server’s behavior on retrying failed
zone transfers. Usually, the SOA retry values for the zone are
used; however, these values are set by the primary, giving
secondary server administrators little control over their contents.</p>
<p>This option allows the administrator to set a minimum
retry time in seconds per-zone, per-view, or globally.
This option is valid for secondary and stub zones, and clamps the SOA
retry time to the specified value.</p>
<p>The default is 500 seconds.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-retry-time">
<span class="sig-name descname"><span class="pre">max-retry-time</span></span><a class="headerlink" href="#namedconf-statement-max-retry-time" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-retry-time</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, secondary, stub)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Limits the zone refresh retry interval to no less often than the specified value, in seconds.</p>
</p>
<p>This option controls the server’s behavior on retrying failed
zone transfers. Usually, the SOA retry values for the zone are
used; however, these values are set by the primary, giving
secondary server administrators little control over their contents.</p>
<p>This option allows the administrator to set a maximum
retry time in seconds per-zone, per-view, or globally.
This option is valid for secondary and stub zones, and clamps the SOA
retry time to the specified value.</p>
<p>The default is 1209600 seconds (2 weeks).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-edns-udp-size">
<span class="sig-name descname"><span class="pre">edns-udp-size</span></span><a class="headerlink" href="#namedconf-statement-edns-udp-size" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">edns-udp-size</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, server, view, view.server</p>
<p><strong>Tags: </strong>query</p>
<p><p>Sets the maximum advertised EDNS UDP buffer size to control the size of packets received from authoritative servers in response to recursive queries.</p>
</p>
<p>This sets the maximum advertised EDNS UDP buffer size, in bytes, to control
the size of packets received from authoritative servers in response
to recursive queries. Valid values are 512 to 4096; values outside
this range are silently adjusted to the nearest value within it.
The default value is 1232.</p>
<p>The usual reason for setting <a class="reference internal" href="#namedconf-statement-edns-udp-size" title="namedconf-statement-edns-udp-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">edns-udp-size</span></code></a> to a non-default value
is to get UDP answers to pass through broken firewalls that block
fragmented packets and/or block UDP DNS packets that are greater than
512 bytes.</p>
<p>When <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> first queries a remote server, it advertises a UDP
buffer size of 1232.</p>
<p>Query timeouts observed for any given server affect the buffer size
advertised in queries sent to that server. Depending on observed packet
dropping patterns, the query is retried over TCP. Per-server EDNS statistics
are only retained in memory for the lifetime of a given server’s ADB entry.</p>
<p>According to measurements taken by multiple parties, the default value
should not be causing the fragmentation. As most of the Internet “core” is able to
cope with IP message sizes between 1400-1500 bytes, the 1232 size was chosen
as a conservative minimal number that could be changed by the DNS operator to
a estimated path MTU, minus the estimated header space. In practice, the
smallest MTU witnessed in the operational DNS community is 1500 octets, the
Ethernet maximum payload size, so a useful default for the maximum DNS/UDP
payload size on <strong>reliable</strong> networks would be 1432.</p>
<p>Any server-specific <a class="reference internal" href="#namedconf-statement-edns-udp-size" title="namedconf-statement-edns-udp-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">edns-udp-size</span></code></a> setting has precedence over all
the above rules, i.e. configures a static value for a given
<a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">server</span></code></a> block.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-udp-size">
<span class="sig-name descname"><span class="pre">max-udp-size</span></span><a class="headerlink" href="#namedconf-statement-max-udp-size" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-udp-size</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, server, view, view.server</p>
<p><strong>Tags: </strong>query</p>
<p><p>Sets the maximum EDNS UDP message size sent by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
</p>
<p>This sets the maximum EDNS UDP message size that <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> sends, in bytes.
Valid values are 512 to 4096; values outside this range are
silently adjusted to the nearest value within it. The default value
is 1232.</p>
<p>This value applies to responses sent by a server; to set the
advertised buffer size in queries, see <a class="reference internal" href="#namedconf-statement-edns-udp-size" title="namedconf-statement-edns-udp-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">edns-udp-size</span></code></a>.</p>
<p>The usual reason for setting <a class="reference internal" href="#namedconf-statement-max-udp-size" title="namedconf-statement-max-udp-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-udp-size</span></code></a> to a non-default value
is to allow UDP answers to pass through broken firewalls that block
fragmented packets and/or block UDP packets that are greater than 512
bytes. This is independent of the advertised receive buffer
(<a class="reference internal" href="#namedconf-statement-edns-udp-size" title="namedconf-statement-edns-udp-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">edns-udp-size</span></code></a>).</p>
<p>Setting this to a low value encourages additional TCP traffic to
the name server.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-masterfile-format">
<span class="sig-name descname"><span class="pre">masterfile-format</span></span><a class="headerlink" href="#namedconf-statement-masterfile-format" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">masterfile-format</span> <span class="pre">(</span> <span class="pre">raw</span> <span class="pre">|</span> <span class="pre">text</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, redirect, secondary, stub)</p>
<p><strong>Tags: </strong>zone, server</p>
<p><p>Specifies the file format of zone files.</p>
</p>
<p>This specifies the file format of zone files (see <a class="reference internal" href="chapter3.html#zonefile-format"><span class="std std-ref">Additional File Formats</span></a>
for details). The default value is <code class="docutils literal notranslate"><span class="pre">text</span></code>, which is the standard
textual representation, except for secondary zones, in which the default
value is <code class="docutils literal notranslate"><span class="pre">raw</span></code>. Files in formats other than <code class="docutils literal notranslate"><span class="pre">text</span></code> are typically
expected to be generated by the <a class="reference internal" href="manpages.html#std-iscman-named-compilezone"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named-compilezone</span></code></a> tool, or dumped by
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
<p>Note that when a zone file in a format other than <code class="docutils literal notranslate"><span class="pre">text</span></code> is loaded,
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> may omit some of the checks which are performed for a file in
<code class="docutils literal notranslate"><span class="pre">text</span></code> format. For example, <a class="reference internal" href="#namedconf-statement-check-names" title="namedconf-statement-check-names"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-names</span></code></a> only applies when loading
zones in <code class="docutils literal notranslate"><span class="pre">text</span></code> format. Zone files in <code class="docutils literal notranslate"><span class="pre">raw</span></code> format should be generated
with the same check level as that specified in the <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
configuration file.</p>
<p>When configured in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>, this statement sets the
<a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">masterfile-format</span></code></a> for all zones, but it can be overridden on a
per-zone or per-view basis by including a <a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">masterfile-format</span></code></a>
statement within the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> or <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> block in the configuration
file.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-masterfile-style">
<span class="sig-name descname"><span class="pre">masterfile-style</span></span><a class="headerlink" href="#namedconf-statement-masterfile-style" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">masterfile-style</span> <span class="pre">(</span> <span class="pre">full</span> <span class="pre">|</span> <span class="pre">relative</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, redirect, secondary, stub)</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the format of zone files during a dump, when the <a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">masterfile-format</span></code></a> is <code class="docutils literal notranslate"><span class="pre">text</span></code>.</p>
</p>
<p>This specifies the formatting of zone files during dump, when the
<a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">masterfile-format</span></code></a> is <code class="docutils literal notranslate"><span class="pre">text</span></code>. This option is ignored with any
other <a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">masterfile-format</span></code></a>.</p>
<p>When set to <code class="docutils literal notranslate"><span class="pre">relative</span></code>, records are printed in a multi-line format,
with owner names expressed relative to a shared origin. When set to
<code class="docutils literal notranslate"><span class="pre">full</span></code>, records are printed in a single-line format with absolute
owner names. The <code class="docutils literal notranslate"><span class="pre">full</span></code> format is most suitable when a zone file
needs to be processed automatically by a script. The <code class="docutils literal notranslate"><span class="pre">relative</span></code>
format is more human-readable, and is thus suitable when a zone is to
be edited by hand. The default is <code class="docutils literal notranslate"><span class="pre">relative</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-query-count">
<span class="sig-name descname"><span class="pre">max-query-count</span></span><a class="headerlink" href="#namedconf-statement-max-query-count" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-query-count</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Sets the maximum number of iterative queries while servicing a recursive query.</p>
</p>
<p>This sets the maximum number of iterative queries that may be sent
by a resolver while looking up a single name. If more queries than this
need to be sent before an answer is reached, then recursion is terminated
and a SERVFAIL response is returned to the client. The default is <code class="docutils literal notranslate"><span class="pre">200</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-recursion-depth">
<span class="sig-name descname"><span class="pre">max-recursion-depth</span></span><a class="headerlink" href="#namedconf-statement-max-recursion-depth" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-recursion-depth</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the maximum number of levels of recursion permitted at any one time while servicing a recursive query.</p>
</p>
<p>This sets the maximum number of levels of recursion that are permitted at
any one time while servicing a recursive query. Resolving a name may
require looking up a name server address, which in turn requires
resolving another name, etc.; if the number of recursions exceeds
this value, the recursive query is terminated and returns SERVFAIL.
The default is 7.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-recursion-queries">
<span class="sig-name descname"><span class="pre">max-recursion-queries</span></span><a class="headerlink" href="#namedconf-statement-max-recursion-queries" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-recursion-queries</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Sets the maximum number of iterative queries while servicing a recursive query.</p>
</p>
<p>This sets the maximum number of iterative queries that may be sent
by a resolver while looking up a single name. If more queries than this
need to be sent before an answer is reached, then recursion is terminated
and a SERVFAIL response is returned to the client. (Note: if the answer
is a CNAME, then the subsequent lookup for the target of the CNAME is
counted separately.) The default is 50.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-query-restarts">
<span class="sig-name descname"><span class="pre">max-query-restarts</span></span><a class="headerlink" href="#namedconf-statement-max-query-restarts" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-query-restarts</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Sets the maximum number of chained CNAMEs to follow</p>
</p>
<p>This sets the maximum number of successive CNAME targets to follow
when resolving a client query, before terminating the query to avoid a
CNAME loop. Valid values are 1 to 255. The default is 11.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-notify-delay">
<span class="sig-name descname"><span class="pre">notify-delay</span></span><a class="headerlink" href="#namedconf-statement-notify-delay" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">notify-delay</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>transfer, zone</p>
<p><p>Sets the delay (in seconds) between sending sets of NOTIFY messages for a zone.</p>
</p>
<p>This sets the delay, in seconds, between sending sets of NOTIFY messages
for a zone. Whenever a NOTIFY message is sent for a zone, a timer will
be set for this duration. If the zone is updated again before the timer
expires, the NOTIFY for that update will be postponed. The default is 5
seconds.</p>
<p>The overall rate at which NOTIFY messages are sent for all zones is
controlled by <a class="reference internal" href="#namedconf-statement-notify-rate" title="namedconf-statement-notify-rate"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-rate</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-rsa-exponent-size">
<span class="sig-name descname"><span class="pre">max-rsa-exponent-size</span></span><a class="headerlink" href="#namedconf-statement-max-rsa-exponent-size" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-rsa-exponent-size</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>dnssec, query</p>
<p><p>Sets the maximum RSA exponent size (in bits) when validating.</p>
</p>
<p>This sets the maximum RSA exponent size, in bits, that is accepted when
validating. Valid values are 35 to 4096 bits. The default, zero, is
also accepted and is equivalent to 4096.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-prefetch">
<span class="sig-name descname"><span class="pre">prefetch</span></span><a class="headerlink" href="#namedconf-statement-prefetch" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">prefetch</span> <span class="pre"><integer></span> <span class="pre">[</span> <span class="pre"><integer></span> <span class="pre">];</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Specifies the “trigger” time-to-live (TTL) value at which prefetch of the current query takes place.</p>
</p>
<p>When a query is received for cached data which is to expire shortly,
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> can refresh the data from the authoritative server
immediately, ensuring that the cache always has an answer available.</p>
<p><a class="reference internal" href="#namedconf-statement-prefetch" title="namedconf-statement-prefetch"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">prefetch</span></code></a> specifies the “trigger” TTL value at which prefetch
of the current query takes place; when a cache record with an
equal or lower TTL value is encountered during query processing, it is
refreshed. Valid trigger TTL values are 1 to 10 seconds. Values
larger than 10 seconds are silently reduced to 10. Setting a
trigger TTL to zero causes prefetch to be disabled. The default
trigger TTL is <code class="docutils literal notranslate"><span class="pre">2</span></code>.</p>
<p>An optional second argument specifies the “eligibility” TTL: the
smallest <em>original</em> TTL value that is accepted for a record to
be eligible for prefetching. The eligibility TTL must be at least six
seconds longer than the trigger TTL; if not, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
silently adjusts it upward. The default eligibility TTL is <code class="docutils literal notranslate"><span class="pre">9</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-v6-bias">
<span class="sig-name descname"><span class="pre">v6-bias</span></span><a class="headerlink" href="#namedconf-statement-v6-bias" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">v6-bias</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Indicates the number of milliseconds of preference to give to IPv6 name servers.</p>
</p>
<p>When determining the next name server to try, this indicates by how many
milliseconds to prefer IPv6 name servers. The default is <code class="docutils literal notranslate"><span class="pre">50</span></code>
milliseconds.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tcp-receive-buffer">
<span class="sig-name descname"><span class="pre">tcp-receive-buffer</span></span><a class="headerlink" href="#namedconf-statement-tcp-receive-buffer" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tcp-receive-buffer</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the operating system’s receive buffer size for TCP sockets.</p>
</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-udp-receive-buffer">
<span class="sig-name descname"><span class="pre">udp-receive-buffer</span></span><a class="headerlink" href="#namedconf-statement-udp-receive-buffer" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">udp-receive-buffer</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the operating system’s receive buffer size for UDP sockets.</p>
</p>
<p>These options control the operating system’s receive buffer sizes
(<code class="docutils literal notranslate"><span class="pre">SO_RCVBUF</span></code>) for TCP and UDP sockets, respectively. Buffering at
the operating system level can prevent packet drops during brief load
spikes, but if the buffer size is set too high, a running server
could get clogged with outstanding queries that have already timed
out. The default is <code class="docutils literal notranslate"><span class="pre">0</span></code>, which means the operating system’s default
value should be used. The minimum configurable value is <code class="docutils literal notranslate"><span class="pre">4096</span></code>; any
nonzero value lower than that is silently raised. The maximum value
is determined by the kernel, and values exceeding the maximum are
silently reduced.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tcp-send-buffer">
<span class="sig-name descname"><span class="pre">tcp-send-buffer</span></span><a class="headerlink" href="#namedconf-statement-tcp-send-buffer" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tcp-send-buffer</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the operating system’s send buffer size for TCP sockets.</p>
</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-udp-send-buffer">
<span class="sig-name descname"><span class="pre">udp-send-buffer</span></span><a class="headerlink" href="#namedconf-statement-udp-send-buffer" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">udp-send-buffer</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the operating system’s send buffer size for UDP sockets.</p>
</p>
<p>These options control the operating system’s send buffer sizes
(<code class="docutils literal notranslate"><span class="pre">SO_SNDBUF</span></code>) for TCP and UDP sockets, respectively. Buffering at
the operating system level can prevent packet drops during brief load
spikes, but if the buffer size is set too high, a running server
could get clogged with outstanding queries that have already timed
out. The default is <code class="docutils literal notranslate"><span class="pre">0</span></code>, which means the operating system’s default
value should be used. The minimum configurable value is <code class="docutils literal notranslate"><span class="pre">4096</span></code>; any
nonzero value lower than that is silently raised. The maximum value
is determined by the kernel, and values exceeding the maximum are
silently reduced.</p>
</dd></dl>
</section>
<section id="built-in-server-information-zones">
<span id="builtin"></span><h4><span class="section-number">8.2.14.14. </span>Built-in Server Information Zones<a class="headerlink" href="#built-in-server-information-zones" title="Link to this heading"></a></h4>
<p>The server provides some helpful diagnostic information through a number
of built-in zones under the pseudo-top-level-domain <code class="docutils literal notranslate"><span class="pre">bind</span></code> in the
<code class="docutils literal notranslate"><span class="pre">CHAOS</span></code> class. These zones are part of a built-in view
(see <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>) of class <code class="docutils literal notranslate"><span class="pre">CHAOS</span></code>, which is
separate from the default view of class <code class="docutils literal notranslate"><span class="pre">IN</span></code>. Most global
configuration options (<a class="reference internal" href="#namedconf-statement-allow-query" title="namedconf-statement-allow-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query</span></code></a>, etc.) apply to this view,
but some are locally overridden: <a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify</span></code></a>, <a class="reference internal" href="#namedconf-statement-recursion" title="namedconf-statement-recursion"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursion</span></code></a>, and
<a class="reference internal" href="#namedconf-statement-allow-new-zones" title="namedconf-statement-allow-new-zones"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-new-zones</span></code></a> are always set to <code class="docutils literal notranslate"><span class="pre">no</span></code>, and <a class="reference internal" href="#namedconf-statement-rate-limit" title="namedconf-statement-rate-limit"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rate-limit</span></code></a> is set
to allow three responses per second.</p>
<p>To disable these zones, use the options below or hide the
built-in <code class="docutils literal notranslate"><span class="pre">CHAOS</span></code> view by defining an explicit view of class <code class="docutils literal notranslate"><span class="pre">CHAOS</span></code>
that matches all clients.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-version">
<span class="sig-name descname"><span class="pre">version</span></span><a class="headerlink" href="#namedconf-statement-version" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">version</span> <span class="pre">(</span> <span class="pre"><quoted_string></span> <span class="pre">|</span> <span class="pre">none</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the version number of the server to return in response to a <code class="docutils literal notranslate"><span class="pre">version.bind</span></code> query.</p>
</p>
<p>This is the version the server should report via a query of the name
<code class="docutils literal notranslate"><span class="pre">version.bind</span></code> with type <code class="docutils literal notranslate"><span class="pre">TXT</span></code> and class <code class="docutils literal notranslate"><span class="pre">CHAOS</span></code>. The default is
the real version number of this server. Specifying <code class="docutils literal notranslate"><span class="pre">version</span> <span class="pre">none</span></code>
disables processing of the queries.</p>
<p>Setting <a class="reference internal" href="#namedconf-statement-version" title="namedconf-statement-version"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">version</span></code></a> to any value (including <code class="docutils literal notranslate"><span class="pre">none</span></code>) also disables
queries for <code class="docutils literal notranslate"><span class="pre">authors.bind</span> <span class="pre">TXT</span> <span class="pre">CH</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-hostname">
<span class="sig-name descname"><span class="pre">hostname</span></span><a class="headerlink" href="#namedconf-statement-hostname" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">hostname</span> <span class="pre">(</span> <span class="pre"><quoted_string></span> <span class="pre">|</span> <span class="pre">none</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the hostname of the server to return in response to a <code class="docutils literal notranslate"><span class="pre">hostname.bind</span></code> query.</p>
</p>
<p>This is the hostname the server should report via a query of the name
<code class="docutils literal notranslate"><span class="pre">hostname.bind</span></code> with type <code class="docutils literal notranslate"><span class="pre">TXT</span></code> and class <code class="docutils literal notranslate"><span class="pre">CHAOS</span></code>. This defaults
to the hostname of the machine hosting the name server, as found by
the <code class="docutils literal notranslate"><span class="pre">gethostname()</span></code> function. The primary purpose of such queries is to
identify which of a group of anycast servers is actually answering
the queries. Specifying <code class="docutils literal notranslate"><span class="pre">hostname</span> <span class="pre">none;</span></code> disables processing of
the queries.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-server-id">
<span class="sig-name descname"><span class="pre">server-id</span></span><a class="headerlink" href="#namedconf-statement-server-id" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">server-id</span> <span class="pre">(</span> <span class="pre"><quoted_string></span> <span class="pre">|</span> <span class="pre">none</span> <span class="pre">|</span> <span class="pre">hostname</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the ID of the server to return in response to a <code class="docutils literal notranslate"><span class="pre">ID.SERVER</span></code> query.</p>
</p>
<p>This is the ID the server should report when receiving a Name Server
Identifier (NSID) query, or a query of the name <code class="docutils literal notranslate"><span class="pre">ID.SERVER</span></code> with
type <code class="docutils literal notranslate"><span class="pre">TXT</span></code> and class <code class="docutils literal notranslate"><span class="pre">CHAOS</span></code>. The primary purpose of such queries is
to identify which of a group of anycast servers is actually answering
the queries. Specifying <code class="docutils literal notranslate"><span class="pre">server-id</span> <span class="pre">none;</span></code> disables processing of
the queries. Specifying <code class="docutils literal notranslate"><span class="pre">server-id</span> <span class="pre">hostname;</span></code> causes <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
to use the hostname as found by the <code class="docutils literal notranslate"><span class="pre">gethostname()</span></code> function. The
default <a class="reference internal" href="#namedconf-statement-server-id" title="namedconf-statement-server-id"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">server-id</span></code></a> is <code class="docutils literal notranslate"><span class="pre">none</span></code>.</p>
</dd></dl>
</section>
<section id="built-in-empty-zones">
<span id="empty"></span><h4><span class="section-number">8.2.14.15. </span>Built-in Empty Zones<a class="headerlink" href="#built-in-empty-zones" title="Link to this heading"></a></h4>
<p>The <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> server has some built-in empty zones, for SOA and NS records
only. These are for zones that should normally be answered locally and for
which queries should not be sent to the Internet’s root servers. The
official servers that cover these namespaces return NXDOMAIN responses
to these queries. In particular, these cover the reverse namespaces for
addresses from <span class="target" id="index-20"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1918.html"><strong>RFC 1918</strong></a>, <span class="target" id="index-21"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc4193.html"><strong>RFC 4193</strong></a>, <span class="target" id="index-22"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc5737.html"><strong>RFC 5737</strong></a>, and <span class="target" id="index-23"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc6598.html"><strong>RFC 6598</strong></a>. They also
include the reverse namespace for the IPv6 local address (locally assigned),
IPv6 link local addresses, the IPv6 loopback address, and the IPv6
unknown address.</p>
<p>The server attempts to determine if a built-in zone already exists
or is active (covered by a forward-only forwarding declaration) and does
not create an empty zone if either is true.</p>
<p>The current list of empty zones is:</p>
<ul class="simple">
<li><p>10.IN-ADDR.ARPA</p></li>
<li><p>16.172.IN-ADDR.ARPA</p></li>
<li><p>17.172.IN-ADDR.ARPA</p></li>
<li><p>18.172.IN-ADDR.ARPA</p></li>
<li><p>19.172.IN-ADDR.ARPA</p></li>
<li><p>20.172.IN-ADDR.ARPA</p></li>
<li><p>21.172.IN-ADDR.ARPA</p></li>
<li><p>22.172.IN-ADDR.ARPA</p></li>
<li><p>23.172.IN-ADDR.ARPA</p></li>
<li><p>24.172.IN-ADDR.ARPA</p></li>
<li><p>25.172.IN-ADDR.ARPA</p></li>
<li><p>26.172.IN-ADDR.ARPA</p></li>
<li><p>27.172.IN-ADDR.ARPA</p></li>
<li><p>28.172.IN-ADDR.ARPA</p></li>
<li><p>29.172.IN-ADDR.ARPA</p></li>
<li><p>30.172.IN-ADDR.ARPA</p></li>
<li><p>31.172.IN-ADDR.ARPA</p></li>
<li><p>168.192.IN-ADDR.ARPA</p></li>
<li><p>64.100.IN-ADDR.ARPA</p></li>
<li><p>65.100.IN-ADDR.ARPA</p></li>
<li><p>66.100.IN-ADDR.ARPA</p></li>
<li><p>67.100.IN-ADDR.ARPA</p></li>
<li><p>68.100.IN-ADDR.ARPA</p></li>
<li><p>69.100.IN-ADDR.ARPA</p></li>
<li><p>70.100.IN-ADDR.ARPA</p></li>
<li><p>71.100.IN-ADDR.ARPA</p></li>
<li><p>72.100.IN-ADDR.ARPA</p></li>
<li><p>73.100.IN-ADDR.ARPA</p></li>
<li><p>74.100.IN-ADDR.ARPA</p></li>
<li><p>75.100.IN-ADDR.ARPA</p></li>
<li><p>76.100.IN-ADDR.ARPA</p></li>
<li><p>77.100.IN-ADDR.ARPA</p></li>
<li><p>78.100.IN-ADDR.ARPA</p></li>
<li><p>79.100.IN-ADDR.ARPA</p></li>
<li><p>80.100.IN-ADDR.ARPA</p></li>
<li><p>81.100.IN-ADDR.ARPA</p></li>
<li><p>82.100.IN-ADDR.ARPA</p></li>
<li><p>83.100.IN-ADDR.ARPA</p></li>
<li><p>84.100.IN-ADDR.ARPA</p></li>
<li><p>85.100.IN-ADDR.ARPA</p></li>
<li><p>86.100.IN-ADDR.ARPA</p></li>
<li><p>87.100.IN-ADDR.ARPA</p></li>
<li><p>88.100.IN-ADDR.ARPA</p></li>
<li><p>89.100.IN-ADDR.ARPA</p></li>
<li><p>90.100.IN-ADDR.ARPA</p></li>
<li><p>91.100.IN-ADDR.ARPA</p></li>
<li><p>92.100.IN-ADDR.ARPA</p></li>
<li><p>93.100.IN-ADDR.ARPA</p></li>
<li><p>94.100.IN-ADDR.ARPA</p></li>
<li><p>95.100.IN-ADDR.ARPA</p></li>
<li><p>96.100.IN-ADDR.ARPA</p></li>
<li><p>97.100.IN-ADDR.ARPA</p></li>
<li><p>98.100.IN-ADDR.ARPA</p></li>
<li><p>99.100.IN-ADDR.ARPA</p></li>
<li><p>100.100.IN-ADDR.ARPA</p></li>
<li><p>101.100.IN-ADDR.ARPA</p></li>
<li><p>102.100.IN-ADDR.ARPA</p></li>
<li><p>103.100.IN-ADDR.ARPA</p></li>
<li><p>104.100.IN-ADDR.ARPA</p></li>
<li><p>105.100.IN-ADDR.ARPA</p></li>
<li><p>106.100.IN-ADDR.ARPA</p></li>
<li><p>107.100.IN-ADDR.ARPA</p></li>
<li><p>108.100.IN-ADDR.ARPA</p></li>
<li><p>109.100.IN-ADDR.ARPA</p></li>
<li><p>110.100.IN-ADDR.ARPA</p></li>
<li><p>111.100.IN-ADDR.ARPA</p></li>
<li><p>112.100.IN-ADDR.ARPA</p></li>
<li><p>113.100.IN-ADDR.ARPA</p></li>
<li><p>114.100.IN-ADDR.ARPA</p></li>
<li><p>115.100.IN-ADDR.ARPA</p></li>
<li><p>116.100.IN-ADDR.ARPA</p></li>
<li><p>117.100.IN-ADDR.ARPA</p></li>
<li><p>118.100.IN-ADDR.ARPA</p></li>
<li><p>119.100.IN-ADDR.ARPA</p></li>
<li><p>120.100.IN-ADDR.ARPA</p></li>
<li><p>121.100.IN-ADDR.ARPA</p></li>
<li><p>122.100.IN-ADDR.ARPA</p></li>
<li><p>123.100.IN-ADDR.ARPA</p></li>
<li><p>124.100.IN-ADDR.ARPA</p></li>
<li><p>125.100.IN-ADDR.ARPA</p></li>
<li><p>126.100.IN-ADDR.ARPA</p></li>
<li><p>127.100.IN-ADDR.ARPA</p></li>
<li><p>0.IN-ADDR.ARPA</p></li>
<li><p>127.IN-ADDR.ARPA</p></li>
<li><p>254.169.IN-ADDR.ARPA</p></li>
<li><p>2.0.192.IN-ADDR.ARPA</p></li>
<li><p>100.51.198.IN-ADDR.ARPA</p></li>
<li><p>113.0.203.IN-ADDR.ARPA</p></li>
<li><p>255.255.255.255.IN-ADDR.ARPA</p></li>
<li><p>0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA</p></li>
<li><p>1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA</p></li>
<li><p>8.B.D.0.1.0.0.2.IP6.ARPA</p></li>
<li><p>D.F.IP6.ARPA</p></li>
<li><p>8.E.F.IP6.ARPA</p></li>
<li><p>9.E.F.IP6.ARPA</p></li>
<li><p>A.E.F.IP6.ARPA</p></li>
<li><p>B.E.F.IP6.ARPA</p></li>
<li><p>EMPTY.AS112.ARPA</p></li>
<li><p>HOME.ARPA</p></li>
<li><p>RESOLVER.ARPA</p></li>
</ul>
<p>Empty zones can be set at the view level and only apply to views of
class IN. Disabled empty zones are only inherited from options if there
are no disabled empty zones specified at the view level. To override the
options list of disabled zones, disable the root zone at the
view level. For example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">disable</span><span class="o">-</span><span class="n">empty</span><span class="o">-</span><span class="n">zone</span> <span class="s2">"."</span><span class="p">;</span>
</pre></div>
</div>
<p>If using the address ranges covered here,
reverse zones covering the addresses should already be in place. In practice this
appears to not be the case, with many queries being made to the
infrastructure servers for names in these spaces. So many, in fact, that
sacrificial servers had to be deployed to channel the query load
away from the infrastructure servers.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>The real parent servers for these zones should disable all empty zones
under the parent zone they serve. For the real root servers, this is
all built-in empty zones. This enables them to return referrals
to deeper in the tree.</p>
</div>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-empty-server">
<span class="sig-name descname"><span class="pre">empty-server</span></span><a class="headerlink" href="#namedconf-statement-empty-server" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">empty-server</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, zone</p>
<p><p>Specifies the server name in the returned SOA record for empty zones.</p>
</p>
<p>This specifies the server name that appears in the returned SOA record for
empty zones. If none is specified, the zone’s name is used.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-empty-contact">
<span class="sig-name descname"><span class="pre">empty-contact</span></span><a class="headerlink" href="#namedconf-statement-empty-contact" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">empty-contact</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, zone</p>
<p><p>Specifies the contact name in the returned SOA record for empty zones.</p>
</p>
<p>This specifies the contact name that appears in the returned SOA record for
empty zones. If none is specified, “.” is used.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-empty-zones-enable">
<span class="sig-name descname"><span class="pre">empty-zones-enable</span></span><a class="headerlink" href="#namedconf-statement-empty-zones-enable" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">empty-zones-enable</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, zone</p>
<p><p>Enables or disables all empty zones.</p>
</p>
<p>This enables or disables all empty zones. By default, they are enabled.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-disable-empty-zone">
<span class="sig-name descname"><span class="pre">disable-empty-zone</span></span><a class="headerlink" href="#namedconf-statement-disable-empty-zone" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">disable-empty-zone</span> <span class="pre"><string>;</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, zone</p>
<p><p>Disables individual empty zones.</p>
</p>
<p>This disables individual empty zones. By default, none are disabled. This
option can be specified multiple times.</p>
</dd></dl>
</section>
<section id="content-filtering">
<span id="id13"></span><h4><span class="section-number">8.2.14.16. </span>Content Filtering<a class="headerlink" href="#content-filtering" title="Link to this heading"></a></h4>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-deny-answer-addresses">
<span class="sig-name descname"><span class="pre">deny-answer-addresses</span></span><a class="headerlink" href="#namedconf-statement-deny-answer-addresses" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">deny-answer-addresses</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">[</span> <span class="pre">except-from</span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">];</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Rejects A or AAAA records if the corresponding IPv4 or IPv6 addresses match a given <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a>.</p>
</p>
<p>BIND 9 provides the ability to filter out responses from external
DNS servers containing certain types of data in the answer section.
Specifically, it can reject address (A or AAAA) records if the
corresponding IPv4 or IPv6 addresses match the given
<a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> of the <a class="reference internal" href="#namedconf-statement-deny-answer-addresses" title="namedconf-statement-deny-answer-addresses"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">deny-answer-addresses</span></code></a> option.</p>
<p>In the <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> of the <a class="reference internal" href="#namedconf-statement-deny-answer-addresses" title="namedconf-statement-deny-answer-addresses"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">deny-answer-addresses</span></code></a> option,
only <a class="reference internal" href="#term-ip_address"><span class="xref std std-term">ip_address</span></a> and <a class="reference internal" href="#term-netprefix"><span class="xref std std-term">netprefix</span></a> are meaningful; any <a class="reference internal" href="#term-server_key"><span class="xref std std-term">server_key</span></a> is
silently ignored.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-deny-answer-aliases">
<span class="sig-name descname"><span class="pre">deny-answer-aliases</span></span><a class="headerlink" href="#namedconf-statement-deny-answer-aliases" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">deny-answer-aliases</span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">[</span> <span class="pre">except-from</span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">];</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Rejects CNAME or DNAME records if the “alias” name matches a given list of <a class="reference internal" href="#term-domain_name"><code class="xref any std std-term docutils literal notranslate"><span class="pre">domain_name</span></code></a> elements.</p>
</p>
<p>It can
also reject CNAME or DNAME records if the “alias” name (i.e., the CNAME
alias or the substituted query name due to DNAME) matches the given
list of <a class="reference internal" href="#term-domain_name"><span class="xref std std-term">domain_name</span></a> elements of the <a class="reference internal" href="#namedconf-statement-deny-answer-aliases" title="namedconf-statement-deny-answer-aliases"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">deny-answer-aliases</span></code></a> option,
where “match” means the alias name is a subdomain of one of the listed domain names. If
the optional list is specified in the <code class="docutils literal notranslate"><span class="pre">except-from</span></code> argument, records
whose query name matches the list are accepted regardless of the
filter setting. Likewise, if the alias name is a subdomain of the
corresponding zone, the <a class="reference internal" href="#namedconf-statement-deny-answer-aliases" title="namedconf-statement-deny-answer-aliases"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">deny-answer-aliases</span></code></a> filter does not apply;
for example, even if “example.com” is specified for
<a class="reference internal" href="#namedconf-statement-deny-answer-aliases" title="namedconf-statement-deny-answer-aliases"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">deny-answer-aliases</span></code></a>,</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">www</span><span class="o">.</span><span class="n">example</span><span class="o">.</span><span class="n">com</span><span class="o">.</span> <span class="n">CNAME</span> <span class="n">xxx</span><span class="o">.</span><span class="n">example</span><span class="o">.</span><span class="n">com</span><span class="o">.</span>
</pre></div>
</div>
<p>returned by an “example.com” server is accepted.</p>
</dd></dl>
<p>If a response message is rejected due to the filtering, the entire
message is discarded without being cached, and a SERVFAIL error is
returned to the client.</p>
<p>This filtering is intended to prevent “DNS rebinding attacks,” in which
an attacker, in response to a query for a domain name the attacker
controls, returns an IP address within the user’s own network or an alias name
within the user’s own domain. A naive web browser or script could then serve
as an unintended proxy, allowing the attacker to get access to an
internal node of the local network that could not be externally accessed
otherwise. See the paper available at
<a class="reference external" href="https://dl.acm.org/doi/10.1145/1315245.1315298">https://dl.acm.org/doi/10.1145/1315245.1315298</a> for more details
about these attacks.</p>
<p>For example, with a domain named “example.net” and an internal
network using an IPv4 prefix 192.0.2.0/24, an administrator might specify the
following rules:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">deny</span><span class="o">-</span><span class="n">answer</span><span class="o">-</span><span class="n">addresses</span> <span class="p">{</span> <span class="mf">192.0.2.0</span><span class="o">/</span><span class="mi">24</span><span class="p">;</span> <span class="p">}</span> <span class="k">except</span><span class="o">-</span><span class="kn">from</span> <span class="p">{</span> <span class="s2">"example.net"</span><span class="p">;</span> <span class="p">};</span>
<span class="n">deny</span><span class="o">-</span><span class="n">answer</span><span class="o">-</span><span class="n">aliases</span> <span class="p">{</span> <span class="s2">"example.net"</span><span class="p">;</span> <span class="p">};</span>
</pre></div>
</div>
<p>If an external attacker let a web browser in the local network look up
an IPv4 address of “attacker.example.com”, the attacker’s DNS server
would return a response like this:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">attacker</span><span class="o">.</span><span class="n">example</span><span class="o">.</span><span class="n">com</span><span class="o">.</span> <span class="n">A</span> <span class="mf">192.0.2.1</span>
</pre></div>
</div>
<p>in the answer section. Since the rdata of this record (the IPv4 address)
matches the specified prefix 192.0.2.0/24, this response would be
ignored.</p>
<p>On the other hand, if the browser looked up a legitimate internal web
server “www.example.net” and the following response were returned to the
BIND 9 server:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">www</span><span class="o">.</span><span class="n">example</span><span class="o">.</span><span class="n">net</span><span class="o">.</span> <span class="n">A</span> <span class="mf">192.0.2.2</span>
</pre></div>
</div>
<p>it would be accepted, since the owner name “www.example.net” matches the
<code class="docutils literal notranslate"><span class="pre">except-from</span></code> element, “example.net”.</p>
<p>Note that this is not really an attack on the DNS per se. In fact, there
is nothing wrong with having an “external” name mapped to an “internal”
IP address or domain name from the DNS point of view; it might actually
be provided for a legitimate purpose, such as for debugging. As long as
the mapping is provided by the correct owner, it either is not possible or does
not make sense to detect whether the intent of the mapping is legitimate
within the DNS. The “rebinding” attack must primarily be
protected at the application that uses the DNS. For a large site,
however, it may be difficult to protect all possible applications at
once. This filtering feature is provided only to help such an
operational environment; turning it on is generally discouraged
unless there is no other choice and the attack is a
real threat to applications.</p>
<p>Care should be particularly taken if using this option for
addresses within 127.0.0.0/8. These addresses are obviously “internal,”
but many applications conventionally rely on a DNS mapping from some
name to such an address. Filtering out DNS records containing this
address spuriously can break such applications.</p>
</section>
<section id="response-policy-zone-rpz-rewriting">
<span id="rpz"></span><h4><span class="section-number">8.2.14.17. </span>Response Policy Zone (RPZ) Rewriting<a class="headerlink" href="#response-policy-zone-rpz-rewriting" title="Link to this heading"></a></h4>
<p>BIND 9 includes a limited mechanism to modify DNS responses for requests
analogous to email anti-spam DNS rejection lists. Responses can be changed to
deny the existence of domains (NXDOMAIN), deny the existence of IP
addresses for domains (NODATA), or contain other IP addresses or data.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-response-policy">
<span class="sig-name descname"><span class="pre">response-policy</span></span><a class="headerlink" href="#namedconf-statement-response-policy" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">response-policy</span> <span class="pre">{</span> <span class="pre">zone</span> <span class="pre"><string></span> <span class="pre">[</span> <span class="pre">add-soa</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">log</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">max-policy-ttl</span> <span class="pre"><duration></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">min-update-interval</span> <span class="pre"><duration></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">policy</span> <span class="pre">(</span> <span class="pre">cname</span> <span class="pre">|</span> <span class="pre">disabled</span> <span class="pre">|</span> <span class="pre">drop</span> <span class="pre">|</span> <span class="pre">given</span> <span class="pre">|</span> <span class="pre">no-op</span> <span class="pre">|</span> <span class="pre">nodata</span> <span class="pre">|</span> <span class="pre">nxdomain</span> <span class="pre">|</span> <span class="pre">passthru</span> <span class="pre">|</span> <span class="pre">tcp-only</span> <span class="pre"><quoted_string></span> <span class="pre">)</span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">recursive-only</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">nsip-enable</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">nsdname-enable</span> <span class="pre"><boolean></span> <span class="pre">];</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">[</span> <span class="pre">add-soa</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">break-dnssec</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">max-policy-ttl</span> <span class="pre"><duration></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">min-update-interval</span> <span class="pre"><duration></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">min-ns-dots</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">nsip-wait-recurse</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">nsdname-wait-recurse</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">qname-wait-recurse</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">recursive-only</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">nsip-enable</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">nsdname-enable</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">dnsrps-enable</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">dnsrps-options</span> <span class="pre">{</span> <span class="pre"><unspecified-text></span> <span class="pre">}</span> <span class="pre">];</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, query, zone, security</p>
<p><p>Specifies response policy zones for the view or among global options.</p>
</p>
<p>Response policy zones are named in the <a class="reference internal" href="#namedconf-statement-response-policy" title="namedconf-statement-response-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">response-policy</span></code></a> option for
the view, or among the global options if there is no <a class="reference internal" href="#namedconf-statement-response-policy" title="namedconf-statement-response-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">response-policy</span></code></a>
option for the view. Response policy zones are ordinary DNS zones
containing RRsets that can be queried normally if allowed. It is usually
best to restrict those queries with something like
<code class="docutils literal notranslate"><span class="pre">allow-query</span> <span class="pre">{</span> <span class="pre">localhost;</span> <span class="pre">};</span></code>.</p>
<p>A <a class="reference internal" href="#namedconf-statement-response-policy" title="namedconf-statement-response-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">response-policy</span></code></a> option can support multiple policy zones. To
maximize performance, a radix tree is used to quickly identify response
policy zones containing triggers that match the current query. This
imposes an upper limit of 64 on the number of policy zones in a single
<a class="reference internal" href="#namedconf-statement-response-policy" title="namedconf-statement-response-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">response-policy</span></code></a> option; more than that is a configuration error.</p>
</dd></dl>
<p>Rules encoded in response policy zones are processed after those defined in
<a class="reference internal" href="#access-control"><span class="std std-ref">Access Control</span></a>. All queries from clients which are not permitted access
to the resolver are answered with a status code of REFUSED, regardless of
configured RPZ rules.</p>
<p>Five policy triggers can be encoded in RPZ records.</p>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">RPZ-CLIENT-IP</span></code></dt><dd><p>IP records are triggered by the IP address of the DNS client. Client
IP address triggers are encoded in records that have owner names that
are subdomains of <code class="docutils literal notranslate"><span class="pre">rpz-client-ip</span></code>, relativized to the policy zone
origin name, and that encode an address or address block. IPv4 addresses
are represented as <code class="docutils literal notranslate"><span class="pre">prefixlength.B4.B3.B2.B1.rpz-client-ip</span></code>. The
IPv4 prefix length must be between 1 and 32. All four bytes - B4, B3,
B2, and B1 - must be present. B4 is the decimal value of the least
significant byte of the IPv4 address as in IN-ADDR.ARPA.</p>
<p>IPv6 addresses are encoded in a format similar to the standard IPv6
text representation,
<code class="docutils literal notranslate"><span class="pre">prefixlength.W8.W7.W6.W5.W4.W3.W2.W1.rpz-client-ip</span></code>. Each of
W8,…,W1 is a one- to four-digit hexadecimal number representing 16
bits of the IPv6 address as in the standard text representation of
IPv6 addresses, but reversed as in IP6.ARPA. (Note that this
representation of IPv6 addresses is different from IP6.ARPA, where each
hex digit occupies a label.) All 8 words must be present except when
one set of consecutive zero words is replaced with <code class="docutils literal notranslate"><span class="pre">.zz.</span></code>, analogous
to double colons (::) in standard IPv6 text encodings. The IPv6
prefix length must be between 1 and 128.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QNAME</span></code></dt><dd><p>QNAME policy records are triggered by query names of requests and
targets of CNAME records resolved to generate the response. The owner
name of a QNAME policy record is the query name relativized to the
policy zone.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">RPZ-IP</span></code></dt><dd><p>IP triggers are IP addresses in an A or AAAA record in the ANSWER
section of a response. They are encoded like client-IP triggers,
except as subdomains of <code class="docutils literal notranslate"><span class="pre">rpz-ip</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">RPZ-NSDNAME</span></code></dt><dd><p>NSDNAME triggers match names of authoritative servers for the query name, a
parent of the query name, a CNAME for the query name, or a parent of a CNAME.
They are encoded as subdomains of <code class="docutils literal notranslate"><span class="pre">rpz-nsdname</span></code>, relativized
to the RPZ origin name. NSIP triggers match IP addresses in A and AAAA
RRsets for domains that can be checked against NSDNAME policy records. The
<code class="docutils literal notranslate"><span class="pre">nsdname-enable</span></code> phrase turns NSDNAME triggers off or on for a single
policy zone or for all zones.</p>
<p>If authoritative name servers for the query name are not yet known, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
recursively looks up the authoritative servers for the query name before
applying an RPZ-NSDNAME rule, which can cause a processing delay. To speed up
processing at the cost of precision, the <code class="docutils literal notranslate"><span class="pre">nsdname-wait-recurse</span></code> option can
be used; when set to <code class="docutils literal notranslate"><span class="pre">no</span></code>, RPZ-NSDNAME rules are only applied when
authoritative servers for the query name have already been looked up and
cached. If authoritative servers for the query name are not in the cache,
the RPZ-NSDNAME rule is ignored, but the authoritative servers for
the query name are looked up in the background and the rule is
applied to subsequent queries. The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>,
meaning RPZ-NSDNAME rules are always applied, even if authoritative
servers for the query name need to be looked up first.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">RPZ-NSIP</span></code></dt><dd><p>NSIP triggers match the IP addresses of authoritative servers. They
are encoded like IP triggers, except as subdomains of <code class="docutils literal notranslate"><span class="pre">rpz-nsip</span></code>.
NSDNAME and NSIP triggers are checked only for names with at least
<code class="docutils literal notranslate"><span class="pre">min-ns-dots</span></code> dots. The default value of <code class="docutils literal notranslate"><span class="pre">min-ns-dots</span></code> is 1, to
exclude top-level domains. The <code class="docutils literal notranslate"><span class="pre">nsip-enable</span></code> phrase turns NSIP
triggers off or on for a single policy zone or for all zones.</p>
<p>If a name server’s IP address is not yet known, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
recursively looks up the IP address before applying an RPZ-NSIP rule,
which can cause a processing delay. To speed up processing at the cost
of precision, the <code class="docutils literal notranslate"><span class="pre">nsip-wait-recurse</span></code> option can be used; when set
to <code class="docutils literal notranslate"><span class="pre">no</span></code>, RPZ-NSIP rules are only applied when a name server’s
IP address has already been looked up and cached. If a server’s IP
address is not in the cache, the RPZ-NSIP rule is ignored,
but the address is looked up in the background and the rule
is applied to subsequent queries. The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>,
meaning RPZ-NSIP rules are always applied, even if an address
needs to be looked up first.</p>
</dd>
</dl>
<p>The query response is checked against all response policy zones, so two
or more policy records can be triggered by a response. Because DNS
responses are rewritten according to at most one policy record, a single
record encoding an action (other than <code class="docutils literal notranslate"><span class="pre">DISABLED</span></code> actions) must be
chosen. Triggers, or the records that encode them, are chosen for
rewriting in the following order:</p>
<ol class="arabic simple">
<li><p>Choose the triggered record in the zone that appears first in the
response-policy option.</p></li>
<li><p>Prefer CLIENT-IP to QNAME to IP to NSDNAME to NSIP triggers in a
single zone.</p></li>
<li><p>Among NSDNAME triggers, prefer the trigger that matches the smallest
name under the DNSSEC ordering.</p></li>
<li><p>Among IP or NSIP triggers, prefer the trigger with the longest
prefix.</p></li>
<li><p>Among triggers with the same prefix length, prefer the IP or NSIP
trigger that matches the smallest IP address.</p></li>
</ol>
<p>When the processing of a response is restarted to resolve DNAME or CNAME
records and a policy record set has not been triggered, all response
policy zones are again consulted for the DNAME or CNAME names and
addresses.</p>
<p>RPZ record sets are any types of DNS record, except DNAME or DNSSEC, that
encode actions or responses to individual queries. Any of the policies
can be used with any of the triggers. For example, while the
<code class="docutils literal notranslate"><span class="pre">TCP-only</span></code> policy is commonly used with <code class="docutils literal notranslate"><span class="pre">client-IP</span></code> triggers, it can
be used with any type of trigger to force the use of TCP for responses
with owner names in a zone.</p>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">PASSTHRU</span></code></dt><dd><p>The auto-acceptance policy is specified by a CNAME whose target is
<code class="docutils literal notranslate"><span class="pre">rpz-passthru</span></code>. It causes the response to not be rewritten and is
most often used to “poke holes” in policies for CIDR blocks.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">DROP</span></code></dt><dd><p>The auto-rejection policy is specified by a CNAME whose target is
<code class="docutils literal notranslate"><span class="pre">rpz-drop</span></code>. It causes the response to be discarded. Nothing is sent
to the DNS client.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">TCP-Only</span></code></dt><dd><p>The “slip” policy is specified by a CNAME whose target is
<code class="docutils literal notranslate"><span class="pre">rpz-tcp-only</span></code>. It changes UDP responses to short, truncated DNS
responses that require the DNS client to try again with TCP. It is
used to mitigate distributed DNS reflection attacks.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">NXDOMAIN</span></code></dt><dd><p>The “domain undefined” response is encoded by a CNAME whose target is
the root domain (.).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">NODATA</span></code></dt><dd><p>The empty set of resource records is specified by a CNAME whose target
is the wildcard top-level domain (<code class="docutils literal notranslate"><span class="pre">*.</span></code>). It rewrites the response to
NODATA or ANCOUNT=0.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Local</span> <span class="pre">Data</span></code></dt><dd><p>A set of ordinary DNS records can be used to answer queries. Queries
for record types not in the set are answered with NODATA.</p>
<p>A special form of local data is a CNAME whose target is a wildcard
such as *.example.com. It is used as if an ordinary CNAME after
the asterisk (*) has been replaced with the query name.
This special form is useful for query logging in the walled garden’s
authoritative DNS server.</p>
</dd>
</dl>
<p>All of the actions specified in all of the individual records in a
policy zone can be overridden with a <code class="docutils literal notranslate"><span class="pre">policy</span></code> clause in the
<a class="reference internal" href="#namedconf-statement-response-policy" title="namedconf-statement-response-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">response-policy</span></code></a> option. An organization using a policy zone provided
by another organization might use this mechanism to redirect domains to
its own walled garden.</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">GIVEN</span></code></dt><dd><p>The placeholder policy says “do not override but perform the action
specified in the zone.”</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">DISABLED</span></code></dt><dd><p>The testing override policy causes policy zone records to do nothing
but log what they would have done if the policy zone were not
disabled. The response to the DNS query is written (or not)
according to any triggered policy records that are not disabled.
Disabled policy zones should appear first, because they are often
not logged if a higher-precedence trigger is found first.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">PASSTHRU</span></code>; <code class="docutils literal notranslate"><span class="pre">DROP</span></code>; <code class="docutils literal notranslate"><span class="pre">TCP-Only</span></code>; <code class="docutils literal notranslate"><span class="pre">NXDOMAIN</span></code>; <code class="docutils literal notranslate"><span class="pre">NODATA</span></code></dt><dd><p>These settings each override the corresponding per-record policy.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">CNAME</span> <span class="pre">domain</span></code></dt><dd><p>This causes all RPZ policy records to act as if they were “cname domain”
records.</p>
</dd>
</dl>
<p>By default, the actions encoded in a response policy zone are applied
only to queries that ask for recursion (RD=1). That default can be
changed for a single policy zone, or for all response policy zones in a view,
with a <code class="docutils literal notranslate"><span class="pre">recursive-only</span> <span class="pre">no</span></code> clause. This feature is useful for serving
the same zone files both inside and outside an <span class="target" id="index-24"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1918.html"><strong>RFC 1918</strong></a> cloud and using
RPZ to delete answers that would otherwise contain <span class="target" id="index-25"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1918.html"><strong>RFC 1918</strong></a> values on
the externally visible name server or view.</p>
<p>Also by default, RPZ actions are applied only to DNS requests that
either do not request DNSSEC metadata (DO=0) or when no DNSSEC records
are available for the requested name in the original zone (not the response
policy zone). This default can be changed for all response policy zones
in a view with a <code class="docutils literal notranslate"><span class="pre">break-dnssec</span> <span class="pre">yes</span></code> clause. In that case, RPZ actions
are applied regardless of DNSSEC. The name of the clause option reflects
the fact that results rewritten by RPZ actions cannot verify.</p>
<p>No DNS records are needed for a QNAME or Client-IP trigger; the name or
IP address itself is sufficient, so in principle the query name need not
be recursively resolved. However, not resolving the requested name can
leak the fact that response policy rewriting is in use, and that the name
is listed in a policy zone, to operators of servers for listed names. To
prevent that information leak, by default any recursion needed for a
request is done before any policy triggers are considered. Because
listed domains often have slow authoritative servers, this behavior can
cost significant time. The <code class="docutils literal notranslate"><span class="pre">qname-wait-recurse</span> <span class="pre">no</span></code> option overrides
the default and enables that behavior when recursion cannot change a
non-error response. The option does not affect QNAME or client-IP
triggers in policy zones listed after other zones containing IP, NSIP,
and NSDNAME triggers, because those may depend on the A, AAAA, and NS
records that would be found during recursive resolution. It also does
not affect DNSSEC requests (DO=1) unless <code class="docutils literal notranslate"><span class="pre">break-dnssec</span> <span class="pre">yes</span></code> is in use,
because the response would depend on whether RRSIG records were
found during resolution. Using this option can cause error responses
such as SERVFAIL to appear to be rewritten, since no recursion is being
done to discover problems at the authoritative server.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnsrps-enable">
<span class="sig-name descname"><span class="pre">dnsrps-enable</span></span><a class="headerlink" href="#namedconf-statement-dnsrps-enable" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnsrps-enable</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, security</p>
<p><p>Turns on the DNS Response Policy Service (DNSRPS) interface.</p>
</p>
<p>The <code class="docutils literal notranslate"><span class="pre">dnsrps-enable</span> <span class="pre">yes</span></code> option turns on the DNS Response Policy Service
(DNSRPS) interface, if it has been compiled in <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> using
<code class="docutils literal notranslate"><span class="pre">configure</span> <span class="pre">--enable-dnsrps</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnsrps-options">
<span class="sig-name descname"><span class="pre">dnsrps-options</span></span><a class="headerlink" href="#namedconf-statement-dnsrps-options" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnsrps-options</span> <span class="pre">{</span> <span class="pre"><unspecified-text></span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>server, security</p>
<p><p>Provides additional RPZ configuration settings, which are passed to the DNS Response Policy Service (DNSRPS) provider library.</p>
</p>
<p>The block provides additional RPZ configuration
settings, which are passed through to the DNSRPS provider library.
Multiple DNSRPS settings in an <a class="reference internal" href="#namedconf-statement-dnsrps-options" title="namedconf-statement-dnsrps-options"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnsrps-options</span></code></a> string should be
separated with semi-colons (;). The DNSRPS provider, librpz, is passed a
configuration string consisting of the <a class="reference internal" href="#namedconf-statement-dnsrps-options" title="namedconf-statement-dnsrps-options"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnsrps-options</span></code></a> text,
concatenated with settings derived from the <a class="reference internal" href="#namedconf-statement-response-policy" title="namedconf-statement-response-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">response-policy</span></code></a>
statement.</p>
<p>Note: the <a class="reference internal" href="#namedconf-statement-dnsrps-options" title="namedconf-statement-dnsrps-options"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnsrps-options</span></code></a> text should only include configuration
settings that are specific to the DNSRPS provider. For example, the
DNSRPS provider from Farsight Security takes options such as
<code class="docutils literal notranslate"><span class="pre">dnsrpzd-conf</span></code>, <code class="docutils literal notranslate"><span class="pre">dnsrpzd-sock</span></code>, and <code class="docutils literal notranslate"><span class="pre">dnzrpzd-args</span></code> (for details of
these options, see the <code class="docutils literal notranslate"><span class="pre">librpz</span></code> documentation). Other RPZ
configuration settings could be included in <a class="reference internal" href="#namedconf-statement-dnsrps-options" title="namedconf-statement-dnsrps-options"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnsrps-options</span></code></a> as well,
but if <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> were switched back to traditional RPZ by setting
<a class="reference internal" href="#namedconf-statement-dnsrps-enable" title="namedconf-statement-dnsrps-enable"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnsrps-enable</span></code></a> to “no”, those options would be ignored.</p>
</dd></dl>
<p>The TTL of a record modified by RPZ policies is set from the TTL of the
relevant record in the policy zone. It is then limited to a maximum value.
The <code class="docutils literal notranslate"><span class="pre">max-policy-ttl</span></code> clause changes the maximum number of seconds from its
default of 5. For convenience, TTL-style time-unit suffixes may be used
to specify the value. It also accepts ISO 8601 duration formats.</p>
<p>For example, an administrator might use this option statement:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">response</span><span class="o">-</span><span class="n">policy</span> <span class="p">{</span> <span class="n">zone</span> <span class="s2">"badlist"</span><span class="p">;</span> <span class="p">};</span>
</pre></div>
</div>
<p>and this zone statement:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="s2">"badlist"</span> <span class="p">{</span><span class="nb">type</span> <span class="n">primary</span><span class="p">;</span> <span class="n">file</span> <span class="s2">"primary/badlist"</span><span class="p">;</span> <span class="n">allow</span><span class="o">-</span><span class="n">query</span> <span class="p">{</span><span class="n">none</span><span class="p">;};</span> <span class="p">};</span>
</pre></div>
</div>
<p>with this zone file:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>$TTL 1H
@ SOA LOCALHOST. named-mgr.example.com (1 1h 15m 30d 2h)
NS LOCALHOST.
; QNAME policy records. There are no periods (.) after the owner names.
nxdomain.domain.com CNAME . ; NXDOMAIN policy
*.nxdomain.domain.com CNAME . ; NXDOMAIN policy
nodata.domain.com CNAME *. ; NODATA policy
*.nodata.domain.com CNAME *. ; NODATA policy
bad.domain.com A 10.0.0.1 ; redirect to a walled garden
AAAA 2001:2::1
bzone.domain.com CNAME garden.example.com.
; do not rewrite (PASSTHRU) OK.DOMAIN.COM
ok.domain.com CNAME rpz-passthru.
; redirect x.bzone.domain.com to x.bzone.domain.com.garden.example.com
*.bzone.domain.com CNAME *.garden.example.com.
; IP policy records that rewrite all responses containing A records in 127/8
; except 127.0.0.1
8.0.0.0.127.rpz-ip CNAME .
32.1.0.0.127.rpz-ip CNAME rpz-passthru.
; NSDNAME and NSIP policy records
ns.domain.com.rpz-nsdname CNAME .
48.zz.2.2001.rpz-nsip CNAME .
; auto-reject and auto-accept some DNS clients
112.zz.2001.rpz-client-ip CNAME rpz-drop.
8.0.0.0.127.rpz-client-ip CNAME rpz-drop.
; force some DNS clients and responses in the example.com zone to TCP
16.0.0.1.10.rpz-client-ip CNAME rpz-tcp-only.
example.com CNAME rpz-tcp-only.
*.example.com CNAME rpz-tcp-only.
</pre></div>
</div>
<p>RPZ can affect server performance. Each configured response policy zone
requires the server to perform one to four additional database lookups
before a query can be answered. For example, a DNS server with four
policy zones, each with all four kinds of response triggers (QNAME, IP,
NSIP, and NSDNAME), requires a total of 17 times as many database lookups
as a similar DNS server with no response policy zones. A BIND 9 server
with adequate memory and one response policy zone with QNAME and IP
triggers might achieve a maximum queries-per-second (QPS) rate about 20%
lower. A server with four response policy zones with QNAME and IP
triggers might have a maximum QPS rate about 50% lower.</p>
<p>Responses rewritten by RPZ are counted in the <code class="docutils literal notranslate"><span class="pre">RPZRewrites</span></code>
statistics.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">log</span></code> clause can be used to optionally turn off rewrite logging
for a particular response policy zone. By default, all rewrites are
logged.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">add-soa</span></code> option controls whether the RPZ’s SOA record is added to
the section for traceback of changes from this zone.
This can be set at the individual policy zone level or at the
response-policy level. The default is <code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
<p>Updates to RPZ zones are processed asynchronously; if there is more than
one update pending they are bundled together. If an update to a RPZ zone
(for example, via IXFR) happens less than <code class="docutils literal notranslate"><span class="pre">min-update-interval</span></code>
seconds after the most recent update, the changes are not
carried out until this interval has elapsed. The default is <code class="docutils literal notranslate"><span class="pre">60</span></code>
seconds. For convenience, TTL-style time-unit suffixes may be used to
specify the value. It also accepts ISO 8601 duration formats.</p>
</section>
<section id="response-rate-limiting">
<span id="rrl"></span><h4><span class="section-number">8.2.14.18. </span>Response Rate Limiting<a class="headerlink" href="#response-rate-limiting" title="Link to this heading"></a></h4>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-rate-limit">
<span class="sig-name descname"><span class="pre">rate-limit</span></span><a class="headerlink" href="#namedconf-statement-rate-limit" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">rate</span><span class="o">-</span><span class="n">limit</span> <span class="p">{</span>
<span class="nb">all</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">second</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">errors</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">second</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">exempt</span><span class="o">-</span><span class="n">clients</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">ipv4</span><span class="o">-</span><span class="n">prefix</span><span class="o">-</span><span class="n">length</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">ipv6</span><span class="o">-</span><span class="n">prefix</span><span class="o">-</span><span class="n">length</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">log</span><span class="o">-</span><span class="n">only</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">table</span><span class="o">-</span><span class="n">size</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">min</span><span class="o">-</span><span class="n">table</span><span class="o">-</span><span class="n">size</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">nodata</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">second</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">nxdomains</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">second</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">qps</span><span class="o">-</span><span class="n">scale</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">referrals</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">second</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">responses</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">second</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">slip</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">window</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Controls excessive UDP responses, to prevent BIND 9 from being used to amplify reflection denial-of-service (DoS) attacks.</p>
</p>
<p>Excessive, almost-identical UDP <em>responses</em> can be controlled by
configuring a <a class="reference internal" href="#namedconf-statement-rate-limit" title="namedconf-statement-rate-limit"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rate-limit</span></code></a> clause in an <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> or <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>
statement. This mechanism keeps authoritative BIND 9 from being used to
amplify reflection denial-of-service (DoS) attacks. Short BADCOOKIE errors or
truncated (TC=1) responses can be sent to provide rate-limited responses to
legitimate clients within a range of forged, attacked IP addresses.
Legitimate clients react to dropped responses by retrying,
to BADCOOKIE errors by including a server cookie when retrying,
and to truncated responses by switching to TCP.</p>
<p>This mechanism is intended for authoritative DNS servers. It can be used
on recursive servers, but can slow applications such as SMTP servers
(mail receivers) and HTTP clients (web browsers) that repeatedly request
the same domains. When possible, closing “open” recursive servers is
better.</p>
<p>Response rate limiting uses a “credit” or “token bucket” scheme. Each
combination of identical response and client has a conceptual “account”
that earns a specified number of credits every second. A prospective
response debits its account by one. Responses are dropped or truncated
while the account is negative.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-window">
<span class="sig-name descname"><span class="pre">window</span></span><a class="headerlink" href="#namedconf-statement-window" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">window</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>query</p>
<p><p>Specifies the length of time during which responses are tracked.</p>
</p>
<p>Responses are tracked within a rolling
window of time which defaults to 15 seconds, but which can be configured with
the <a class="reference internal" href="#namedconf-statement-window" title="namedconf-statement-window"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">window</span></code></a> option to any value from 1 to 3600 seconds (1 hour). The
account cannot become more positive than the per-second limit or more
negative than <a class="reference internal" href="#namedconf-statement-window" title="namedconf-statement-window"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">window</span></code></a> times the per-second limit. When the specified
number of credits for a class of responses is set to 0, those responses
are not rate-limited.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-ipv4-prefix-length">
<span class="sig-name descname"><span class="pre">ipv4-prefix-length</span></span><a class="headerlink" href="#namedconf-statement-ipv4-prefix-length" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">ipv4-prefix-length</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the prefix lengths of IPv4 address blocks.</p>
</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-ipv6-prefix-length">
<span class="sig-name descname"><span class="pre">ipv6-prefix-length</span></span><a class="headerlink" href="#namedconf-statement-ipv6-prefix-length" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">ipv6-prefix-length</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>server</p>
<p><p>Specifies the prefix lengths of IPv6 address blocks.</p>
</p>
<p>The notions of “identical response” and “DNS client” for rate limiting
are not simplistic. All responses to an address block are counted as if
to a single client. The prefix lengths of address blocks are specified
with <a class="reference internal" href="#namedconf-statement-ipv4-prefix-length" title="namedconf-statement-ipv4-prefix-length"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ipv4-prefix-length</span></code></a> (default 24) and <a class="reference internal" href="#namedconf-statement-ipv6-prefix-length" title="namedconf-statement-ipv6-prefix-length"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ipv6-prefix-length</span></code></a>
(default 56).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-responses-per-second">
<span class="sig-name descname"><span class="pre">responses-per-second</span></span><a class="headerlink" href="#namedconf-statement-responses-per-second" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">responses-per-second</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>query</p>
<p><p>Limits the number of non-empty responses for a valid domain name and record type.</p>
</p>
<p>All non-empty responses for a valid domain name (qname) and record type
(qtype) are identical and have a limit specified with
<a class="reference internal" href="#namedconf-statement-responses-per-second" title="namedconf-statement-responses-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">responses-per-second</span></code></a> (default 0 or no limit). All valid wildcard
domain names are interpreted as the zone’s origin name concatenated to the
“*” name.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-nodata-per-second">
<span class="sig-name descname"><span class="pre">nodata-per-second</span></span><a class="headerlink" href="#namedconf-statement-nodata-per-second" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">nodata-per-second</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>query</p>
<p><p>Limits the number of empty (NODATA) responses for a valid domain name.</p>
</p>
<p>All empty (NODATA)
responses for a valid domain, regardless of query type, are identical.
Responses in the NODATA class are limited by <a class="reference internal" href="#namedconf-statement-nodata-per-second" title="namedconf-statement-nodata-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">nodata-per-second</span></code></a>
(default <a class="reference internal" href="#namedconf-statement-responses-per-second" title="namedconf-statement-responses-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">responses-per-second</span></code></a>).</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-nxdomains-per-second">
<span class="sig-name descname"><span class="pre">nxdomains-per-second</span></span><a class="headerlink" href="#namedconf-statement-nxdomains-per-second" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">nxdomains-per-second</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>query</p>
<p><p>Limits the number of undefined subdomains for a valid domain name.</p>
</p>
<p>Requests for any and all undefined
subdomains of a given valid domain result in NXDOMAIN errors, and are
identical regardless of query type. They are limited by
<a class="reference internal" href="#namedconf-statement-nxdomains-per-second" title="namedconf-statement-nxdomains-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">nxdomains-per-second</span></code></a> (default <a class="reference internal" href="#namedconf-statement-responses-per-second" title="namedconf-statement-responses-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">responses-per-second</span></code></a>). This
controls some attacks using random names, but can be relaxed or turned
off (set to 0) on servers that expect many legitimate NXDOMAIN
responses, such as from anti-spam rejection lists.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-referrals-per-second">
<span class="sig-name descname"><span class="pre">referrals-per-second</span></span><a class="headerlink" href="#namedconf-statement-referrals-per-second" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">referrals-per-second</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>query</p>
<p><p>Limits the number of referrals or delegations to a server for a given domain.</p>
</p>
<p>Referrals or delegations
to the server of a given domain are identical and are limited by
<a class="reference internal" href="#namedconf-statement-referrals-per-second" title="namedconf-statement-referrals-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">referrals-per-second</span></code></a> (default <a class="reference internal" href="#namedconf-statement-responses-per-second" title="namedconf-statement-responses-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">responses-per-second</span></code></a>).</p>
</dd></dl>
<p>Responses generated from local wildcards are counted and limited as if
they were for the parent domain name. This controls flooding using
random.wild.example.com.</p>
<p>All requests that result in DNS errors other than NXDOMAIN, such as
SERVFAIL and FORMERR, are identical regardless of requested name (qname)
or record type (qtype). This controls attacks using invalid requests or
distant, broken authoritative servers.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-errors-per-second">
<span class="sig-name descname"><span class="pre">errors-per-second</span></span><a class="headerlink" href="#namedconf-statement-errors-per-second" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">errors-per-second</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>server</p>
<p><p>Limits the number of errors for a valid domain name and record type.</p>
</p>
<p>By default the limit on errors is
the same as the <a class="reference internal" href="#namedconf-statement-responses-per-second" title="namedconf-statement-responses-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">responses-per-second</span></code></a> value, but it can be set
separately with <a class="reference internal" href="#namedconf-statement-errors-per-second" title="namedconf-statement-errors-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">errors-per-second</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-slip">
<span class="sig-name descname"><span class="pre">slip</span></span><a class="headerlink" href="#namedconf-statement-slip" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">slip</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>query</p>
<p><p>Sets the number of “slipped” responses to minimize the use of forged source addresses for an attack.</p>
</p>
<p>Many attacks using DNS involve UDP requests with forged source
addresses. Rate limiting prevents the use of BIND 9 to flood a network
with responses to requests with forged source addresses, but could let a
third party block responses to legitimate requests. There is a mechanism
that can answer some legitimate requests from a client whose address is
being forged in a flood. Setting <a class="reference internal" href="#namedconf-statement-slip" title="namedconf-statement-slip"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">slip</span></code></a> to 2 (its default) causes
every other UDP request without a valid server cookie to be answered with
a small response. The small size and reduced frequency, and resulting lack of
amplification, of “slipped” responses make them unattractive for
reflection DoS attacks. <a class="reference internal" href="#namedconf-statement-slip" title="namedconf-statement-slip"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">slip</span></code></a> must be between 0 and 10. A value of 0
does not “slip”; no small responses are sent due to rate limiting. Rather,
all responses are dropped. A value of 1 causes every response to slip;
values between 2 and 10 cause every nth response to slip.</p>
<p>If the request included a client cookie, then a “slipped” response is
a BADCOOKIE error with a server cookie, which allows a legitimate client
to include the server cookie to be exempted from the rate limiting
when it retries the request.
If the request did not include a cookie, then a “slipped” response is
a truncated (TC=1) response, which prompts a legitimate client to
switch to TCP and thus be exempted from the rate limiting. Some error
responses, including REFUSED and SERVFAIL, cannot be replaced with
truncated responses and are instead leaked at the <a class="reference internal" href="#namedconf-statement-slip" title="namedconf-statement-slip"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">slip</span></code></a> rate.</p>
<p>(Note: dropped responses from an authoritative server may reduce the
difficulty of a third party successfully forging a response to a
recursive resolver. The best security against forged responses is for
authoritative operators to sign their zones using DNSSEC and for
resolver operators to validate the responses. When this is not an
option, operators who are more concerned with response integrity than
with flood mitigation may consider setting <a class="reference internal" href="#namedconf-statement-slip" title="namedconf-statement-slip"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">slip</span></code></a> to 1, causing all
rate-limited responses to be truncated rather than dropped. This reduces
the effectiveness of rate-limiting against reflection attacks.)</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-qps-scale">
<span class="sig-name descname"><span class="pre">qps-scale</span></span><a class="headerlink" href="#namedconf-statement-qps-scale" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">qps-scale</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>query</p>
<p><p>Tightens defenses during DNS attacks by scaling back the ratio of the current query-per-second rate.</p>
</p>
<p>When the approximate query-per-second rate exceeds the <a class="reference internal" href="#namedconf-statement-qps-scale" title="namedconf-statement-qps-scale"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">qps-scale</span></code></a>
value, the <a class="reference internal" href="#namedconf-statement-responses-per-second" title="namedconf-statement-responses-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">responses-per-second</span></code></a>, <a class="reference internal" href="#namedconf-statement-errors-per-second" title="namedconf-statement-errors-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">errors-per-second</span></code></a>,
<a class="reference internal" href="#namedconf-statement-nxdomains-per-second" title="namedconf-statement-nxdomains-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">nxdomains-per-second</span></code></a>, and <a class="reference internal" href="#namedconf-statement-all-per-second" title="namedconf-statement-all-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">all-per-second</span></code></a> values are reduced by
the ratio of the current rate to the <a class="reference internal" href="#namedconf-statement-qps-scale" title="namedconf-statement-qps-scale"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">qps-scale</span></code></a> value. This feature
can tighten defenses during attacks. For example, with
<code class="docutils literal notranslate"><span class="pre">qps-scale</span> <span class="pre">250;</span> <span class="pre">responses-per-second</span> <span class="pre">20;</span></code> and a total query rate of
1000 queries/second for all queries from all DNS clients including via
TCP, then the effective responses/second limit changes to (250/1000)*20,
or 5. Responses to requests that included a valid server cookie,
and responses sent via TCP, are not limited but are counted to compute
the query-per-second rate.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-exempt-clients">
<span class="sig-name descname"><span class="pre">exempt-clients</span></span><a class="headerlink" href="#namedconf-statement-exempt-clients" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">exempt-clients</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>query</p>
<p><p>Exempts specific clients or client groups from rate limiting.</p>
</p>
<p>Communities of DNS clients can be given their own parameters or no
rate limiting by putting <a class="reference internal" href="#namedconf-statement-rate-limit" title="namedconf-statement-rate-limit"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rate-limit</span></code></a> statements in <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statements
instead of in the global <code class="docutils literal notranslate"><span class="pre">option</span></code> statement. A <a class="reference internal" href="#namedconf-statement-rate-limit" title="namedconf-statement-rate-limit"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rate-limit</span></code></a> statement
in a view replaces, rather than supplements, a <a class="reference internal" href="#namedconf-statement-rate-limit" title="namedconf-statement-rate-limit"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rate-limit</span></code></a>
statement among the main options.</p>
<p>DNS clients within a view can be
exempted from rate limits with the <a class="reference internal" href="#namedconf-statement-exempt-clients" title="namedconf-statement-exempt-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">exempt-clients</span></code></a> clause.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-all-per-second">
<span class="sig-name descname"><span class="pre">all-per-second</span></span><a class="headerlink" href="#namedconf-statement-all-per-second" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">all-per-second</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>query</p>
<p><p>Limits UDP responses of all kinds.</p>
</p>
<p>UDP responses of all kinds can be limited with the <a class="reference internal" href="#namedconf-statement-all-per-second" title="namedconf-statement-all-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">all-per-second</span></code></a>
phrase. This rate limiting is unlike the rate limiting provided by
<a class="reference internal" href="#namedconf-statement-responses-per-second" title="namedconf-statement-responses-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">responses-per-second</span></code></a>, <a class="reference internal" href="#namedconf-statement-errors-per-second" title="namedconf-statement-errors-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">errors-per-second</span></code></a>, and
<a class="reference internal" href="#namedconf-statement-nxdomains-per-second" title="namedconf-statement-nxdomains-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">nxdomains-per-second</span></code></a> on a DNS server, which are often invisible to
the victim of a DNS reflection attack. Unless the forged requests of the
attack are the same as the legitimate requests of the victim, the
victim’s requests are not affected. Responses affected by an
<a class="reference internal" href="#namedconf-statement-all-per-second" title="namedconf-statement-all-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">all-per-second</span></code></a> limit are always dropped; the <a class="reference internal" href="#namedconf-statement-slip" title="namedconf-statement-slip"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">slip</span></code></a> value has no
effect. An <a class="reference internal" href="#namedconf-statement-all-per-second" title="namedconf-statement-all-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">all-per-second</span></code></a> limit should be at least 4 times as large
as the other limits, because single DNS clients often send bursts of
legitimate requests. For example, the receipt of a single mail message
can prompt requests from an SMTP server for NS, PTR, A, and AAAA records
as the incoming SMTP/TCP/IP connection is considered. The SMTP server
can need additional NS, A, AAAA, MX, TXT, and SPF records as it
considers the SMTP <code class="docutils literal notranslate"><span class="pre">Mail</span> <span class="pre">From</span></code> command. Web browsers often repeatedly
resolve the same names that are duplicated in HTML <IMG> tags in a page.
<a class="reference internal" href="#namedconf-statement-all-per-second" title="namedconf-statement-all-per-second"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">all-per-second</span></code></a> is similar to the rate limiting offered by firewalls
but is often inferior. Attacks that justify ignoring the contents of DNS
responses are likely to be attacks on the DNS server itself. They
usually should be discarded before the DNS server spends resources making
TCP connections or parsing DNS requests, but that rate limiting must be
done before the DNS server sees the requests.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-table-size">
<span class="sig-name descname"><span class="pre">max-table-size</span></span><a class="headerlink" href="#namedconf-statement-max-table-size" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">max-table-size</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the maximum size of the table used to track requests and rate-limit responses.</p>
</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-min-table-size">
<span class="sig-name descname"><span class="pre">min-table-size</span></span><a class="headerlink" href="#namedconf-statement-min-table-size" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">min-table-size</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>query</p>
<p><p>Sets the minimum size of the table used to track requests and rate-limit responses.</p>
</p>
<p>The maximum size of the table used to track requests and rate-limit
responses is set with <a class="reference internal" href="#namedconf-statement-max-table-size" title="namedconf-statement-max-table-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-table-size</span></code></a>. Each entry in the table is
between 40 and 80 bytes. The table needs approximately as many entries
as the number of requests received per second. The default is 20,000. To
reduce the cold start of growing the table, <a class="reference internal" href="#namedconf-statement-min-table-size" title="namedconf-statement-min-table-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">min-table-size</span></code></a> (default 500)
can set the minimum table size. Enable <a class="reference internal" href="#namedconf-statement-rate-limit" title="namedconf-statement-rate-limit"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rate-limit</span></code></a> category
logging to monitor expansions of the table and inform choices for the
initial and maximum table size.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-log-only">
<span class="sig-name descname"><span class="pre">log-only</span></span><a class="headerlink" href="#namedconf-statement-log-only" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">log-only</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>options.rate-limit, view.rate-limit</p>
<p><strong>Tags: </strong>logging, query</p>
<p><p>Tests rate-limiting parameters without actually dropping any requests.</p>
</p>
<p>Use <code class="docutils literal notranslate"><span class="pre">log-only</span> <span class="pre">yes</span></code> to test rate-limiting parameters without actually
dropping any requests.</p>
</dd></dl>
<p>Responses dropped by rate limits are included in the <code class="docutils literal notranslate"><span class="pre">RateDropped</span></code> and
<code class="docutils literal notranslate"><span class="pre">QryDropped</span></code> statistics. Responses that are truncated by rate limits are
included in <code class="docutils literal notranslate"><span class="pre">RateSlipped</span></code> and <code class="docutils literal notranslate"><span class="pre">RespTruncated</span></code>.</p>
</dd></dl>
</section>
<section id="nxdomain-redirection">
<h4><span class="section-number">8.2.14.19. </span>NXDOMAIN Redirection<a class="headerlink" href="#nxdomain-redirection" title="Link to this heading"></a></h4>
<p><a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> supports NXDOMAIN redirection via two methods:</p>
<ul class="simple">
<li><p><a class="reference internal" href="#namedconf-statement-type redirect" title="namedconf-statement-type redirect"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">Redirect</span> <span class="pre">zone</span></code></a></p></li>
<li><p>Redirect namespace</p></li>
</ul>
<p>With either method, when <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> gets an NXDOMAIN response it examines a
separate namespace to see if the NXDOMAIN response should be replaced
with an alternative response.</p>
<p>With a redirect zone (<code class="docutils literal notranslate"><span class="pre">zone</span> <span class="pre">"."</span> <span class="pre">{</span> <span class="pre">type</span> <span class="pre">redirect;</span> <span class="pre">};</span></code>), the data used
to replace the NXDOMAIN is held in a single zone which is not part of
the normal namespace. All the redirect information is contained in the
zone; there are no delegations.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-nxdomain-redirect">
<span class="sig-name descname"><span class="pre">nxdomain-redirect</span></span><a class="headerlink" href="#namedconf-statement-nxdomain-redirect" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">nxdomain-redirect</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>options, view</p>
<p><strong>Tags: </strong>query</p>
<p><p>Appends the specified suffix to the original query name, when replacing an NXDOMAIN with a redirect namespace.</p>
</p>
<p>With a redirect namespace (<code class="docutils literal notranslate"><span class="pre">option</span> <span class="pre">{</span> <span class="pre">nxdomain-redirect</span> <span class="pre"><suffix></span> <span class="pre">};</span></code>),
the data used to replace the NXDOMAIN is part of the normal namespace
and is looked up by appending the specified suffix to the original
query name. This roughly doubles the cache required to process
NXDOMAIN responses, as both the original NXDOMAIN response and the
replacement data (or an NXDOMAIN indicating that there is no
replacement) must be stored.</p>
</dd></dl>
<p>If both a redirect zone and a redirect namespace are configured, the
redirect zone is tried first.</p>
</section>
</section>
<section id="server-block-grammar">
<h3><span class="section-number">8.2.15. </span><code class="docutils literal notranslate"><span class="pre">server</span></code> Block Grammar<a class="headerlink" href="#server-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-server">
<span class="sig-name descname"><span class="pre">server</span></span><a class="headerlink" href="#namedconf-statement-server" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">server</span> <span class="o"><</span><span class="n">netprefix</span><span class="o">></span> <span class="p">{</span>
<span class="n">bogus</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">edns</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">edns</span><span class="o">-</span><span class="n">udp</span><span class="o">-</span><span class="n">size</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">edns</span><span class="o">-</span><span class="n">version</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">keys</span> <span class="o"><</span><span class="n">server_key</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">udp</span><span class="o">-</span><span class="n">size</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">notify</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">notify</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">padding</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">provide</span><span class="o">-</span><span class="n">ixfr</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">query</span><span class="o">-</span><span class="n">source</span> <span class="p">[</span> <span class="n">address</span> <span class="p">]</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">query</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">[</span> <span class="n">address</span> <span class="p">]</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">request</span><span class="o">-</span><span class="n">expire</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">request</span><span class="o">-</span><span class="n">ixfr</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">request</span><span class="o">-</span><span class="n">nsid</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">send</span><span class="o">-</span><span class="n">cookie</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">tcp</span><span class="o">-</span><span class="n">keepalive</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">tcp</span><span class="o">-</span><span class="n">only</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">transfer</span><span class="o">-</span><span class="nb">format</span> <span class="p">(</span> <span class="n">many</span><span class="o">-</span><span class="n">answers</span> <span class="o">|</span> <span class="n">one</span><span class="o">-</span><span class="n">answer</span> <span class="p">);</span>
<span class="n">transfer</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">transfer</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">transfers</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="p">};</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>topmost, view</p>
<p><strong>Tags: </strong>server</p>
<p><p>Defines characteristics to be associated with a remote name server.</p>
</p>
</dd></dl>
</section>
<section id="server-block-definition-and-usage">
<h3><span class="section-number">8.2.16. </span><code class="docutils literal notranslate"><span class="pre">server</span></code> Block Definition and Usage<a class="headerlink" href="#server-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">server</span></code></a> statement defines characteristics to be associated with a
remote name server. If a prefix length is specified, then a range of
servers is covered. Only the most specific server clause applies,
regardless of the order in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>.</p>
<p>The <a class="reference internal" href="chapter4.html#rndcconf-statement-server" title="rndcconf-statement-server"><code class="xref rndcconf rndcconf-ref docutils literal notranslate"><span class="pre">server</span></code></a> statement can occur at the top level of the configuration
file or inside a <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statement. If a <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statement contains
one or more <a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">server</span></code></a> statements, only those apply to the view and any
top-level ones are ignored. If a view contains no <a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">server</span></code></a> statements,
any top-level <a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">server</span></code></a> statements are used as defaults.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-bogus">
<span class="sig-name descname"><span class="pre">bogus</span></span><a class="headerlink" href="#namedconf-statement-bogus" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">bogus</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>server, view.server</p>
<p><strong>Tags: </strong>server</p>
<p><p>Allows a remote server to be ignored.</p>
</p>
<p>If a remote server is giving out bad data, marking it
as bogus prevents further queries to it. The default value of
<a class="reference internal" href="#namedconf-statement-bogus" title="namedconf-statement-bogus"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">bogus</span></code></a> is <code class="docutils literal notranslate"><span class="pre">no</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-edns">
<span class="sig-name descname"><span class="pre">edns</span></span><a class="headerlink" href="#namedconf-statement-edns" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">edns</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>server, view.server</p>
<p><strong>Tags: </strong>server</p>
<p><p>Controls the use of the EDNS0 (<span class="target" id="index-27"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc2671.html"><strong>RFC 2671</strong></a>) feature.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-edns" title="namedconf-statement-edns"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">edns</span></code></a> clause determines whether the local server attempts to
use EDNS when communicating with the remote server. The default is
<code class="docutils literal notranslate"><span class="pre">yes</span></code>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-edns-version">
<span class="sig-name descname"><span class="pre">edns-version</span></span><a class="headerlink" href="#namedconf-statement-edns-version" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">edns-version</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>server, view.server</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the maximum EDNS VERSION that is sent to the server(s) by the resolver.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-edns-version" title="namedconf-statement-edns-version"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">edns-version</span></code></a> option sets the maximum EDNS VERSION that is
sent to the server(s) by the resolver. The actual EDNS version sent is
still subject to normal EDNS version-negotiation rules (see <span class="target" id="index-28"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc6891.html"><strong>RFC 6891</strong></a>),
the maximum EDNS version supported by the server, and any other
heuristics that indicate that a lower version should be sent. This
option is intended to be used when a remote server reacts badly to a
given EDNS version or higher; it should be set to the highest version
the remote server is known to support. Valid values are 0 to 255; higher
values are silently adjusted. This option is not needed until
higher EDNS versions than 0 are in use.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-padding">
<span class="sig-name descname"><span class="pre">padding</span></span><a class="headerlink" href="#namedconf-statement-padding" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">padding</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>server, view.server</p>
<p><strong>Tags: </strong>server</p>
<p><p>Adds EDNS Padding options to outgoing messages to increase the packet size.</p>
</p>
<p>The option adds EDNS Padding options to outgoing messages,
increasing the packet size to a multiple of the specified block size.
Valid block sizes range from 0 (the default, which disables the use of
EDNS Padding) to 512 bytes. Larger values are reduced to 512, with a
logged warning. Note: this option is not currently compatible with no
TSIG or SIG(0), as the EDNS OPT record containing the padding would have
to be added to the packet after it had already been signed.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tcp-only">
<span class="sig-name descname"><span class="pre">tcp-only</span></span><a class="headerlink" href="#namedconf-statement-tcp-only" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tcp-only</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>server, view.server</p>
<p><strong>Tags: </strong>server</p>
<p><p>Sets the transport protocol to TCP.</p>
</p>
<p>The option sets the transport protocol to TCP. The default
is to use the UDP transport and to fallback on TCP only when a truncated
response is received.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tcp-keepalive">
<span class="sig-name descname"><span class="pre">tcp-keepalive</span></span><a class="headerlink" href="#namedconf-statement-tcp-keepalive" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">tcp-keepalive</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>server, view.server</p>
<p><strong>Tags: </strong>server</p>
<p><p>Adds EDNS TCP keepalive to messages sent over TCP.</p>
</p>
<p>The option adds EDNS TCP keepalive to messages sent
over TCP. Note that currently idle timeouts in responses are ignored.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-transfers">
<span class="sig-name descname"><span class="pre">transfers</span></span><a class="headerlink" href="#namedconf-statement-transfers" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">transfers</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>server, view.server</p>
<p><strong>Tags: </strong>server</p>
<p><p>Limits the number of concurrent inbound zone transfers from a server.</p>
</p>
<p><a class="reference internal" href="#namedconf-statement-transfers" title="namedconf-statement-transfers"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfers</span></code></a> is used to limit the number of concurrent inbound zone
transfers from the specified server. If no <a class="reference internal" href="#namedconf-statement-transfers" title="namedconf-statement-transfers"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfers</span></code></a> clause is
specified, the limit is set according to the <a class="reference internal" href="#namedconf-statement-transfers-per-ns" title="namedconf-statement-transfers-per-ns"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfers-per-ns</span></code></a>
option.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-keys">
<span class="sig-name descname"><span class="pre">keys</span></span><a class="headerlink" href="#namedconf-statement-keys" title="Link to this definition"></a></dt>
<dd><p><strong>Blocks: </strong>dnssec-policy, server, view.server</p>
<p><strong>Tags: </strong>server, security</p>
<p><p>Specifies one or more <a class="reference internal" href="#term-server_key"><code class="xref any std std-term docutils literal notranslate"><span class="pre">server_key</span></code></a> s to be used with a remote server.</p>
</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Not to be confused with <a class="reference internal" href="#namedconf-statement-keys" title="namedconf-statement-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">keys</span></code></a> in <a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> specification.
Although statements with the same name exist in both contexts, they refer
to fundamentally incompatible concepts.</p>
</div>
<p>In the context of a <a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">server</span></code></a> block, the option identifies a
<a class="reference internal" href="#term-server_key"><span class="xref std std-term">server_key</span></a> defined by the <a class="reference internal" href="#namedconf-statement-key" title="namedconf-statement-key"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">key</span></code></a> statement, to be used for
transaction security (see <a class="reference internal" href="chapter7.html#tsig"><span class="std std-ref">TSIG</span></a>)
when talking to the remote server. When a request is sent to the remote
server, a request signature is generated using the key specified
here and appended to the message. A request originating from the remote
server is not required to be signed by this key.</p>
<p>Only a single key per server is currently supported.</p>
</dd></dl>
<p>It is possible to override the following values defined in <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>
and <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> blocks:</p>
<blockquote>
<div><ul class="simple">
<li><p><a class="reference internal" href="#namedconf-statement-edns-udp-size" title="namedconf-statement-edns-udp-size"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">edns-udp-size</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-max-udp-size" title="namedconf-statement-max-udp-size"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-udp-size</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-notify-source-v6" title="namedconf-statement-notify-source-v6"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-source-v6</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-notify-source" title="namedconf-statement-notify-source"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-source</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-provide-ixfr" title="namedconf-statement-provide-ixfr"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">provide-ixfr</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-query-source-v6" title="namedconf-statement-query-source-v6"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">query-source-v6</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-query-source" title="namedconf-statement-query-source"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">query-source</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-request-expire" title="namedconf-statement-request-expire"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">request-expire</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-request-ixfr" title="namedconf-statement-request-ixfr"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">request-ixfr</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-request-nsid" title="namedconf-statement-request-nsid"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">request-nsid</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-send-cookie" title="namedconf-statement-send-cookie"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">send-cookie</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-transfer-format" title="namedconf-statement-transfer-format"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-format</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-transfer-source-v6" title="namedconf-statement-transfer-source-v6"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source-v6</span></code></a></p></li>
<li><p><a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a></p></li>
</ul>
</div></blockquote>
</section>
<section id="statistics-channels-block-grammar">
<h3><span class="section-number">8.2.17. </span><a class="reference internal" href="#namedconf-statement-statistics-channels" title="namedconf-statement-statistics-channels"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">statistics-channels</span></code></a> Block Grammar<a class="headerlink" href="#statistics-channels-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-statistics-channels">
<span class="sig-name descname"><span class="pre">statistics-channels</span></span><a class="headerlink" href="#namedconf-statement-statistics-channels" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">statistics</span><span class="o">-</span><span class="n">channels</span> <span class="p">{</span>
<span class="n">inet</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">)</span> <span class="p">[</span> <span class="n">port</span> <span class="p">(</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">)</span> <span class="p">]</span> <span class="p">[</span> <span class="n">allow</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">}</span> <span class="p">];</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
<span class="p">};</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>topmost</p>
<p><strong>Tags: </strong>logging</p>
<p><p>Specifies the communication channels to be used by system administrators to access statistics information on the name server.</p>
</p>
</dd></dl>
</section>
<section id="statistics-channels-block-definition-and-usage">
<h3><span class="section-number">8.2.18. </span><a class="reference internal" href="#namedconf-statement-statistics-channels" title="namedconf-statement-statistics-channels"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">statistics-channels</span></code></a> Block Definition and Usage<a class="headerlink" href="#statistics-channels-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-statistics-channels" title="namedconf-statement-statistics-channels"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">statistics-channels</span></code></a> statement declares communication channels to
be used by system administrators to get access to statistics information
on the name server.</p>
<p>This statement is intended to be flexible to support multiple communication
protocols in the future, but currently only HTTP access is supported. It
requires that BIND 9 be compiled with libxml2 and/or json-c (also known
as libjson0); the <a class="reference internal" href="#namedconf-statement-statistics-channels" title="namedconf-statement-statistics-channels"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">statistics-channels</span></code></a> statement is still accepted
even if it is built without the library, but any HTTP access fails
with an error.</p>
<p>An <a class="reference internal" href="#namedconf-statement-inet" title="namedconf-statement-inet"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">inet</span></code></a> control channel is a TCP socket listening at the specified
<a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a> on the specified <a class="reference internal" href="#term-ip_address"><span class="xref std std-term">ip_address</span></a>, which can be an IPv4 or IPv6
address. An <a class="reference internal" href="#term-ip_address"><span class="xref std std-term">ip_address</span></a> of <code class="docutils literal notranslate"><span class="pre">*</span></code> (asterisk) is interpreted as the IPv4
wildcard address; connections are accepted on any of the system’s
IPv4 addresses. To listen on the IPv6 wildcard address, use an
<a class="reference internal" href="#term-ip_address"><span class="xref std std-term">ip_address</span></a> of <code class="docutils literal notranslate"><span class="pre">::</span></code>.</p>
<p>If no port is specified, port 80 is used for HTTP channels. The asterisk
(<code class="docutils literal notranslate"><span class="pre">*</span></code>) cannot be used for <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a>.</p>
<p>Attempts to open a statistics channel are restricted by the
optional <code class="docutils literal notranslate"><span class="pre">allow</span></code> clause. Connections to the statistics channel are
permitted based on the <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a>. If no <code class="docutils literal notranslate"><span class="pre">allow</span></code> clause is
present, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> accepts connection attempts from any address. Since
the statistics may contain sensitive internal information, the source of
connection requests must be restricted appropriately so that only
trusted parties can access the statistics channel.</p>
<p>Gathering data exposed by the statistics channel locks various subsystems in
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>, which could slow down query processing if statistics data is
requested too often.</p>
<p>An issue in the statistics channel would be considered a security issue
only if it could be exploited by unprivileged users circumventing the access
control list. In other words, any issue in the statistics channel that could be
used to access information unavailable otherwise, or to crash <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>, is
not considered a security issue if it can be avoided through the
use of a secure configuration.</p>
<p>If no <a class="reference internal" href="#namedconf-statement-statistics-channels" title="namedconf-statement-statistics-channels"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">statistics-channels</span></code></a> statement is present, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> does not
open any communication channels.</p>
<p>The statistics are available in various formats and views, depending on
the URI used to access them. For example, if the statistics channel is
configured to listen on 127.0.0.1 port 8888, then the statistics are
accessible in XML format at <a class="reference external" href="http://127.0.0.1:8888/">http://127.0.0.1:8888/</a> or
<a class="reference external" href="http://127.0.0.1:8888/xml">http://127.0.0.1:8888/xml</a>. A CSS file is included, which can format the
XML statistics into tables when viewed with a stylesheet-capable
browser, and into charts and graphs using the Google Charts API when
using a JavaScript-capable browser.</p>
<p>Broken-out subsets of the statistics can be viewed at
<a class="reference external" href="http://127.0.0.1:8888/xml/v3/status">http://127.0.0.1:8888/xml/v3/status</a> (server uptime and last
reconfiguration time), <a class="reference external" href="http://127.0.0.1:8888/xml/v3/server">http://127.0.0.1:8888/xml/v3/server</a> (server and
resolver statistics), <a class="reference external" href="http://127.0.0.1:8888/xml/v3/zones">http://127.0.0.1:8888/xml/v3/zones</a> (zone
statistics), <a class="reference external" href="http://127.0.0.1:8888/xml/v3/net">http://127.0.0.1:8888/xml/v3/net</a> (network status and socket
statistics), <a class="reference external" href="http://127.0.0.1:8888/xml/v3/mem">http://127.0.0.1:8888/xml/v3/mem</a> (memory manager
statistics), <a class="reference external" href="http://127.0.0.1:8888/xml/v3/tasks">http://127.0.0.1:8888/xml/v3/tasks</a> (task manager
statistics), and <a class="reference external" href="http://127.0.0.1:8888/xml/v3/traffic">http://127.0.0.1:8888/xml/v3/traffic</a> (traffic sizes).</p>
<p>The full set of statistics can also be read in JSON format at
<a class="reference external" href="http://127.0.0.1:8888/json">http://127.0.0.1:8888/json</a>, with the broken-out subsets at
<a class="reference external" href="http://127.0.0.1:8888/json/v1/status">http://127.0.0.1:8888/json/v1/status</a> (server uptime and last
reconfiguration time), <a class="reference external" href="http://127.0.0.1:8888/json/v1/server">http://127.0.0.1:8888/json/v1/server</a> (server and
resolver statistics), <a class="reference external" href="http://127.0.0.1:8888/json/v1/zones">http://127.0.0.1:8888/json/v1/zones</a> (zone
statistics), <a class="reference external" href="http://127.0.0.1:8888/json/v1/net">http://127.0.0.1:8888/json/v1/net</a> (network status and
socket statistics), <a class="reference external" href="http://127.0.0.1:8888/json/v1/mem">http://127.0.0.1:8888/json/v1/mem</a> (memory manager
statistics), <a class="reference external" href="http://127.0.0.1:8888/json/v1/tasks">http://127.0.0.1:8888/json/v1/tasks</a> (task manager
statistics), and <a class="reference external" href="http://127.0.0.1:8888/json/v1/traffic">http://127.0.0.1:8888/json/v1/traffic</a> (traffic sizes).</p>
</section>
<section id="tls-block-grammar">
<h3><span class="section-number">8.2.19. </span><a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> Block Grammar<a class="headerlink" href="#tls-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-tls">
<span class="sig-name descname"><span class="pre">tls</span></span><a class="headerlink" href="#namedconf-statement-tls" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">tls</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">{</span>
<span class="n">ca</span><span class="o">-</span><span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">cert</span><span class="o">-</span><span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">ciphers</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="n">dhparam</span><span class="o">-</span><span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">key</span><span class="o">-</span><span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">prefer</span><span class="o">-</span><span class="n">server</span><span class="o">-</span><span class="n">ciphers</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">protocols</span> <span class="p">{</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">remote</span><span class="o">-</span><span class="n">hostname</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">session</span><span class="o">-</span><span class="n">tickets</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="p">};</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>topmost</p>
<p><strong>Tags: </strong>security</p>
<p><p>Configures a TLS connection.</p>
</p>
</dd></dl>
</section>
<section id="tls-block-definition-and-usage">
<h3><span class="section-number">8.2.20. </span><a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> Block Definition and Usage<a class="headerlink" href="#tls-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> statement is used to configure a TLS connection; this
configuration can then be referenced by a <a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> or <a class="reference internal" href="#namedconf-statement-listen-on-v6" title="namedconf-statement-listen-on-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on-v6</span></code></a>
statement to cause <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to listen for incoming requests via TLS,
or in the <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> statement for a zone of <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span> <span class="pre">secondary</span></code></a> to
cause zone transfer requests to be sent via TLS.</p>
<p><a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> can only be set at the top level of <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>.</p>
<p>The following options can be specified in a <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> statement:</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-key-file">
<span class="sig-name descname"><span class="pre">key-file</span></span><a class="headerlink" href="#namedconf-statement-key-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">key-file</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>tls</p>
<p><strong>Tags: </strong>server, security</p>
<p><p>Specifies the path to a file containing the private TLS key for a connection.</p>
</p>
<blockquote>
<div><p>Path to a file containing the private TLS key to be used for
the connection.</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-cert-file">
<span class="sig-name descname"><span class="pre">cert-file</span></span><a class="headerlink" href="#namedconf-statement-cert-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">cert-file</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>tls</p>
<p><strong>Tags: </strong>server, security</p>
<p><p>Specifies the path to a file containing the TLS certificate for a connection.</p>
</p>
<blockquote>
<div><p>Path to a file containing the TLS certificate to be used for
the connection.</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-ca-file">
<span class="sig-name descname"><span class="pre">ca-file</span></span><a class="headerlink" href="#namedconf-statement-ca-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">ca-file</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>tls</p>
<p><strong>Tags: </strong>server, security</p>
<p><p>Specifies the path to a file containing TLS certificates for trusted CA authorities, used to verify remote peer certificates.</p>
</p>
<blockquote>
<div><p>Path to a file containing trusted CA authorities’ TLS
certificates used to verify remote peer certificates. Specifying
this option enables remote peer certificates’ verification. For
incoming connections, specifying this option makes BIND require
a valid TLS certificate from a client. In the case of outgoing
connections, if <a class="reference internal" href="#namedconf-statement-remote-hostname" title="namedconf-statement-remote-hostname"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">remote-hostname</span></code></a> is not specified, then the remote
server IP address is used instead.</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dhparam-file">
<span class="sig-name descname"><span class="pre">dhparam-file</span></span><a class="headerlink" href="#namedconf-statement-dhparam-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dhparam-file</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>tls</p>
<p><strong>Tags: </strong>server, security</p>
<p><p>Specifies the path to a file containing Diffie-Hellman parameters, for enabling cipher suites.</p>
</p>
<blockquote>
<div><p>Path to a file containing Diffie-Hellman parameters,
which is needed to enable the cipher suites depending on the
Diffie-Hellman ephemeral key exchange (DHE). Having these parameters
specified is essential for enabling perfect forward secrecy capable
ciphers in TLSv1.2.</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-remote-hostname">
<span class="sig-name descname"><span class="pre">remote-hostname</span></span><a class="headerlink" href="#namedconf-statement-remote-hostname" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">remote-hostname</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>tls</p>
<p><strong>Tags: </strong>security</p>
<p><p>Specifies the expected hostname in the TLS certificate of the remote server.</p>
</p>
<blockquote>
<div><p>The expected hostname in the TLS certificate of the
remote server. This option enables a remote server certificate
verification. If <a class="reference internal" href="#namedconf-statement-ca-file" title="namedconf-statement-ca-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ca-file</span></code></a> is not specified, then the
platform-specific certificates store is used for
verification. This option is used when connecting to a remote peer
only and, thus, is ignored when <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> statements are referenced
by <a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> or <a class="reference internal" href="#namedconf-statement-listen-on-v6" title="namedconf-statement-listen-on-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on-v6</span></code></a> statements.</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-protocols">
<span class="sig-name descname"><span class="pre">protocols</span></span><a class="headerlink" href="#namedconf-statement-protocols" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">protocols</span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>tls</p>
<p><strong>Tags: </strong>security</p>
<p><p>Specifies the allowed versions of the TLS protocol.</p>
</p>
<blockquote>
<div><p>Allowed versions of the TLS protocol. TLS version 1.2 and higher are
supported, depending on the cryptographic library in use. Multiple
versions might be specified (e.g.
<code class="docutils literal notranslate"><span class="pre">protocols</span> <span class="pre">{</span> <span class="pre">TLSv1.2;</span> <span class="pre">TLSv1.3;</span> <span class="pre">};</span></code>).</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-ciphers">
<span class="sig-name descname"><span class="pre">ciphers</span></span><a class="headerlink" href="#namedconf-statement-ciphers" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">ciphers</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>tls</p>
<p><strong>Tags: </strong>security</p>
<p><p>Specifies a list of allowed ciphers.</p>
</p>
<blockquote>
<div><p>Cipher list which defines allowed ciphers, such as
<code class="docutils literal notranslate"><span class="pre">HIGH:!aNULL:!MD5:!SHA1:!SHA256:!SHA384</span></code>. The string must be
formed according to the rules specified in the OpenSSL documentation
(see <a class="reference external" href="https://docs.openssl.org/1.1.1/man1/ciphers/">https://docs.openssl.org/1.1.1/man1/ciphers/</a>
for details).</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-prefer-server-ciphers">
<span class="sig-name descname"><span class="pre">prefer-server-ciphers</span></span><a class="headerlink" href="#namedconf-statement-prefer-server-ciphers" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">prefer-server-ciphers</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>tls</p>
<p><strong>Tags: </strong>server, security</p>
<p><p>Specifies that server ciphers should be preferred over client ones.</p>
</p>
<blockquote>
<div><p>Specifies that server ciphers should be preferred over client ones.</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-session-tickets">
<span class="sig-name descname"><span class="pre">session-tickets</span></span><a class="headerlink" href="#namedconf-statement-session-tickets" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">session-tickets</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>tls</p>
<p><strong>Tags: </strong>security</p>
<p><p>Enables or disables session resumption through TLS session tickets.</p>
</p>
<blockquote>
<div><p>Enables or disables session resumption through TLS session tickets,
as defined in RFC5077. Disabling the stateless session tickets
might be required in the cases when forward secrecy is needed,
or the TLS certificate and key pair is planned to be used across
multiple BIND instances.</p>
</div></blockquote>
</dd></dl>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>TLS configuration is subject to change and incompatible changes might
be introduced in the future. Users of TLS are encouraged to carefully
read release notes when upgrading.</p>
</div>
<p>The options described above are used to control different aspects of
TLS functioning. Thus, most of them have no well-defined default
values, as these depend on the cryptographic library version in use
and system-wide cryptographic policy. On the other hand, by specifying
the needed options one could have a uniform configuration deployable
across a range of platforms.</p>
<p>An example of privacy-oriented, perfect forward secrecy enabled
configuration can be found below. It can be used as a
starting point.</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">tls</span> <span class="n">local</span><span class="o">-</span><span class="n">tls</span> <span class="p">{</span>
<span class="n">key</span><span class="o">-</span><span class="n">file</span> <span class="s2">"/path/to/key.pem"</span><span class="p">;</span>
<span class="n">cert</span><span class="o">-</span><span class="n">file</span> <span class="s2">"/path/to/fullchain_cert.pem"</span><span class="p">;</span>
<span class="n">dhparam</span><span class="o">-</span><span class="n">file</span> <span class="s2">"/path/to/dhparam.pem"</span><span class="p">;</span>
<span class="n">ciphers</span> <span class="s2">"HIGH:!kRSA:!aNULL:!eNULL:!RC4:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!SHA1:!SHA256:!SHA384"</span><span class="p">;</span>
<span class="n">prefer</span><span class="o">-</span><span class="n">server</span><span class="o">-</span><span class="n">ciphers</span> <span class="n">yes</span><span class="p">;</span>
<span class="n">session</span><span class="o">-</span><span class="n">tickets</span> <span class="n">no</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
<p>A Diffie-Hellman parameters file can be generated using e.g. OpenSSL,
like follows:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">openssl</span> <span class="n">dhparam</span> <span class="o">-</span><span class="n">out</span> <span class="o">/</span><span class="n">path</span><span class="o">/</span><span class="n">to</span><span class="o">/</span><span class="n">dhparam</span><span class="o">.</span><span class="n">pem</span> <span class="o"><</span><span class="mi">3072</span><span class="n">_or_4096</span><span class="o">></span>
</pre></div>
</div>
<p>Ensure that it gets generated on a machine with enough entropy from
external sources (e.g. the computer you work on should be fine,
the remote virtual machine or server might be not). These files do
not contain any sensitive data and can be shared if required.</p>
<p>There are two built-in TLS connection configurations: <code class="docutils literal notranslate"><span class="pre">ephemeral</span></code>,
uses a temporary key and certificate created for the current <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
session only, and <code class="docutils literal notranslate"><span class="pre">none</span></code>, which can be used when setting up an HTTP
listener with no encryption.</p>
<p>The main motivation behind having the <code class="docutils literal notranslate"><span class="pre">ephemeral</span></code> configuration is
to aid in testing, as trusted certificate authorities do not issue the
certificates associated with this configuration. Thus, these
certificates will never be trusted by any clients that verify TLS
certificates; they provide encryption of the traffic but no
authentication of the transmission channel. That might be enough in
the case of deployment in a controlled environment.</p>
<p>It should be noted that on reconfiguration, the <code class="docutils literal notranslate"><span class="pre">ephemeral</span></code> TLS key
and the certificate are recreated, and all TLS certificates and keys,
as well as associated data, are reloaded from the disk. In that case,
listening sockets associated with TLS remain intact.</p>
<p>Please keep in mind that performing a reconfiguration can cause a short
interruption in BIND’s ability to process inbound client packets. The
length of interruption is environment- and configuration-specific. A
good example of when reconfiguration is necessary is when TLS keys and
certificates are updated on the disk.</p>
<p>BIND supports the following TLS authentication mechanisms described in
the RFC 9103, Section 9.3: Opportunistic TLS, Strict TLS, and Mutual
TLS.</p>
<p id="opportunistic-tls">Opportunistic TLS provides encryption for data but does not provide
any authentication for the channel. This mode is the default one and
it is used whenever <a class="reference internal" href="#namedconf-statement-remote-hostname" title="namedconf-statement-remote-hostname"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">remote-hostname</span></code></a> and <a class="reference internal" href="#namedconf-statement-ca-file" title="namedconf-statement-ca-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ca-file</span></code></a> options are not set
in <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> statements in use. RFC 9103 allows optional fallback to
clear-text DNS in the cases when TLS is not available. Still, BIND
intentionally does not support that in order to protect from
unexpected data leaks due to misconfiguration. Both BIND and its
complementary tools either successfully establish a secure channel via
TLS when instructed to do so or fail to establish a connection
otherwise.</p>
<p id="strict-tls">Strict TLS provides server authentication via a pre-configured
hostname for outgoing connections. This mechanism offers both channel
confidentiality and channel authentication (of the server). In order
to achieve Strict TLS, one needs to use <a class="reference internal" href="#namedconf-statement-remote-hostname" title="namedconf-statement-remote-hostname"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">remote-hostname</span></code></a> and, optionally,
<a class="reference internal" href="#namedconf-statement-ca-file" title="namedconf-statement-ca-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ca-file</span></code></a> options in the <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> statements used for establishing
outgoing connections (e.g. the ones used to download zone from
primaries via TLS). Providing any of the mentioned options will enable
server authentication. If <a class="reference internal" href="#namedconf-statement-remote-hostname" title="namedconf-statement-remote-hostname"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">remote-hostname</span></code></a> is provided but <a class="reference internal" href="#namedconf-statement-ca-file" title="namedconf-statement-ca-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ca-file</span></code></a> is
missing, then the platform-specific certificate authority certificates
are used for authentication. The set roughly corresponds to the one
used by WEB-browsers to authenticate HTTPS hosts. On the other hand,
if <a class="reference internal" href="#namedconf-statement-ca-file" title="namedconf-statement-ca-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ca-file</span></code></a> is provided but <a class="reference internal" href="#namedconf-statement-remote-hostname" title="namedconf-statement-remote-hostname"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">remote-hostname</span></code></a> is missing, then the
remote side’s IP address is used instead.</p>
<p id="mutual-tls">Mutual TLS is an extension to Strict TLS that provides channel
confidentiality and mutual channel authentication. It builds up upon
the clients offering client certificates when establishing connections
and them doing the server authentication as in the case of Strict
TLS. The server verifies the provided client certificates and accepts
the TLS connection in case of successful verification or rejects it
otherwise. In order to instruct the server to require and verify
client TLS certificates, one needs to specify the <a class="reference internal" href="#namedconf-statement-ca-file" title="namedconf-statement-ca-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ca-file</span></code></a> option
in <a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">tls</span></code></a> configurations used to configure server listeners. The
provided file must contain certificate authority certificates used to
issue client certificates. In most cases, one should build one’s own
TLS certificate authority specifically to issue client certificates
and include the certificate authority certificate into the file.</p>
<p>For authenticating zone transfers over TLS, Mutual TLS might be
considered a standalone solution, while Strict TLS paired with
TSIG-based authentication and, optionally, IP-based access lists,
might be considered acceptable for most practical purposes. Mutual TLS
has the advantage of not requiring TSIG and thus, not having security
issues related to shared cryptographic secrets.</p>
</section>
<section id="http-block-grammar">
<h3><span class="section-number">8.2.21. </span><a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http</span></code></a> Block Grammar<a class="headerlink" href="#http-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-http">
<span class="sig-name descname"><span class="pre">http</span></span><a class="headerlink" href="#namedconf-statement-http" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">http</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">{</span>
<span class="n">endpoints</span> <span class="p">{</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">listener</span><span class="o">-</span><span class="n">clients</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">streams</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">connection</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="p">};</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>topmost</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Configures HTTP endpoints on which to listen for DNS-over-HTTPS (DoH) queries.</p>
</p>
</dd></dl>
</section>
<section id="http-block-definition-and-usage">
<h3><span class="section-number">8.2.22. </span><a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http</span></code></a> Block Definition and Usage<a class="headerlink" href="#http-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http</span></code></a> statement is used to configure HTTP endpoints on which
to listen for DNS-over-HTTPS (DoH) queries. This configuration can
then be referenced by a <a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on</span></code></a> or <a class="reference internal" href="#namedconf-statement-listen-on-v6" title="namedconf-statement-listen-on-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">listen-on-v6</span></code></a> statement to
cause <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to listen for incoming requests over HTTPS.</p>
<p><a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http</span></code></a> can only be set at the top level of <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>.</p>
<p>The following options can be specified in an <a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http</span></code></a> statement:</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-endpoints">
<span class="sig-name descname"><span class="pre">endpoints</span></span><a class="headerlink" href="#namedconf-statement-endpoints" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">endpoints</span> <span class="pre">{</span> <span class="pre"><quoted_string>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>http</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Specifies a list of HTTP query paths on which to listen.</p>
</p>
<blockquote>
<div><p>A list of HTTP query paths on which to listen. This is the portion
of an <span class="target" id="index-29"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc3986.html"><strong>RFC 3986</strong></a>-compliant URI following the hostname; it must be
an absolute path, beginning with “/”. The default value
is <code class="docutils literal notranslate"><span class="pre">"/dns-query"</span></code>, if omitted.</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-listener-clients">
<span class="sig-name descname"><span class="pre">listener-clients</span></span><a class="headerlink" href="#namedconf-statement-listener-clients" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">listener-clients</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>http</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Specifies a per-listener quota for active connections.</p>
</p>
<blockquote>
<div><p>The option specifies a per-listener quota for active connections.</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-streams-per-connection">
<span class="sig-name descname"><span class="pre">streams-per-connection</span></span><a class="headerlink" href="#namedconf-statement-streams-per-connection" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">streams-per-connection</span> <span class="pre"><integer>;</span></code></p>
<p><strong>Blocks: </strong>http</p>
<p><strong>Tags: </strong>server, query</p>
<p><p>Specifies the maximum number of concurrent HTTP/2 streams over an HTTP/2 connection.</p>
</p>
<blockquote>
<div><p>The option specifies the hard limit on the number of concurrent
HTTP/2 streams over an HTTP/2 connection.</p>
</div></blockquote>
</dd></dl>
<p>Any of the options above could be omitted. In such a case, a global value
specified in the <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> statement is used
(see <a class="reference internal" href="#namedconf-statement-http-listener-clients" title="namedconf-statement-http-listener-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http-listener-clients</span></code></a>, <a class="reference internal" href="#namedconf-statement-http-streams-per-connection" title="namedconf-statement-http-streams-per-connection"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">http-streams-per-connection</span></code></a>.</p>
<p>For example, the following configuration enables DNS-over-HTTPS queries on
all local addresses:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">http</span> <span class="n">local</span> <span class="p">{</span>
<span class="n">endpoints</span> <span class="p">{</span> <span class="s2">"/dns-query"</span><span class="p">;</span> <span class="p">};</span>
<span class="p">};</span>
<span class="n">options</span> <span class="p">{</span>
<span class="o">....</span>
<span class="n">listen</span><span class="o">-</span><span class="n">on</span> <span class="n">tls</span> <span class="n">ephemeral</span> <span class="n">http</span> <span class="n">local</span> <span class="p">{</span> <span class="nb">any</span><span class="p">;</span> <span class="p">};</span>
<span class="n">listen</span><span class="o">-</span><span class="n">on</span><span class="o">-</span><span class="n">v6</span> <span class="n">tls</span> <span class="n">ephemeral</span> <span class="n">http</span> <span class="n">local</span> <span class="p">{</span> <span class="nb">any</span><span class="p">;</span> <span class="p">};</span>
<span class="p">};</span>
</pre></div>
</div>
</section>
<section id="trust-anchors-block-grammar">
<h3><span class="section-number">8.2.23. </span><a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> Block Grammar<a class="headerlink" href="#trust-anchors-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-trust-anchors">
<span class="sig-name descname"><span class="pre">trust-anchors</span></span><a class="headerlink" href="#namedconf-statement-trust-anchors" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">trust-anchors</span> <span class="pre">{</span> <span class="pre"><string></span> <span class="pre">(</span> <span class="pre">static-key</span> <span class="pre">|</span> <span class="pre">initial-key</span> <span class="pre">|</span> <span class="pre">static-ds</span> <span class="pre">|</span> <span class="pre">initial-ds</span> <span class="pre">)</span> <span class="pre"><integer></span> <span class="pre"><integer></span> <span class="pre"><integer></span> <span class="pre"><quoted_string>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times</span></code></p>
<p><strong>Blocks: </strong>topmost, view</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Defines <a class="reference internal" href="chapter5.html#dnssec"><span class="std std-ref">DNSSEC</span></a> trust anchors.</p>
</p>
</dd></dl>
</section>
<section id="trust-anchors-block-definition-and-usage">
<h3><span class="section-number">8.2.24. </span><a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> Block Definition and Usage<a class="headerlink" href="#trust-anchors-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> statement defines DNSSEC trust anchors. DNSSEC is
described in <a class="reference internal" href="chapter5.html#dnssec"><span class="std std-ref">DNSSEC</span></a>.</p>
<p>A trust anchor is defined when the public key or public key digest for a non-authoritative
zone is known but cannot be securely obtained through DNS, either
because it is the DNS root zone or because its parent zone is unsigned.
Once a key or digest has been configured as a trust anchor, it is treated as if it
has been validated and proven secure.</p>
<p>The resolver attempts DNSSEC validation on all DNS data in subdomains of
configured trust anchors. Validation below specified names can be
temporarily disabled by using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-nta"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">nta</span></code></a>, or permanently disabled with
the <a class="reference internal" href="#namedconf-statement-validate-except" title="namedconf-statement-validate-except"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">validate-except</span></code></a> option.</p>
<p>All keys listed in <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>, and their corresponding zones, are
deemed to exist regardless of what parent zones say. Only keys
configured as trust anchors are used to validate the DNSKEY RRset for
the corresponding name. The parent’s DS RRset is not used.</p>
<p><a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> may be set at the top level of <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a> or within
a view. If it is set in both places, the configurations are additive;
keys defined at the top level are inherited by all views, but keys
defined in a view are only used within that view.</p>
<p>The <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> statement can contain
multiple trust-anchor entries, each consisting of a
domain name, followed by an “anchor type” keyword indicating
the trust anchor’s format, followed by the key or digest data.</p>
<p>If the anchor type is <code class="docutils literal notranslate"><span class="pre">static-key</span></code> or
<code class="docutils literal notranslate"><span class="pre">initial-key</span></code>, then it is followed with the
key’s flags, protocol, and algorithm, plus the Base64 representation
of the public key data. This is identical to the text
representation of a DNSKEY record. Spaces, tabs, newlines, and
carriage returns are ignored in the key data, so the
configuration may be split into multiple lines.</p>
<p>If the anchor type is <code class="docutils literal notranslate"><span class="pre">static-ds</span></code> or
<code class="docutils literal notranslate"><span class="pre">initial-ds</span></code>, it is followed with the
key tag, algorithm, digest type, and the hexadecimal
representation of the key digest. This is identical to the
text representation of a DS record. Spaces, tabs, newlines,
and carriage returns are ignored.</p>
<p>Trust anchors configured with the
<code class="docutils literal notranslate"><span class="pre">static-key</span></code> or <code class="docutils literal notranslate"><span class="pre">static-ds</span></code>
anchor types are immutable, while keys configured with
<code class="docutils literal notranslate"><span class="pre">initial-key</span></code> or <code class="docutils literal notranslate"><span class="pre">initial-ds</span></code>
can be kept up-to-date automatically, without intervention from the resolver operator.
(<code class="docutils literal notranslate"><span class="pre">static-key</span></code> keys are identical to keys configured using the
deprecated <a class="reference internal" href="#namedconf-statement-trusted-keys" title="namedconf-statement-trusted-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trusted-keys</span></code></a> statement.)</p>
<p>Suppose, for example, that a zone’s key-signing key was compromised, and
the zone owner had to revoke and replace the key. A resolver which had
the original key
configured using <code class="docutils literal notranslate"><span class="pre">static-key</span></code> or
<code class="docutils literal notranslate"><span class="pre">static-ds</span></code> would be unable to validate
this zone any longer; it would reply with a SERVFAIL response
code. This would continue until the resolver operator had
updated the <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> statement with
the new key.</p>
<p>If, however, the trust anchor had been configured using
<code class="docutils literal notranslate"><span class="pre">initial-key</span></code> or <code class="docutils literal notranslate"><span class="pre">initial-ds</span></code>
instead, the zone owner could add a “stand-by” key to
the zone in advance. <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> would store
the stand-by key, and when the original key was revoked,
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> would be able to transition smoothly
to the new key. It would also recognize that the old key had
been revoked and cease using that key to validate answers,
minimizing the damage that the compromised key could do.
This is the process used to keep the ICANN root DNSSEC key
up-to-date.</p>
<p>Whereas <code class="docutils literal notranslate"><span class="pre">static-key</span></code> and
<code class="docutils literal notranslate"><span class="pre">static-ds</span></code> trust anchors continue
to be trusted until they are removed from
<a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>, an
<code class="docutils literal notranslate"><span class="pre">initial-key</span></code> or <code class="docutils literal notranslate"><span class="pre">initial-ds</span></code>
is only trusted <em>once</em>: for as long as it
takes to load the managed key database and start the
<span class="target" id="index-30"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc5011.html"><strong>RFC 5011</strong></a> key maintenance process.</p>
<p>It is not possible to mix static with initial trust anchors
for the same domain name.</p>
<p>The first time <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> runs with an
<code class="docutils literal notranslate"><span class="pre">initial-key</span></code> or <code class="docutils literal notranslate"><span class="pre">initial-ds</span></code>
configured in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>, it fetches the
DNSKEY RRset directly from the zone apex,
and validates it
using the trust anchor specified in <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>.
If the DNSKEY RRset is validly signed by a key matching
the trust anchor, then it is used as the basis for a new
managed-keys database.</p>
<p>From that point on, whenever <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> runs, it sees the <code class="docutils literal notranslate"><span class="pre">initial-key</span></code> or <code class="docutils literal notranslate"><span class="pre">initial-ds</span></code>
listed in <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>, checks to make sure <span class="target" id="index-31"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc5011.html"><strong>RFC 5011</strong></a> key maintenance
has already been initialized for the specified domain, and if so,
simply moves on. The key specified in the <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> statement is
not used to validate answers; it is superseded by the key or keys stored
in the managed-keys database.</p>
<p>The next time <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> runs after an <code class="docutils literal notranslate"><span class="pre">initial-key</span></code> or <code class="docutils literal notranslate"><span class="pre">initial-ds</span></code> has been <em>removed</em>
from the <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> statement (or changed to a <code class="docutils literal notranslate"><span class="pre">static-key</span></code> or <code class="docutils literal notranslate"><span class="pre">static-ds</span></code>), the
corresponding zone is removed from the managed-keys database, and
<span class="target" id="index-32"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc5011.html"><strong>RFC 5011</strong></a> key maintenance is no longer used for that domain.</p>
<p>In the current implementation, the managed-keys database is stored as a
master-format zone file.</p>
<p>On servers which do not use views, this file is named
<code class="docutils literal notranslate"><span class="pre">managed-keys.bind</span></code>. When views are in use, there is a separate
managed-keys database for each view; the filename is the view name
(or, if a view name contains characters which would make it illegal as a
filename, a hash of the view name), followed by the suffix <code class="docutils literal notranslate"><span class="pre">.mkeys</span></code>.</p>
<p>When the key database is changed, the zone is updated. As with any other
dynamic zone, changes are written into a journal file, e.g.,
<code class="docutils literal notranslate"><span class="pre">managed-keys.bind.jnl</span></code> or <code class="docutils literal notranslate"><span class="pre">internal.mkeys.jnl</span></code>. Changes are
committed to the primary file as soon as possible afterward,
usually within 30 seconds. Whenever <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is using
automatic key maintenance, the zone file and journal file can be
expected to exist in the working directory. (For this reason, among
others, the working directory should be always be writable by
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.)</p>
<p>If the <a class="reference internal" href="#namedconf-statement-dnssec-validation" title="namedconf-statement-dnssec-validation"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-validation</span></code></a> option is set to <code class="docutils literal notranslate"><span class="pre">auto</span></code>, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
automatically initializes an <code class="docutils literal notranslate"><span class="pre">initial-key</span></code> for the root zone. The key
that is used to initialize the key-maintenance process is stored in
<code class="docutils literal notranslate"><span class="pre">bind.keys</span></code>; the location of this file can be overridden with the
<a class="reference internal" href="#namedconf-statement-bindkeys-file" title="namedconf-statement-bindkeys-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">bindkeys-file</span></code></a> option. As a fallback in the event no <code class="docutils literal notranslate"><span class="pre">bind.keys</span></code>
can be found, the initializing key is also compiled directly into
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
</section>
<section id="dnssec-policy-block-grammar">
<h3><span class="section-number">8.2.25. </span><a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> Block Grammar<a class="headerlink" href="#dnssec-policy-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnssec-policy">
<span class="sig-name descname"><span class="pre">dnssec-policy</span></span><a class="headerlink" href="#namedconf-statement-dnssec-policy" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar options, view, zone (primary, secondary): </strong><code class="docutils literal notranslate"><span class="pre">dnssec-policy</span> <span class="pre"><string>;</span></code></p>
<p><strong>Grammar topmost: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">dnssec</span><span class="o">-</span><span class="n">policy</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">{</span>
<span class="n">dnskey</span><span class="o">-</span><span class="n">ttl</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="n">keys</span> <span class="p">{</span> <span class="p">(</span> <span class="n">csk</span> <span class="o">|</span> <span class="n">ksk</span> <span class="o">|</span> <span class="n">zsk</span> <span class="p">)</span> <span class="p">[</span> <span class="p">(</span> <span class="n">key</span><span class="o">-</span><span class="n">directory</span> <span class="p">)</span> <span class="p">]</span> <span class="n">lifetime</span> <span class="o"><</span><span class="n">duration_or_unlimited</span><span class="o">></span> <span class="n">algorithm</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="nb">max</span><span class="o">-</span><span class="n">zone</span><span class="o">-</span><span class="n">ttl</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="n">nsec3param</span> <span class="p">[</span> <span class="n">iterations</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">optout</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">salt</span><span class="o">-</span><span class="n">length</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">];</span>
<span class="n">parent</span><span class="o">-</span><span class="n">ds</span><span class="o">-</span><span class="n">ttl</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="n">parent</span><span class="o">-</span><span class="n">propagation</span><span class="o">-</span><span class="n">delay</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="n">parent</span><span class="o">-</span><span class="n">registration</span><span class="o">-</span><span class="n">delay</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span> <span class="o">//</span> <span class="n">obsolete</span>
<span class="n">publish</span><span class="o">-</span><span class="n">safety</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="n">purge</span><span class="o">-</span><span class="n">keys</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="n">retire</span><span class="o">-</span><span class="n">safety</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="n">signatures</span><span class="o">-</span><span class="n">jitter</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="n">signatures</span><span class="o">-</span><span class="n">refresh</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="n">signatures</span><span class="o">-</span><span class="n">validity</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="n">signatures</span><span class="o">-</span><span class="n">validity</span><span class="o">-</span><span class="n">dnskey</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="n">zone</span><span class="o">-</span><span class="n">propagation</span><span class="o">-</span><span class="n">delay</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span><span class="p">;</span>
<span class="p">};</span> <span class="o">//</span> <span class="n">may</span> <span class="n">occur</span> <span class="n">multiple</span> <span class="n">times</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>topmost, options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Defines a key and signing policy (KASP) for zones.</p>
</p>
</dd></dl>
</section>
<section id="dnssec-policy-block-definition-and-usage">
<h3><span class="section-number">8.2.26. </span><a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> Block Definition and Usage<a class="headerlink" href="#dnssec-policy-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> statement defines a key and signing policy (KASP)
for zones.</p>
<p>A KASP determines how one or more zones are signed with DNSSEC. For
example, it specifies how often keys should roll, which cryptographic
algorithms to use, and how often RRSIG records need to be refreshed.
Multiple key and signing policies can be configured with unique policy names.</p>
<p>A policy for a zone is selected using a <a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> statement in the
<a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> block, specifying the name of the policy that should be
used.</p>
<dl class="simple">
<dt>There are three built-in policies:</dt><dd><ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">default</span></code>, which uses the <a class="reference internal" href="#dnssec-policy-default"><span class="std std-ref">default policy</span></a>,</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">insecure</span></code>, to be used when you want to gracefully unsign your zone,</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">none</span></code>, which means no DNSSEC policy (the same as not selecting
<a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> at all; the zone is not signed.)</p></li>
</ul>
</dd>
</dl>
<p>Keys are not shared among zones, which means that one set of keys per
zone is generated even if they have the same policy. If multiple views
are configured with different versions of the same zone, each separate
version uses the same set of signing keys.</p>
<p>If the expected key files that were previously observed have gone missing or
are inaccessible, key management is halted. This will prevent rollovers
from being started if there is a temporary file access issue. If his problem
is permanent it will eventually lead to expired signatures in your zone.
Note that if the key files are missing or inaccessible during <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
startup, BIND 9 will try to generate new keys according to the DNSSEC policy,
because it has no cached information about existing keys yet.</p>
<p>The <a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> statement requires dynamic DNS to be set up, or
<a class="reference internal" href="#namedconf-statement-inline-signing" title="namedconf-statement-inline-signing"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">inline-signing</span></code></a> to be enabled.</p>
<p>If <a class="reference internal" href="#namedconf-statement-inline-signing" title="namedconf-statement-inline-signing"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">inline-signing</span></code></a> is enabled, this means that a signed version of the
zone is maintained separately and is written out to a different file on disk
(the zone’s filename plus a <code class="docutils literal notranslate"><span class="pre">.signed</span></code> extension).</p>
<p>If the zone is dynamic because it is configured with an <a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> or
<a class="reference internal" href="#namedconf-statement-allow-update" title="namedconf-statement-allow-update"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-update</span></code></a>, the DNSSEC records are written to the filename set in the
original zone’s <a class="reference internal" href="#namedconf-statement-file" title="namedconf-statement-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">file</span></code></a>, unless <a class="reference internal" href="#namedconf-statement-inline-signing" title="namedconf-statement-inline-signing"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">inline-signing</span></code></a> is explicitly set.</p>
<p>Key rollover timing is computed for each key according to the key
lifetime defined in the KASP. The lifetime may be modified by zone TTLs
and propagation delays, to prevent validation failures. When a key
reaches the end of its lifetime, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> generates and publishes a new
key automatically, then deactivates the old key and activates the new
one; finally, the old key is retired according to a computed schedule.</p>
<p>Zone-signing key (ZSK) rollovers require no operator input. Key-signing
key (KSK) and combined-signing key (CSK) rollovers require action to be
taken to submit a DS record to the parent. Rollover timing for KSKs and
CSKs is adjusted to take into account delays in processing and
propagating DS updates.</p>
<p id="dnssec-policy-default">The policy <code class="docutils literal notranslate"><span class="pre">default</span></code> causes the zone to be signed with a single combined-signing
key (CSK) using the algorithm ECDSAP256SHA256; this key has an unlimited
lifetime. This policy can be displayed using the command <a class="reference internal" href="manpages.html#cmdoption-named-C"><code class="xref std std-option docutils literal notranslate"><span class="pre">named</span> <span class="pre">-C</span></code></a>.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>The default signing policy may change in future releases.
This could require changes to a signing policy when upgrading to a
new version of BIND. Check the release notes carefully when
upgrading to be informed of such changes. To prevent policy changes
on upgrade, use an explicitly defined <a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a>, rather than
<code class="docutils literal notranslate"><span class="pre">default</span></code>.</p>
</div>
<p>If a <a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> statement is modified and the server restarted or
reconfigured, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> attempts to change the policy smoothly from the
old one to the new. For example, if the key algorithm is changed, then
a new key is generated with the new algorithm, and the old algorithm is
retired when the existing key’s lifetime ends.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Rolling to a new policy while another key rollover is already
in progress is not yet supported, and may result in unexpected
behavior.</p>
</div>
<p>The following options can be specified in a <a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-policy</span></code></a> statement:</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-dnskey-ttl">
<span class="sig-name descname"><span class="pre">dnskey-ttl</span></span><a class="headerlink" href="#namedconf-statement-dnskey-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">dnskey-ttl</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the time to live (TTL) for DNSKEY resource records.</p>
</p>
<blockquote>
<div><p>This indicates the TTL to use when generating DNSKEY resource
records. The default is 1 hour (3600 seconds).</p>
</div></blockquote>
</dd></dl>
<dl id="dnssec-policy-keys">
<dt>keys</dt><dd><p>This is a list specifying the algorithms and roles to use when
generating keys and signing the zone. Entries in this list do not
represent specific DNSSEC keys, which may be changed on a regular
basis, but the roles that keys play in the signing policy. For
example, configuring a KSK of algorithm RSASHA256 ensures that the
DNSKEY RRset always includes a key-signing key for that algorithm.</p>
<p>Here is an example (for illustration purposes only) of some possible
entries in a <code class="docutils literal notranslate"><span class="pre">keys</span></code> list:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">keys</span> <span class="p">{</span>
<span class="n">ksk</span> <span class="n">key</span><span class="o">-</span><span class="n">directory</span> <span class="n">lifetime</span> <span class="n">unlimited</span> <span class="n">algorithm</span> <span class="n">rsasha256</span> <span class="mi">2048</span><span class="p">;</span>
<span class="n">zsk</span> <span class="n">lifetime</span> <span class="mi">30</span><span class="n">d</span> <span class="n">algorithm</span> <span class="mi">8</span><span class="p">;</span>
<span class="n">csk</span> <span class="n">lifetime</span> <span class="n">P6MT12H3M15S</span> <span class="n">algorithm</span> <span class="n">ecdsa256</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
<p>This example specifies that three keys should be used in the zone.
The first token determines which role the key plays in signing
RRsets. If set to <code class="docutils literal notranslate"><span class="pre">ksk</span></code>, then this is a key-signing key; it has
the KSK flag set and is only used to sign DNSKEY, CDS, and CDNSKEY
RRsets. If set to <code class="docutils literal notranslate"><span class="pre">zsk</span></code>, this is a zone-signing key; the KSK flag
is unset, and the key signs all RRsets <em>except</em> DNSKEY, CDS, and
CDNSKEY. If set to <code class="docutils literal notranslate"><span class="pre">csk</span></code>, the key has the KSK flag set and is
used to sign all RRsets.</p>
<p>An optional second token determines where the key is stored.
Currently, keys can only be stored in the configured
<a class="reference internal" href="#namedconf-statement-key-directory" title="namedconf-statement-key-directory"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">key-directory</span></code></a>. This token may be used in the future to store
keys in hardware security modules or separate directories.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">lifetime</span></code> parameter specifies how long a key may be used
before rolling over. For convenience, TTL-style time-unit suffixes
can be used to specify the key lifetime. It also accepts ISO 8601
duration formats.</p>
<p>In the example above, the first key has an
unlimited lifetime, the second key may be used for 30 days, and the
third key has a rather peculiar lifetime of 6 months, 12 hours, 3
minutes, and 15 seconds. A lifetime of 0 seconds is the same as
<code class="docutils literal notranslate"><span class="pre">unlimited</span></code>.</p>
<p>Note that the lifetime of a key may be extended if retiring it too
soon would cause validation failures. The key lifetime must be
longer than the time it takes to do a rollover; that is, the lifetime
must be more than the publication interval (which is the sum of
<a class="reference internal" href="#namedconf-statement-dnskey-ttl" title="namedconf-statement-dnskey-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnskey-ttl</span></code></a>, <a class="reference internal" href="#namedconf-statement-publish-safety" title="namedconf-statement-publish-safety"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">publish-safety</span></code></a>, and <a class="reference internal" href="#namedconf-statement-zone-propagation-delay" title="namedconf-statement-zone-propagation-delay"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone-propagation-delay</span></code></a>).
It must also be more than the retire interval (which is the sum of
<a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-zone-ttl</span></code></a>, <a class="reference internal" href="#namedconf-statement-retire-safety" title="namedconf-statement-retire-safety"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">retire-safety</span></code></a>, <a class="reference internal" href="#namedconf-statement-zone-propagation-delay" title="namedconf-statement-zone-propagation-delay"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone-propagation-delay</span></code></a>,
and signing delay (<a class="reference internal" href="#namedconf-statement-signatures-validity" title="namedconf-statement-signatures-validity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">signatures-validity</span></code></a> minus
<a class="reference internal" href="#namedconf-statement-signatures-refresh" title="namedconf-statement-signatures-refresh"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">signatures-refresh</span></code></a>) for ZSKs, and the sum of <a class="reference internal" href="#namedconf-statement-parent-ds-ttl" title="namedconf-statement-parent-ds-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parent-ds-ttl</span></code></a>,
<a class="reference internal" href="#namedconf-statement-retire-safety" title="namedconf-statement-retire-safety"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">retire-safety</span></code></a>, and <a class="reference internal" href="#namedconf-statement-parent-propagation-delay" title="namedconf-statement-parent-propagation-delay"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parent-propagation-delay</span></code></a> for KSKs and
CSKs). BIND 9 treats a key lifetime that is too short as an error.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">algorithm</span></code> parameter specifies the key’s algorithm, expressed
either as a string (“rsasha256”, “ecdsa384”, etc.) or as a decimal
number. An optional second parameter specifies the key’s size in
bits. If it is omitted, as shown in the example for the second and
third keys, an appropriate default size for the algorithm is used.
Each KSK/ZSK pair must have the same algorithm. A CSK combines the
functionality of a ZSK and a KSK.</p>
</dd>
</dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-purge-keys">
<span class="sig-name descname"><span class="pre">purge-keys</span></span><a class="headerlink" href="#namedconf-statement-purge-keys" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">purge-keys</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the amount of time after which DNSSEC keys that have been deleted from the zone can be removed from disk.</p>
</p>
<blockquote>
<div><p>This is the amount of time after which DNSSEC keys that have been deleted from
the zone can be removed from disk. If a key still determined to have
presence (for example in some resolver cache), <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> will not
remove the key files.</p>
<p>The default is <code class="docutils literal notranslate"><span class="pre">P90D</span></code> (90 days). Set this option to <code class="docutils literal notranslate"><span class="pre">0</span></code> to never
purge deleted keys.</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-publish-safety">
<span class="sig-name descname"><span class="pre">publish-safety</span></span><a class="headerlink" href="#namedconf-statement-publish-safety" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">publish-safety</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Increases the amount of time between when keys are published and when they become active, to allow for unforeseen events.</p>
</p>
<blockquote>
<div><p>This is a margin that is added to the pre-publication interval in
rollover timing calculations, to give some extra time to cover
unforeseen events. This increases the time between when keys are
published and when they become active. The default is <code class="docutils literal notranslate"><span class="pre">PT1H</span></code> (1
hour).</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-retire-safety">
<span class="sig-name descname"><span class="pre">retire-safety</span></span><a class="headerlink" href="#namedconf-statement-retire-safety" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">retire-safety</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Increases the amount of time a key remains published after it is no longer active, to allow for unforeseen events.</p>
</p>
<blockquote>
<div><p>This is a margin that is added to the post-publication interval in
rollover timing calculations, to give some extra time to cover
unforeseen events. This increases the time a key remains published
after it is no longer active. The default is <code class="docutils literal notranslate"><span class="pre">PT1H</span></code> (1 hour).</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-signatures-jitter">
<span class="sig-name descname"><span class="pre">signatures-jitter</span></span><a class="headerlink" href="#namedconf-statement-signatures-jitter" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">signatures-jitter</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies a range for signature expirations.</p>
</p>
<blockquote>
<div><p>To prevent all signatures from expiring at the same moment, BIND 9 may
vary the validity interval of individual signatures. The validity of a
newly generated signature is in the range between <a class="reference internal" href="#namedconf-statement-signatures-validity" title="namedconf-statement-signatures-validity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">signatures-validity</span></code></a>
(maximum) and <a class="reference internal" href="#namedconf-statement-signatures-validity" title="namedconf-statement-signatures-validity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">signatures-validity</span></code></a>, minus <a class="reference internal" href="#namedconf-statement-signatures-jitter" title="namedconf-statement-signatures-jitter"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">signatures-jitter</span></code></a>
(minimum). The default jitter is 12 hours, and the configured value must
be lower than both <a class="reference internal" href="#namedconf-statement-signatures-validity" title="namedconf-statement-signatures-validity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">signatures-validity</span></code></a> and
<a class="reference internal" href="#namedconf-statement-signatures-validity-dnskey" title="namedconf-statement-signatures-validity-dnskey"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">signatures-validity-dnskey</span></code></a>.</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-signatures-refresh">
<span class="sig-name descname"><span class="pre">signatures-refresh</span></span><a class="headerlink" href="#namedconf-statement-signatures-refresh" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">signatures-refresh</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies how frequently an RRSIG record is refreshed.</p>
</p>
<blockquote>
<div><p>This determines how frequently an RRSIG record needs to be
refreshed. The signature is renewed when the time until the
expiration time is less than the specified interval. The default is
<code class="docutils literal notranslate"><span class="pre">P5D</span></code> (5 days), meaning signatures that expire in 5 days or sooner
are refreshed. The <a class="reference internal" href="#namedconf-statement-signatures-refresh" title="namedconf-statement-signatures-refresh"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">signatures-refresh</span></code></a> value must be less than
90% of the minimum value of <a class="reference internal" href="#namedconf-statement-signatures-validity" title="namedconf-statement-signatures-validity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">signatures-validity</span></code></a> and
<a class="reference internal" href="#namedconf-statement-signatures-validity-dnskey" title="namedconf-statement-signatures-validity-dnskey"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">signatures-validity-dnskey</span></code></a>.</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-signatures-validity">
<span class="sig-name descname"><span class="pre">signatures-validity</span></span><a class="headerlink" href="#namedconf-statement-signatures-validity" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">signatures-validity</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Indicates the validity period of an RRSIG record.</p>
</p>
<blockquote>
<div><p>This indicates the validity period of an RRSIG record (subject to
inception offset and jitter). The default is <code class="docutils literal notranslate"><span class="pre">P2W</span></code> (2 weeks).</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-signatures-validity-dnskey">
<span class="sig-name descname"><span class="pre">signatures-validity-dnskey</span></span><a class="headerlink" href="#namedconf-statement-signatures-validity-dnskey" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">signatures-validity-dnskey</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Indicates the validity period of DNSKEY records.</p>
</p>
<blockquote>
<div><p>This is similar to <a class="reference internal" href="#namedconf-statement-signatures-validity" title="namedconf-statement-signatures-validity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">signatures-validity</span></code></a>, but for DNSKEY records.
The default is <code class="docutils literal notranslate"><span class="pre">P2W</span></code> (2 weeks).</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-max-zone-ttl">
<span class="sig-name descname"><span class="pre">max-zone-ttl</span></span><a class="headerlink" href="#namedconf-statement-max-zone-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar dnssec-policy: </strong><code class="docutils literal notranslate"><span class="pre">max-zone-ttl</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Grammar options, view, zone (primary, redirect): </strong><code class="docutils literal notranslate"><span class="pre">max-zone-ttl</span> <span class="pre">(</span> <span class="pre">unlimited</span> <span class="pre">|</span> <span class="pre"><duration></span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy, options, view, zone (primary, redirect)</p>
<p><strong>Tags: </strong>zone, query</p>
<p><p>Specifies a maximum permissible time-to-live (TTL) value, in seconds.</p>
</p>
<p>This specifies the maximum permissible TTL value for the zone. When
a zone file is loaded, any record encountered with a TTL higher than
<a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-zone-ttl</span></code></a> causes the zone to be rejected.</p>
<p>This ensures that when rolling to a new DNSKEY, the old key will remain
available until RRSIG records have expired from caches. The
<a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-zone-ttl</span></code></a> option guarantees that the largest TTL in the
zone is no higher than a known and predictable value.</p>
<p>The default value <code class="docutils literal notranslate"><span class="pre">PT24H</span></code> (24 hours). A value of zero is treated
as if the default value were in use.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-nsec3param">
<span class="sig-name descname"><span class="pre">nsec3param</span></span><a class="headerlink" href="#namedconf-statement-nsec3param" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">nsec3param</span> <span class="pre">[</span> <span class="pre">iterations</span> <span class="pre"><integer></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">optout</span> <span class="pre"><boolean></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">salt-length</span> <span class="pre"><integer></span> <span class="pre">];</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies the use of NSEC3 instead of NSEC, and sets NSEC3 parameters.</p>
</p>
<blockquote>
<div><p>Use NSEC3 instead of NSEC, and optionally set the NSEC3 parameters.</p>
<p>Here is an example of an <code class="docutils literal notranslate"><span class="pre">nsec3</span></code> configuration:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">nsec3param</span> <span class="n">iterations</span> <span class="mi">0</span> <span class="n">optout</span> <span class="n">no</span> <span class="n">salt</span><span class="o">-</span><span class="n">length</span> <span class="mi">0</span><span class="p">;</span>
</pre></div>
</div>
<p>The default is to use <a class="reference internal" href="dnssec-guide.html#nsec"><span class="std std-ref">NSEC</span></a>. The <code class="docutils literal notranslate"><span class="pre">iterations</span></code>, <code class="docutils literal notranslate"><span class="pre">optout</span></code>, and
<code class="docutils literal notranslate"><span class="pre">salt-length</span></code> parts are optional, but if not set, the values in
the example above are the default <a class="reference internal" href="dnssec-guide.html#nsec3"><span class="std std-ref">NSEC3</span></a> parameters. Note that the
specific salt string is not specified by the user; <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> creates a salt
of the indicated length.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Do not use extra <a class="reference internal" href="dnssec-guide.html#term-Iterations"><span class="xref std std-term">iterations</span></a>, <a class="reference internal" href="dnssec-guide.html#term-Salt"><span class="xref std std-term">salt</span></a>, and
<a class="reference internal" href="dnssec-guide.html#term-Opt-out"><span class="xref std std-term">opt-out</span></a> unless their implications are fully understood.
A higher number of iterations causes interoperability problems and opens
servers to CPU-exhausting DoS attacks. See <span class="target" id="index-33"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc9276.html"><strong>RFC 9276</strong></a>.</p>
</div>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-zone-propagation-delay">
<span class="sig-name descname"><span class="pre">zone-propagation-delay</span></span><a class="headerlink" href="#namedconf-statement-zone-propagation-delay" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">zone-propagation-delay</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec, zone</p>
<p><p>Sets the propagation delay from the time a zone is first updated to when the new version of the zone is served by all secondary servers.</p>
</p>
<blockquote>
<div><p>This is the expected propagation delay from the time when a zone is
first updated to the time when the new version of the zone is served
by all secondary servers. The default is <code class="docutils literal notranslate"><span class="pre">PT5M</span></code> (5 minutes).</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-parent-ds-ttl">
<span class="sig-name descname"><span class="pre">parent-ds-ttl</span></span><a class="headerlink" href="#namedconf-statement-parent-ds-ttl" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">parent-ds-ttl</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Sets the time to live (TTL) of the DS RRset used by the parent zone.</p>
</p>
<blockquote>
<div><p>This is the TTL of the DS RRset that the parent zone uses. The
default is <code class="docutils literal notranslate"><span class="pre">P1D</span></code> (1 day).</p>
</div></blockquote>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-parent-propagation-delay">
<span class="sig-name descname"><span class="pre">parent-propagation-delay</span></span><a class="headerlink" href="#namedconf-statement-parent-propagation-delay" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">parent-propagation-delay</span> <span class="pre"><duration>;</span></code></p>
<p><strong>Blocks: </strong>dnssec-policy</p>
<p><strong>Tags: </strong>dnssec, zone</p>
<p><p>Sets the propagation delay from the time the parent zone is updated to when the new version is served by all of the parent zone’s name servers.</p>
</p>
<blockquote>
<div><p>This is the expected propagation delay from the time when the parent
zone is updated to the time when the new version is served by all of
the parent zone’s name servers. The default is <code class="docutils literal notranslate"><span class="pre">PT1H</span></code> (1 hour).</p>
</div></blockquote>
</dd></dl>
<section id="automated-ksk-rollovers">
<h4><span class="section-number">8.2.26.1. </span>Automated KSK Rollovers<a class="headerlink" href="#automated-ksk-rollovers" title="Link to this heading"></a></h4>
<p>BIND has mechanisms in place to facilitate automated KSK rollovers. It
publishes CDS and CDNSKEY records that can be used by the parent zone to
publish or withdraw the zone’s DS records. BIND will query the parental
agents to see if the new DS is actually published before withdrawing the
old DNSSEC key.</p>
<blockquote>
<div><div class="admonition note">
<p class="admonition-title">Note</p>
<p>The DS response is not validated so it is recommended to set up a
trust relationship with the parental agent. For example, use TSIG to
authenticate the parental agent, or point to a validating resolver.</p>
</div>
</div></blockquote>
<p>The following options apply to DS queries sent to <a class="reference internal" href="#namedconf-statement-parental-agents" title="namedconf-statement-parental-agents"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parental-agents</span></code></a>:</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-parental-source">
<span class="sig-name descname"><span class="pre">parental-source</span></span><a class="headerlink" href="#namedconf-statement-parental-source" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">parental-source</span> <span class="pre">(</span> <span class="pre"><ipv4_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies which local IPv4 source address is used to send parental DS queries.</p>
</p>
<p><a class="reference internal" href="#namedconf-statement-parental-source" title="namedconf-statement-parental-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parental-source</span></code></a> determines which local source address, and optionally
UDP port, is used to send parental DS queries. This statement sets the
<a class="reference internal" href="#namedconf-statement-parental-source" title="namedconf-statement-parental-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parental-source</span></code></a> for all zones, but can be overridden on a per-zone or
per-view basis by including a <a class="reference internal" href="#namedconf-statement-parental-source" title="namedconf-statement-parental-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parental-source</span></code></a> statement within the
<a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> or <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> block in the configuration file.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p><code class="docutils literal notranslate"><span class="pre">port</span></code> configuration is deprecated. A warning will be logged
when this parameter is used.</p>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>Specifying a single port is discouraged, as it removes a layer of
protection against spoofing errors.</p>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The configured <a class="reference internal" href="#term-port"><span class="xref std std-term">port</span></a> must not be the same as the listening port.</p>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-parental-source-v6">
<span class="sig-name descname"><span class="pre">parental-source-v6</span></span><a class="headerlink" href="#namedconf-statement-parental-source-v6" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">parental-source-v6</span> <span class="pre">(</span> <span class="pre"><ipv6_address></span> <span class="pre">|</span> <span class="pre">*</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>options, view, zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec</p>
<p><p>Specifies which local IPv6 source address is used to send parental DS queries.</p>
</p>
<p>This option acts like <a class="reference internal" href="#namedconf-statement-parental-source" title="namedconf-statement-parental-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">parental-source</span></code></a>, but applies to parental DS
queries sent to IPv6 addresses.</p>
</dd></dl>
</section>
</section>
<section id="managed-keys-block-grammar">
<h3><span class="section-number">8.2.27. </span><a class="reference internal" href="#namedconf-statement-managed-keys" title="namedconf-statement-managed-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">managed-keys</span></code></a> Block Grammar<a class="headerlink" href="#managed-keys-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-managed-keys">
<span class="sig-name descname"><span class="pre">managed-keys</span></span><a class="headerlink" href="#namedconf-statement-managed-keys" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">managed-keys</span> <span class="pre">{</span> <span class="pre"><string></span> <span class="pre">(</span> <span class="pre">static-key</span> <span class="pre">|</span> <span class="pre">initial-key</span> <span class="pre">|</span> <span class="pre">static-ds</span> <span class="pre">|</span> <span class="pre">initial-ds</span> <span class="pre">)</span> <span class="pre"><integer></span> <span class="pre"><integer></span> <span class="pre"><integer></span> <span class="pre"><quoted_string>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times,</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>topmost, view</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Deprecated, use <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>.</p>
</p>
</dd></dl>
</section>
<section id="managed-keys-block-definition-and-usage">
<h3><span class="section-number">8.2.28. </span><a class="reference internal" href="#namedconf-statement-managed-keys" title="namedconf-statement-managed-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">managed-keys</span></code></a> Block Definition and Usage<a class="headerlink" href="#managed-keys-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-managed-keys" title="namedconf-statement-managed-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">managed-keys</span></code></a> statement has been
deprecated in favor of <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>
with the <code class="docutils literal notranslate"><span class="pre">initial-key</span></code> keyword.</p>
</section>
<section id="trusted-keys-block-grammar">
<h3><span class="section-number">8.2.29. </span><a class="reference internal" href="#namedconf-statement-trusted-keys" title="namedconf-statement-trusted-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trusted-keys</span></code></a> Block Grammar<a class="headerlink" href="#trusted-keys-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-trusted-keys">
<span class="sig-name descname"><span class="pre">trusted-keys</span></span><a class="headerlink" href="#namedconf-statement-trusted-keys" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">trusted-keys</span> <span class="pre">{</span> <span class="pre"><string></span> <span class="pre"><integer></span> <span class="pre"><integer></span> <span class="pre"><integer></span> <span class="pre"><quoted_string>;</span> <span class="pre">...</span> <span class="pre">};</span> <span class="pre">//</span> <span class="pre">may</span> <span class="pre">occur</span> <span class="pre">multiple</span> <span class="pre">times,</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>topmost, view</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Deprecated, use <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>.</p>
</p>
</dd></dl>
</section>
<section id="trusted-keys-block-definition-and-usage">
<h3><span class="section-number">8.2.30. </span><a class="reference internal" href="#namedconf-statement-trusted-keys" title="namedconf-statement-trusted-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trusted-keys</span></code></a> Block Definition and Usage<a class="headerlink" href="#trusted-keys-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-trusted-keys" title="namedconf-statement-trusted-keys"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trusted-keys</span></code></a> statement has been deprecated in favor of
<a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a> with the <code class="docutils literal notranslate"><span class="pre">static-key</span></code> keyword.</p>
</section>
<section id="view-block-grammar">
<h3><span class="section-number">8.2.31. </span><a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> Block Grammar<a class="headerlink" href="#view-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-view">
<span class="sig-name descname"><span class="pre">view</span></span><a class="headerlink" href="#namedconf-statement-view" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span>view <string> [ <class> ] {
allow-new-zones <boolean>;
allow-notify { <address_match_element>; ... };
allow-query { <address_match_element>; ... };
allow-query-cache { <address_match_element>; ... };
allow-query-cache-on { <address_match_element>; ... };
allow-query-on { <address_match_element>; ... };
allow-recursion { <address_match_element>; ... };
allow-recursion-on { <address_match_element>; ... };
allow-transfer [ port <integer> ] [ transport <string> ] { <address_match_element>; ... };
allow-update { <address_match_element>; ... };
allow-update-forwarding { <address_match_element>; ... };
also-notify [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... };
alt-transfer-source ( <ipv4_address> | * ); // deprecated
alt-transfer-source-v6 ( <ipv6_address> | * ); // deprecated
attach-cache <string>;
auth-nxdomain <boolean>;
auto-dnssec ( allow | maintain | off ); // deprecated
catalog-zones { zone <string> [ default-primaries [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... } ] [ zone-directory <quoted_string> ] [ in-memory <boolean> ] [ min-update-interval <duration> ]; ... };
check-dup-records ( fail | warn | ignore );
check-integrity <boolean>;
check-mx ( fail | warn | ignore );
check-mx-cname ( fail | warn | ignore );
check-names ( primary | master | secondary | slave | response ) ( fail | warn | ignore ); // may occur multiple times
check-sibling <boolean>;
check-spf ( warn | ignore );
check-srv-cname ( fail | warn | ignore );
check-wildcard <boolean>;
clients-per-query <integer>;
deny-answer-addresses { <address_match_element>; ... } [ except-from { <string>; ... } ];
deny-answer-aliases { <string>; ... } [ except-from { <string>; ... } ];
dialup ( notify | notify-passive | passive | refresh | <boolean> ); // deprecated
disable-algorithms <string> { <string>; ... }; // may occur multiple times
disable-ds-digests <string> { <string>; ... }; // may occur multiple times
disable-empty-zone <string>; // may occur multiple times
dlz <string> {
database <string>;
search <boolean>;
}; // may occur multiple times
dns64 <netprefix> {
break-dnssec <boolean>;
clients { <address_match_element>; ... };
exclude { <address_match_element>; ... };
mapped { <address_match_element>; ... };
recursive-only <boolean>;
suffix <ipv6_address>;
}; // may occur multiple times
dns64-contact <string>;
dns64-server <string>;
dnskey-sig-validity <integer>;
dnsrps-enable <boolean>;
dnsrps-options { <unspecified-text> };
dnssec-accept-expired <boolean>;
dnssec-dnskey-kskonly <boolean>;
dnssec-loadkeys-interval <integer>;
dnssec-must-be-secure <string> <boolean>; // may occur multiple times, deprecated
dnssec-policy <string>;
dnssec-secure-to-insecure <boolean>;
dnssec-update-mode ( maintain | no-resign );
dnssec-validation ( yes | no | auto );
dnstap { ( all | auth | client | forwarder | resolver | update ) [ ( query | response ) ]; ... };
dual-stack-servers [ port <integer> ] { ( <quoted_string> [ port <integer> ] | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ); ... };
dyndb <string> <quoted_string> { <unspecified-text> }; // may occur multiple times
edns-udp-size <integer>;
empty-contact <string>;
empty-server <string>;
empty-zones-enable <boolean>;
fetch-quota-params <integer> <fixedpoint> <fixedpoint> <fixedpoint>;
fetches-per-server <integer> [ ( drop | fail ) ];
fetches-per-zone <integer> [ ( drop | fail ) ];
forward ( first | only );
forwarders [ port <integer> ] { ( <ipv4_address> | <ipv6_address> ) [ port <integer> ]; ... };
glue-cache <boolean>; // deprecated
ipv4only-contact <string>;
ipv4only-enable <boolean>;
ipv4only-server <string>;
ixfr-from-differences ( primary | master | secondary | slave | <boolean> );
key <string> {
algorithm <string>;
secret <string>;
}; // may occur multiple times
key-directory <quoted_string>;
lame-ttl <duration>;
lmdb-mapsize <sizeval>;
managed-keys { <string> ( static-key | initial-key | static-ds | initial-ds ) <integer> <integer> <integer> <quoted_string>; ... }; // may occur multiple times, deprecated
masterfile-format ( raw | text );
masterfile-style ( full | relative );
match-clients { <address_match_element>; ... };
match-destinations { <address_match_element>; ... };
match-recursive-only <boolean>;
max-cache-size ( default | unlimited | <sizeval> | <percentage> );
max-cache-ttl <duration>;
max-clients-per-query <integer>;
max-ixfr-ratio ( unlimited | <percentage> );
max-journal-size ( default | unlimited | <sizeval> );
max-ncache-ttl <duration>;
max-query-count <integer>;
max-query-restarts <integer>;
max-records <integer>;
max-records-per-type <integer>;
max-recursion-depth <integer>;
max-recursion-queries <integer>;
max-refresh-time <integer>;
max-retry-time <integer>;
max-stale-ttl <duration>;
max-transfer-idle-in <integer>;
max-transfer-idle-out <integer>;
max-transfer-time-in <integer>;
max-transfer-time-out <integer>;
max-types-per-name <integer>;
max-udp-size <integer>;
max-zone-ttl ( unlimited | <duration> );
message-compression <boolean>;
min-cache-ttl <duration>;
min-ncache-ttl <duration>;
min-refresh-time <integer>;
min-retry-time <integer>;
minimal-any <boolean>;
minimal-responses ( no-auth | no-auth-recursive | <boolean> );
multi-master <boolean>;
new-zones-directory <quoted_string>;
no-case-compress { <address_match_element>; ... };
nocookie-udp-size <integer>;
notify ( explicit | master-only | primary-only | <boolean> );
notify-delay <integer>;
notify-source ( <ipv4_address> | * );
notify-source-v6 ( <ipv6_address> | * );
notify-to-soa <boolean>;
nsec3-test-zone <boolean>; // test only
nta-lifetime <duration>;
nta-recheck <duration>;
nxdomain-redirect <string>;
parental-source ( <ipv4_address> | * );
parental-source-v6 ( <ipv6_address> | * );
plugin ( query ) <string> [ { <unspecified-text> } ]; // may occur multiple times
preferred-glue <string>;
prefetch <integer> [ <integer> ];
provide-ixfr <boolean>;
qname-minimization ( strict | relaxed | disabled | off );
query-source [ address ] ( <ipv4_address> | * );
query-source-v6 [ address ] ( <ipv6_address> | * );
rate-limit {
all-per-second <integer>;
errors-per-second <integer>;
exempt-clients { <address_match_element>; ... };
ipv4-prefix-length <integer>;
ipv6-prefix-length <integer>;
log-only <boolean>;
max-table-size <integer>;
min-table-size <integer>;
nodata-per-second <integer>;
nxdomains-per-second <integer>;
qps-scale <integer>;
referrals-per-second <integer>;
responses-per-second <integer>;
slip <integer>;
window <integer>;
};
recursion <boolean>;
request-expire <boolean>;
request-ixfr <boolean>;
request-nsid <boolean>;
require-server-cookie <boolean>;
resolver-nonbackoff-tries <integer>; // deprecated
resolver-query-timeout <integer>;
resolver-retry-interval <integer>; // deprecated
response-padding { <address_match_element>; ... } block-size <integer>;
response-policy { zone <string> [ add-soa <boolean> ] [ log <boolean> ] [ max-policy-ttl <duration> ] [ min-update-interval <duration> ] [ policy ( cname | disabled | drop | given | no-op | nodata | nxdomain | passthru | tcp-only <quoted_string> ) ] [ recursive-only <boolean> ] [ nsip-enable <boolean> ] [ nsdname-enable <boolean> ]; ... } [ add-soa <boolean> ] [ break-dnssec <boolean> ] [ max-policy-ttl <duration> ] [ min-update-interval <duration> ] [ min-ns-dots <integer> ] [ nsip-wait-recurse <boolean> ] [ nsdname-wait-recurse <boolean> ] [ qname-wait-recurse <boolean> ] [ recursive-only <boolean> ] [ nsip-enable <boolean> ] [ nsdname-enable <boolean> ] [ dnsrps-enable <boolean> ] [ dnsrps-options { <unspecified-text> } ];
root-delegation-only [ exclude { <string>; ... } ]; // deprecated
root-key-sentinel <boolean>;
rrset-order { [ class <string> ] [ type <string> ] [ name <quoted_string> ] <string> <string>; ... };
send-cookie <boolean>;
serial-update-method ( date | increment | unixtime );
server <netprefix> {
bogus <boolean>;
edns <boolean>;
edns-udp-size <integer>;
edns-version <integer>;
keys <server_key>;
max-udp-size <integer>;
notify-source ( <ipv4_address> | * );
notify-source-v6 ( <ipv6_address> | * );
padding <integer>;
provide-ixfr <boolean>;
query-source [ address ] ( <ipv4_address> | * );
query-source-v6 [ address ] ( <ipv6_address> | * );
request-expire <boolean>;
request-ixfr <boolean>;
request-nsid <boolean>;
send-cookie <boolean>;
tcp-keepalive <boolean>;
tcp-only <boolean>;
transfer-format ( many-answers | one-answer );
transfer-source ( <ipv4_address> | * );
transfer-source-v6 ( <ipv6_address> | * );
transfers <integer>;
}; // may occur multiple times
servfail-ttl <duration>;
sig-signing-nodes <integer>;
sig-signing-signatures <integer>;
sig-signing-type <integer>;
sig-validity-interval <integer> [ <integer> ];
sortlist { <address_match_element>; ... };
stale-answer-client-timeout ( disabled | off | <integer> );
stale-answer-enable <boolean>;
stale-answer-ttl <duration>;
stale-cache-enable <boolean>;
stale-refresh-time <duration>;
suppress-initial-notify <boolean>; // obsolete
synth-from-dnssec <boolean>;
transfer-format ( many-answers | one-answer );
transfer-source ( <ipv4_address> | * );
transfer-source-v6 ( <ipv6_address> | * );
trust-anchor-telemetry <boolean>;
trust-anchors { <string> ( static-key | initial-key | static-ds | initial-ds ) <integer> <integer> <integer> <quoted_string>; ... }; // may occur multiple times
trusted-keys { <string> <integer> <integer> <integer> <quoted_string>; ... }; // may occur multiple times, deprecated
try-tcp-refresh <boolean>;
update-check-ksk <boolean>;
use-alt-transfer-source <boolean>; // deprecated
v6-bias <integer>;
validate-except { <string>; ... };
zero-no-soa-ttl <boolean>;
zero-no-soa-ttl-cache <boolean>;
zone <string> [ <class> ] {
in-view <string>;
};
zone <string> [ <class> ] {
type delegation-only;
};
zone <string> [ <class> ] {
type forward;
delegation-only <boolean>; // deprecated
forward ( first | only );
forwarders [ port <integer> ] { ( <ipv4_address> | <ipv6_address> ) [ port <integer> ]; ... };
};
zone <string> [ <class> ] {
type hint;
check-names ( fail | warn | ignore );
delegation-only <boolean>; // deprecated
file <quoted_string>;
};
zone <string> [ <class> ] {
type mirror;
allow-notify { <address_match_element>; ... };
allow-query { <address_match_element>; ... };
allow-query-on { <address_match_element>; ... };
allow-transfer [ port <integer> ] [ transport <string> ] { <address_match_element>; ... };
allow-update-forwarding { <address_match_element>; ... };
also-notify [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... };
alt-transfer-source ( <ipv4_address> | * ); // deprecated
alt-transfer-source-v6 ( <ipv6_address> | * ); // deprecated
check-names ( fail | warn | ignore );
database <string>;
file <quoted_string>;
ixfr-from-differences <boolean>;
journal <quoted_string>;
masterfile-format ( raw | text );
masterfile-style ( full | relative );
max-ixfr-ratio ( unlimited | <percentage> );
max-journal-size ( default | unlimited | <sizeval> );
max-records <integer>;
max-records-per-type <integer>;
max-refresh-time <integer>;
max-retry-time <integer>;
max-transfer-idle-in <integer>;
max-transfer-idle-out <integer>;
max-transfer-time-in <integer>;
max-transfer-time-out <integer>;
max-types-per-name <integer>;
min-refresh-time <integer>;
min-retry-time <integer>;
multi-master <boolean>;
notify ( explicit | master-only | primary-only | <boolean> );
notify-delay <integer>;
notify-source ( <ipv4_address> | * );
notify-source-v6 ( <ipv6_address> | * );
primaries [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... };
request-expire <boolean>;
request-ixfr <boolean>;
transfer-source ( <ipv4_address> | * );
transfer-source-v6 ( <ipv6_address> | * );
try-tcp-refresh <boolean>;
use-alt-transfer-source <boolean>; // deprecated
zero-no-soa-ttl <boolean>;
zone-statistics ( full | terse | none | <boolean> );
};
zone <string> [ <class> ] {
type primary;
allow-query { <address_match_element>; ... };
allow-query-on { <address_match_element>; ... };
allow-transfer [ port <integer> ] [ transport <string> ] { <address_match_element>; ... };
allow-update { <address_match_element>; ... };
also-notify [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... };
alt-transfer-source ( <ipv4_address> | * ); // deprecated
alt-transfer-source-v6 ( <ipv6_address> | * ); // deprecated
auto-dnssec ( allow | maintain | off ); // deprecated
check-dup-records ( fail | warn | ignore );
check-integrity <boolean>;
check-mx ( fail | warn | ignore );
check-mx-cname ( fail | warn | ignore );
check-names ( fail | warn | ignore );
check-sibling <boolean>;
check-spf ( warn | ignore );
check-srv-cname ( fail | warn | ignore );
check-wildcard <boolean>;
database <string>;
dialup ( notify | notify-passive | passive | refresh | <boolean> ); // deprecated
dlz <string>;
dnskey-sig-validity <integer>;
dnssec-dnskey-kskonly <boolean>;
dnssec-loadkeys-interval <integer>;
dnssec-policy <string>;
dnssec-secure-to-insecure <boolean>;
dnssec-update-mode ( maintain | no-resign );
file <quoted_string>;
forward ( first | only );
forwarders [ port <integer> ] { ( <ipv4_address> | <ipv6_address> ) [ port <integer> ]; ... };
inline-signing <boolean>;
ixfr-from-differences <boolean>;
journal <quoted_string>;
key-directory <quoted_string>;
masterfile-format ( raw | text );
masterfile-style ( full | relative );
max-ixfr-ratio ( unlimited | <percentage> );
max-journal-size ( default | unlimited | <sizeval> );
max-records <integer>;
max-records-per-type <integer>;
max-transfer-idle-out <integer>;
max-transfer-time-out <integer>;
max-types-per-name <integer>;
max-zone-ttl ( unlimited | <duration> );
notify ( explicit | master-only | primary-only | <boolean> );
notify-delay <integer>;
notify-source ( <ipv4_address> | * );
notify-source-v6 ( <ipv6_address> | * );
notify-to-soa <boolean>;
nsec3-test-zone <boolean>; // test only
parental-agents [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... };
parental-source ( <ipv4_address> | * );
parental-source-v6 ( <ipv6_address> | * );
serial-update-method ( date | increment | unixtime );
sig-signing-nodes <integer>;
sig-signing-signatures <integer>;
sig-signing-type <integer>;
sig-validity-interval <integer> [ <integer> ];
update-check-ksk <boolean>;
update-policy ( local | { ( deny | grant ) <string> ( 6to4-self | external | krb5-self | krb5-selfsub | krb5-subdomain | krb5-subdomain-self-rhs | ms-self | ms-selfsub | ms-subdomain | ms-subdomain-self-rhs | name | self | selfsub | selfwild | subdomain | tcp-self | wildcard | zonesub ) [ <string> ] <rrtypelist>; ... } );
zero-no-soa-ttl <boolean>;
zone-statistics ( full | terse | none | <boolean> );
};
zone <string> [ <class> ] {
type redirect;
allow-query { <address_match_element>; ... };
allow-query-on { <address_match_element>; ... };
dlz <string>;
file <quoted_string>;
masterfile-format ( raw | text );
masterfile-style ( full | relative );
max-records <integer>;
max-records-per-type <integer>;
max-types-per-name <integer>;
max-zone-ttl ( unlimited | <duration> );
primaries [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... };
zone-statistics ( full | terse | none | <boolean> );
};
zone <string> [ <class> ] {
type secondary;
allow-notify { <address_match_element>; ... };
allow-query { <address_match_element>; ... };
allow-query-on { <address_match_element>; ... };
allow-transfer [ port <integer> ] [ transport <string> ] { <address_match_element>; ... };
allow-update-forwarding { <address_match_element>; ... };
also-notify [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... };
alt-transfer-source ( <ipv4_address> | * ); // deprecated
alt-transfer-source-v6 ( <ipv6_address> | * ); // deprecated
auto-dnssec ( allow | maintain | off ); // deprecated
check-names ( fail | warn | ignore );
database <string>;
dialup ( notify | notify-passive | passive | refresh | <boolean> ); // deprecated
dlz <string>;
dnskey-sig-validity <integer>;
dnssec-dnskey-kskonly <boolean>;
dnssec-loadkeys-interval <integer>;
dnssec-policy <string>;
dnssec-update-mode ( maintain | no-resign );
file <quoted_string>;
forward ( first | only );
forwarders [ port <integer> ] { ( <ipv4_address> | <ipv6_address> ) [ port <integer> ]; ... };
inline-signing <boolean>;
ixfr-from-differences <boolean>;
journal <quoted_string>;
key-directory <quoted_string>;
masterfile-format ( raw | text );
masterfile-style ( full | relative );
max-ixfr-ratio ( unlimited | <percentage> );
max-journal-size ( default | unlimited | <sizeval> );
max-records <integer>;
max-records-per-type <integer>;
max-refresh-time <integer>;
max-retry-time <integer>;
max-transfer-idle-in <integer>;
max-transfer-idle-out <integer>;
max-transfer-time-in <integer>;
max-transfer-time-out <integer>;
max-types-per-name <integer>;
min-refresh-time <integer>;
min-retry-time <integer>;
multi-master <boolean>;
notify ( explicit | master-only | primary-only | <boolean> );
notify-delay <integer>;
notify-source ( <ipv4_address> | * );
notify-source-v6 ( <ipv6_address> | * );
notify-to-soa <boolean>;
nsec3-test-zone <boolean>; // test only
parental-agents [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... };
parental-source ( <ipv4_address> | * );
parental-source-v6 ( <ipv6_address> | * );
primaries [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... };
request-expire <boolean>;
request-ixfr <boolean>;
sig-signing-nodes <integer>;
sig-signing-signatures <integer>;
sig-signing-type <integer>;
sig-validity-interval <integer> [ <integer> ];
transfer-source ( <ipv4_address> | * );
transfer-source-v6 ( <ipv6_address> | * );
try-tcp-refresh <boolean>;
update-check-ksk <boolean>;
use-alt-transfer-source <boolean>; // deprecated
zero-no-soa-ttl <boolean>;
zone-statistics ( full | terse | none | <boolean> );
};
zone <string> [ <class> ] {
type static-stub;
allow-query { <address_match_element>; ... };
allow-query-on { <address_match_element>; ... };
forward ( first | only );
forwarders [ port <integer> ] { ( <ipv4_address> | <ipv6_address> ) [ port <integer> ]; ... };
max-records <integer>;
max-records-per-type <integer>;
max-types-per-name <integer>;
server-addresses { ( <ipv4_address> | <ipv6_address> ); ... };
server-names { <string>; ... };
zone-statistics ( full | terse | none | <boolean> );
};
zone <string> [ <class> ] {
type stub;
allow-query { <address_match_element>; ... };
allow-query-on { <address_match_element>; ... };
check-names ( fail | warn | ignore );
database <string>;
delegation-only <boolean>; // deprecated
dialup ( notify | notify-passive | passive | refresh | <boolean> ); // deprecated
file <quoted_string>;
forward ( first | only );
forwarders [ port <integer> ] { ( <ipv4_address> | <ipv6_address> ) [ port <integer> ]; ... };
masterfile-format ( raw | text );
masterfile-style ( full | relative );
max-records <integer>;
max-records-per-type <integer>;
max-refresh-time <integer>;
max-retry-time <integer>;
max-transfer-idle-in <integer>;
max-transfer-time-in <integer>;
max-types-per-name <integer>;
min-refresh-time <integer>;
min-retry-time <integer>;
multi-master <boolean>;
primaries [ port <integer> ] { ( <remote-servers> | <ipv4_address> [ port <integer> ] | <ipv6_address> [ port <integer> ] ) [ key <string> ] [ tls <string> ]; ... };
transfer-source ( <ipv4_address> | * );
transfer-source-v6 ( <ipv6_address> | * );
use-alt-transfer-source <boolean>; // deprecated
zone-statistics ( full | terse | none | <boolean> );
};
zone-statistics ( full | terse | none | <boolean> );
}; // may occur multiple times
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>topmost</p>
<p><strong>Tags: </strong>view</p>
<p><p>Allows a name server to answer a DNS query differently depending on who is asking.</p>
</p>
</dd></dl>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>view view_name [ class ] {
match-clients { address_match_list } ;
match-destinations { address_match_list } ;
match-recursive-only <boolean> ;
[ view_option ; ... ]
[ zone_statement ; ... ]
} ;
</pre></div>
</div>
</section>
<section id="view-block-definition-and-usage">
<h3><span class="section-number">8.2.32. </span><a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> Block Definition and Usage<a class="headerlink" href="#view-block-definition-and-usage" title="Link to this heading"></a></h3>
<p>The <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statement is a powerful feature of BIND 9 that lets a name
server answer a DNS query differently depending on who is asking. It is
particularly useful for implementing split DNS setups without having to
run multiple servers.</p>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-match-clients">
<span class="sig-name descname"><span class="pre">match-clients</span></span><a class="headerlink" href="#namedconf-statement-match-clients" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">match-clients</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>view</p>
<p><strong>Tags: </strong>view</p>
<p><p>Specifies a view of DNS namespace for a given subset of client IP addresses.</p>
</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-match-destinations">
<span class="sig-name descname"><span class="pre">match-destinations</span></span><a class="headerlink" href="#namedconf-statement-match-destinations" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">match-destinations</span> <span class="pre">{</span> <span class="pre"><address_match_element>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>view</p>
<p><strong>Tags: </strong>view</p>
<p><p>Specifies a view of DNS namespace for a given subset of destination IP addresses.</p>
</p>
<p>Each <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statement defines a view of the DNS namespace that is
seen by a subset of clients. A client matches a view if its source IP
address matches the <a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> of the view’s
<a class="reference internal" href="#namedconf-statement-match-clients" title="namedconf-statement-match-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">match-clients</span></code></a> clause, and its destination IP address matches the
<a class="reference internal" href="#term-address_match_list"><span class="xref std std-term">address_match_list</span></a> of the view’s <a class="reference internal" href="#namedconf-statement-match-destinations" title="namedconf-statement-match-destinations"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">match-destinations</span></code></a> clause. If
not specified, both <a class="reference internal" href="#namedconf-statement-match-clients" title="namedconf-statement-match-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">match-clients</span></code></a> and <a class="reference internal" href="#namedconf-statement-match-destinations" title="namedconf-statement-match-destinations"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">match-destinations</span></code></a> default
to matching all addresses. In addition to checking IP addresses,
<a class="reference internal" href="#namedconf-statement-match-clients" title="namedconf-statement-match-clients"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">match-clients</span></code></a> and <a class="reference internal" href="#namedconf-statement-match-destinations" title="namedconf-statement-match-destinations"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">match-destinations</span></code></a> can also take the name of a
TSIG <a class="reference internal" href="#namedconf-statement-key" title="namedconf-statement-key"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">key</span></code></a>, which provides a mechanism for the client to select
the view.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-match-recursive-only">
<span class="sig-name descname"><span class="pre">match-recursive-only</span></span><a class="headerlink" href="#namedconf-statement-match-recursive-only" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">match-recursive-only</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>view</p>
<p><strong>Tags: </strong>view</p>
<p><p>Specifies that only recursive requests can match this view of the DNS namespace.</p>
</p>
<p>A view can
also be specified as <a class="reference internal" href="#namedconf-statement-match-recursive-only" title="namedconf-statement-match-recursive-only"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">match-recursive-only</span></code></a>, which means that only
recursive requests from matching clients match that view. The order
of the <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statements is significant; a client request is
resolved in the context of the first <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> that it matches.</p>
</dd></dl>
<p>Zones defined within a <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statement are only accessible to
clients that match the <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>. By defining a zone of the same name in
multiple views, different zone data can be given to different clients:
for example, “internal” and “external” clients in a split DNS setup.</p>
<p>Many of the options given in the <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> statement can also be used
within a <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statement, and then apply only when resolving queries
with that view. When no view-specific value is given, the value in the
<a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> statement is used as a default. Also, zone options can have
default values specified in the <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statement; these view-specific
defaults take precedence over those in the <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> statement.</p>
<p>Views are class-specific. If no class is given, class IN is assumed.
Note that all non-IN views must contain a hint zone, since only the IN
class has compiled-in default hints.</p>
<p>If there are no <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statements in the config file, a default view
that matches any client is automatically created in class IN. Any
<a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statements specified on the top level of the configuration file
are considered to be part of this default view, and the <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>
statement applies to the default view. If any explicit <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a>
statements are present, all <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statements must occur inside
<a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statements.</p>
<p>Here is an example of a typical split DNS setup implemented using
<a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> statements:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">view</span> <span class="s2">"internal"</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">This</span> <span class="n">should</span> <span class="n">match</span> <span class="n">our</span> <span class="n">internal</span> <span class="n">networks</span><span class="o">.</span>
<span class="k">match</span><span class="o">-</span><span class="n">clients</span> <span class="p">{</span> <span class="mf">10.0.0.0</span><span class="o">/</span><span class="mi">8</span><span class="p">;</span> <span class="p">};</span>
<span class="o">//</span> <span class="n">Provide</span> <span class="n">recursive</span> <span class="n">service</span> <span class="n">to</span> <span class="n">internal</span>
<span class="o">//</span> <span class="n">clients</span> <span class="n">only</span><span class="o">.</span>
<span class="n">recursion</span> <span class="n">yes</span><span class="p">;</span>
<span class="o">//</span> <span class="n">Provide</span> <span class="n">a</span> <span class="n">complete</span> <span class="n">view</span> <span class="n">of</span> <span class="n">the</span> <span class="n">example</span><span class="o">.</span><span class="n">com</span>
<span class="o">//</span> <span class="n">zone</span> <span class="n">including</span> <span class="n">addresses</span> <span class="n">of</span> <span class="n">internal</span> <span class="n">hosts</span><span class="o">.</span>
<span class="n">zone</span> <span class="s2">"example.com"</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">primary</span><span class="p">;</span>
<span class="n">file</span> <span class="s2">"example-internal.db"</span><span class="p">;</span>
<span class="p">};</span>
<span class="p">};</span>
<span class="n">view</span> <span class="s2">"external"</span> <span class="p">{</span>
<span class="o">//</span> <span class="n">Match</span> <span class="nb">all</span> <span class="n">clients</span> <span class="ow">not</span> <span class="n">matched</span> <span class="n">by</span> <span class="n">the</span>
<span class="o">//</span> <span class="n">previous</span> <span class="n">view</span><span class="o">.</span>
<span class="k">match</span><span class="o">-</span><span class="n">clients</span> <span class="p">{</span> <span class="nb">any</span><span class="p">;</span> <span class="p">};</span>
<span class="o">//</span> <span class="n">Refuse</span> <span class="n">recursive</span> <span class="n">service</span> <span class="n">to</span> <span class="n">external</span> <span class="n">clients</span><span class="o">.</span>
<span class="n">recursion</span> <span class="n">no</span><span class="p">;</span>
<span class="o">//</span> <span class="n">Provide</span> <span class="n">a</span> <span class="n">restricted</span> <span class="n">view</span> <span class="n">of</span> <span class="n">the</span> <span class="n">example</span><span class="o">.</span><span class="n">com</span>
<span class="o">//</span> <span class="n">zone</span> <span class="n">containing</span> <span class="n">only</span> <span class="n">publicly</span> <span class="n">accessible</span> <span class="n">hosts</span><span class="o">.</span>
<span class="n">zone</span> <span class="s2">"example.com"</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">primary</span><span class="p">;</span>
<span class="n">file</span> <span class="s2">"example-external.db"</span><span class="p">;</span>
<span class="p">};</span>
<span class="p">};</span>
</pre></div>
</div>
</section>
<section id="zone-block-grammar">
<h3><span class="section-number">8.2.33. </span><a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> Block Grammar<a class="headerlink" href="#zone-block-grammar" title="Link to this heading"></a></h3>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-zone">
<span class="sig-name descname"><span class="pre">zone</span></span><a class="headerlink" href="#namedconf-statement-zone" title="Link to this definition"></a></dt>
<dd><p><strong>Blocks: </strong>topmost, view</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Specifies the zone in a BIND 9 configuration.</p>
</p>
</dd></dl>
</section>
<section id="zone-block-definition-and-usage">
<h3><span class="section-number">8.2.34. </span><a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> Block Definition and Usage<a class="headerlink" href="#zone-block-definition-and-usage" title="Link to this heading"></a></h3>
<section id="zone-types">
<h4><span class="section-number">8.2.34.1. </span>Zone Types<a class="headerlink" href="#zone-types" title="Link to this heading"></a></h4>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-type">
<span class="sig-name descname"><span class="pre">type</span></span><a class="headerlink" href="#namedconf-statement-type" title="Link to this definition"></a></dt>
<dd><p><strong>Blocks: </strong>zone (delegation-only, forward, hint, mirror, primary, redirect, secondary, static-stub, stub)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Specifies the kind of zone in a given configuration.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-type" title="namedconf-statement-type"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span></code></a> keyword is required for the <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> configuration unless
it is an <a class="reference internal" href="#namedconf-statement-in-view" title="namedconf-statement-in-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">in-view</span></code></a> configuration. Its acceptable values are:
<a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primary</span></code></a> (or <code class="docutils literal notranslate"><span class="pre">master</span></code>), <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">secondary</span></code></a> (or <code class="docutils literal notranslate"><span class="pre">slave</span></code>), <a class="reference internal" href="#namedconf-statement-type mirror" title="namedconf-statement-type mirror"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">mirror</span></code></a>, <a class="reference internal" href="#namedconf-statement-type hint" title="namedconf-statement-type hint"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">hint</span></code></a>, <a class="reference internal" href="#namedconf-statement-type stub" title="namedconf-statement-type stub"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">stub</span></code></a>, <a class="reference internal" href="#namedconf-statement-type static-stub" title="namedconf-statement-type static-stub"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">static-stub</span></code></a>,
<a class="reference internal" href="#namedconf-statement-type forward" title="namedconf-statement-type forward"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forward</span></code></a>, <a class="reference internal" href="#namedconf-statement-type redirect" title="namedconf-statement-type redirect"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">redirect</span></code></a>, or
<a class="reference internal" href="#namedconf-statement-type delegation-only" title="namedconf-statement-type delegation-only"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">delegation-only</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-type primary">
<span class="sig-name descname"><span class="pre">type</span> <span class="pre">primary</span></span><a class="headerlink" href="#namedconf-statement-type primary" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">class</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">primary</span><span class="p">;</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span><span class="o">-</span><span class="n">on</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">transfer</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">transport</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">update</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">also</span><span class="o">-</span><span class="n">notify</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">remote</span><span class="o">-</span><span class="n">servers</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">)</span> <span class="p">[</span> <span class="n">key</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">tls</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">alt</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">alt</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">auto</span><span class="o">-</span><span class="n">dnssec</span> <span class="p">(</span> <span class="n">allow</span> <span class="o">|</span> <span class="n">maintain</span> <span class="o">|</span> <span class="n">off</span> <span class="p">);</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">check</span><span class="o">-</span><span class="n">dup</span><span class="o">-</span><span class="n">records</span> <span class="p">(</span> <span class="n">fail</span> <span class="o">|</span> <span class="n">warn</span> <span class="o">|</span> <span class="n">ignore</span> <span class="p">);</span>
<span class="n">check</span><span class="o">-</span><span class="n">integrity</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">check</span><span class="o">-</span><span class="n">mx</span> <span class="p">(</span> <span class="n">fail</span> <span class="o">|</span> <span class="n">warn</span> <span class="o">|</span> <span class="n">ignore</span> <span class="p">);</span>
<span class="n">check</span><span class="o">-</span><span class="n">mx</span><span class="o">-</span><span class="n">cname</span> <span class="p">(</span> <span class="n">fail</span> <span class="o">|</span> <span class="n">warn</span> <span class="o">|</span> <span class="n">ignore</span> <span class="p">);</span>
<span class="n">check</span><span class="o">-</span><span class="n">names</span> <span class="p">(</span> <span class="n">fail</span> <span class="o">|</span> <span class="n">warn</span> <span class="o">|</span> <span class="n">ignore</span> <span class="p">);</span>
<span class="n">check</span><span class="o">-</span><span class="n">sibling</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">check</span><span class="o">-</span><span class="n">spf</span> <span class="p">(</span> <span class="n">warn</span> <span class="o">|</span> <span class="n">ignore</span> <span class="p">);</span>
<span class="n">check</span><span class="o">-</span><span class="n">srv</span><span class="o">-</span><span class="n">cname</span> <span class="p">(</span> <span class="n">fail</span> <span class="o">|</span> <span class="n">warn</span> <span class="o">|</span> <span class="n">ignore</span> <span class="p">);</span>
<span class="n">check</span><span class="o">-</span><span class="n">wildcard</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">database</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="n">dialup</span> <span class="p">(</span> <span class="n">notify</span> <span class="o">|</span> <span class="n">notify</span><span class="o">-</span><span class="n">passive</span> <span class="o">|</span> <span class="n">passive</span> <span class="o">|</span> <span class="n">refresh</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">dlz</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="n">dnskey</span><span class="o">-</span><span class="n">sig</span><span class="o">-</span><span class="n">validity</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">dnssec</span><span class="o">-</span><span class="n">dnskey</span><span class="o">-</span><span class="n">kskonly</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">dnssec</span><span class="o">-</span><span class="n">loadkeys</span><span class="o">-</span><span class="n">interval</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">dnssec</span><span class="o">-</span><span class="n">policy</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="n">dnssec</span><span class="o">-</span><span class="n">secure</span><span class="o">-</span><span class="n">to</span><span class="o">-</span><span class="n">insecure</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">dnssec</span><span class="o">-</span><span class="n">update</span><span class="o">-</span><span class="n">mode</span> <span class="p">(</span> <span class="n">maintain</span> <span class="o">|</span> <span class="n">no</span><span class="o">-</span><span class="n">resign</span> <span class="p">);</span>
<span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">forward</span> <span class="p">(</span> <span class="n">first</span> <span class="o">|</span> <span class="n">only</span> <span class="p">);</span>
<span class="n">forwarders</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">)</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">inline</span><span class="o">-</span><span class="n">signing</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">ixfr</span><span class="o">-</span><span class="n">from</span><span class="o">-</span><span class="n">differences</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">journal</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">key</span><span class="o">-</span><span class="n">directory</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">masterfile</span><span class="o">-</span><span class="nb">format</span> <span class="p">(</span> <span class="n">raw</span> <span class="o">|</span> <span class="n">text</span> <span class="p">);</span>
<span class="n">masterfile</span><span class="o">-</span><span class="n">style</span> <span class="p">(</span> <span class="n">full</span> <span class="o">|</span> <span class="n">relative</span> <span class="p">);</span>
<span class="nb">max</span><span class="o">-</span><span class="n">ixfr</span><span class="o">-</span><span class="n">ratio</span> <span class="p">(</span> <span class="n">unlimited</span> <span class="o">|</span> <span class="o"><</span><span class="n">percentage</span><span class="o">></span> <span class="p">);</span>
<span class="nb">max</span><span class="o">-</span><span class="n">journal</span><span class="o">-</span><span class="n">size</span> <span class="p">(</span> <span class="n">default</span> <span class="o">|</span> <span class="n">unlimited</span> <span class="o">|</span> <span class="o"><</span><span class="n">sizeval</span><span class="o">></span> <span class="p">);</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="nb">type</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">idle</span><span class="o">-</span><span class="n">out</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">time</span><span class="o">-</span><span class="n">out</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">types</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">name</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">zone</span><span class="o">-</span><span class="n">ttl</span> <span class="p">(</span> <span class="n">unlimited</span> <span class="o">|</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span> <span class="p">);</span>
<span class="n">notify</span> <span class="p">(</span> <span class="n">explicit</span> <span class="o">|</span> <span class="n">master</span><span class="o">-</span><span class="n">only</span> <span class="o">|</span> <span class="n">primary</span><span class="o">-</span><span class="n">only</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span>
<span class="n">notify</span><span class="o">-</span><span class="n">delay</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">notify</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">notify</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">notify</span><span class="o">-</span><span class="n">to</span><span class="o">-</span><span class="n">soa</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">nsec3</span><span class="o">-</span><span class="n">test</span><span class="o">-</span><span class="n">zone</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span> <span class="o">//</span> <span class="n">test</span> <span class="n">only</span>
<span class="n">parental</span><span class="o">-</span><span class="n">agents</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">remote</span><span class="o">-</span><span class="n">servers</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">)</span> <span class="p">[</span> <span class="n">key</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">tls</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">parental</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">parental</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">serial</span><span class="o">-</span><span class="n">update</span><span class="o">-</span><span class="n">method</span> <span class="p">(</span> <span class="n">date</span> <span class="o">|</span> <span class="n">increment</span> <span class="o">|</span> <span class="n">unixtime</span> <span class="p">);</span>
<span class="n">sig</span><span class="o">-</span><span class="n">signing</span><span class="o">-</span><span class="n">nodes</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">sig</span><span class="o">-</span><span class="n">signing</span><span class="o">-</span><span class="n">signatures</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">sig</span><span class="o">-</span><span class="n">signing</span><span class="o">-</span><span class="nb">type</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">sig</span><span class="o">-</span><span class="n">validity</span><span class="o">-</span><span class="n">interval</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">];</span>
<span class="n">update</span><span class="o">-</span><span class="n">check</span><span class="o">-</span><span class="n">ksk</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">update</span><span class="o">-</span><span class="n">policy</span> <span class="p">(</span> <span class="n">local</span> <span class="o">|</span> <span class="p">{</span> <span class="p">(</span> <span class="n">deny</span> <span class="o">|</span> <span class="n">grant</span> <span class="p">)</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">(</span> <span class="mi">6</span><span class="n">to4</span><span class="o">-</span><span class="bp">self</span> <span class="o">|</span> <span class="n">external</span> <span class="o">|</span> <span class="n">krb5</span><span class="o">-</span><span class="bp">self</span> <span class="o">|</span> <span class="n">krb5</span><span class="o">-</span><span class="n">selfsub</span> <span class="o">|</span> <span class="n">krb5</span><span class="o">-</span><span class="n">subdomain</span> <span class="o">|</span> <span class="n">krb5</span><span class="o">-</span><span class="n">subdomain</span><span class="o">-</span><span class="bp">self</span><span class="o">-</span><span class="n">rhs</span> <span class="o">|</span> <span class="n">ms</span><span class="o">-</span><span class="bp">self</span> <span class="o">|</span> <span class="n">ms</span><span class="o">-</span><span class="n">selfsub</span> <span class="o">|</span> <span class="n">ms</span><span class="o">-</span><span class="n">subdomain</span> <span class="o">|</span> <span class="n">ms</span><span class="o">-</span><span class="n">subdomain</span><span class="o">-</span><span class="bp">self</span><span class="o">-</span><span class="n">rhs</span> <span class="o">|</span> <span class="n">name</span> <span class="o">|</span> <span class="bp">self</span> <span class="o">|</span> <span class="n">selfsub</span> <span class="o">|</span> <span class="n">selfwild</span> <span class="o">|</span> <span class="n">subdomain</span> <span class="o">|</span> <span class="n">tcp</span><span class="o">-</span><span class="bp">self</span> <span class="o">|</span> <span class="n">wildcard</span> <span class="o">|</span> <span class="n">zonesub</span> <span class="p">)</span> <span class="p">[</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="o"><</span><span class="n">rrtypelist</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">}</span> <span class="p">);</span>
<span class="n">zero</span><span class="o">-</span><span class="n">no</span><span class="o">-</span><span class="n">soa</span><span class="o">-</span><span class="n">ttl</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">zone</span><span class="o">-</span><span class="n">statistics</span> <span class="p">(</span> <span class="n">full</span> <span class="o">|</span> <span class="n">terse</span> <span class="o">|</span> <span class="n">none</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>zone, view.zone</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Contains the main copy of the data for a zone.</p>
</p>
<p>A primary zone has a master copy of the data for the zone and is able
to provide authoritative answers for it. Type <code class="docutils literal notranslate"><span class="pre">master</span></code> is a synonym
for <a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primary</span></code></a>.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-type secondary">
<span class="sig-name descname"><span class="pre">type</span> <span class="pre">secondary</span></span><a class="headerlink" href="#namedconf-statement-type secondary" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">class</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">secondary</span><span class="p">;</span>
<span class="n">allow</span><span class="o">-</span><span class="n">notify</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span><span class="o">-</span><span class="n">on</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">transfer</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">transport</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">update</span><span class="o">-</span><span class="n">forwarding</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">also</span><span class="o">-</span><span class="n">notify</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">remote</span><span class="o">-</span><span class="n">servers</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">)</span> <span class="p">[</span> <span class="n">key</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">tls</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">alt</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">alt</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">auto</span><span class="o">-</span><span class="n">dnssec</span> <span class="p">(</span> <span class="n">allow</span> <span class="o">|</span> <span class="n">maintain</span> <span class="o">|</span> <span class="n">off</span> <span class="p">);</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">check</span><span class="o">-</span><span class="n">names</span> <span class="p">(</span> <span class="n">fail</span> <span class="o">|</span> <span class="n">warn</span> <span class="o">|</span> <span class="n">ignore</span> <span class="p">);</span>
<span class="n">database</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="n">dialup</span> <span class="p">(</span> <span class="n">notify</span> <span class="o">|</span> <span class="n">notify</span><span class="o">-</span><span class="n">passive</span> <span class="o">|</span> <span class="n">passive</span> <span class="o">|</span> <span class="n">refresh</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">dlz</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="n">dnskey</span><span class="o">-</span><span class="n">sig</span><span class="o">-</span><span class="n">validity</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">dnssec</span><span class="o">-</span><span class="n">dnskey</span><span class="o">-</span><span class="n">kskonly</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">dnssec</span><span class="o">-</span><span class="n">loadkeys</span><span class="o">-</span><span class="n">interval</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">dnssec</span><span class="o">-</span><span class="n">policy</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="n">dnssec</span><span class="o">-</span><span class="n">update</span><span class="o">-</span><span class="n">mode</span> <span class="p">(</span> <span class="n">maintain</span> <span class="o">|</span> <span class="n">no</span><span class="o">-</span><span class="n">resign</span> <span class="p">);</span>
<span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">forward</span> <span class="p">(</span> <span class="n">first</span> <span class="o">|</span> <span class="n">only</span> <span class="p">);</span>
<span class="n">forwarders</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">)</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">inline</span><span class="o">-</span><span class="n">signing</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">ixfr</span><span class="o">-</span><span class="n">from</span><span class="o">-</span><span class="n">differences</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">journal</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">key</span><span class="o">-</span><span class="n">directory</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">masterfile</span><span class="o">-</span><span class="nb">format</span> <span class="p">(</span> <span class="n">raw</span> <span class="o">|</span> <span class="n">text</span> <span class="p">);</span>
<span class="n">masterfile</span><span class="o">-</span><span class="n">style</span> <span class="p">(</span> <span class="n">full</span> <span class="o">|</span> <span class="n">relative</span> <span class="p">);</span>
<span class="nb">max</span><span class="o">-</span><span class="n">ixfr</span><span class="o">-</span><span class="n">ratio</span> <span class="p">(</span> <span class="n">unlimited</span> <span class="o">|</span> <span class="o"><</span><span class="n">percentage</span><span class="o">></span> <span class="p">);</span>
<span class="nb">max</span><span class="o">-</span><span class="n">journal</span><span class="o">-</span><span class="n">size</span> <span class="p">(</span> <span class="n">default</span> <span class="o">|</span> <span class="n">unlimited</span> <span class="o">|</span> <span class="o"><</span><span class="n">sizeval</span><span class="o">></span> <span class="p">);</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="nb">type</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">refresh</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">retry</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">idle</span><span class="o">-</span><span class="ow">in</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">idle</span><span class="o">-</span><span class="n">out</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">time</span><span class="o">-</span><span class="ow">in</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">time</span><span class="o">-</span><span class="n">out</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">types</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">name</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">min</span><span class="o">-</span><span class="n">refresh</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">min</span><span class="o">-</span><span class="n">retry</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">multi</span><span class="o">-</span><span class="n">master</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">notify</span> <span class="p">(</span> <span class="n">explicit</span> <span class="o">|</span> <span class="n">master</span><span class="o">-</span><span class="n">only</span> <span class="o">|</span> <span class="n">primary</span><span class="o">-</span><span class="n">only</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span>
<span class="n">notify</span><span class="o">-</span><span class="n">delay</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">notify</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">notify</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">notify</span><span class="o">-</span><span class="n">to</span><span class="o">-</span><span class="n">soa</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">nsec3</span><span class="o">-</span><span class="n">test</span><span class="o">-</span><span class="n">zone</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span> <span class="o">//</span> <span class="n">test</span> <span class="n">only</span>
<span class="n">parental</span><span class="o">-</span><span class="n">agents</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">remote</span><span class="o">-</span><span class="n">servers</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">)</span> <span class="p">[</span> <span class="n">key</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">tls</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">parental</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">parental</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">primaries</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">remote</span><span class="o">-</span><span class="n">servers</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">)</span> <span class="p">[</span> <span class="n">key</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">tls</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">request</span><span class="o">-</span><span class="n">expire</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">request</span><span class="o">-</span><span class="n">ixfr</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">sig</span><span class="o">-</span><span class="n">signing</span><span class="o">-</span><span class="n">nodes</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">sig</span><span class="o">-</span><span class="n">signing</span><span class="o">-</span><span class="n">signatures</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">sig</span><span class="o">-</span><span class="n">signing</span><span class="o">-</span><span class="nb">type</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">sig</span><span class="o">-</span><span class="n">validity</span><span class="o">-</span><span class="n">interval</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">];</span>
<span class="n">transfer</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">transfer</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="k">try</span><span class="o">-</span><span class="n">tcp</span><span class="o">-</span><span class="n">refresh</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">update</span><span class="o">-</span><span class="n">check</span><span class="o">-</span><span class="n">ksk</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">use</span><span class="o">-</span><span class="n">alt</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">source</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">zero</span><span class="o">-</span><span class="n">no</span><span class="o">-</span><span class="n">soa</span><span class="o">-</span><span class="n">ttl</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">zone</span><span class="o">-</span><span class="n">statistics</span> <span class="p">(</span> <span class="n">full</span> <span class="o">|</span> <span class="n">terse</span> <span class="o">|</span> <span class="n">none</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>zone, view.zone</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Contains a duplicate of the data for a zone that has been transferred from a primary server.</p>
</p>
<p>A secondary zone is a replica of a primary zone. Type <code class="docutils literal notranslate"><span class="pre">slave</span></code> is a
synonym for <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">secondary</span></code></a>. The <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> list
specifies one or more IP addresses of primary servers that the secondary
contacts to update its copy of the zone.</p>
<p>Primaries list elements can also be names of other primaries lists. By
default, transfers are made from port 53 on the servers; this can be
changed for all servers by specifying a port number before the list of IP
addresses, or on a per-server basis after the IP address. Authentication
to the primary can also be done with per-server TSIG keys.</p>
<p>A secondary zone is a replica of a primary zone. Type <code class="docutils literal notranslate"><span class="pre">slave</span></code> is a
synonym for <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">secondary</span></code></a>. The <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> list
specifies one or more IP addresses of primary servers that the secondary
contacts to update its copy of the zone.</p>
<p>A zone may refresh on timer or on receipt of a notify. If a valid notify is
received where the notify carries a serial number larger than the one in the
SOA currently served, then the secondary will schedule a zone refresh.</p>
<p>A notify is considered valid if the sender is one of the servers in the NS
RRset for the zone, has been explicitly allowed using an <a class="reference internal" href="#namedconf-statement-allow-notify" title="namedconf-statement-allow-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-notify</span></code></a>
clause, or is from an address listed in the primary servers clause.</p>
<p>If no notifies have been received, the server will try to refresh the zone.
The REFRESH field in the SOA record determines how long after the last zone
update it should query the primaries for the SOA record. Again, if the
SOA record contains a serial number larger than the one in the SOA currently
served, a zone refresh is scheduled. If a notify is received while a
refresh is in progress, the serial number of the notify is checked and if
it is larger, another refresh for the zone is queued. There will at most
be one zone refresh queued.</p>
<p>The primary servers are queried in turn, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref any std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> will move on to the
next server in the list if either it is unable to get a valid response from
the server it is currently querying, or the primary being queried returns
the same or smaller SOA than the secondary is currently serving. On the
first SOA received that has a serial bigger than the one currently served,
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref any std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> will initiate a zone transfer with that server. Once the zone
transfer has been received and the zone has been updated, then this zone
refresh is complete, and no other servers are tried.</p>
<p>When receiving a notify, <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref any std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> does not first query the sender of
the notify. It will continue with the next server in the list that
transferred the zone, skipping over unreachable servers. A primary is
considered unreachable if the secondary cannot get a response from the
server. This state will be cached for 10 minutes, or until a notify is
received from that address.</p>
<p>Furthermore, a zone is refreshed when the secondary server is restarted,
or when a <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-refresh"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">refresh</span></code></a> command is received.</p>
<p>If a file is specified, then the replica is written to this file whenever the zone
is changed, and reloaded from this file on a server restart. Use of a file
is recommended, since it often speeds server startup and eliminates a
needless waste of bandwidth. Note that for large numbers (in the tens or
hundreds of thousands) of zones per server, it is best to use a two-level
naming scheme for zone filenames. For example, a secondary server for the
zone <code class="docutils literal notranslate"><span class="pre">example.com</span></code> might place the zone contents into a file called
<code class="docutils literal notranslate"><span class="pre">ex/example.com</span></code>, where <code class="docutils literal notranslate"><span class="pre">ex/</span></code> is just the first two letters of the zone
name. (Most operating systems behave very slowly if there are 100,000 files
in a single directory.)</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-type mirror">
<span class="sig-name descname"><span class="pre">type</span> <span class="pre">mirror</span></span><a class="headerlink" href="#namedconf-statement-type mirror" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">class</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">mirror</span><span class="p">;</span>
<span class="n">allow</span><span class="o">-</span><span class="n">notify</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span><span class="o">-</span><span class="n">on</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">transfer</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">transport</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">update</span><span class="o">-</span><span class="n">forwarding</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">also</span><span class="o">-</span><span class="n">notify</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">remote</span><span class="o">-</span><span class="n">servers</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">)</span> <span class="p">[</span> <span class="n">key</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">tls</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">alt</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">alt</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">check</span><span class="o">-</span><span class="n">names</span> <span class="p">(</span> <span class="n">fail</span> <span class="o">|</span> <span class="n">warn</span> <span class="o">|</span> <span class="n">ignore</span> <span class="p">);</span>
<span class="n">database</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">ixfr</span><span class="o">-</span><span class="n">from</span><span class="o">-</span><span class="n">differences</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">journal</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">masterfile</span><span class="o">-</span><span class="nb">format</span> <span class="p">(</span> <span class="n">raw</span> <span class="o">|</span> <span class="n">text</span> <span class="p">);</span>
<span class="n">masterfile</span><span class="o">-</span><span class="n">style</span> <span class="p">(</span> <span class="n">full</span> <span class="o">|</span> <span class="n">relative</span> <span class="p">);</span>
<span class="nb">max</span><span class="o">-</span><span class="n">ixfr</span><span class="o">-</span><span class="n">ratio</span> <span class="p">(</span> <span class="n">unlimited</span> <span class="o">|</span> <span class="o"><</span><span class="n">percentage</span><span class="o">></span> <span class="p">);</span>
<span class="nb">max</span><span class="o">-</span><span class="n">journal</span><span class="o">-</span><span class="n">size</span> <span class="p">(</span> <span class="n">default</span> <span class="o">|</span> <span class="n">unlimited</span> <span class="o">|</span> <span class="o"><</span><span class="n">sizeval</span><span class="o">></span> <span class="p">);</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="nb">type</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">refresh</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">retry</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">idle</span><span class="o">-</span><span class="ow">in</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">idle</span><span class="o">-</span><span class="n">out</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">time</span><span class="o">-</span><span class="ow">in</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">time</span><span class="o">-</span><span class="n">out</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">types</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">name</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">min</span><span class="o">-</span><span class="n">refresh</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">min</span><span class="o">-</span><span class="n">retry</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">multi</span><span class="o">-</span><span class="n">master</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">notify</span> <span class="p">(</span> <span class="n">explicit</span> <span class="o">|</span> <span class="n">master</span><span class="o">-</span><span class="n">only</span> <span class="o">|</span> <span class="n">primary</span><span class="o">-</span><span class="n">only</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span>
<span class="n">notify</span><span class="o">-</span><span class="n">delay</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">notify</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">notify</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">primaries</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">remote</span><span class="o">-</span><span class="n">servers</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">)</span> <span class="p">[</span> <span class="n">key</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">tls</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">request</span><span class="o">-</span><span class="n">expire</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">request</span><span class="o">-</span><span class="n">ixfr</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">transfer</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">transfer</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="k">try</span><span class="o">-</span><span class="n">tcp</span><span class="o">-</span><span class="n">refresh</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">use</span><span class="o">-</span><span class="n">alt</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">source</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">zero</span><span class="o">-</span><span class="n">no</span><span class="o">-</span><span class="n">soa</span><span class="o">-</span><span class="n">ttl</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">zone</span><span class="o">-</span><span class="n">statistics</span> <span class="p">(</span> <span class="n">full</span> <span class="o">|</span> <span class="n">terse</span> <span class="o">|</span> <span class="n">none</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>zone, view.zone</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Contains a DNSSEC-validated duplicate of the main data for a zone.</p>
</p>
<p>A mirror zone is similar to a zone of <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span> <span class="pre">secondary</span></code></a>, except its
data is subject to DNSSEC validation before being used in answers.
Validation is applied to the entire zone during the zone transfer
process, and again when the zone file is loaded from disk upon
restarting <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>. If validation of a new version of a mirror zone
fails, a retransfer is scheduled; in the meantime, the most recent
correctly validated version of that zone is used until it either
expires or a newer version validates correctly. If no usable zone
data is available for a mirror zone, due to either transfer failure
or expiration, traditional DNS recursion is used to look up the
answers instead. Mirror zones cannot be used in a view that does not
have recursion enabled.</p>
<p>Answers coming from a mirror zone look almost exactly like answers
from a zone of <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span> <span class="pre">secondary</span></code></a>, with the notable exceptions that
the AA bit (“authoritative answer”) is not set, and the AD bit
(“authenticated data”) is.</p>
<p>Mirror zones are intended to be used to set up a fast local copy of
the root zone (see <span class="target" id="index-34"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc8806.html"><strong>RFC 8806</strong></a>). A default list of primary servers
for the IANA root zone is built into <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>, so its mirroring can
be enabled using the following configuration:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="s2">"."</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">mirror</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
<p>Mirror zone validation always happens for the entire zone contents.
This ensures that each version of the zone used by the resolver is
fully self-consistent with respect to DNSSEC. For incoming mirror
zone IXFRs, every revision of the zone contained in the IXFR sequence
is validated independently, in the order in which the zone revisions
appear on the wire. For this reason, it might be useful to force use
of AXFR for mirror zones by setting <code class="docutils literal notranslate"><span class="pre">request-ixfr</span> <span class="pre">no;</span></code> for the
relevant zone (or view). Other, more efficient zone verification
methods may be added in the future.</p>
<p>To make mirror zone contents persist between <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> restarts, use
the <a class="reference internal" href="#namedconf-statement-file" title="namedconf-statement-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">file</span></code></a> option.</p>
<p>Mirroring a zone other than root requires an explicit list of primary
servers to be provided using the <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> option (see
<a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> for details), and a key-signing key (KSK)
for the specified zone to be explicitly configured as a trust anchor
(see <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>).</p>
<p>When configuring NOTIFY for a mirror zone, only <code class="docutils literal notranslate"><span class="pre">notify</span> <span class="pre">no;</span></code> and
<code class="docutils literal notranslate"><span class="pre">notify</span> <span class="pre">explicit;</span></code> can be used at the zone level; any other
<a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify</span></code></a> setting at the zone level is a configuration error. Using
any other <a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify</span></code></a> setting at the <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> or <a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">view</span></code></a> level
causes that setting to be overridden with <code class="docutils literal notranslate"><span class="pre">notify</span> <span class="pre">explicit;</span></code> for
the mirror zone. The global default for the <a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify</span></code></a> option is
<code class="docutils literal notranslate"><span class="pre">yes</span></code>, so mirror zones are by default configured with <code class="docutils literal notranslate"><span class="pre">notify</span>
<span class="pre">explicit;</span></code>.</p>
<p>Outgoing transfers of mirror zones are disabled by default but may be
enabled using <a class="reference internal" href="#namedconf-statement-allow-transfer" title="namedconf-statement-allow-transfer"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-transfer</span></code></a>.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Use of this zone type with any zone other than the root should be
considered <em>experimental</em> and may cause performance issues,
especially for zones that are large and/or frequently updated.</p>
</div>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-type hint">
<span class="sig-name descname"><span class="pre">type</span> <span class="pre">hint</span></span><a class="headerlink" href="#namedconf-statement-type hint" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">class</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">hint</span><span class="p">;</span>
<span class="n">check</span><span class="o">-</span><span class="n">names</span> <span class="p">(</span> <span class="n">fail</span> <span class="o">|</span> <span class="n">warn</span> <span class="o">|</span> <span class="n">ignore</span> <span class="p">);</span>
<span class="n">delegation</span><span class="o">-</span><span class="n">only</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>zone, view.zone</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Contains the initial set of root name servers to be used at BIND 9 startup.</p>
</p>
<p>The initial set of root name servers is specified using a hint zone.
When the server starts, it uses the root hints to find a root name
server and get the most recent list of root name servers. If no hint zone
is specified for class IN, the server uses a compiled-in default set of
root servers hints. Classes other than IN have no built-in default hints.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-type stub">
<span class="sig-name descname"><span class="pre">type</span> <span class="pre">stub</span></span><a class="headerlink" href="#namedconf-statement-type stub" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">class</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">stub</span><span class="p">;</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span><span class="o">-</span><span class="n">on</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">check</span><span class="o">-</span><span class="n">names</span> <span class="p">(</span> <span class="n">fail</span> <span class="o">|</span> <span class="n">warn</span> <span class="o">|</span> <span class="n">ignore</span> <span class="p">);</span>
<span class="n">database</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="n">delegation</span><span class="o">-</span><span class="n">only</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">dialup</span> <span class="p">(</span> <span class="n">notify</span> <span class="o">|</span> <span class="n">notify</span><span class="o">-</span><span class="n">passive</span> <span class="o">|</span> <span class="n">passive</span> <span class="o">|</span> <span class="n">refresh</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">forward</span> <span class="p">(</span> <span class="n">first</span> <span class="o">|</span> <span class="n">only</span> <span class="p">);</span>
<span class="n">forwarders</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">)</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">masterfile</span><span class="o">-</span><span class="nb">format</span> <span class="p">(</span> <span class="n">raw</span> <span class="o">|</span> <span class="n">text</span> <span class="p">);</span>
<span class="n">masterfile</span><span class="o">-</span><span class="n">style</span> <span class="p">(</span> <span class="n">full</span> <span class="o">|</span> <span class="n">relative</span> <span class="p">);</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="nb">type</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">refresh</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">retry</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">idle</span><span class="o">-</span><span class="ow">in</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">time</span><span class="o">-</span><span class="ow">in</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">types</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">name</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">min</span><span class="o">-</span><span class="n">refresh</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">min</span><span class="o">-</span><span class="n">retry</span><span class="o">-</span><span class="n">time</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">multi</span><span class="o">-</span><span class="n">master</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span>
<span class="n">primaries</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">remote</span><span class="o">-</span><span class="n">servers</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">)</span> <span class="p">[</span> <span class="n">key</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">tls</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">transfer</span><span class="o">-</span><span class="n">source</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">transfer</span><span class="o">-</span><span class="n">source</span><span class="o">-</span><span class="n">v6</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="o">|</span> <span class="o">*</span> <span class="p">);</span>
<span class="n">use</span><span class="o">-</span><span class="n">alt</span><span class="o">-</span><span class="n">transfer</span><span class="o">-</span><span class="n">source</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">zone</span><span class="o">-</span><span class="n">statistics</span> <span class="p">(</span> <span class="n">full</span> <span class="o">|</span> <span class="n">terse</span> <span class="o">|</span> <span class="n">none</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>zone, view.zone</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Contains a duplicate of the NS records of a primary zone.</p>
</p>
<p>A stub zone is similar to a secondary zone, except that it replicates only
the NS records of a primary zone instead of the entire zone. Stub zones
are not a standard part of the DNS; they are a feature specific to the
BIND implementation.</p>
<p>Stub zones can be used to eliminate the need for a glue NS record in a parent
zone, at the expense of maintaining a stub zone entry and a set of name
server addresses in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>. This usage is not recommended for
new configurations, and BIND 9 supports it only in a limited way. If a BIND 9
primary, serving a parent zone, has child stub
zones configured, all the secondary servers for the parent zone also need to
have the same child stub zones configured.</p>
<p>Stub zones can also be used as a way to force the resolution of a given
domain to use a particular set of authoritative servers. For example, the
caching name servers on a private network using <span class="target" id="index-35"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1918.html"><strong>RFC 1918</strong></a> addressing may be
configured with stub zones for <code class="docutils literal notranslate"><span class="pre">10.in-addr.arpa</span></code> to use a set of
internal name servers as the authoritative servers for that domain.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-type static-stub">
<span class="sig-name descname"><span class="pre">type</span> <span class="pre">static-stub</span></span><a class="headerlink" href="#namedconf-statement-type static-stub" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">class</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">static</span><span class="o">-</span><span class="n">stub</span><span class="p">;</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span><span class="o">-</span><span class="n">on</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">forward</span> <span class="p">(</span> <span class="n">first</span> <span class="o">|</span> <span class="n">only</span> <span class="p">);</span>
<span class="n">forwarders</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">)</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="nb">type</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">types</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">name</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="n">server</span><span class="o">-</span><span class="n">addresses</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">);</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">server</span><span class="o">-</span><span class="n">names</span> <span class="p">{</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">zone</span><span class="o">-</span><span class="n">statistics</span> <span class="p">(</span> <span class="n">full</span> <span class="o">|</span> <span class="n">terse</span> <span class="o">|</span> <span class="n">none</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>zone, view.zone</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Contains a duplicate of the NS records of a primary zone, but statically configured rather than transferred from a primary server.</p>
</p>
<p>A static-stub zone is similar to a stub zone, with the following
exceptions: the zone data is statically configured, rather than
transferred from a primary server; and when recursion is necessary for a query
that matches a static-stub zone, the locally configured data (name server
names and glue addresses) is always used, even if different authoritative
information is cached.</p>
<p>Zone data is configured via the <a class="reference internal" href="#namedconf-statement-server-addresses" title="namedconf-statement-server-addresses"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">server-addresses</span></code></a> and <a class="reference internal" href="#namedconf-statement-server-names" title="namedconf-statement-server-names"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">server-names</span></code></a>
zone options.</p>
<p>The zone data is maintained in the form of NS and (if necessary) glue A or
AAAA RRs internally, which can be seen by dumping zone databases with
<a class="reference internal" href="manpages.html#cmdoption-rndc-arg-dumpdb"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">dumpdb</span> <span class="pre">-all</span></code></a>. The configured RRs are considered local configuration
parameters rather than public data. Non-recursive queries (i.e., those
with the RD bit off) to a static-stub zone are therefore prohibited and
are responded to with REFUSED.</p>
<p>Since the data is statically configured, no zone maintenance action takes
place for a static-stub zone. For example, there is no periodic refresh
attempt, and an incoming notify message is rejected with an rcode
of NOTAUTH.</p>
<p>Each static-stub zone is configured with internally generated NS and (if
necessary) glue A or AAAA RRs.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-type forward">
<span class="sig-name descname"><span class="pre">type</span> <span class="pre">forward</span></span><a class="headerlink" href="#namedconf-statement-type forward" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">class</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">forward</span><span class="p">;</span>
<span class="n">delegation</span><span class="o">-</span><span class="n">only</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span><span class="p">;</span> <span class="o">//</span> <span class="n">deprecated</span>
<span class="n">forward</span> <span class="p">(</span> <span class="n">first</span> <span class="o">|</span> <span class="n">only</span> <span class="p">);</span>
<span class="n">forwarders</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">)</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>zone, view.zone</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Contains forwarding statements that apply to queries within a given domain.</p>
</p>
<p>A forward zone is a way to configure forwarding on a per-domain basis.
A <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statement of type <a class="reference internal" href="#namedconf-statement-forward" title="namedconf-statement-forward"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forward</span></code></a> can contain a <a class="reference internal" href="#namedconf-statement-forward" title="namedconf-statement-forward"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forward</span></code></a> and/or
<a class="reference internal" href="#namedconf-statement-forwarders" title="namedconf-statement-forwarders"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forwarders</span></code></a> statement, which applies to queries within the domain
given by the zone name. If no <a class="reference internal" href="#namedconf-statement-forwarders" title="namedconf-statement-forwarders"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forwarders</span></code></a> statement is present, or an
empty list for <a class="reference internal" href="#namedconf-statement-forwarders" title="namedconf-statement-forwarders"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forwarders</span></code></a> is given, then no forwarding is done
for the domain, canceling the effects of any forwarders in the <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>
statement. Thus, to use this type of zone to change the
behavior of the global <a class="reference internal" href="#namedconf-statement-forward" title="namedconf-statement-forward"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forward</span></code></a> option (that is, “forward first” to,
then “forward only”, or vice versa), but use the same servers as set
globally, re-specify the global forwarders.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-type redirect">
<span class="sig-name descname"><span class="pre">type</span> <span class="pre">redirect</span></span><a class="headerlink" href="#namedconf-statement-type redirect" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">class</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">redirect</span><span class="p">;</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">allow</span><span class="o">-</span><span class="n">query</span><span class="o">-</span><span class="n">on</span> <span class="p">{</span> <span class="o"><</span><span class="n">address_match_element</span><span class="o">></span><span class="p">;</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">dlz</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="n">file</span> <span class="o"><</span><span class="n">quoted_string</span><span class="o">></span><span class="p">;</span>
<span class="n">masterfile</span><span class="o">-</span><span class="nb">format</span> <span class="p">(</span> <span class="n">raw</span> <span class="o">|</span> <span class="n">text</span> <span class="p">);</span>
<span class="n">masterfile</span><span class="o">-</span><span class="n">style</span> <span class="p">(</span> <span class="n">full</span> <span class="o">|</span> <span class="n">relative</span> <span class="p">);</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">records</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="nb">type</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">types</span><span class="o">-</span><span class="n">per</span><span class="o">-</span><span class="n">name</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span><span class="p">;</span>
<span class="nb">max</span><span class="o">-</span><span class="n">zone</span><span class="o">-</span><span class="n">ttl</span> <span class="p">(</span> <span class="n">unlimited</span> <span class="o">|</span> <span class="o"><</span><span class="n">duration</span><span class="o">></span> <span class="p">);</span>
<span class="n">primaries</span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span> <span class="p">(</span> <span class="o"><</span><span class="n">remote</span><span class="o">-</span><span class="n">servers</span><span class="o">></span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv4_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="o">|</span> <span class="o"><</span><span class="n">ipv6_address</span><span class="o">></span> <span class="p">[</span> <span class="n">port</span> <span class="o"><</span><span class="n">integer</span><span class="o">></span> <span class="p">]</span> <span class="p">)</span> <span class="p">[</span> <span class="n">key</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">]</span> <span class="p">[</span> <span class="n">tls</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">];</span> <span class="o">...</span> <span class="p">};</span>
<span class="n">zone</span><span class="o">-</span><span class="n">statistics</span> <span class="p">(</span> <span class="n">full</span> <span class="o">|</span> <span class="n">terse</span> <span class="o">|</span> <span class="n">none</span> <span class="o">|</span> <span class="o"><</span><span class="n">boolean</span><span class="o">></span> <span class="p">);</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>zone, view.zone</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Contains information to answer queries when normal resolution would return NXDOMAIN.</p>
</p>
<p>Redirect zones are used to provide answers to queries when normal
resolution would result in NXDOMAIN being returned. Only one redirect zone
is supported per view. <a class="reference internal" href="#namedconf-statement-allow-query" title="namedconf-statement-allow-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query</span></code></a> can be used to restrict which
clients see these answers.</p>
<p>If the client has requested DNSSEC records (DO=1) and the NXDOMAIN response
is signed, no substitution occurs.</p>
<p>To redirect all NXDOMAIN responses to 100.100.100.2 and
2001:ffff:ffff::100.100.100.2, configure a type <a class="reference internal" href="#namedconf-statement-type redirect" title="namedconf-statement-type redirect"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">redirect</span></code></a> zone
named “.”, with the zone file containing wildcard records that point to
the desired addresses: <code class="docutils literal notranslate"><span class="pre">*.</span> <span class="pre">IN</span> <span class="pre">A</span> <span class="pre">100.100.100.2</span></code> and
<code class="docutils literal notranslate"><span class="pre">*.</span> <span class="pre">IN</span> <span class="pre">AAAA</span> <span class="pre">2001:ffff:ffff::100.100.100.2</span></code>.</p>
<p>As another example, to redirect all Spanish names (under .ES), use similar entries
but with the names <code class="docutils literal notranslate"><span class="pre">*.ES.</span></code> instead of <code class="docutils literal notranslate"><span class="pre">*.</span></code>. To redirect all commercial
Spanish names (under COM.ES), use wildcard entries
called <code class="docutils literal notranslate"><span class="pre">*.COM.ES.</span></code>.</p>
<p>Note that the redirect zone supports all possible types; it is not
limited to A and AAAA records.</p>
<p>If a redirect zone is configured with a <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> option, then it is
transferred in as if it were a secondary zone. Otherwise, it is loaded from a
file as if it were a primary zone.</p>
<p>Because redirect zones are not referenced directly by name, they are not
kept in the zone lookup table with normal primary and secondary zones. To reload
a redirect zone, use <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-reload"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">reload</span> <span class="pre">-redirect</span></code></a>; to retransfer a
redirect zone configured as a secondary, use <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-retransfer"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">retransfer</span> <span class="pre">-redirect</span></code></a>.
When using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-reload"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">reload</span></code></a> without specifying a zone name, redirect
zones are reloaded along with other zones.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-type delegation-only">
<span class="sig-name descname"><span class="pre">type</span> <span class="pre">delegation-only</span></span><a class="headerlink" href="#namedconf-statement-type delegation-only" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">class</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">delegation</span><span class="o">-</span><span class="n">only</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Blocks: </strong>zone, view.zone</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Enforces the delegation-only status of infrastructure zones (COM, NET, ORG, etc.).</p>
</p>
<p>This zone type is used to enforce the delegation-only status of
infrastructure zones (e.g., COM, NET, ORG). Any answer that is received
without an explicit or implicit delegation in the authority section is
treated as NXDOMAIN. This does not apply to the zone apex, and should
not be applied to leaf zones.</p>
<p><a class="reference internal" href="#namedconf-statement-delegation-only" title="namedconf-statement-delegation-only"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">delegation-only</span></code></a> has no effect on answers received from forwarders.</p>
<p>See caveats in <a class="reference internal" href="#namedconf-statement-root-delegation-only" title="namedconf-statement-root-delegation-only"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">root-delegation-only</span></code></a>.</p>
<p>This zone type is deprecated, and will be rendered non-operational in a
future release.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-in-view">
<span class="sig-name descname"><span class="pre">in-view</span></span><a class="headerlink" href="#namedconf-statement-in-view" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar zone, view.zone: </strong><div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">zone</span> <span class="o"><</span><span class="n">string</span><span class="o">></span> <span class="p">[</span> <span class="o"><</span><span class="n">class</span><span class="o">></span> <span class="p">]</span> <span class="p">{</span>
<span class="ow">in</span><span class="o">-</span><span class="n">view</span> <span class="o"><</span><span class="n">string</span><span class="o">></span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
</p>
<p><strong>Grammar zone (in-view): </strong><code class="docutils literal notranslate"><span class="pre">in-view</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>zone, zone (in-view), view.zone</p>
<p><strong>Tags: </strong>view, zone</p>
<p><p>Specifies the view in which a given zone is defined.</p>
</p>
<p>When using multiple views, a <a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span> <span class="pre">primary</span></code></a> or <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span> <span class="pre">secondary</span></code></a> zone configured
in one view can be referenced in a subsequent view. This allows both views
to use the same zone without the overhead of loading it more than once. This
is configured using a <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statement, with an <a class="reference internal" href="#namedconf-statement-in-view" title="namedconf-statement-in-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">in-view</span></code></a> option
specifying the view in which the zone is defined. A <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statement
containing <a class="reference internal" href="#namedconf-statement-in-view" title="namedconf-statement-in-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">in-view</span></code></a> does not need to specify a type, since that is part
of the zone definition in the other view.</p>
<p>See <a class="reference internal" href="#multiple-views"><span class="std std-ref">Multiple Views</span></a> for more information.</p>
</dd></dl>
</section>
<section id="class">
<h4><span class="section-number">8.2.34.2. </span>Class<a class="headerlink" href="#class" title="Link to this heading"></a></h4>
<p>The zone’s name may optionally be followed by a class. If a class is not
specified, class <code class="docutils literal notranslate"><span class="pre">IN</span></code> (for <code class="docutils literal notranslate"><span class="pre">Internet</span></code>) is assumed. This is correct
for the vast majority of cases.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">hesiod</span></code> class is named for an information service from MIT’s
Project Athena. It was used to share information about various systems
databases, such as users, groups, printers, and so on. The keyword <code class="docutils literal notranslate"><span class="pre">HS</span></code>
is a synonym for hesiod.</p>
<p>Another MIT development is Chaosnet, a LAN protocol created in the
mid-1970s. Zone data for it can be specified with the <code class="docutils literal notranslate"><span class="pre">CHAOS</span></code> class.</p>
</section>
<section id="zone-options">
<span id="id14"></span><h4><span class="section-number">8.2.34.3. </span>Zone Options<a class="headerlink" href="#zone-options" title="Link to this heading"></a></h4>
<dl class="simple">
<dt><a class="reference internal" href="#namedconf-statement-allow-notify" title="namedconf-statement-allow-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-notify</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-allow-notify" title="namedconf-statement-allow-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-notify</span></code></a> in <a class="reference internal" href="#access-control"><span class="std std-ref">Access Control</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-allow-query" title="namedconf-statement-allow-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-allow-query" title="namedconf-statement-allow-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query</span></code></a> in <a class="reference internal" href="#access-control"><span class="std std-ref">Access Control</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-allow-query-on" title="namedconf-statement-allow-query-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-on</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-allow-query-on" title="namedconf-statement-allow-query-on"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-query-on</span></code></a> in <a class="reference internal" href="#access-control"><span class="std std-ref">Access Control</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-allow-transfer" title="namedconf-statement-allow-transfer"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-transfer</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-allow-transfer" title="namedconf-statement-allow-transfer"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-transfer</span></code></a> in <a class="reference internal" href="#access-control"><span class="std std-ref">Access Control</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-allow-update" title="namedconf-statement-allow-update"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-update</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-allow-update" title="namedconf-statement-allow-update"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-update</span></code></a> in <a class="reference internal" href="#access-control"><span class="std std-ref">Access Control</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a></dt><dd><p>This specifies a “Simple Secure Update” policy. See <a class="reference internal" href="#dynamic-update-policies"><span class="std std-ref">Dynamic Update Policies</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-allow-update-forwarding" title="namedconf-statement-allow-update-forwarding"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-update-forwarding</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-allow-update-forwarding" title="namedconf-statement-allow-update-forwarding"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-update-forwarding</span></code></a> in <a class="reference internal" href="#access-control"><span class="std std-ref">Access Control</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a></dt><dd><p>This option is only meaningful if <a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify</span></code></a> is active for this zone. The set of
machines that receive a <code class="docutils literal notranslate"><span class="pre">DNS</span> <span class="pre">NOTIFY</span></code> message for this zone is
made up of all the listed name servers (other than the primary)
for the zone, plus any IP addresses specified with
<a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a>. A port may be specified with each <a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a>
address to send the notify messages to a port other than the default
of 53. A TSIG key may also be specified to cause the <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> to be
signed by the given key. <a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">also-notify</span></code></a> is not meaningful for stub
zones. The default is the empty list.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-check-names" title="namedconf-statement-check-names"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-names</span></code></a></dt><dd><p>This option is used to restrict the character set and syntax of
certain domain names in primary files and/or DNS responses received
from the network. The default varies according to zone type. For
<a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primary</span></code></a> zones the default is <code class="docutils literal notranslate"><span class="pre">fail</span></code>; for <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">secondary</span></code></a> zones the
default is <code class="docutils literal notranslate"><span class="pre">warn</span></code>. It is not implemented for <a class="reference internal" href="#namedconf-statement-type hint" title="namedconf-statement-type hint"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">hint</span></code></a> zones.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-check-mx" title="namedconf-statement-check-mx"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-mx</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-check-mx" title="namedconf-statement-check-mx"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-mx</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-check-spf" title="namedconf-statement-check-spf"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-spf</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-check-spf" title="namedconf-statement-check-spf"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-spf</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-check-wildcard" title="namedconf-statement-check-wildcard"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-wildcard</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-check-wildcard" title="namedconf-statement-check-wildcard"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-wildcard</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-check-integrity" title="namedconf-statement-check-integrity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-integrity</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-check-integrity" title="namedconf-statement-check-integrity"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-integrity</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-check-sibling" title="namedconf-statement-check-sibling"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-sibling</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-check-sibling" title="namedconf-statement-check-sibling"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">check-sibling</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-zero-no-soa-ttl" title="namedconf-statement-zero-no-soa-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zero-no-soa-ttl</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-zero-no-soa-ttl" title="namedconf-statement-zero-no-soa-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zero-no-soa-ttl</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-update-check-ksk" title="namedconf-statement-update-check-ksk"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-check-ksk</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-update-check-ksk" title="namedconf-statement-update-check-ksk"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-check-ksk</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-dnssec-loadkeys-interval" title="namedconf-statement-dnssec-loadkeys-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-loadkeys-interval</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-dnssec-loadkeys-interval" title="namedconf-statement-dnssec-loadkeys-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-loadkeys-interval</span></code></a> in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-dnssec-update-mode" title="namedconf-statement-dnssec-update-mode"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-update-mode</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-dnssec-update-mode" title="namedconf-statement-dnssec-update-mode"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-update-mode</span></code></a> in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-dnssec-dnskey-kskonly" title="namedconf-statement-dnssec-dnskey-kskonly"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-dnskey-kskonly</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-dnssec-dnskey-kskonly" title="namedconf-statement-dnssec-dnskey-kskonly"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-dnskey-kskonly</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-try-tcp-refresh" title="namedconf-statement-try-tcp-refresh"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">try-tcp-refresh</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-try-tcp-refresh" title="namedconf-statement-try-tcp-refresh"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">try-tcp-refresh</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
</dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-database">
<span class="sig-name descname"><span class="pre">database</span></span><a class="headerlink" href="#namedconf-statement-database" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">database</span> <span class="pre"><string>;</span></code></p>
<p><strong>Blocks: </strong>dlz, zone (mirror, primary, secondary, stub), view.dlz</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Specifies the type of database to be used to store zone data.</p>
</p>
<p>This specifies the type of database to be used to store the zone data.
The string following the <a class="reference internal" href="#namedconf-statement-database" title="namedconf-statement-database"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">database</span></code></a> keyword is interpreted as a
list of whitespace-delimited words. The first word identifies the
database type, and any subsequent words are passed as arguments to
the database to be interpreted in a way specific to the database
type.</p>
<p>The default is <code class="docutils literal notranslate"><span class="pre">rbt</span></code>, BIND 9’s native in-memory red-black tree
database. This database does not take arguments.</p>
<p>Other values are possible if additional database drivers have been
linked into the server. Some sample drivers are included with the
distribution but none are linked in by default.</p>
</dd></dl>
<dl class="simple">
<dt><a class="reference internal" href="#namedconf-statement-dialup" title="namedconf-statement-dialup"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dialup</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-dialup" title="namedconf-statement-dialup"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dialup</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
</dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-delegation-only">
<span class="sig-name descname"><span class="pre">delegation-only</span></span><a class="headerlink" href="#namedconf-statement-delegation-only" title="Link to this definition"></a></dt>
<dd><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This option is deprecated and will be removed in a future version of BIND.</p>
</div>
<p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">delegation-only</span> <span class="pre"><boolean>;</span> <span class="pre">//</span> <span class="pre">deprecated</span></code></p>
<p><strong>Blocks: </strong>zone (forward, hint, stub)</p>
<p><strong>Tags: </strong>deprecated</p>
<p><p>Indicates that a forward, hint, or stub zone is to be treated as a delegation-only type zone.</p>
</p>
<p>This flag only applies to forward, hint, and stub zones. If set to
<code class="docutils literal notranslate"><span class="pre">yes</span></code>, then the zone is treated as if it is also a
delegation-only type zone.</p>
<p>See caveats in <a class="reference internal" href="#namedconf-statement-root-delegation-only" title="namedconf-statement-root-delegation-only"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">root-delegation-only</span></code></a>.</p>
<p>This option is deprecated, and will be rendered non-operational in a
future release.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-file">
<span class="sig-name descname"><span class="pre">file</span></span><a class="headerlink" href="#namedconf-statement-file" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar logging.channel: </strong><code class="docutils literal notranslate"><span class="pre">file</span> <span class="pre"><quoted_string></span> <span class="pre">[</span> <span class="pre">versions</span> <span class="pre">(</span> <span class="pre">unlimited</span> <span class="pre">|</span> <span class="pre"><integer></span> <span class="pre">)</span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">size</span> <span class="pre"><size></span> <span class="pre">]</span> <span class="pre">[</span> <span class="pre">suffix</span> <span class="pre">(</span> <span class="pre">increment</span> <span class="pre">|</span> <span class="pre">timestamp</span> <span class="pre">)</span> <span class="pre">];</span></code></p>
<p><strong>Grammar zone (hint, mirror, primary, redirect, secondary, stub): </strong><code class="docutils literal notranslate"><span class="pre">file</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>zone (hint, mirror, primary, redirect, secondary, stub), logging.channel</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Specifies the zone’s filename.</p>
</p>
<p>This sets the zone’s filename. In <a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primary</span></code></a>, <a class="reference internal" href="#namedconf-statement-type hint" title="namedconf-statement-type hint"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">hint</span></code></a>, and <a class="reference internal" href="#namedconf-statement-type redirect" title="namedconf-statement-type redirect"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">redirect</span></code></a>
zones which do not have <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> defined, zone data is loaded from
this file. In <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">secondary</span></code></a>, <a class="reference internal" href="#namedconf-statement-type mirror" title="namedconf-statement-type mirror"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">mirror</span></code></a>, <a class="reference internal" href="#namedconf-statement-type stub" title="namedconf-statement-type stub"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">stub</span></code></a>, and <a class="reference internal" href="#namedconf-statement-type redirect" title="namedconf-statement-type redirect"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">redirect</span></code></a> zones
which do have <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> defined, zone data is retrieved from
another server and saved in this file. This option is not applicable
to other zone types.</p>
</dd></dl>
<dl class="simple">
<dt><a class="reference internal" href="#namedconf-statement-forward" title="namedconf-statement-forward"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forward</span></code></a></dt><dd><p>This option is only meaningful if the zone has a forwarders list. The <code class="docutils literal notranslate"><span class="pre">only</span></code> value
causes the lookup to fail after trying the forwarders and getting no
answer, while <code class="docutils literal notranslate"><span class="pre">first</span></code> allows a normal lookup to be tried.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-forwarders" title="namedconf-statement-forwarders"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forwarders</span></code></a></dt><dd><p>This is used to override the list of global forwarders. If it is not
specified in a zone of type <a class="reference internal" href="#namedconf-statement-forward" title="namedconf-statement-forward"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forward</span></code></a>, no forwarding is done for
the zone and the global options are not used.</p>
</dd>
</dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-journal">
<span class="sig-name descname"><span class="pre">journal</span></span><a class="headerlink" href="#namedconf-statement-journal" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">journal</span> <span class="pre"><quoted_string>;</span></code></p>
<p><strong>Blocks: </strong>zone (mirror, primary, secondary)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Allows the default journal’s filename to be overridden.</p>
</p>
<p>This allows the default journal’s filename to be overridden. The default is
the zone’s filename with “<code class="docutils literal notranslate"><span class="pre">.jnl</span></code>” appended. This is applicable to
<a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primary</span></code></a> and <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">secondary</span></code></a> zones.</p>
</dd></dl>
<dl class="simple">
<dt><a class="reference internal" href="#namedconf-statement-max-ixfr-ratio" title="namedconf-statement-max-ixfr-ratio"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-ixfr-ratio</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-max-ixfr-ratio" title="namedconf-statement-max-ixfr-ratio"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-ixfr-ratio</span></code></a> in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-max-journal-size" title="namedconf-statement-max-journal-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-journal-size</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-max-journal-size" title="namedconf-statement-max-journal-size"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-journal-size</span></code></a> in <a class="reference internal" href="#server-resource-limits"><span class="std std-ref">Server Resource Limits</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-max-records" title="namedconf-statement-max-records"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-records</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-max-records" title="namedconf-statement-max-records"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-records</span></code></a> in <a class="reference internal" href="#server-resource-limits"><span class="std std-ref">Server Resource Limits</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-max-transfer-time-in" title="namedconf-statement-max-transfer-time-in"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-transfer-time-in</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-max-transfer-time-in" title="namedconf-statement-max-transfer-time-in"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-transfer-time-in</span></code></a> in <a class="reference internal" href="#zone-transfers"><span class="std std-ref">Zone Transfers</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-max-transfer-idle-in" title="namedconf-statement-max-transfer-idle-in"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-transfer-idle-in</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-max-transfer-idle-in" title="namedconf-statement-max-transfer-idle-in"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-transfer-idle-in</span></code></a> in <a class="reference internal" href="#zone-transfers"><span class="std std-ref">Zone Transfers</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-max-transfer-time-out" title="namedconf-statement-max-transfer-time-out"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-transfer-time-out</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-max-transfer-time-out" title="namedconf-statement-max-transfer-time-out"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-transfer-time-out</span></code></a> in <a class="reference internal" href="#zone-transfers"><span class="std std-ref">Zone Transfers</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-max-transfer-idle-out" title="namedconf-statement-max-transfer-idle-out"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-transfer-idle-out</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-max-transfer-idle-out" title="namedconf-statement-max-transfer-idle-out"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-transfer-idle-out</span></code></a> in <a class="reference internal" href="#zone-transfers"><span class="std std-ref">Zone Transfers</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-notify-delay" title="namedconf-statement-notify-delay"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-delay</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-notify-delay" title="namedconf-statement-notify-delay"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-delay</span></code></a> in <a class="reference internal" href="#tuning"><span class="std std-ref">Tuning</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-notify-to-soa" title="namedconf-statement-notify-to-soa"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-to-soa</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-notify-to-soa" title="namedconf-statement-notify-to-soa"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-to-soa</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-zone-statistics" title="namedconf-statement-zone-statistics"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone-statistics</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-zone-statistics" title="namedconf-statement-zone-statistics"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone-statistics</span></code></a> in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>.</p>
</dd>
</dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-server-addresses">
<span class="sig-name descname"><span class="pre">server-addresses</span></span><a class="headerlink" href="#namedconf-statement-server-addresses" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">server-addresses</span> <span class="pre">{</span> <span class="pre">(</span> <span class="pre"><ipv4_address></span> <span class="pre">|</span> <span class="pre"><ipv6_address></span> <span class="pre">);</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>zone (static-stub)</p>
<p><strong>Tags: </strong>query, zone</p>
<p><p>Specifies a list of IP addresses to which queries should be sent in recursive resolution for a static-stub zone.</p>
</p>
<p>This option is only meaningful for static-stub zones. This is a list of IP addresses
to which queries should be sent in recursive resolution for the zone.
A non-empty list for this option internally configures the apex
NS RR with associated glue A or AAAA RRs.</p>
<p>For example, if “example.com” is configured as a static-stub zone
with 192.0.2.1 and 2001:db8::1234 in a <a class="reference internal" href="#namedconf-statement-server-addresses" title="namedconf-statement-server-addresses"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">server-addresses</span></code></a> option,
the following RRs are internally configured:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">example</span><span class="o">.</span><span class="n">com</span><span class="o">.</span> <span class="n">NS</span> <span class="n">example</span><span class="o">.</span><span class="n">com</span><span class="o">.</span>
<span class="n">example</span><span class="o">.</span><span class="n">com</span><span class="o">.</span> <span class="n">A</span> <span class="mf">192.0.2.1</span>
<span class="n">example</span><span class="o">.</span><span class="n">com</span><span class="o">.</span> <span class="n">AAAA</span> <span class="mi">2001</span><span class="p">:</span><span class="n">db8</span><span class="p">::</span><span class="mi">1234</span>
</pre></div>
</div>
<p>These records are used internally to resolve names under the
static-stub zone. For instance, if the server receives a query for
“www.example.com” with the RD bit on, the server initiates
recursive resolution and sends queries to 192.0.2.1 and/or
2001:db8::1234.</p>
</dd></dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-server-names">
<span class="sig-name descname"><span class="pre">server-names</span></span><a class="headerlink" href="#namedconf-statement-server-names" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">server-names</span> <span class="pre">{</span> <span class="pre"><string>;</span> <span class="pre">...</span> <span class="pre">};</span></code></p>
<p><strong>Blocks: </strong>zone (static-stub)</p>
<p><strong>Tags: </strong>zone</p>
<p><p>Specifies a list of domain names of name servers that act as authoritative servers of a static-stub zone.</p>
</p>
<p>This option is only meaningful for static-stub zones. This is a list of domain names
of name servers that act as authoritative servers of the static-stub
zone. These names are resolved to IP addresses when <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>
needs to send queries to these servers. For this supplemental
resolution to be successful, these names must not be a subdomain of the
origin name of the static-stub zone. That is, when “example.net” is the
origin of a static-stub zone, “ns.example” and “master.example.com”
can be specified in the <a class="reference internal" href="#namedconf-statement-server-names" title="namedconf-statement-server-names"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">server-names</span></code></a> option, but “ns.example.net”
cannot; it is rejected by the configuration parser.</p>
<p>A non-empty list for this option internally configures the apex
NS RR with the specified names. For example, if “example.com” is
configured as a static-stub zone with “ns1.example.net” and
“ns2.example.net” in a <a class="reference internal" href="#namedconf-statement-server-names" title="namedconf-statement-server-names"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">server-names</span></code></a> option, the following RRs
are internally configured:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">example</span><span class="o">.</span><span class="n">com</span><span class="o">.</span> <span class="n">NS</span> <span class="n">ns1</span><span class="o">.</span><span class="n">example</span><span class="o">.</span><span class="n">net</span><span class="o">.</span>
<span class="n">example</span><span class="o">.</span><span class="n">com</span><span class="o">.</span> <span class="n">NS</span> <span class="n">ns2</span><span class="o">.</span><span class="n">example</span><span class="o">.</span><span class="n">net</span><span class="o">.</span>
</pre></div>
</div>
<p>These records are used internally to resolve names under the
static-stub zone. For instance, if the server receives a query for
“www.example.com” with the RD bit on, the server initiates recursive
resolution, resolves “ns1.example.net” and/or “ns2.example.net” to IP
addresses, and then sends queries to one or more of these addresses.</p>
</dd></dl>
<dl class="simple">
<dt><a class="reference internal" href="#namedconf-statement-sig-validity-interval" title="namedconf-statement-sig-validity-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-validity-interval</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-sig-validity-interval" title="namedconf-statement-sig-validity-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-validity-interval</span></code></a> in <a class="reference internal" href="#tuning"><span class="std std-ref">Tuning</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-sig-signing-nodes" title="namedconf-statement-sig-signing-nodes"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-signing-nodes</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-sig-signing-nodes" title="namedconf-statement-sig-signing-nodes"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-signing-nodes</span></code></a> in <a class="reference internal" href="#tuning"><span class="std std-ref">Tuning</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-sig-signing-signatures" title="namedconf-statement-sig-signing-signatures"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-signing-signatures</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-sig-signing-signatures" title="namedconf-statement-sig-signing-signatures"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-signing-signatures</span></code></a> in
<a class="reference internal" href="#tuning"><span class="std std-ref">Tuning</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-sig-signing-type" title="namedconf-statement-sig-signing-type"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-signing-type</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-sig-signing-type" title="namedconf-statement-sig-signing-type"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">sig-signing-type</span></code></a> in <a class="reference internal" href="#tuning"><span class="std std-ref">Tuning</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a> in <a class="reference internal" href="#zone-transfers"><span class="std std-ref">Zone Transfers</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-transfer-source-v6" title="namedconf-statement-transfer-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source-v6</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-transfer-source-v6" title="namedconf-statement-transfer-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source-v6</span></code></a> in <a class="reference internal" href="#zone-transfers"><span class="std std-ref">Zone Transfers</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-alt-transfer-source" title="namedconf-statement-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">alt-transfer-source</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-alt-transfer-source" title="namedconf-statement-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">alt-transfer-source</span></code></a> in <a class="reference internal" href="#zone-transfers"><span class="std std-ref">Zone Transfers</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-alt-transfer-source-v6" title="namedconf-statement-alt-transfer-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">alt-transfer-source-v6</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-alt-transfer-source-v6" title="namedconf-statement-alt-transfer-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">alt-transfer-source-v6</span></code></a> in <a class="reference internal" href="#zone-transfers"><span class="std std-ref">Zone Transfers</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-use-alt-transfer-source" title="namedconf-statement-use-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-alt-transfer-source</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-use-alt-transfer-source" title="namedconf-statement-use-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-alt-transfer-source</span></code></a> in <a class="reference internal" href="#zone-transfers"><span class="std std-ref">Zone Transfers</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-notify-source" title="namedconf-statement-notify-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-source</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-notify-source" title="namedconf-statement-notify-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-source</span></code></a> in <a class="reference internal" href="#zone-transfers"><span class="std std-ref">Zone Transfers</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-notify-source-v6" title="namedconf-statement-notify-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-source-v6</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-notify-source-v6" title="namedconf-statement-notify-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">notify-source-v6</span></code></a> in <a class="reference internal" href="#zone-transfers"><span class="std std-ref">Zone Transfers</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-min-refresh-time" title="namedconf-statement-min-refresh-time"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">min-refresh-time</span></code></a>; <a class="reference internal" href="#namedconf-statement-max-refresh-time" title="namedconf-statement-max-refresh-time"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-refresh-time</span></code></a>; <a class="reference internal" href="#namedconf-statement-min-retry-time" title="namedconf-statement-min-retry-time"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">min-retry-time</span></code></a>; <a class="reference internal" href="#namedconf-statement-max-retry-time" title="namedconf-statement-max-retry-time"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-retry-time</span></code></a></dt><dd><p>See the descriptions in <a class="reference internal" href="#tuning"><span class="std std-ref">Tuning</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-ixfr-from-differences" title="namedconf-statement-ixfr-from-differences"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ixfr-from-differences</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-ixfr-from-differences" title="namedconf-statement-ixfr-from-differences"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ixfr-from-differences</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.
(Note that the <a class="reference internal" href="#namedconf-statement-ixfr-from-differences" title="namedconf-statement-ixfr-from-differences"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">ixfr-from-differences</span></code></a> choices of <a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primary</span></code></a> and <a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">secondary</span></code></a>
are not available at the zone level.)</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-key-directory" title="namedconf-statement-key-directory"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">key-directory</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-key-directory" title="namedconf-statement-key-directory"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">key-directory</span></code></a> in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-auto-dnssec" title="namedconf-statement-auto-dnssec"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">auto-dnssec</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-auto-dnssec" title="namedconf-statement-auto-dnssec"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">auto-dnssec</span></code></a> in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-serial-update-method" title="namedconf-statement-serial-update-method"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">serial-update-method</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-serial-update-method" title="namedconf-statement-serial-update-method"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">serial-update-method</span></code></a> in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>.</p>
</dd>
</dl>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-inline-signing">
<span class="sig-name descname"><span class="pre">inline-signing</span></span><a class="headerlink" href="#namedconf-statement-inline-signing" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">inline-signing</span> <span class="pre"><boolean>;</span></code></p>
<p><strong>Blocks: </strong>zone (primary, secondary)</p>
<p><strong>Tags: </strong>dnssec, zone</p>
<p><p>Specifies whether BIND 9 maintains a separate signed version of a zone.</p>
</p>
<p>If <code class="docutils literal notranslate"><span class="pre">yes</span></code>, BIND 9 maintains a separate signed version of the zone.
An unsigned zone is transferred in or loaded from disk and the signed
version of the zone is served with, possibly, a different serial
number. The signed version of the zone is stored in a file that is
the zone’s filename (set in <a class="reference internal" href="#namedconf-statement-file" title="namedconf-statement-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">file</span></code></a>) with a <code class="docutils literal notranslate"><span class="pre">.signed</span></code> extension.
This behavior is disabled by default.</p>
</dd></dl>
<dl class="simple">
<dt><a class="reference internal" href="#namedconf-statement-multi-master" title="namedconf-statement-multi-master"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">multi-master</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-multi-master" title="namedconf-statement-multi-master"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">multi-master</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">masterfile-format</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">masterfile-format</span></code></a> in <a class="reference internal" href="#tuning"><span class="std std-ref">Tuning</span></a>.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-zone-ttl</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-zone-ttl</span></code></a> in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a>.
The use of this option in <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> blocks is deprecated and
will be rendered nonoperational in a future release.</p>
</dd>
<dt><a class="reference internal" href="#namedconf-statement-dnssec-secure-to-insecure" title="namedconf-statement-dnssec-secure-to-insecure"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-secure-to-insecure</span></code></a></dt><dd><p>See the description of <a class="reference internal" href="#namedconf-statement-dnssec-secure-to-insecure" title="namedconf-statement-dnssec-secure-to-insecure"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnssec-secure-to-insecure</span></code></a> in <a class="reference internal" href="#boolean-options"><span class="std std-ref">Boolean Options</span></a>.</p>
</dd>
</dl>
</section>
<section id="dynamic-update-policies">
<span id="id15"></span><h4><span class="section-number">8.2.34.4. </span>Dynamic Update Policies<a class="headerlink" href="#dynamic-update-policies" title="Link to this heading"></a></h4>
<p>BIND 9 supports two methods of granting clients the right to
perform dynamic updates to a zone:</p>
<ul class="simple">
<li><p><a class="reference internal" href="#namedconf-statement-allow-update" title="namedconf-statement-allow-update"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-update</span></code></a> - a simple access control list</p></li>
<li><p><a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> - fine-grained access control</p></li>
</ul>
<p>In both cases, BIND 9 writes the updates to the zone’s filename
set in <a class="reference internal" href="#namedconf-statement-file" title="namedconf-statement-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">file</span></code></a>.</p>
<p>In the case of a DNSSEC zone, DNSSEC records are also written to
the zone’s filename, unless <a class="reference internal" href="#namedconf-statement-inline-signing" title="namedconf-statement-inline-signing"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">inline-signing</span></code></a> is enabled.</p>
<blockquote>
<div><div class="admonition note">
<p class="admonition-title">Note</p>
<p>The zone file can no longer be manually updated while <code class="docutils literal notranslate"><span class="pre">named</span></code>
is running; it is now necessary to perform <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-freeze"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">freeze</span></code></a>, edit,
and then perform <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-thaw"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">thaw</span></code></a>. Comments and formatting
in the zone file are lost when dynamic updates occur.</p>
</div>
</div></blockquote>
<dl class="namedconf statement">
<dt class="sig sig-object namedconf" id="namedconf-statement-update-policy">
<span class="sig-name descname"><span class="pre">update-policy</span></span><a class="headerlink" href="#namedconf-statement-update-policy" title="Link to this definition"></a></dt>
<dd><p><strong>Grammar: </strong><code class="docutils literal notranslate"><span class="pre">update-policy</span> <span class="pre">(</span> <span class="pre">local</span> <span class="pre">|</span> <span class="pre">{</span> <span class="pre">(</span> <span class="pre">deny</span> <span class="pre">|</span> <span class="pre">grant</span> <span class="pre">)</span> <span class="pre"><string></span> <span class="pre">(</span> <span class="pre">6to4-self</span> <span class="pre">|</span> <span class="pre">external</span> <span class="pre">|</span> <span class="pre">krb5-self</span> <span class="pre">|</span> <span class="pre">krb5-selfsub</span> <span class="pre">|</span> <span class="pre">krb5-subdomain</span> <span class="pre">|</span> <span class="pre">krb5-subdomain-self-rhs</span> <span class="pre">|</span> <span class="pre">ms-self</span> <span class="pre">|</span> <span class="pre">ms-selfsub</span> <span class="pre">|</span> <span class="pre">ms-subdomain</span> <span class="pre">|</span> <span class="pre">ms-subdomain-self-rhs</span> <span class="pre">|</span> <span class="pre">name</span> <span class="pre">|</span> <span class="pre">self</span> <span class="pre">|</span> <span class="pre">selfsub</span> <span class="pre">|</span> <span class="pre">selfwild</span> <span class="pre">|</span> <span class="pre">subdomain</span> <span class="pre">|</span> <span class="pre">tcp-self</span> <span class="pre">|</span> <span class="pre">wildcard</span> <span class="pre">|</span> <span class="pre">zonesub</span> <span class="pre">)</span> <span class="pre">[</span> <span class="pre"><string></span> <span class="pre">]</span> <span class="pre"><rrtypelist>;</span> <span class="pre">...</span> <span class="pre">}</span> <span class="pre">);</span></code></p>
<p><strong>Blocks: </strong>zone (primary)</p>
<p><strong>Tags: </strong>transfer</p>
<p><p>Sets fine-grained rules to allow or deny dynamic updates (DDNS), based on requester identity, updated content, etc.</p>
</p>
<p>The <a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> clause allows more fine-grained control over which
updates are allowed. It specifies a set of rules, in which each rule
either grants or denies permission for one or more names in the zone to
be updated by one or more identities. Identity is determined by the key
that signed the update request, using TSIG. In most
cases, <a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> rules only apply to key-based identities. There
is no way to specify update permissions based on the client source address.</p>
<p><a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> rules are only meaningful for zones of
<a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">type</span> <span class="pre">primary</span></code></a>, and are not allowed in any other zone type. It is a
configuration error to specify both <a class="reference internal" href="#namedconf-statement-allow-update" title="namedconf-statement-allow-update"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">allow-update</span></code></a> and
<a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> at the same time.</p>
<p>A pre-defined <a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> rule can be switched on with the command
<code class="docutils literal notranslate"><span class="pre">update-policy</span> <span class="pre">local;</span></code>. <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> automatically
generates a TSIG session key when starting and stores it in a file;
this key can then be used by local clients to update the zone while
<a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> is running. By default, the session key is stored in the file
<code class="docutils literal notranslate"><span class="pre">/run/session.key</span></code>, the key name is “local-ddns”, and the
key algorithm is HMAC-SHA256. These values are configurable with the
<a class="reference internal" href="#namedconf-statement-session-keyfile" title="namedconf-statement-session-keyfile"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">session-keyfile</span></code></a>, <a class="reference internal" href="#namedconf-statement-session-keyname" title="namedconf-statement-session-keyname"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">session-keyname</span></code></a>, and <a class="reference internal" href="#namedconf-statement-session-keyalg" title="namedconf-statement-session-keyalg"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">session-keyalg</span></code></a> options,
respectively. A client running on the local system, if run with
appropriate permissions, may read the session key from the key file and
use it to sign update requests. The zone’s update policy is set to
allow that key to change any record within the zone. Assuming the key
name is “local-ddns”, this policy is equivalent to:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">update</span><span class="o">-</span><span class="n">policy</span> <span class="p">{</span> <span class="n">grant</span> <span class="n">local</span><span class="o">-</span><span class="n">ddns</span> <span class="n">zonesub</span> <span class="nb">any</span><span class="p">;</span> <span class="p">};</span>
</pre></div>
</div>
<p>with the additional restriction that only clients connecting from the
local system are permitted to send updates.</p>
<p>Note that only one session key is generated by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>; all zones
configured to use <code class="docutils literal notranslate"><span class="pre">update-policy</span> <span class="pre">local</span></code> accept the same key.</p>
<p>The command <code class="docutils literal notranslate"><span class="pre">nsupdate</span> <span class="pre">-l</span></code> implements this feature, sending requests to
localhost and signing them using the key retrieved from the session key
file.</p>
<p>Other rule definitions look like this:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="p">(</span> <span class="n">grant</span> <span class="o">|</span> <span class="n">deny</span> <span class="p">)</span> <span class="n">identity</span> <span class="n">ruletype</span> <span class="n">name</span> <span class="n">types</span>
</pre></div>
</div>
<p>Each rule grants or denies privileges. Rules are checked in the order in
which they are specified in the <a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> statement. Once a
message has successfully matched a rule, the operation is immediately
granted or denied, and no further rules are examined. There are 16 types
of rules; the rule type is specified by the <code class="docutils literal notranslate"><span class="pre">ruletype</span></code> field, and the
interpretation of other fields varies depending on the rule type.</p>
<p>In general, a rule is matched when the key that signed an update request
matches the <code class="docutils literal notranslate"><span class="pre">identity</span></code> field, the name of the record to be updated
matches the <code class="docutils literal notranslate"><span class="pre">name</span></code> field (in the manner specified by the <code class="docutils literal notranslate"><span class="pre">ruletype</span></code>
field), and the type of the record to be updated matches the <code class="docutils literal notranslate"><span class="pre">types</span></code>
field. Details for each rule type are described below.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">identity</span></code> field must be set to a fully qualified domain name. In
most cases, this represents the name of the TSIG key that
must be used to sign the update request. If the specified name is a
wildcard, it is subject to DNS wildcard expansion, and the rule may
apply to multiple identities. When a TKEY exchange has been used to
create a shared secret, the identity of the key used to authenticate the
TKEY exchange is used as the identity of the shared secret. Some
rule types use identities matching the client’s Kerberos principal (e.g,
<code class="docutils literal notranslate"><span class="pre">"host/machine@REALM"</span></code>) or Windows realm (<code class="docutils literal notranslate"><span class="pre">machine$@REALM</span></code>).</p>
<p>The <code class="docutils literal notranslate"><span class="pre">name</span></code> field also specifies a fully qualified domain name. This often
represents the name of the record to be updated. Interpretation of this
field is dependent on rule type.</p>
<p>If no <code class="docutils literal notranslate"><span class="pre">types</span></code> are explicitly specified, then a rule matches all types
except RRSIG, NS, SOA, NSEC, and NSEC3. Types may be specified by name,
including <code class="docutils literal notranslate"><span class="pre">ANY</span></code>; ANY matches all types except NSEC and NSEC3, which can
never be updated. Note that when an attempt is made to delete all
records associated with a name, the rules are checked for each existing
record type.</p>
<p>If the type is immediately followed by a number in parentheses,
that number is the maximum number of records of that type permitted
to exist in the RRset after an update has been applied. For example,
<code class="docutils literal notranslate"><span class="pre">PTR(1)</span></code> indicates that only one PTR record is allowed. If an
attempt is made to add two PTR records in an update, the second one
is silently discarded. If a PTR record already exists, both
new records are silently discarded.</p>
<p>If type ANY is specified with a limit, then that limit applies to
all types that are not otherwise specified. For example, <code class="docutils literal notranslate"><span class="pre">A</span> <span class="pre">PTR(1)</span>
<span class="pre">ANY(2)</span></code> indicates that an unlimited number of A records can exist,
but only one PTR record, and no more than two of any other type.</p>
<p>Typical use with a rule <code class="docutils literal notranslate"><span class="pre">grant</span> <span class="pre">*</span> <span class="pre">tcp-self</span> <span class="pre">.</span> <span class="pre">PTR(1);</span></code> in the zone
2.0.192.IN-ADDR.ARPA looks like this:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">nsupdate</span> <span class="o">-</span><span class="n">v</span> <span class="o"><<</span><span class="n">EOF</span>
<span class="n">local</span> <span class="mf">192.0.2.1</span>
<span class="k">del</span> <span class="mf">1.2.0.192</span><span class="o">.</span><span class="n">IN</span><span class="o">-</span><span class="n">ADDR</span><span class="o">.</span><span class="n">ARPA</span> <span class="n">PTR</span>
<span class="n">add</span> <span class="mf">1.2.0.192</span><span class="o">.</span><span class="n">IN</span><span class="o">-</span><span class="n">ADDR</span><span class="o">.</span><span class="n">ARPA</span> <span class="mi">0</span> <span class="n">PTR</span> <span class="n">EXAMPLE</span><span class="o">.</span><span class="n">COM</span>
<span class="n">send</span>
<span class="n">EOF</span>
</pre></div>
</div>
<p>The ruletype field has 18 values: <code class="docutils literal notranslate"><span class="pre">name</span></code>, <code class="docutils literal notranslate"><span class="pre">subdomain</span></code>, <code class="docutils literal notranslate"><span class="pre">zonesub</span></code>,
<code class="docutils literal notranslate"><span class="pre">wildcard</span></code>, <code class="docutils literal notranslate"><span class="pre">self</span></code>, <code class="docutils literal notranslate"><span class="pre">selfsub</span></code>, <code class="docutils literal notranslate"><span class="pre">selfwild</span></code>, <code class="docutils literal notranslate"><span class="pre">ms-self</span></code>,
<code class="docutils literal notranslate"><span class="pre">ms-selfsub</span></code>, <code class="docutils literal notranslate"><span class="pre">ms-subdomain</span></code>, <code class="docutils literal notranslate"><span class="pre">ms-subdomain-self-rhs</span></code>, <code class="docutils literal notranslate"><span class="pre">krb5-self</span></code>,
<code class="docutils literal notranslate"><span class="pre">krb5-selfsub</span></code>, <code class="docutils literal notranslate"><span class="pre">krb5-subdomain</span></code>, <code class="docutils literal notranslate"><span class="pre">krb5-subdomain-self-rhs</span></code>,
<code class="docutils literal notranslate"><span class="pre">tcp-self</span></code>, <code class="docutils literal notranslate"><span class="pre">6to4-self</span></code>, and <code class="docutils literal notranslate"><span class="pre">external</span></code>.</p>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">name</span></code></dt><dd><p>With exact-match semantics, this rule matches when the name being updated is identical to the contents of the <code class="docutils literal notranslate"><span class="pre">name</span></code> field.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">subdomain</span></code></dt><dd><p>This rule matches when the name being updated is a subdomain of, or identical to, the contents of the <code class="docutils literal notranslate"><span class="pre">name</span></code> field.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">zonesub</span></code></dt><dd><p>This rule is similar to subdomain, except that it matches when the name being updated is a subdomain of the zone in which the <a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> statement appears. This obviates the need to type the zone name twice, and enables the use of a standard <a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> statement in multiple zones without modification.
When this rule is used, the <code class="docutils literal notranslate"><span class="pre">name</span></code> field is omitted.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">wildcard</span></code></dt><dd><p>The <code class="docutils literal notranslate"><span class="pre">name</span></code> field is subject to DNS wildcard expansion, and this rule matches when the name being updated is a valid expansion of the wildcard.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">self</span></code></dt><dd><p>This rule matches when the name of the record being updated matches the contents of the <code class="docutils literal notranslate"><span class="pre">identity</span></code> field. The <code class="docutils literal notranslate"><span class="pre">name</span></code> field is ignored. To avoid confusion, it is recommended that this field be set to the same value as the <code class="docutils literal notranslate"><span class="pre">identity</span></code> field or to “.”
The <code class="docutils literal notranslate"><span class="pre">self</span></code> rule type is most useful when allowing one key per name to update, where the key has the same name as the record to be updated. In this case, the <code class="docutils literal notranslate"><span class="pre">identity</span></code> field can be specified as <code class="docutils literal notranslate"><span class="pre">*</span></code> (asterisk).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">selfsub</span></code></dt><dd><p>This rule is similar to <code class="docutils literal notranslate"><span class="pre">self</span></code>, except that subdomains of <code class="docutils literal notranslate"><span class="pre">self</span></code> can also be updated.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">selfwild</span></code></dt><dd><p>This rule is similar to <code class="docutils literal notranslate"><span class="pre">self</span></code>, except that only subdomains of <code class="docutils literal notranslate"><span class="pre">self</span></code> can be updated.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ms-self</span></code></dt><dd><p>When a client sends an UPDATE using a Windows machine principal (for example, <code class="docutils literal notranslate"><span class="pre">machine$@REALM</span></code>), this rule allows records with the absolute name of <code class="docutils literal notranslate"><span class="pre">machine.REALM</span></code> to be updated.</p>
<p>The realm to be matched is specified in the <code class="docutils literal notranslate"><span class="pre">identity</span></code> field.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">name</span></code> field has no effect on this rule; it should be set to “.” as a placeholder.</p>
<p>For example, <code class="docutils literal notranslate"><span class="pre">grant</span> <span class="pre">EXAMPLE.COM</span> <span class="pre">ms-self</span> <span class="pre">.</span> <span class="pre">A</span> <span class="pre">AAAA</span></code> allows any machine with a valid principal in the realm <code class="docutils literal notranslate"><span class="pre">EXAMPLE.COM</span></code> to update its own address records.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ms-selfsub</span></code></dt><dd><p>This is similar to <code class="docutils literal notranslate"><span class="pre">ms-self</span></code>, except it also allows updates to any subdomain of the name specified in the Windows machine principal, not just to the name itself.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ms-subdomain</span></code></dt><dd><p>When a client sends an UPDATE using a Windows machine principal (for example, <code class="docutils literal notranslate"><span class="pre">machine$@REALM</span></code>), this rule allows any machine in the specified realm to update any record in the zone or in a specified subdomain of the zone.</p>
<p>The realm to be matched is specified in the <code class="docutils literal notranslate"><span class="pre">identity</span></code> field.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">name</span></code> field specifies the subdomain that may be updated. If set to “.” or any other name at or above the zone apex, any name in the zone can be updated.</p>
<p>For example, if <a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-policy</span></code></a> for the zone “example.com” includes <code class="docutils literal notranslate"><span class="pre">grant</span> <span class="pre">EXAMPLE.COM</span> <span class="pre">ms-subdomain</span> <span class="pre">hosts.example.com.</span> <span class="pre">AA</span> <span class="pre">AAAA</span></code>, any machine with a valid principal in the realm <code class="docutils literal notranslate"><span class="pre">EXAMPLE.COM</span></code> is able to update address records at or below <code class="docutils literal notranslate"><span class="pre">hosts.example.com</span></code>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ms-subdomain-self-rhs</span></code></dt><dd><p>This rule is similar to <code class="docutils literal notranslate"><span class="pre">ms-subdomain</span></code>, with an additional
restriction that PTR and SRV target names must match the name of the
machine identified in the principal.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">krb5-self</span></code></dt><dd><p>When a client sends an UPDATE using a Kerberos machine principal (for example, <code class="docutils literal notranslate"><span class="pre">host/machine@REALM</span></code>), this rule allows records with the absolute name of <code class="docutils literal notranslate"><span class="pre">machine</span></code> to be updated, provided it has been authenticated by REALM. This is similar but not identical to <code class="docutils literal notranslate"><span class="pre">ms-self</span></code>, due to the <code class="docutils literal notranslate"><span class="pre">machine</span></code> part of the Kerberos principal being an absolute name instead of an unqualified name.</p>
<p>The realm to be matched is specified in the <code class="docutils literal notranslate"><span class="pre">identity</span></code> field.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">name</span></code> field has no effect on this rule; it should be set to “.” as a placeholder.</p>
<p>For example, <code class="docutils literal notranslate"><span class="pre">grant</span> <span class="pre">EXAMPLE.COM</span> <span class="pre">krb5-self</span> <span class="pre">.</span> <span class="pre">A</span> <span class="pre">AAAA</span></code> allows any machine with a valid principal in the realm <code class="docutils literal notranslate"><span class="pre">EXAMPLE.COM</span></code> to update its own address records.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">krb5-selfsub</span></code></dt><dd><p>This is similar to <code class="docutils literal notranslate"><span class="pre">krb5-self</span></code>, except it also allows updates to any subdomain of the name specified in the <code class="docutils literal notranslate"><span class="pre">machine</span></code> part of the Kerberos principal, not just to the name itself.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">krb5-subdomain</span></code></dt><dd><p>This rule is identical to <code class="docutils literal notranslate"><span class="pre">ms-subdomain</span></code>, except that it works with Kerberos machine principals (i.e., <code class="docutils literal notranslate"><span class="pre">host/machine@REALM</span></code>) rather than Windows machine principals.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">krb5-subdomain-self-rhs</span></code></dt><dd><p>This rule is similar to <code class="docutils literal notranslate"><span class="pre">krb5-subdomain</span></code>, with an additional
restriction that PTR and SRV target names must match the name of the
machine identified in the principal.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">tcp-self</span></code></dt><dd><p>This rule allows updates that have been sent via TCP and for which the standard mapping from the client’s IP address into the <code class="docutils literal notranslate"><span class="pre">in-addr.arpa</span></code> and <code class="docutils literal notranslate"><span class="pre">ip6.arpa</span></code> namespaces matches the name to be updated. The <code class="docutils literal notranslate"><span class="pre">identity</span></code> field must match that name. The <code class="docutils literal notranslate"><span class="pre">name</span></code> field should be set to “.”. Note that, since identity is based on the client’s IP address, it is not necessary for update request messages to be signed.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>It is theoretically possible to spoof these TCP sessions.</p>
</div>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">6to4-self</span></code></dt><dd><p>This allows the name matching a 6to4 IPv6 prefix, as specified in <span class="target" id="index-36"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc3056.html"><strong>RFC 3056</strong></a>, to be updated by any TCP connection from either the 6to4 network or from the corresponding IPv4 address. This is intended to allow NS or DNAME RRsets to be added to the <code class="docutils literal notranslate"><span class="pre">ip6.arpa</span></code> reverse tree.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">identity</span></code> field must match the 6to4 prefix in <code class="docutils literal notranslate"><span class="pre">ip6.arpa</span></code>. The <code class="docutils literal notranslate"><span class="pre">name</span></code> field should be set to “.”. Note that, since identity is based on the client’s IP address, it is not necessary for update request messages to be signed.</p>
<p>In addition, if specified for an <code class="docutils literal notranslate"><span class="pre">ip6.arpa</span></code> name outside of the <code class="docutils literal notranslate"><span class="pre">2.0.0.2.ip6.arpa</span></code> namespace, the corresponding /48 reverse name can be updated. For example, TCP/IPv6 connections from 2001:DB8:ED0C::/48 can update records at <code class="docutils literal notranslate"><span class="pre">C.0.D.E.8.B.D.0.1.0.0.2.ip6.arpa</span></code>.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>It is theoretically possible to spoof these TCP sessions.</p>
</div>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">external</span></code></dt><dd><p>This rule allows <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to defer the decision of whether to allow a given update to an external daemon.</p>
<p>The method of communicating with the daemon is specified in the <code class="docutils literal notranslate"><span class="pre">identity</span></code> field, the format of which is “<code class="docutils literal notranslate"><span class="pre">local:</span></code>path”, where “path” is the location of a Unix-domain socket. (Currently, “local” is the only supported mechanism.)</p>
<p>Requests to the external daemon are sent over the Unix-domain socket as datagrams with the following format:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">Protocol</span> <span class="n">version</span> <span class="n">number</span> <span class="p">(</span><span class="mi">4</span> <span class="nb">bytes</span><span class="p">,</span> <span class="n">network</span> <span class="n">byte</span> <span class="n">order</span><span class="p">,</span> <span class="n">currently</span> <span class="mi">1</span><span class="p">)</span>
<span class="n">Request</span> <span class="n">length</span> <span class="p">(</span><span class="mi">4</span> <span class="nb">bytes</span><span class="p">,</span> <span class="n">network</span> <span class="n">byte</span> <span class="n">order</span><span class="p">)</span>
<span class="n">Signer</span> <span class="p">(</span><span class="n">null</span><span class="o">-</span><span class="n">terminated</span> <span class="n">string</span><span class="p">)</span>
<span class="n">Name</span> <span class="p">(</span><span class="n">null</span><span class="o">-</span><span class="n">terminated</span> <span class="n">string</span><span class="p">)</span>
<span class="n">TCP</span> <span class="n">source</span> <span class="n">address</span> <span class="p">(</span><span class="n">null</span><span class="o">-</span><span class="n">terminated</span> <span class="n">string</span><span class="p">)</span>
<span class="n">Rdata</span> <span class="nb">type</span> <span class="p">(</span><span class="n">null</span><span class="o">-</span><span class="n">terminated</span> <span class="n">string</span><span class="p">)</span>
<span class="n">Key</span> <span class="p">(</span><span class="n">null</span><span class="o">-</span><span class="n">terminated</span> <span class="n">string</span><span class="p">)</span>
<span class="n">TKEY</span> <span class="n">token</span> <span class="n">length</span> <span class="p">(</span><span class="mi">4</span> <span class="nb">bytes</span><span class="p">,</span> <span class="n">network</span> <span class="n">byte</span> <span class="n">order</span><span class="p">)</span>
<span class="n">TKEY</span> <span class="n">token</span> <span class="p">(</span><span class="n">remainder</span> <span class="n">of</span> <span class="n">packet</span><span class="p">)</span>
</pre></div>
</div>
<p>The daemon replies with a four-byte value in network byte order, containing either 0 or 1; 0 indicates that the specified update is not permitted, and 1 indicates that it is.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The external daemon must not delay communication. This policy is evaluated synchronously; any wait period negatively affects <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> performance.</p>
</div>
</dd>
</dl>
</dd></dl>
</section>
<section id="multiple-views">
<span id="id16"></span><h4><span class="section-number">8.2.34.5. </span>Multiple Views<a class="headerlink" href="#multiple-views" title="Link to this heading"></a></h4>
<p>When multiple views are in use, a zone may be referenced by more than
one of them. Often, the views contain different zones with the same
name, allowing different clients to receive different answers for the
same queries. At times, however, it is desirable for multiple views to
contain identical zones. The <a class="reference internal" href="#namedconf-statement-in-view" title="namedconf-statement-in-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">in-view</span></code></a> zone option provides an
efficient way to do this; it allows a view to reference a zone that was
defined in a previously configured view. For example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">view</span> <span class="n">internal</span> <span class="p">{</span>
<span class="k">match</span><span class="o">-</span><span class="n">clients</span> <span class="p">{</span> <span class="mi">10</span><span class="o">/</span><span class="mi">8</span><span class="p">;</span> <span class="p">};</span>
<span class="n">zone</span> <span class="n">example</span><span class="o">.</span><span class="n">com</span> <span class="p">{</span>
<span class="nb">type</span> <span class="n">primary</span><span class="p">;</span>
<span class="n">file</span> <span class="s2">"example-external.db"</span><span class="p">;</span>
<span class="p">};</span>
<span class="p">};</span>
<span class="n">view</span> <span class="n">external</span> <span class="p">{</span>
<span class="k">match</span><span class="o">-</span><span class="n">clients</span> <span class="p">{</span> <span class="nb">any</span><span class="p">;</span> <span class="p">};</span>
<span class="n">zone</span> <span class="n">example</span><span class="o">.</span><span class="n">com</span> <span class="p">{</span>
<span class="ow">in</span><span class="o">-</span><span class="n">view</span> <span class="n">internal</span><span class="p">;</span>
<span class="p">};</span>
<span class="p">};</span>
</pre></div>
</div>
<p>An <a class="reference internal" href="#namedconf-statement-in-view" title="namedconf-statement-in-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">in-view</span></code></a> option cannot refer to a view that is configured later in
the configuration file.</p>
<p>A <a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone</span></code></a> statement which uses the <a class="reference internal" href="#namedconf-statement-in-view" title="namedconf-statement-in-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">in-view</span></code></a> option may not use any
other options, with the exception of <a class="reference internal" href="#namedconf-statement-forward" title="namedconf-statement-forward"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forward</span></code></a> and <a class="reference internal" href="#namedconf-statement-forwarders" title="namedconf-statement-forwarders"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forwarders</span></code></a>.
(These options control the behavior of the containing view, rather than
change the zone object itself.)</p>
<p>Zone-level ACLs (e.g., allow-query, allow-transfer), and other
configuration details of the zone, are all set in the view the referenced
zone is defined in. Be careful to ensure that ACLs are wide
enough for all views referencing the zone.</p>
<p>An <a class="reference internal" href="#namedconf-statement-in-view" title="namedconf-statement-in-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">in-view</span></code></a> zone cannot be used as a response policy zone.</p>
<p>An <a class="reference internal" href="#namedconf-statement-in-view" title="namedconf-statement-in-view"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">in-view</span></code></a> zone is not intended to reference a <a class="reference internal" href="#namedconf-statement-forward" title="namedconf-statement-forward"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forward</span></code></a> zone.</p>
</section>
</section>
</section>
<section id="statements">
<h2><span class="section-number">8.3. </span>Statements<a class="headerlink" href="#statements" title="Link to this heading"></a></h2>
<p>BIND 9 supports many hundreds of statements; finding the right statement to
control a specific behavior or solve a particular problem can be a daunting
task. To simplify the task for users, all statements have been assigned one or more tags.
Tags are designed to group together statements that have broadly similar
functionality; thus, for example, all statements that control the handling of
queries or of zone transfers are respectively tagged under <strong>query</strong> and <strong>transfer</strong>.</p>
<p><a class="reference internal" href="#dnssec-tag-statements"><span class="std std-ref">DNSSEC Tag Statements</span></a> are those that relate to or control DNSSEC.</p>
<p><a class="reference internal" href="#logging-tag-statements"><span class="std std-ref">Logging Tag Statements</span></a> relate to or control logging, and typically only
appear in a logging block.</p>
<p><a class="reference internal" href="#query-tag-statements"><span class="std std-ref">Query Tag Statements</span></a> relate to or control queries.</p>
<p><a class="reference internal" href="#security-tag-statements"><span class="std std-ref">Security Tag Statements</span></a> relate to or control security features.</p>
<p><a class="reference internal" href="#server-tag-statements"><span class="std std-ref">Server Tag Statements</span></a> relate to or control server behavior, and typically
only appear in a server block.</p>
<p><a class="reference internal" href="#transfer-tag-statements"><span class="std std-ref">Transfer Tag Statements</span></a> relate to or control zone transfers.</p>
<p><a class="reference internal" href="#view-tag-statements"><span class="std std-ref">View Tag Statements</span></a> relate to or control view selection criteria, and
typically only appear in a view block.</p>
<p><a class="reference internal" href="#zone-tag-statements"><span class="std std-ref">Zone Tag Statements</span></a> relate to or control zone behavior, and typically
only appear in a zone block.</p>
<p><a class="reference internal" href="#deprecated-tag-statements"><span class="std std-ref">Deprecated Tag Statements</span></a> are those that are now deprecated, but are
included here for historical reference.</p>
<p>The following table lists all statements permissible in <code class="file docutils literal notranslate"><span class="pre">named.conf</span></code>, with their
associated tags; the next section groups the statements by tag. Please note that these
sections are a work in progress.</p>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Statement</p></th>
<th class="head"><p>Description</p></th>
<th class="head"><p>Tags</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-acl" title="namedconf-statement-acl">acl</a></span></td>
<td><p><p>Assigns a symbolic name to an address match list.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-algorithm" title="namedconf-statement-algorithm">algorithm</a></span></td>
<td><p><p>Defines the algorithm to be used in a key clause.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-all-per-second" title="namedconf-statement-all-per-second">all-per-second</a></span></td>
<td><p><p>Limits UDP responses of all kinds.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-new-zones" title="namedconf-statement-allow-new-zones">allow-new-zones</a></span></td>
<td><p><p>Controls the ability to add zones at runtime via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-addzone"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">addzone</span></code></a>.</p>
</p></td>
<td><p>server, zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-notify" title="namedconf-statement-allow-notify">allow-notify</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> that is allowed to send <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages for the zone, in addition to addresses defined in the <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> option for the zone.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-query" title="namedconf-statement-allow-query">allow-query</a></span></td>
<td><p><p>Specifies which hosts (an IP address list) are allowed to send queries to this resolver.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-query-cache" title="namedconf-statement-allow-query-cache">allow-query-cache</a></span></td>
<td><p><p>Specifies which hosts (an IP address list) can access this server's cache and thus effectively controls recursion.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-query-cache-on" title="namedconf-statement-allow-query-cache-on">allow-query-cache-on</a></span></td>
<td><p><p>Specifies which hosts (an IP address list) can access this server's cache. Used on servers with multiple interfaces.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-query-on" title="namedconf-statement-allow-query-on">allow-query-on</a></span></td>
<td><p><p>Specifies which local addresses (an IP address list) are allowed to send queries to this resolver. Used in multi-homed configurations.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-recursion" title="namedconf-statement-allow-recursion">allow-recursion</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of clients that are allowed to perform recursive queries.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-recursion-on" title="namedconf-statement-allow-recursion-on">allow-recursion-on</a></span></td>
<td><p><p>Specifies which local addresses can accept recursive queries.</p>
</p></td>
<td><p>query, server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-transfer" title="namedconf-statement-allow-transfer">allow-transfer</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts that are allowed to transfer the zone information from this server.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-update" title="namedconf-statement-allow-update">allow-update</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts that are allowed to submit dynamic updates for primary zones.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-update-forwarding" title="namedconf-statement-allow-update-forwarding">allow-update-forwarding</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts that are allowed to submit dynamic updates to a secondary server for transmission to a primary.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify">also-notify</a></span></td>
<td><p><p>Defines one or more hosts that are sent <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages when zone changes occur.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-alt-transfer-source" title="namedconf-statement-alt-transfer-source">alt-transfer-source</a></span></td>
<td><p><p>Defines alternate local IPv4 address(es) to be used by the server for inbound zone transfers, if the address(es) defined by <a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a> fail and <a class="reference internal" href="#namedconf-statement-use-alt-transfer-source" title="namedconf-statement-use-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-alt-transfer-source</span></code></a> is enabled.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-alt-transfer-source-v6" title="namedconf-statement-alt-transfer-source-v6">alt-transfer-source-v6</a></span></td>
<td><p><p>Defines alternate local IPv6 address(es) to be used by the server for inbound zone transfers.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-answer-cookie" title="namedconf-statement-answer-cookie">answer-cookie</a></span></td>
<td><p><p>Controls whether COOKIE EDNS replies are sent in response to client queries.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-attach-cache" title="namedconf-statement-attach-cache">attach-cache</a></span></td>
<td><p><p>Allows multiple views to share a single cache database.</p>
</p></td>
<td><p>view</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-auth-nxdomain" title="namedconf-statement-auth-nxdomain">auth-nxdomain</a></span></td>
<td><p><p>Controls whether BIND, acting as a resolver, provides authoritative NXDOMAIN (domain does not exist) answers.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-auto-dnssec" title="namedconf-statement-auto-dnssec">auto-dnssec</a></span></td>
<td><p><p>Permits varying levels of automatic DNSSEC key management.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-automatic-interface-scan" title="namedconf-statement-automatic-interface-scan">automatic-interface-scan</a></span></td>
<td><p><p>Controls the automatic rescanning of network interfaces when addresses are added or removed.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-avoid-v4-udp-ports" title="namedconf-statement-avoid-v4-udp-ports">avoid-v4-udp-ports</a></span></td>
<td><p><p>Specifies the range(s) of ports to be excluded from use as sources for UDP/IPv4 messages.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-avoid-v6-udp-ports" title="namedconf-statement-avoid-v6-udp-ports">avoid-v6-udp-ports</a></span></td>
<td><p><p>Specifies the range(s) of ports to be excluded from use as sources for UDP/IPv6 messages.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-bindkeys-file" title="namedconf-statement-bindkeys-file">bindkeys-file</a></span></td>
<td><p><p>Specifies the pathname of a file to override the built-in trusted keys provided by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-blackhole" title="namedconf-statement-blackhole">blackhole</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts to ignore. The server will neither respond to queries from nor send queries to these addresses.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-bogus" title="namedconf-statement-bogus">bogus</a></span></td>
<td><p><p>Allows a remote server to be ignored.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-break-dnssec" title="namedconf-statement-break-dnssec">break-dnssec</a></span></td>
<td><p><p>Enables <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> synthesis even if the validated result would cause a DNSSEC validation failure.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-buffered" title="namedconf-statement-buffered">buffered</a></span></td>
<td><p><p>Controls flushing of log messages.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ca-file" title="namedconf-statement-ca-file">ca-file</a></span></td>
<td><p><p>Specifies the path to a file containing TLS certificates for trusted CA authorities, used to verify remote peer certificates.</p>
</p></td>
<td><p>server, security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="chapter6.html#namedconf-statement-catalog-zones" title="namedconf-statement-catalog-zones">catalog-zones</a></span></td>
<td><p><p>Configures catalog zones in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-category" title="namedconf-statement-category">category</a></span></td>
<td><p><p>Specifies the type of data logged to a particular channel.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-cert-file" title="namedconf-statement-cert-file">cert-file</a></span></td>
<td><p><p>Specifies the path to a file containing the TLS certificate for a connection.</p>
</p></td>
<td><p>server, security</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-channel" title="namedconf-statement-channel">channel</a></span></td>
<td><p><p>Defines a stream of data that can be independently logged.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-check-dup-records" title="namedconf-statement-check-dup-records">check-dup-records</a></span></td>
<td><p><p>Checks primary zones for records that are treated as different by DNSSEC but are semantically equal in plain DNS.</p>
</p></td>
<td><p>dnssec, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-check-integrity" title="namedconf-statement-check-integrity">check-integrity</a></span></td>
<td><p><p>Performs post-load zone integrity checks on primary zones.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-check-mx" title="namedconf-statement-check-mx">check-mx</a></span></td>
<td><p><p>Checks whether an MX record appears to refer to an IP address.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-check-mx-cname" title="namedconf-statement-check-mx-cname">check-mx-cname</a></span></td>
<td><p><p>Sets the response to MX records that refer to CNAMEs.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-check-names" title="namedconf-statement-check-names">check-names</a></span></td>
<td><p><p>Restricts the character set and syntax of certain domain names in primary files and/or DNS responses received from the network.</p>
</p></td>
<td><p>query, server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-check-sibling" title="namedconf-statement-check-sibling">check-sibling</a></span></td>
<td><p><p>Specifies whether to check for sibling glue when performing integrity checks.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-check-spf" title="namedconf-statement-check-spf">check-spf</a></span></td>
<td><p><p>Specifies whether to check for a TXT Sender Policy Framework record, if an SPF record is present.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-check-srv-cname" title="namedconf-statement-check-srv-cname">check-srv-cname</a></span></td>
<td><p><p>Sets the response to SRV records that refer to CNAMEs.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-check-wildcard" title="namedconf-statement-check-wildcard">check-wildcard</a></span></td>
<td><p><p>Checks for non-terminal wildcards.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ciphers" title="namedconf-statement-ciphers">ciphers</a></span></td>
<td><p><p>Specifies a list of allowed ciphers.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-clients" title="namedconf-statement-clients">clients</a></span></td>
<td><p><p>Specifies an access control list (ACL) of clients that are affected by a given <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> directive.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-clients-per-query" title="namedconf-statement-clients-per-query">clients-per-query</a></span></td>
<td><p><p>Sets the initial minimum number of simultaneous recursive clients accepted by the server for any given query before the server drops additional clients.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-controls" title="namedconf-statement-controls">controls</a></span></td>
<td><p><p>Specifies control channels to be used to manage the name server.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-cookie-algorithm" title="namedconf-statement-cookie-algorithm">cookie-algorithm</a></span></td>
<td><p><p>Sets the algorithm to be used when generating a server cookie.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-cookie-secret" title="namedconf-statement-cookie-secret">cookie-secret</a></span></td>
<td><p><p>Specifies a shared secret used for generating and verifying EDNS COOKIE options within an anycast cluster.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-coresize" title="namedconf-statement-coresize">coresize</a></span></td>
<td><p><p>Sets the maximum size of a core dump.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-database" title="namedconf-statement-database">database</a></span></td>
<td><p><p>Specifies the type of database to be used to store zone data.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-datasize" title="namedconf-statement-datasize">datasize</a></span></td>
<td><p><p>Sets the maximum amount of data memory that can be used by the server.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-delegation-only" title="namedconf-statement-delegation-only">delegation-only</a></span></td>
<td><p><p>Indicates that a forward, hint, or stub zone is to be treated as a delegation-only type zone.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-deny-answer-addresses" title="namedconf-statement-deny-answer-addresses">deny-answer-addresses</a></span></td>
<td><p><p>Rejects A or AAAA records if the corresponding IPv4 or IPv6 addresses match a given <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a>.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-deny-answer-aliases" title="namedconf-statement-deny-answer-aliases">deny-answer-aliases</a></span></td>
<td><p><p>Rejects CNAME or DNAME records if the "alias" name matches a given list of <a class="reference internal" href="#term-domain_name"><code class="xref any std std-term docutils literal notranslate"><span class="pre">domain_name</span></code></a> elements.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dhparam-file" title="namedconf-statement-dhparam-file">dhparam-file</a></span></td>
<td><p><p>Specifies the path to a file containing Diffie-Hellman parameters, for enabling cipher suites.</p>
</p></td>
<td><p>server, security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dialup" title="namedconf-statement-dialup">dialup</a></span></td>
<td><p><p>Concentrates zone maintenance so that all transfers take place once every <a class="reference internal" href="#namedconf-statement-heartbeat-interval" title="namedconf-statement-heartbeat-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">heartbeat-interval</span></code></a>, ideally during a single call.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-directory" title="namedconf-statement-directory">directory</a></span></td>
<td><p><p>Sets the server's working directory.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-disable-algorithms" title="namedconf-statement-disable-algorithms">disable-algorithms</a></span></td>
<td><p><p>Disables DNSSEC algorithms from a specified zone.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-disable-ds-digests" title="namedconf-statement-disable-ds-digests">disable-ds-digests</a></span></td>
<td><p><p>Disables DS digest types from a specified zone.</p>
</p></td>
<td><p>dnssec, zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-disable-empty-zone" title="namedconf-statement-disable-empty-zone">disable-empty-zone</a></span></td>
<td><p><p>Disables individual empty zones.</p>
</p></td>
<td><p>server, zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="chapter6.html#namedconf-statement-dlz" title="namedconf-statement-dlz">dlz</a></span></td>
<td><p><p>Configures a Dynamically Loadable Zone (DLZ) database in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64">dns64</a></span></td>
<td><p><p>Instructs <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to return mapped IPv4 addresses to AAAA queries when there are no AAAA records.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dns64-contact" title="namedconf-statement-dns64-contact">dns64-contact</a></span></td>
<td><p><p>Specifies the name of the contact for <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> zones.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dns64-server" title="namedconf-statement-dns64-server">dns64-server</a></span></td>
<td><p><p>Specifies the name of the server for <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> zones.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnskey-sig-validity" title="namedconf-statement-dnskey-sig-validity">dnskey-sig-validity</a></span></td>
<td><p><p>Specifies the number of days in the future when automatically generated DNSSEC signatures expire.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnskey-ttl" title="namedconf-statement-dnskey-ttl">dnskey-ttl</a></span></td>
<td><p><p>Specifies the time to live (TTL) for DNSKEY resource records.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnsrps-enable" title="namedconf-statement-dnsrps-enable">dnsrps-enable</a></span></td>
<td><p><p>Turns on the DNS Response Policy Service (DNSRPS) interface.</p>
</p></td>
<td><p>server, security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnsrps-options" title="namedconf-statement-dnsrps-options">dnsrps-options</a></span></td>
<td><p><p>Provides additional RPZ configuration settings, which are passed to the DNS Response Policy Service (DNSRPS) provider library.</p>
</p></td>
<td><p>server, security</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-accept-expired" title="namedconf-statement-dnssec-accept-expired">dnssec-accept-expired</a></span></td>
<td><p><p>Instructs BIND 9 to accept expired DNSSEC signatures when validating.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-dnskey-kskonly" title="namedconf-statement-dnssec-dnskey-kskonly">dnssec-dnskey-kskonly</a></span></td>
<td><p><p>Specifies that only key-signing keys are used to sign the DNSKEY, CDNSKEY, and CDS RRsets at a zone's apex.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-loadkeys-interval" title="namedconf-statement-dnssec-loadkeys-interval">dnssec-loadkeys-interval</a></span></td>
<td><p><p>Sets the frequency of automatic checks of the DNSSEC key repository.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-must-be-secure" title="namedconf-statement-dnssec-must-be-secure">dnssec-must-be-secure</a></span></td>
<td><p><p>Defines hierarchies that must or may not be secure (signed and validated).</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy">dnssec-policy</a></span></td>
<td><p><p>Defines a key and signing policy (KASP) for zones.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-secure-to-insecure" title="namedconf-statement-dnssec-secure-to-insecure">dnssec-secure-to-insecure</a></span></td>
<td><p><p>Allows a dynamic zone to transition from secure to insecure by deleting all DNSKEY records.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-update-mode" title="namedconf-statement-dnssec-update-mode">dnssec-update-mode</a></span></td>
<td><p><p>Controls the scheduled maintenance of DNSSEC signatures.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-validation" title="namedconf-statement-dnssec-validation">dnssec-validation</a></span></td>
<td><p><p>Enables DNSSEC validation in <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap">dnstap</a></span></td>
<td><p><p>Enables logging of <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnstap-identity" title="namedconf-statement-dnstap-identity">dnstap-identity</a></span></td>
<td><p><p>Specifies an <code class="docutils literal notranslate"><span class="pre">identity</span></code> string to send in <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnstap-output" title="namedconf-statement-dnstap-output">dnstap-output</a></span></td>
<td><p><p>Configures the path to which the <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> frame stream is sent.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnstap-version" title="namedconf-statement-dnstap-version">dnstap-version</a></span></td>
<td><p><p>Specifies a <a class="reference internal" href="#namedconf-statement-version" title="namedconf-statement-version"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">version</span></code></a> string to send in <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dscp" title="namedconf-statement-dscp">dscp</a></span></td>
<td><p><p>Sets the Differentiated Services Code Point (DSCP) value (obsolete).</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dual-stack-servers" title="namedconf-statement-dual-stack-servers">dual-stack-servers</a></span></td>
<td><p><p>Specifies host names or addresses of machines with access to both IPv4 and IPv6 transports.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dump-file" title="namedconf-statement-dump-file">dump-file</a></span></td>
<td><p><p>Indicates the pathname of the file where the server dumps the database after <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-dumpdb"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">dumpdb</span></code></a>.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="chapter6.html#namedconf-statement-dyndb" title="namedconf-statement-dyndb">dyndb</a></span></td>
<td><p><p>Configures a DynDB database in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-edns" title="namedconf-statement-edns">edns</a></span></td>
<td><p><p>Controls the use of the EDNS0 (<span class="target" id="index-26"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc2671.html"><strong>RFC 2671</strong></a>) feature.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-edns-udp-size" title="namedconf-statement-edns-udp-size">edns-udp-size</a></span></td>
<td><p><p>Sets the maximum advertised EDNS UDP buffer size to control the size of packets received from authoritative servers in response to recursive queries.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-edns-version" title="namedconf-statement-edns-version">edns-version</a></span></td>
<td><p><p>Sets the maximum EDNS VERSION that is sent to the server(s) by the resolver.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-empty-contact" title="namedconf-statement-empty-contact">empty-contact</a></span></td>
<td><p><p>Specifies the contact name in the returned SOA record for empty zones.</p>
</p></td>
<td><p>server, zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-empty-server" title="namedconf-statement-empty-server">empty-server</a></span></td>
<td><p><p>Specifies the server name in the returned SOA record for empty zones.</p>
</p></td>
<td><p>server, zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-empty-zones-enable" title="namedconf-statement-empty-zones-enable">empty-zones-enable</a></span></td>
<td><p><p>Enables or disables all empty zones.</p>
</p></td>
<td><p>server, zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-endpoints" title="namedconf-statement-endpoints">endpoints</a></span></td>
<td><p><p>Specifies a list of HTTP query paths on which to listen.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-errors-per-second" title="namedconf-statement-errors-per-second">errors-per-second</a></span></td>
<td><p><p>Limits the number of errors for a valid domain name and record type.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-exclude" title="namedconf-statement-exclude">exclude</a></span></td>
<td><p><p>Allows a list of IPv6 addresses to be ignored if they appear in a domain name's AAAA records in <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-exempt-clients" title="namedconf-statement-exempt-clients">exempt-clients</a></span></td>
<td><p><p>Exempts specific clients or client groups from rate limiting.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-fetch-quota-params" title="namedconf-statement-fetch-quota-params">fetch-quota-params</a></span></td>
<td><p><p>Sets the parameters for dynamic resizing of the <a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-server</span></code></a> quota in response to detected congestion.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server">fetches-per-server</a></span></td>
<td><p><p>Sets the maximum number of simultaneous iterative queries allowed to be sent by a server to an upstream name server before the server blocks additional queries.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-fetches-per-zone" title="namedconf-statement-fetches-per-zone">fetches-per-zone</a></span></td>
<td><p><p>Sets the maximum number of simultaneous iterative queries allowed to any one domain before the server blocks new queries for data in or beneath that zone.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-file" title="namedconf-statement-file">file</a></span></td>
<td><p><p>Specifies the zone's filename.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-files" title="namedconf-statement-files">files</a></span></td>
<td><p><p>Sets the maximum number of files the server may have open concurrently.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-flush-zones-on-shutdown" title="namedconf-statement-flush-zones-on-shutdown">flush-zones-on-shutdown</a></span></td>
<td><p><p>Controls whether pending zone writes are flushed when the name server exits.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-forward" title="namedconf-statement-forward">forward</a></span></td>
<td><p><p>Allows or disallows fallback to recursion if forwarding has failed; it is always used in conjunction with the <a class="reference internal" href="#namedconf-statement-forwarders" title="namedconf-statement-forwarders"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forwarders</span></code></a> statement.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-forwarders" title="namedconf-statement-forwarders">forwarders</a></span></td>
<td><p><p>Defines one or more hosts to which queries are forwarded.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-buffer-hint" title="namedconf-statement-fstrm-set-buffer-hint">fstrm-set-buffer-hint</a></span></td>
<td><p><p>Sets the number of accumulated bytes in the output buffer before forcing a buffer flush.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-flush-timeout" title="namedconf-statement-fstrm-set-flush-timeout">fstrm-set-flush-timeout</a></span></td>
<td><p><p>Sets the number of seconds that unflushed data remains in the output buffer.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-input-queue-size" title="namedconf-statement-fstrm-set-input-queue-size">fstrm-set-input-queue-size</a></span></td>
<td><p><p>Sets the number of queue entries to allocate for each input queue.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-output-notify-threshold" title="namedconf-statement-fstrm-set-output-notify-threshold">fstrm-set-output-notify-threshold</a></span></td>
<td><p><p>Sets the number of outstanding queue entries allowed on an input queue before waking the I/O thread.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-output-queue-model" title="namedconf-statement-fstrm-set-output-queue-model">fstrm-set-output-queue-model</a></span></td>
<td><p><p>Sets the queuing semantics to use for queue objects.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-output-queue-size" title="namedconf-statement-fstrm-set-output-queue-size">fstrm-set-output-queue-size</a></span></td>
<td><p><p>Sets the number of queue entries allocated for each output queue.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-reopen-interval" title="namedconf-statement-fstrm-set-reopen-interval">fstrm-set-reopen-interval</a></span></td>
<td><p><p>Sets the number of seconds to wait between attempts to reopen a closed output stream.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-geoip-directory" title="namedconf-statement-geoip-directory">geoip-directory</a></span></td>
<td><p><p>Specifies the directory containing GeoIP database files.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-glue-cache" title="namedconf-statement-glue-cache">glue-cache</a></span></td>
<td><p><p>Deprecated.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-heartbeat-interval" title="namedconf-statement-heartbeat-interval">heartbeat-interval</a></span></td>
<td><p><p>Sets the interval at which the server performs zone maintenance tasks for all zones marked as <a class="reference internal" href="#namedconf-statement-dialup" title="namedconf-statement-dialup"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dialup</span></code></a>.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-hostname" title="namedconf-statement-hostname">hostname</a></span></td>
<td><p><p>Specifies the hostname of the server to return in response to a <code class="docutils literal notranslate"><span class="pre">hostname.bind</span></code> query.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http">http</a></span></td>
<td><p><p>Configures HTTP endpoints on which to listen for DNS-over-HTTPS (DoH) queries.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-http-listener-clients" title="namedconf-statement-http-listener-clients">http-listener-clients</a></span></td>
<td><p><p>Limits the number of active concurrent connections on a per-listener basis.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-http-port" title="namedconf-statement-http-port">http-port</a></span></td>
<td><p><p>Specifies the TCP port number the server uses to receive and send unencrypted DNS traffic via HTTP.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-http-streams-per-connection" title="namedconf-statement-http-streams-per-connection">http-streams-per-connection</a></span></td>
<td><p><p>Limits the number of active concurrent HTTP/2 streams on a per-connection basis.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-https-port" title="namedconf-statement-https-port">https-port</a></span></td>
<td><p><p>Specifies the TCP port number the server uses to receive and send DNS-over-HTTPS protocol traffic.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-in-view" title="namedconf-statement-in-view">in-view</a></span></td>
<td><p><p>Specifies the view in which a given zone is defined.</p>
</p></td>
<td><p>view, zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-inet" title="namedconf-statement-inet">inet</a></span></td>
<td><p><p>Specifies a TCP socket as a control channel.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-inline-signing" title="namedconf-statement-inline-signing">inline-signing</a></span></td>
<td><p><p>Specifies whether BIND 9 maintains a separate signed version of a zone.</p>
</p></td>
<td><p>dnssec, zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-interface-interval" title="namedconf-statement-interface-interval">interface-interval</a></span></td>
<td><p><p>Sets the interval at which the server scans the network interface list.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ipv4-prefix-length" title="namedconf-statement-ipv4-prefix-length">ipv4-prefix-length</a></span></td>
<td><p><p>Specifies the prefix lengths of IPv4 address blocks.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-ipv4only-contact" title="namedconf-statement-ipv4only-contact">ipv4only-contact</a></span></td>
<td><p><p>Specifies the contact for the IPV4ONLY.ARPA zone created by <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ipv4only-enable" title="namedconf-statement-ipv4only-enable">ipv4only-enable</a></span></td>
<td><p><p>Enables automatic IPv4 zones if a <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> block is configured.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-ipv4only-server" title="namedconf-statement-ipv4only-server">ipv4only-server</a></span></td>
<td><p><p>Specifies the name of the server for the IPV4ONLY.ARPA zone created by <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ipv6-prefix-length" title="namedconf-statement-ipv6-prefix-length">ipv6-prefix-length</a></span></td>
<td><p><p>Specifies the prefix lengths of IPv6 address blocks.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-ixfr-from-differences" title="namedconf-statement-ixfr-from-differences">ixfr-from-differences</a></span></td>
<td><p><p>Controls how IXFR transfers are calculated.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-journal" title="namedconf-statement-journal">journal</a></span></td>
<td><p><p>Allows the default journal's filename to be overridden.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-keep-response-order" title="namedconf-statement-keep-response-order">keep-response-order</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of addresses which do not accept reordered answers within a single TCP stream.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-key" title="namedconf-statement-key">key</a></span></td>
<td><p><p>Defines a shared secret key for use with <a class="reference internal" href="chapter7.html#tsig"><span class="std std-ref">TSIG</span></a> or the command channel.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-key-directory" title="namedconf-statement-key-directory">key-directory</a></span></td>
<td><p><p>Indicates the directory where public and private DNSSEC key files are found.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-key-file" title="namedconf-statement-key-file">key-file</a></span></td>
<td><p><p>Specifies the path to a file containing the private TLS key for a connection.</p>
</p></td>
<td><p>server, security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-keys" title="namedconf-statement-keys">keys</a></span></td>
<td><p><p>Specifies one or more <a class="reference internal" href="#term-server_key"><code class="xref any std std-term docutils literal notranslate"><span class="pre">server_key</span></code></a> s to be used with a remote server.</p>
</p></td>
<td><p>server, security</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-lame-ttl" title="namedconf-statement-lame-ttl">lame-ttl</a></span></td>
<td><p><p>Sets the resolver's lame cache.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on">listen-on</a></span></td>
<td><p><p>Specifies the IPv4 addresses on which a server listens for DNS queries.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-listen-on-v6" title="namedconf-statement-listen-on-v6">listen-on-v6</a></span></td>
<td><p><p>Specifies the IPv6 addresses on which a server listens for DNS queries.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-listener-clients" title="namedconf-statement-listener-clients">listener-clients</a></span></td>
<td><p><p>Specifies a per-listener quota for active connections.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-lmdb-mapsize" title="namedconf-statement-lmdb-mapsize">lmdb-mapsize</a></span></td>
<td><p><p>Sets a maximum size for the memory map of the new-zone database in LMDB database format.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-lock-file" title="namedconf-statement-lock-file">lock-file</a></span></td>
<td><p><p>Sets the pathname of the file on which <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> attempts to acquire a file lock when starting for the first time.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-log-only" title="namedconf-statement-log-only">log-only</a></span></td>
<td><p><p>Tests rate-limiting parameters without actually dropping any requests.</p>
</p></td>
<td><p>logging, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-logging" title="namedconf-statement-logging">logging</a></span></td>
<td><p><p>Configures logging options for the name server.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-managed-keys" title="namedconf-statement-managed-keys">managed-keys</a></span></td>
<td><p><p>Deprecated, use <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-managed-keys-directory" title="namedconf-statement-managed-keys-directory">managed-keys-directory</a></span></td>
<td><p><p>Specifies the directory in which to store the files that track managed DNSSEC keys.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-mapped" title="namedconf-statement-mapped">mapped</a></span></td>
<td><p><p>Specifies an access control list (ACL) of IPv4 addresses that are to be mapped to the corresponding A RRset in <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format">masterfile-format</a></span></td>
<td><p><p>Specifies the file format of zone files.</p>
</p></td>
<td><p>zone, server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-masterfile-style" title="namedconf-statement-masterfile-style">masterfile-style</a></span></td>
<td><p><p>Specifies the format of zone files during a dump, when the <a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">masterfile-format</span></code></a> is <code class="docutils literal notranslate"><span class="pre">text</span></code>.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-match-clients" title="namedconf-statement-match-clients">match-clients</a></span></td>
<td><p><p>Specifies a view of DNS namespace for a given subset of client IP addresses.</p>
</p></td>
<td><p>view</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-match-destinations" title="namedconf-statement-match-destinations">match-destinations</a></span></td>
<td><p><p>Specifies a view of DNS namespace for a given subset of destination IP addresses.</p>
</p></td>
<td><p>view</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-match-mapped-addresses" title="namedconf-statement-match-mapped-addresses">match-mapped-addresses</a></span></td>
<td><p><p>Allows IPv4-mapped IPv6 addresses to match address-match list entries for corresponding IPv4 addresses.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-match-recursive-only" title="namedconf-statement-match-recursive-only">match-recursive-only</a></span></td>
<td><p><p>Specifies that only recursive requests can match this view of the DNS namespace.</p>
</p></td>
<td><p>view</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-cache-size" title="namedconf-statement-max-cache-size">max-cache-size</a></span></td>
<td><p><p>Sets the maximum amount of memory to use for an individual cache database and its associated metadata.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-cache-ttl" title="namedconf-statement-max-cache-ttl">max-cache-ttl</a></span></td>
<td><p><p>Specifies the maximum time (in seconds) that the server caches ordinary (positive) answers.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-clients-per-query" title="namedconf-statement-max-clients-per-query">max-clients-per-query</a></span></td>
<td><p><p>Sets the maximum number of simultaneous recursive clients accepted by the server for any given query before the server drops additional clients.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-ixfr-ratio" title="namedconf-statement-max-ixfr-ratio">max-ixfr-ratio</a></span></td>
<td><p><p>Sets the maximum size for IXFR responses to zone transfer requests.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-journal-size" title="namedconf-statement-max-journal-size">max-journal-size</a></span></td>
<td><p><p>Controls the size of journal files.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-ncache-ttl" title="namedconf-statement-max-ncache-ttl">max-ncache-ttl</a></span></td>
<td><p><p>Specifies the maximum retention time (in seconds) for storage of negative answers in the server's cache.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-query-count" title="namedconf-statement-max-query-count">max-query-count</a></span></td>
<td><p><p>Sets the maximum number of iterative queries while servicing a recursive query.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-query-restarts" title="namedconf-statement-max-query-restarts">max-query-restarts</a></span></td>
<td><p><p>Sets the maximum number of chained CNAMEs to follow</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-records" title="namedconf-statement-max-records">max-records</a></span></td>
<td><p><p>Sets the maximum number of records permitted in a zone.</p>
</p></td>
<td><p>zone, server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-records-per-type" title="namedconf-statement-max-records-per-type">max-records-per-type</a></span></td>
<td><p><p>Sets the maximum number of records that can be stored in an RRset.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-recursion-depth" title="namedconf-statement-max-recursion-depth">max-recursion-depth</a></span></td>
<td><p><p>Sets the maximum number of levels of recursion permitted at any one time while servicing a recursive query.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-recursion-queries" title="namedconf-statement-max-recursion-queries">max-recursion-queries</a></span></td>
<td><p><p>Sets the maximum number of iterative queries while servicing a recursive query.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-refresh-time" title="namedconf-statement-max-refresh-time">max-refresh-time</a></span></td>
<td><p><p>Limits the zone refresh interval to no less often than the specified value, in seconds.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-retry-time" title="namedconf-statement-max-retry-time">max-retry-time</a></span></td>
<td><p><p>Limits the zone refresh retry interval to no less often than the specified value, in seconds.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-rsa-exponent-size" title="namedconf-statement-max-rsa-exponent-size">max-rsa-exponent-size</a></span></td>
<td><p><p>Sets the maximum RSA exponent size (in bits) when validating.</p>
</p></td>
<td><p>dnssec, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-stale-ttl" title="namedconf-statement-max-stale-ttl">max-stale-ttl</a></span></td>
<td><p><p>Specifies the maximum time that the server retains records past their normal expiry, to return them as stale records.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-table-size" title="namedconf-statement-max-table-size">max-table-size</a></span></td>
<td><p><p>Sets the maximum size of the table used to track requests and rate-limit responses.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-transfer-idle-in" title="namedconf-statement-max-transfer-idle-in">max-transfer-idle-in</a></span></td>
<td><p><p>Specifies the number of minutes after which inbound zone transfers making no progress are terminated.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-transfer-idle-out" title="namedconf-statement-max-transfer-idle-out">max-transfer-idle-out</a></span></td>
<td><p><p>Specifies the number of minutes after which outbound zone transfers making no progress are terminated.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-transfer-time-in" title="namedconf-statement-max-transfer-time-in">max-transfer-time-in</a></span></td>
<td><p><p>Specifies the number of minutes after which inbound zone transfers are terminated.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-transfer-time-out" title="namedconf-statement-max-transfer-time-out">max-transfer-time-out</a></span></td>
<td><p><p>Specifies the number of minutes after which outbound zone transfers are terminated.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-types-per-name" title="namedconf-statement-max-types-per-name">max-types-per-name</a></span></td>
<td><p><p>Sets the maximum number of RR types that can be stored for an owner name.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-udp-size" title="namedconf-statement-max-udp-size">max-udp-size</a></span></td>
<td><p><p>Sets the maximum EDNS UDP message size sent by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl">max-zone-ttl</a></span></td>
<td><p><p>Specifies a maximum permissible time-to-live (TTL) value, in seconds.</p>
</p></td>
<td><p>zone, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-memstatistics" title="namedconf-statement-memstatistics">memstatistics</a></span></td>
<td><p><p>Controls whether memory statistics are written to the file specified by <a class="reference internal" href="#namedconf-statement-memstatistics-file" title="namedconf-statement-memstatistics-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">memstatistics-file</span></code></a> at exit.</p>
</p></td>
<td><p>server, logging</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-memstatistics-file" title="namedconf-statement-memstatistics-file">memstatistics-file</a></span></td>
<td><p><p>Sets the pathname of the file where the server writes memory usage statistics on exit.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-message-compression" title="namedconf-statement-message-compression">message-compression</a></span></td>
<td><p><p>Controls whether DNS name compression is used in responses to regular queries.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-min-cache-ttl" title="namedconf-statement-min-cache-ttl">min-cache-ttl</a></span></td>
<td><p><p>Specifies the minimum time (in seconds) that the server caches ordinary (positive) answers.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-min-ncache-ttl" title="namedconf-statement-min-ncache-ttl">min-ncache-ttl</a></span></td>
<td><p><p>Specifies the minimum retention time (in seconds) for storage of negative answers in the server's cache.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-min-refresh-time" title="namedconf-statement-min-refresh-time">min-refresh-time</a></span></td>
<td><p><p>Limits the zone refresh interval to no more often than the specified value, in seconds.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-min-retry-time" title="namedconf-statement-min-retry-time">min-retry-time</a></span></td>
<td><p><p>Limits the zone refresh retry interval to no more often than the specified value, in seconds.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-min-table-size" title="namedconf-statement-min-table-size">min-table-size</a></span></td>
<td><p><p>Sets the minimum size of the table used to track requests and rate-limit responses.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-minimal-any" title="namedconf-statement-minimal-any">minimal-any</a></span></td>
<td><p><p>Controls whether the server replies with only one of the RRsets for a query name, when generating a positive response to a query of type ANY over UDP.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-minimal-responses" title="namedconf-statement-minimal-responses">minimal-responses</a></span></td>
<td><p><p>Controls whether the server only adds records to the authority and additional data sections when they are required (e.g. delegations, negative responses). This improves server performance.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-multi-master" title="namedconf-statement-multi-master">multi-master</a></span></td>
<td><p><p>Controls whether serial number mismatch errors are logged.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-new-zones-directory" title="namedconf-statement-new-zones-directory">new-zones-directory</a></span></td>
<td><p><p>Specifies the directory where configuration parameters are stored for zones added by <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-addzone"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">addzone</span></code></a>.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-no-case-compress" title="namedconf-statement-no-case-compress">no-case-compress</a></span></td>
<td><p><p>Specifies a list of addresses that require case-insensitive compression in responses.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-nocookie-udp-size" title="namedconf-statement-nocookie-udp-size">nocookie-udp-size</a></span></td>
<td><p><p>Sets the maximum size of UDP responses that are sent to queries without a valid server COOKIE.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-nodata-per-second" title="namedconf-statement-nodata-per-second">nodata-per-second</a></span></td>
<td><p><p>Limits the number of empty (NODATA) responses for a valid domain name.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify">notify</a></span></td>
<td><p><p>Controls whether <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages are sent on zone changes.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-notify-delay" title="namedconf-statement-notify-delay">notify-delay</a></span></td>
<td><p><p>Sets the delay (in seconds) between sending sets of NOTIFY messages for a zone.</p>
</p></td>
<td><p>transfer, zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-notify-rate" title="namedconf-statement-notify-rate">notify-rate</a></span></td>
<td><p><p>Specifies the rate at which NOTIFY requests are sent during normal zone maintenance operations.</p>
</p></td>
<td><p>transfer, zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-notify-source" title="namedconf-statement-notify-source">notify-source</a></span></td>
<td><p><p>Defines the IPv4 address (and optional port) to be used for outgoing <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-notify-source-v6" title="namedconf-statement-notify-source-v6">notify-source-v6</a></span></td>
<td><p><p>Defines the IPv6 address (and optional port) to be used for outgoing <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-notify-to-soa" title="namedconf-statement-notify-to-soa">notify-to-soa</a></span></td>
<td><p><p>Controls whether the name servers in the NS RRset are checked against the SOA MNAME.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-nsec3param" title="namedconf-statement-nsec3param">nsec3param</a></span></td>
<td><p><p>Specifies the use of NSEC3 instead of NSEC, and sets NSEC3 parameters.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-nta-lifetime" title="namedconf-statement-nta-lifetime">nta-lifetime</a></span></td>
<td><p><p>Specifies the lifetime, in seconds, for negative trust anchors added via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-nta"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">nta</span></code></a>.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-nta-recheck" title="namedconf-statement-nta-recheck">nta-recheck</a></span></td>
<td><p><p>Specifies the time interval for checking whether negative trust anchors added via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-nta"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">nta</span></code></a> are still necessary.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-null" title="namedconf-statement-null">null</a></span></td>
<td><p><p>Causes all messages sent to the logging channel to be discarded.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-nxdomain-redirect" title="namedconf-statement-nxdomain-redirect">nxdomain-redirect</a></span></td>
<td><p><p>Appends the specified suffix to the original query name, when replacing an NXDOMAIN with a redirect namespace.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-nxdomains-per-second" title="namedconf-statement-nxdomains-per-second">nxdomains-per-second</a></span></td>
<td><p><p>Limits the number of undefined subdomains for a valid domain name.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options">options</a></span></td>
<td><p><p>Defines global options to be used by BIND 9.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-padding" title="namedconf-statement-padding">padding</a></span></td>
<td><p><p>Adds EDNS Padding options to outgoing messages to increase the packet size.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-parent-ds-ttl" title="namedconf-statement-parent-ds-ttl">parent-ds-ttl</a></span></td>
<td><p><p>Sets the time to live (TTL) of the DS RRset used by the parent zone.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-parent-propagation-delay" title="namedconf-statement-parent-propagation-delay">parent-propagation-delay</a></span></td>
<td><p><p>Sets the propagation delay from the time the parent zone is updated to when the new version is served by all of the parent zone's name servers.</p>
</p></td>
<td><p>dnssec, zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-parental-agents" title="namedconf-statement-parental-agents">parental-agents</a></span></td>
<td><p><p>Defines a list of delegation agents to be used by primary and secondary zones.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-parental-source" title="namedconf-statement-parental-source">parental-source</a></span></td>
<td><p><p>Specifies which local IPv4 source address is used to send parental DS queries.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-parental-source-v6" title="namedconf-statement-parental-source-v6">parental-source-v6</a></span></td>
<td><p><p>Specifies which local IPv6 source address is used to send parental DS queries.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-pid-file" title="namedconf-statement-pid-file">pid-file</a></span></td>
<td><p><p>Specifies the pathname of the file where the server writes its process ID.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="chapter4.html#namedconf-statement-plugin" title="namedconf-statement-plugin">plugin</a></span></td>
<td><p><p>Configures plugins in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-port" title="namedconf-statement-port">port</a></span></td>
<td><p><p>Specifies the UDP/TCP port number the server uses to receive and send DNS protocol traffic.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-prefer-server-ciphers" title="namedconf-statement-prefer-server-ciphers">prefer-server-ciphers</a></span></td>
<td><p><p>Specifies that server ciphers should be preferred over client ones.</p>
</p></td>
<td><p>server, security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-preferred-glue" title="namedconf-statement-preferred-glue">preferred-glue</a></span></td>
<td><p><p>Controls the order of glue records in an A or AAAA response.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-prefetch" title="namedconf-statement-prefetch">prefetch</a></span></td>
<td><p><p>Specifies the "trigger" time-to-live (TTL) value at which prefetch of the current query takes place.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries">primaries</a></span></td>
<td><p><p>Defines one or more primary servers for a zone.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-print-category" title="namedconf-statement-print-category">print-category</a></span></td>
<td><p><p>Includes the category in log messages.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-print-severity" title="namedconf-statement-print-severity">print-severity</a></span></td>
<td><p><p>Includes the severity in log messages.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-print-time" title="namedconf-statement-print-time">print-time</a></span></td>
<td><p><p>Specifies the time format for log messages.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-protocols" title="namedconf-statement-protocols">protocols</a></span></td>
<td><p><p>Specifies the allowed versions of the TLS protocol.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-provide-ixfr" title="namedconf-statement-provide-ixfr">provide-ixfr</a></span></td>
<td><p><p>Controls whether a primary responds to an incremental zone request (IXFR) or only responds with a full zone transfer (AXFR).</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-publish-safety" title="namedconf-statement-publish-safety">publish-safety</a></span></td>
<td><p><p>Increases the amount of time between when keys are published and when they become active, to allow for unforeseen events.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-purge-keys" title="namedconf-statement-purge-keys">purge-keys</a></span></td>
<td><p><p>Specifies the amount of time after which DNSSEC keys that have been deleted from the zone can be removed from disk.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-qname-minimization" title="namedconf-statement-qname-minimization">qname-minimization</a></span></td>
<td><p><p>Controls QNAME minimization behavior in the BIND 9 resolver.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-qps-scale" title="namedconf-statement-qps-scale">qps-scale</a></span></td>
<td><p><p>Tightens defenses during DNS attacks by scaling back the ratio of the current query-per-second rate.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-query-source" title="namedconf-statement-query-source">query-source</a></span></td>
<td><p><p>Controls the IPv4 address from which queries are issued.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-query-source-v6" title="namedconf-statement-query-source-v6">query-source-v6</a></span></td>
<td><p><p>Controls the IPv6 address from which queries are issued.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-querylog" title="namedconf-statement-querylog">querylog</a></span></td>
<td><p><p>Specifies whether query logging should be active when <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> first starts.</p>
</p></td>
<td><p>logging, server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-rate-limit" title="namedconf-statement-rate-limit">rate-limit</a></span></td>
<td><p><p>Controls excessive UDP responses, to prevent BIND 9 from being used to amplify reflection denial-of-service (DoS) attacks.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-recursing-file" title="namedconf-statement-recursing-file">recursing-file</a></span></td>
<td><p><p>Specifies the pathname of the file where the server dumps queries that are currently recursing via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-recursing"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">recursing</span></code></a>.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-recursion" title="namedconf-statement-recursion">recursion</a></span></td>
<td><p><p>Defines whether recursion and caching are allowed.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients">recursive-clients</a></span></td>
<td><p><p>Specifies the maximum number of concurrent recursive queries the server can perform.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-recursive-only" title="namedconf-statement-recursive-only">recursive-only</a></span></td>
<td><p><p>Toggles whether <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> synthesis occurs only for recursive queries.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-referrals-per-second" title="namedconf-statement-referrals-per-second">referrals-per-second</a></span></td>
<td><p><p>Limits the number of referrals or delegations to a server for a given domain.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-remote-hostname" title="namedconf-statement-remote-hostname">remote-hostname</a></span></td>
<td><p><p>Specifies the expected hostname in the TLS certificate of the remote server.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-request-expire" title="namedconf-statement-request-expire">request-expire</a></span></td>
<td><p><p>Specifies whether the local server requests the EDNS EXPIRE value, when acting as a secondary.</p>
</p></td>
<td><p>transfer, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-request-ixfr" title="namedconf-statement-request-ixfr">request-ixfr</a></span></td>
<td><p><p>Controls whether a secondary requests an incremental zone transfer (IXFR) or a full zone transfer (AXFR).</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-request-nsid" title="namedconf-statement-request-nsid">request-nsid</a></span></td>
<td><p><p>Controls whether an empty EDNS(0) NSID (Name Server Identifier) option is sent with all queries to authoritative name servers during iterative resolution.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-require-server-cookie" title="namedconf-statement-require-server-cookie">require-server-cookie</a></span></td>
<td><p><p>Controls whether a valid server cookie is required before sending a full response to a UDP request.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-reserved-sockets" title="namedconf-statement-reserved-sockets">reserved-sockets</a></span></td>
<td><p><p>Deprecated.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-resolver-nonbackoff-tries" title="namedconf-statement-resolver-nonbackoff-tries">resolver-nonbackoff-tries</a></span></td>
<td><p><p>Specifies the number of retries before exponential backoff.</p>
</p></td>
<td><p>deprecated.</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-resolver-query-timeout" title="namedconf-statement-resolver-query-timeout">resolver-query-timeout</a></span></td>
<td><p><p>Specifies the length of time, in milliseconds, that a resolver attempts to resolve a recursive query before failing.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-resolver-retry-interval" title="namedconf-statement-resolver-retry-interval">resolver-retry-interval</a></span></td>
<td><p><p>Sets the base retry interval (in milliseconds).</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-response-padding" title="namedconf-statement-response-padding">response-padding</a></span></td>
<td><p><p>Adds an EDNS Padding option to encrypted messages, to reduce the chance of guessing the contents based on size.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-response-policy" title="namedconf-statement-response-policy">response-policy</a></span></td>
<td><p><p>Specifies response policy zones for the view or among global options.</p>
</p></td>
<td><p>server, query, zone, security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-responses-per-second" title="namedconf-statement-responses-per-second">responses-per-second</a></span></td>
<td><p><p>Limits the number of non-empty responses for a valid domain name and record type.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-retire-safety" title="namedconf-statement-retire-safety">retire-safety</a></span></td>
<td><p><p>Increases the amount of time a key remains published after it is no longer active, to allow for unforeseen events.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-reuseport" title="namedconf-statement-reuseport">reuseport</a></span></td>
<td><p><p>Enables kernel load-balancing of sockets.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-root-delegation-only" title="namedconf-statement-root-delegation-only">root-delegation-only</a></span></td>
<td><p><p>Turns on enforcement of delegation-only in top-level domains (TLDs) and root zones with an optional exclude list.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-root-key-sentinel" title="namedconf-statement-root-key-sentinel">root-key-sentinel</a></span></td>
<td><p><p>Controls whether BIND 9 responds to root key sentinel probes.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-rrset-order" title="namedconf-statement-rrset-order">rrset-order</a></span></td>
<td><p><p>Defines the order in which equal RRs (RRsets) are returned.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="chapter6.html#namedconf-statement-search" title="namedconf-statement-search">search</a></span></td>
<td><p><p>Specifies whether a Dynamically Loadable Zone (DLZ) module is queried for an answer to a query name.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-secret" title="namedconf-statement-secret">secret</a></span></td>
<td><p><p>Defines a Base64-encoded string to be used as the secret by the algorithm.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-secroots-file" title="namedconf-statement-secroots-file">secroots-file</a></span></td>
<td><p><p>Specifies the pathname of the file where the server dumps security roots, when using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-secroots"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">secroots</span></code></a>.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-send-cookie" title="namedconf-statement-send-cookie">send-cookie</a></span></td>
<td><p><p>Controls whether a COOKIE EDNS option is sent along with a query.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-serial-query-rate" title="namedconf-statement-serial-query-rate">serial-query-rate</a></span></td>
<td><p><p>Defines an upper limit on the number of queries per second issued by the server, when querying the SOA RRs used for zone transfers.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-serial-update-method" title="namedconf-statement-serial-update-method">serial-update-method</a></span></td>
<td><p><p>Specifies the update method to be used for the zone serial number in the SOA record.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server">server</a></span></td>
<td><p><p>Defines characteristics to be associated with a remote name server.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-server-addresses" title="namedconf-statement-server-addresses">server-addresses</a></span></td>
<td><p><p>Specifies a list of IP addresses to which queries should be sent in recursive resolution for a static-stub zone.</p>
</p></td>
<td><p>query, zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-server-id" title="namedconf-statement-server-id">server-id</a></span></td>
<td><p><p>Specifies the ID of the server to return in response to a <code class="docutils literal notranslate"><span class="pre">ID.SERVER</span></code> query.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-server-names" title="namedconf-statement-server-names">server-names</a></span></td>
<td><p><p>Specifies a list of domain names of name servers that act as authoritative servers of a static-stub zone.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-servfail-ttl" title="namedconf-statement-servfail-ttl">servfail-ttl</a></span></td>
<td><p><p>Sets the length of time (in seconds) that a SERVFAIL response is cached.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-session-keyalg" title="namedconf-statement-session-keyalg">session-keyalg</a></span></td>
<td><p><p>Specifies the algorithm to use for the TSIG session key.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-session-keyfile" title="namedconf-statement-session-keyfile">session-keyfile</a></span></td>
<td><p><p>Specifies the pathname of the file where a TSIG session key is written, when generated by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> for use by <code class="docutils literal notranslate"><span class="pre">nsupdate</span> <span class="pre">-l</span></code>.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-session-keyname" title="namedconf-statement-session-keyname">session-keyname</a></span></td>
<td><p><p>Specifies the key name for the TSIG session key.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-session-tickets" title="namedconf-statement-session-tickets">session-tickets</a></span></td>
<td><p><p>Enables or disables session resumption through TLS session tickets.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-severity" title="namedconf-statement-severity">severity</a></span></td>
<td><p><p>Defines the priority level of log messages.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-sig-signing-nodes" title="namedconf-statement-sig-signing-nodes">sig-signing-nodes</a></span></td>
<td><p><p>Specifies the maximum number of nodes to be examined in each quantum, when signing a zone with a new DNSKEY.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-sig-signing-signatures" title="namedconf-statement-sig-signing-signatures">sig-signing-signatures</a></span></td>
<td><p><p>Specifies the threshold for the number of signatures that terminates processing a quantum, when signing a zone with a new DNSKEY.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-sig-signing-type" title="namedconf-statement-sig-signing-type">sig-signing-type</a></span></td>
<td><p><p>Specifies a private RDATA type to use when generating signing-state records.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-sig-validity-interval" title="namedconf-statement-sig-validity-interval">sig-validity-interval</a></span></td>
<td><p><p>Specifies the maximum number of days that RRSIGs generated by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> are valid.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-signatures-jitter" title="namedconf-statement-signatures-jitter">signatures-jitter</a></span></td>
<td><p><p>Specifies a range for signature expirations.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-signatures-refresh" title="namedconf-statement-signatures-refresh">signatures-refresh</a></span></td>
<td><p><p>Specifies how frequently an RRSIG record is refreshed.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-signatures-validity" title="namedconf-statement-signatures-validity">signatures-validity</a></span></td>
<td><p><p>Indicates the validity period of an RRSIG record.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-signatures-validity-dnskey" title="namedconf-statement-signatures-validity-dnskey">signatures-validity-dnskey</a></span></td>
<td><p><p>Indicates the validity period of DNSKEY records.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-slip" title="namedconf-statement-slip">slip</a></span></td>
<td><p><p>Sets the number of "slipped" responses to minimize the use of forged source addresses for an attack.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-sortlist" title="namedconf-statement-sortlist">sortlist</a></span></td>
<td><p><p>Controls the ordering of RRs returned to the client, based on the client's IP address.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-stacksize" title="namedconf-statement-stacksize">stacksize</a></span></td>
<td><p><p>Sets the maximum amount of stack memory that can be used by the server.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-stale-answer-client-timeout" title="namedconf-statement-stale-answer-client-timeout">stale-answer-client-timeout</a></span></td>
<td><p><p>Defines the amount of time (in milliseconds) that <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> waits before attempting to answer a query with a stale RRset from cache.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-stale-answer-enable" title="namedconf-statement-stale-answer-enable">stale-answer-enable</a></span></td>
<td><p><p>Enables the returning of "stale" cached answers when the name servers for a zone are not answering.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-stale-answer-ttl" title="namedconf-statement-stale-answer-ttl">stale-answer-ttl</a></span></td>
<td><p><p>Specifies the time to live (TTL) to be returned on stale answers, in seconds.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-stale-cache-enable" title="namedconf-statement-stale-cache-enable">stale-cache-enable</a></span></td>
<td><p><p>Enables the retention of "stale" cached answers.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-stale-refresh-time" title="namedconf-statement-stale-refresh-time">stale-refresh-time</a></span></td>
<td><p><p>Sets the time window for the return of "stale" cached answers before the next attempt to contact, if the name servers for a given zone are not responding.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-startup-notify-rate" title="namedconf-statement-startup-notify-rate">startup-notify-rate</a></span></td>
<td><p><p>Specifies the rate at which NOTIFY requests are sent when the name server is first starting, or when new zones have been added.</p>
</p></td>
<td><p>transfer, zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-statistics-channels" title="namedconf-statement-statistics-channels">statistics-channels</a></span></td>
<td><p><p>Specifies the communication channels to be used by system administrators to access statistics information on the name server.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-statistics-file" title="namedconf-statement-statistics-file">statistics-file</a></span></td>
<td><p><p>Specifies the pathname of the file where the server appends statistics, when using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-stats"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">stats</span></code></a>.</p>
</p></td>
<td><p>logging, server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-stderr" title="namedconf-statement-stderr">stderr</a></span></td>
<td><p><p>Directs the logging channel output to the server's standard error stream.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-streams-per-connection" title="namedconf-statement-streams-per-connection">streams-per-connection</a></span></td>
<td><p><p>Specifies the maximum number of concurrent HTTP/2 streams over an HTTP/2 connection.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-suffix" title="namedconf-statement-suffix">suffix</a></span></td>
<td><p><p>Defines trailing bits for mapped IPv4 address bits in <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-synth-from-dnssec" title="namedconf-statement-synth-from-dnssec">synth-from-dnssec</a></span></td>
<td><p><p>Enables support for <span class="target" id="index-16"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc8198.html"><strong>RFC 8198</strong></a>, Aggressive Use of DNSSEC-Validated Cache.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog">syslog</a></span></td>
<td><p><p>Directs the logging channel to the system log.</p>
</p></td>
<td><p>logging</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tcp-advertised-timeout" title="namedconf-statement-tcp-advertised-timeout">tcp-advertised-timeout</a></span></td>
<td><p><p>Sets the timeout value (in milliseconds) that the server sends in responses containing the EDNS TCP keepalive option.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tcp-clients" title="namedconf-statement-tcp-clients">tcp-clients</a></span></td>
<td><p><p>Specifies the maximum number of simultaneous client TCP connections accepted by the server.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tcp-idle-timeout" title="namedconf-statement-tcp-idle-timeout">tcp-idle-timeout</a></span></td>
<td><p><p>Sets the amount of time (in milliseconds) that the server waits on an idle TCP connection before closing it, if the EDNS TCP keepalive option is not in use.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tcp-initial-timeout" title="namedconf-statement-tcp-initial-timeout">tcp-initial-timeout</a></span></td>
<td><p><p>Sets the amount of time (in milliseconds) that the server waits on a new TCP connection for the first message from the client.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tcp-keepalive" title="namedconf-statement-tcp-keepalive">tcp-keepalive</a></span></td>
<td><p><p>Adds EDNS TCP keepalive to messages sent over TCP.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tcp-keepalive-timeout" title="namedconf-statement-tcp-keepalive-timeout">tcp-keepalive-timeout</a></span></td>
<td><p><p>Sets the amount of time (in milliseconds) that the server waits on an idle TCP connection before closing it, if the EDNS TCP keepalive option is in use.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tcp-listen-queue" title="namedconf-statement-tcp-listen-queue">tcp-listen-queue</a></span></td>
<td><p><p>Sets the listen-queue depth.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tcp-only" title="namedconf-statement-tcp-only">tcp-only</a></span></td>
<td><p><p>Sets the transport protocol to TCP.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tcp-receive-buffer" title="namedconf-statement-tcp-receive-buffer">tcp-receive-buffer</a></span></td>
<td><p><p>Sets the operating system's receive buffer size for TCP sockets.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tcp-send-buffer" title="namedconf-statement-tcp-send-buffer">tcp-send-buffer</a></span></td>
<td><p><p>Sets the operating system's send buffer size for TCP sockets.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tkey-dhkey" title="namedconf-statement-tkey-dhkey">tkey-dhkey</a></span></td>
<td><p><p>Sets the Diffie-Hellman key used by the server to generate shared keys.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tkey-domain" title="namedconf-statement-tkey-domain">tkey-domain</a></span></td>
<td><p><p>Sets the domain appended to the names of all shared keys generated with <code class="docutils literal notranslate"><span class="pre">TKEY</span></code>.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tkey-gssapi-credential" title="namedconf-statement-tkey-gssapi-credential">tkey-gssapi-credential</a></span></td>
<td><p><p>Sets the security credential for authentication keys requested by the GSS-TSIG protocol.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tkey-gssapi-keytab" title="namedconf-statement-tkey-gssapi-keytab">tkey-gssapi-keytab</a></span></td>
<td><p><p>Sets the KRB5 keytab file to use for GSS-TSIG updates.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls">tls</a></span></td>
<td><p><p>Configures a TLS connection.</p>
</p></td>
<td><p>security</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tls-port" title="namedconf-statement-tls-port">tls-port</a></span></td>
<td><p><p>Specifies the TCP port number the server uses to receive and send DNS-over-TLS protocol traffic.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-transfer-format" title="namedconf-statement-transfer-format">transfer-format</a></span></td>
<td><p><p>Controls whether multiple records can be packed into a message during zone transfers.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-transfer-message-size" title="namedconf-statement-transfer-message-size">transfer-message-size</a></span></td>
<td><p><p>Limits the uncompressed size of DNS messages used in zone transfers over TCP.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source">transfer-source</a></span></td>
<td><p><p>Defines which local IPv4 address(es) are bound to TCP connections used to fetch zones transferred inbound by the server.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-transfer-source-v6" title="namedconf-statement-transfer-source-v6">transfer-source-v6</a></span></td>
<td><p><p>Defines which local IPv6 address(es) are bound to TCP connections used to fetch zones transferred inbound by the server.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-transfers" title="namedconf-statement-transfers">transfers</a></span></td>
<td><p><p>Limits the number of concurrent inbound zone transfers from a server.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-transfers-in" title="namedconf-statement-transfers-in">transfers-in</a></span></td>
<td><p><p>Limits the number of concurrent inbound zone transfers.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-transfers-out" title="namedconf-statement-transfers-out">transfers-out</a></span></td>
<td><p><p>Limits the number of concurrent outbound zone transfers.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-transfers-per-ns" title="namedconf-statement-transfers-per-ns">transfers-per-ns</a></span></td>
<td><p><p>Limits the number of concurrent inbound zone transfers from a remote server.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-trust-anchor-telemetry" title="namedconf-statement-trust-anchor-telemetry">trust-anchor-telemetry</a></span></td>
<td><p><p>Instructs <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to send specially formed queries once per day to domains for which trust anchors have been configured.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors">trust-anchors</a></span></td>
<td><p><p>Defines <a class="reference internal" href="chapter5.html#dnssec"><span class="std std-ref">DNSSEC</span></a> trust anchors.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-trusted-keys" title="namedconf-statement-trusted-keys">trusted-keys</a></span></td>
<td><p><p>Deprecated, use <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-try-tcp-refresh" title="namedconf-statement-try-tcp-refresh">try-tcp-refresh</a></span></td>
<td><p><p>Specifies that BIND 9 should attempt to refresh a zone using TCP if UDP queries fail.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-type" title="namedconf-statement-type">type</a></span></td>
<td><p><p>Specifies the kind of zone in a given configuration.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-type delegation-only" title="namedconf-statement-type delegation-only">type delegation-only</a></span></td>
<td><p><p>Enforces the delegation-only status of infrastructure zones (COM, NET, ORG, etc.).</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-type forward" title="namedconf-statement-type forward">type forward</a></span></td>
<td><p><p>Contains forwarding statements that apply to queries within a given domain.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-type hint" title="namedconf-statement-type hint">type hint</a></span></td>
<td><p><p>Contains the initial set of root name servers to be used at BIND 9 startup.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-type mirror" title="namedconf-statement-type mirror">type mirror</a></span></td>
<td><p><p>Contains a DNSSEC-validated duplicate of the main data for a zone.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary">type primary</a></span></td>
<td><p><p>Contains the main copy of the data for a zone.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-type redirect" title="namedconf-statement-type redirect">type redirect</a></span></td>
<td><p><p>Contains information to answer queries when normal resolution would return NXDOMAIN.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary">type secondary</a></span></td>
<td><p><p>Contains a duplicate of the data for a zone that has been transferred from a primary server.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-type static-stub" title="namedconf-statement-type static-stub">type static-stub</a></span></td>
<td><p><p>Contains a duplicate of the NS records of a primary zone, but statically configured rather than transferred from a primary server.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-type stub" title="namedconf-statement-type stub">type stub</a></span></td>
<td><p><p>Contains a duplicate of the NS records of a primary zone.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-udp-receive-buffer" title="namedconf-statement-udp-receive-buffer">udp-receive-buffer</a></span></td>
<td><p><p>Sets the operating system's receive buffer size for UDP sockets.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-udp-send-buffer" title="namedconf-statement-udp-send-buffer">udp-send-buffer</a></span></td>
<td><p><p>Sets the operating system's send buffer size for UDP sockets.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-unix" title="namedconf-statement-unix">unix</a></span></td>
<td><p><p>Specifies a Unix domain socket as a control channel.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-update-check-ksk" title="namedconf-statement-update-check-ksk">update-check-ksk</a></span></td>
<td><p><p>Specifies whether to check the KSK bit to determine how a key should be used, when generating RRSIGs for a secure zone.</p>
</p></td>
<td><p>zone, dnssec</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy">update-policy</a></span></td>
<td><p><p>Sets fine-grained rules to allow or deny dynamic updates (DDNS), based on requester identity, updated content, etc.</p>
</p></td>
<td><p>transfer</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-update-quota" title="namedconf-statement-update-quota">update-quota</a></span></td>
<td><p><p>Specifies the maximum number of concurrent DNS UPDATE messages that can be processed by the server.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-use-alt-transfer-source" title="namedconf-statement-use-alt-transfer-source">use-alt-transfer-source</a></span></td>
<td><p><p>Indicates whether <a class="reference internal" href="#namedconf-statement-alt-transfer-source" title="namedconf-statement-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">alt-transfer-source</span></code></a> and <a class="reference internal" href="#namedconf-statement-alt-transfer-source-v6" title="namedconf-statement-alt-transfer-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">alt-transfer-source-v6</span></code></a> can be used.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-use-v4-udp-ports" title="namedconf-statement-use-v4-udp-ports">use-v4-udp-ports</a></span></td>
<td><p><p>Specifies a list of ports that are valid sources for UDP/IPv4 messages.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-use-v6-udp-ports" title="namedconf-statement-use-v6-udp-ports">use-v6-udp-ports</a></span></td>
<td><p><p>Specifies a list of ports that are valid sources for UDP/IPv6 messages.</p>
</p></td>
<td><p>deprecated</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-v6-bias" title="namedconf-statement-v6-bias">v6-bias</a></span></td>
<td><p><p>Indicates the number of milliseconds of preference to give to IPv6 name servers.</p>
</p></td>
<td><p>server, query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-validate-except" title="namedconf-statement-validate-except">validate-except</a></span></td>
<td><p><p>Specifies a list of domain names at and beneath which DNSSEC validation should not be performed.</p>
</p></td>
<td><p>dnssec</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-version" title="namedconf-statement-version">version</a></span></td>
<td><p><p>Specifies the version number of the server to return in response to a <code class="docutils literal notranslate"><span class="pre">version.bind</span></code> query.</p>
</p></td>
<td><p>server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view">view</a></span></td>
<td><p><p>Allows a name server to answer a DNS query differently depending on who is asking.</p>
</p></td>
<td><p>view</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-window" title="namedconf-statement-window">window</a></span></td>
<td><p><p>Specifies the length of time during which responses are tracked.</p>
</p></td>
<td><p>query</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-zero-no-soa-ttl" title="namedconf-statement-zero-no-soa-ttl">zero-no-soa-ttl</a></span></td>
<td><p><p>Specifies whether to set the time to live (TTL) of the SOA record to zero, when returning authoritative negative responses to SOA queries.</p>
</p></td>
<td><p>zone, query, server</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-zero-no-soa-ttl-cache" title="namedconf-statement-zero-no-soa-ttl-cache">zero-no-soa-ttl-cache</a></span></td>
<td><p><p>Sets the time to live (TTL) to zero when caching a negative response to an SOA query.</p>
</p></td>
<td><p>zone, query, server</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone">zone</a></span></td>
<td><p><p>Specifies the zone in a BIND 9 configuration.</p>
</p></td>
<td><p>zone</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-zone-propagation-delay" title="namedconf-statement-zone-propagation-delay">zone-propagation-delay</a></span></td>
<td><p><p>Sets the propagation delay from the time a zone is first updated to when the new version of the zone is served by all secondary servers.</p>
</p></td>
<td><p>dnssec, zone</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-zone-statistics" title="namedconf-statement-zone-statistics">zone-statistics</a></span></td>
<td><p><p>Controls the level of statistics gathered for all zones.</p>
</p></td>
<td><p>zone, logging</p></td>
</tr>
</tbody>
</table>
</section>
<section id="statements-by-tag">
<h2><span class="section-number">8.4. </span>Statements by Tag<a class="headerlink" href="#statements-by-tag" title="Link to this heading"></a></h2>
<p>These tables group the various statements permissible in <code class="file docutils literal notranslate"><span class="pre">named.conf</span></code> by
their corresponding tag.</p>
<section id="dnssec-tag-statements">
<span id="id17"></span><h3><span class="section-number">8.4.1. </span>DNSSEC Tag Statements<a class="headerlink" href="#dnssec-tag-statements" title="Link to this heading"></a></h3>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Statement</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-auto-dnssec" title="namedconf-statement-auto-dnssec">auto-dnssec</a></span></td>
<td><p><p>Permits varying levels of automatic DNSSEC key management.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-bindkeys-file" title="namedconf-statement-bindkeys-file">bindkeys-file</a></span></td>
<td><p><p>Specifies the pathname of a file to override the built-in trusted keys provided by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-check-dup-records" title="namedconf-statement-check-dup-records">check-dup-records</a></span></td>
<td><p><p>Checks primary zones for records that are treated as different by DNSSEC but are semantically equal in plain DNS.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-disable-algorithms" title="namedconf-statement-disable-algorithms">disable-algorithms</a></span></td>
<td><p><p>Disables DNSSEC algorithms from a specified zone.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-disable-ds-digests" title="namedconf-statement-disable-ds-digests">disable-ds-digests</a></span></td>
<td><p><p>Disables DS digest types from a specified zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnskey-sig-validity" title="namedconf-statement-dnskey-sig-validity">dnskey-sig-validity</a></span></td>
<td><p><p>Specifies the number of days in the future when automatically generated DNSSEC signatures expire.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnskey-ttl" title="namedconf-statement-dnskey-ttl">dnskey-ttl</a></span></td>
<td><p><p>Specifies the time to live (TTL) for DNSKEY resource records.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-accept-expired" title="namedconf-statement-dnssec-accept-expired">dnssec-accept-expired</a></span></td>
<td><p><p>Instructs BIND 9 to accept expired DNSSEC signatures when validating.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-dnskey-kskonly" title="namedconf-statement-dnssec-dnskey-kskonly">dnssec-dnskey-kskonly</a></span></td>
<td><p><p>Specifies that only key-signing keys are used to sign the DNSKEY, CDNSKEY, and CDS RRsets at a zone's apex.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-loadkeys-interval" title="namedconf-statement-dnssec-loadkeys-interval">dnssec-loadkeys-interval</a></span></td>
<td><p><p>Sets the frequency of automatic checks of the DNSSEC key repository.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-policy" title="namedconf-statement-dnssec-policy">dnssec-policy</a></span></td>
<td><p><p>Defines a key and signing policy (KASP) for zones.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-secure-to-insecure" title="namedconf-statement-dnssec-secure-to-insecure">dnssec-secure-to-insecure</a></span></td>
<td><p><p>Allows a dynamic zone to transition from secure to insecure by deleting all DNSKEY records.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-update-mode" title="namedconf-statement-dnssec-update-mode">dnssec-update-mode</a></span></td>
<td><p><p>Controls the scheduled maintenance of DNSSEC signatures.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-validation" title="namedconf-statement-dnssec-validation">dnssec-validation</a></span></td>
<td><p><p>Enables DNSSEC validation in <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-inline-signing" title="namedconf-statement-inline-signing">inline-signing</a></span></td>
<td><p><p>Specifies whether BIND 9 maintains a separate signed version of a zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-key-directory" title="namedconf-statement-key-directory">key-directory</a></span></td>
<td><p><p>Indicates the directory where public and private DNSSEC key files are found.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-managed-keys-directory" title="namedconf-statement-managed-keys-directory">managed-keys-directory</a></span></td>
<td><p><p>Specifies the directory in which to store the files that track managed DNSSEC keys.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-rsa-exponent-size" title="namedconf-statement-max-rsa-exponent-size">max-rsa-exponent-size</a></span></td>
<td><p><p>Sets the maximum RSA exponent size (in bits) when validating.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-nsec3param" title="namedconf-statement-nsec3param">nsec3param</a></span></td>
<td><p><p>Specifies the use of NSEC3 instead of NSEC, and sets NSEC3 parameters.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-nta-lifetime" title="namedconf-statement-nta-lifetime">nta-lifetime</a></span></td>
<td><p><p>Specifies the lifetime, in seconds, for negative trust anchors added via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-nta"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">nta</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-nta-recheck" title="namedconf-statement-nta-recheck">nta-recheck</a></span></td>
<td><p><p>Specifies the time interval for checking whether negative trust anchors added via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-nta"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">nta</span></code></a> are still necessary.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-parent-ds-ttl" title="namedconf-statement-parent-ds-ttl">parent-ds-ttl</a></span></td>
<td><p><p>Sets the time to live (TTL) of the DS RRset used by the parent zone.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-parent-propagation-delay" title="namedconf-statement-parent-propagation-delay">parent-propagation-delay</a></span></td>
<td><p><p>Sets the propagation delay from the time the parent zone is updated to when the new version is served by all of the parent zone's name servers.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-parental-source" title="namedconf-statement-parental-source">parental-source</a></span></td>
<td><p><p>Specifies which local IPv4 source address is used to send parental DS queries.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-parental-source-v6" title="namedconf-statement-parental-source-v6">parental-source-v6</a></span></td>
<td><p><p>Specifies which local IPv6 source address is used to send parental DS queries.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-publish-safety" title="namedconf-statement-publish-safety">publish-safety</a></span></td>
<td><p><p>Increases the amount of time between when keys are published and when they become active, to allow for unforeseen events.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-purge-keys" title="namedconf-statement-purge-keys">purge-keys</a></span></td>
<td><p><p>Specifies the amount of time after which DNSSEC keys that have been deleted from the zone can be removed from disk.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-retire-safety" title="namedconf-statement-retire-safety">retire-safety</a></span></td>
<td><p><p>Increases the amount of time a key remains published after it is no longer active, to allow for unforeseen events.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-secroots-file" title="namedconf-statement-secroots-file">secroots-file</a></span></td>
<td><p><p>Specifies the pathname of the file where the server dumps security roots, when using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-secroots"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">secroots</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-sig-signing-nodes" title="namedconf-statement-sig-signing-nodes">sig-signing-nodes</a></span></td>
<td><p><p>Specifies the maximum number of nodes to be examined in each quantum, when signing a zone with a new DNSKEY.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-sig-signing-signatures" title="namedconf-statement-sig-signing-signatures">sig-signing-signatures</a></span></td>
<td><p><p>Specifies the threshold for the number of signatures that terminates processing a quantum, when signing a zone with a new DNSKEY.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-sig-signing-type" title="namedconf-statement-sig-signing-type">sig-signing-type</a></span></td>
<td><p><p>Specifies a private RDATA type to use when generating signing-state records.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-sig-validity-interval" title="namedconf-statement-sig-validity-interval">sig-validity-interval</a></span></td>
<td><p><p>Specifies the maximum number of days that RRSIGs generated by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> are valid.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-signatures-jitter" title="namedconf-statement-signatures-jitter">signatures-jitter</a></span></td>
<td><p><p>Specifies a range for signature expirations.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-signatures-refresh" title="namedconf-statement-signatures-refresh">signatures-refresh</a></span></td>
<td><p><p>Specifies how frequently an RRSIG record is refreshed.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-signatures-validity" title="namedconf-statement-signatures-validity">signatures-validity</a></span></td>
<td><p><p>Indicates the validity period of an RRSIG record.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-signatures-validity-dnskey" title="namedconf-statement-signatures-validity-dnskey">signatures-validity-dnskey</a></span></td>
<td><p><p>Indicates the validity period of DNSKEY records.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-synth-from-dnssec" title="namedconf-statement-synth-from-dnssec">synth-from-dnssec</a></span></td>
<td><p><p>Enables support for <span class="target" id="index-16"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc8198.html"><strong>RFC 8198</strong></a>, Aggressive Use of DNSSEC-Validated Cache.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-trust-anchor-telemetry" title="namedconf-statement-trust-anchor-telemetry">trust-anchor-telemetry</a></span></td>
<td><p><p>Instructs <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to send specially formed queries once per day to domains for which trust anchors have been configured.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors">trust-anchors</a></span></td>
<td><p><p>Defines <a class="reference internal" href="chapter5.html#dnssec"><span class="std std-ref">DNSSEC</span></a> trust anchors.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-update-check-ksk" title="namedconf-statement-update-check-ksk">update-check-ksk</a></span></td>
<td><p><p>Specifies whether to check the KSK bit to determine how a key should be used, when generating RRSIGs for a secure zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-validate-except" title="namedconf-statement-validate-except">validate-except</a></span></td>
<td><p><p>Specifies a list of domain names at and beneath which DNSSEC validation should not be performed.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-zone-propagation-delay" title="namedconf-statement-zone-propagation-delay">zone-propagation-delay</a></span></td>
<td><p><p>Sets the propagation delay from the time a zone is first updated to when the new version of the zone is served by all secondary servers.</p>
</p></td>
</tr>
</tbody>
</table>
</section>
<section id="logging-tag-statements">
<span id="id18"></span><h3><span class="section-number">8.4.2. </span>Logging Tag Statements<a class="headerlink" href="#logging-tag-statements" title="Link to this heading"></a></h3>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Statement</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-buffered" title="namedconf-statement-buffered">buffered</a></span></td>
<td><p><p>Controls flushing of log messages.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-category" title="namedconf-statement-category">category</a></span></td>
<td><p><p>Specifies the type of data logged to a particular channel.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-channel" title="namedconf-statement-channel">channel</a></span></td>
<td><p><p>Defines a stream of data that can be independently logged.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap">dnstap</a></span></td>
<td><p><p>Enables logging of <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnstap-identity" title="namedconf-statement-dnstap-identity">dnstap-identity</a></span></td>
<td><p><p>Specifies an <code class="docutils literal notranslate"><span class="pre">identity</span></code> string to send in <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnstap-output" title="namedconf-statement-dnstap-output">dnstap-output</a></span></td>
<td><p><p>Configures the path to which the <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> frame stream is sent.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnstap-version" title="namedconf-statement-dnstap-version">dnstap-version</a></span></td>
<td><p><p>Specifies a <a class="reference internal" href="#namedconf-statement-version" title="namedconf-statement-version"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">version</span></code></a> string to send in <a class="reference internal" href="#namedconf-statement-dnstap" title="namedconf-statement-dnstap"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dnstap</span></code></a> messages.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dump-file" title="namedconf-statement-dump-file">dump-file</a></span></td>
<td><p><p>Indicates the pathname of the file where the server dumps the database after <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-dumpdb"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">dumpdb</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-buffer-hint" title="namedconf-statement-fstrm-set-buffer-hint">fstrm-set-buffer-hint</a></span></td>
<td><p><p>Sets the number of accumulated bytes in the output buffer before forcing a buffer flush.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-flush-timeout" title="namedconf-statement-fstrm-set-flush-timeout">fstrm-set-flush-timeout</a></span></td>
<td><p><p>Sets the number of seconds that unflushed data remains in the output buffer.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-input-queue-size" title="namedconf-statement-fstrm-set-input-queue-size">fstrm-set-input-queue-size</a></span></td>
<td><p><p>Sets the number of queue entries to allocate for each input queue.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-output-notify-threshold" title="namedconf-statement-fstrm-set-output-notify-threshold">fstrm-set-output-notify-threshold</a></span></td>
<td><p><p>Sets the number of outstanding queue entries allowed on an input queue before waking the I/O thread.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-output-queue-model" title="namedconf-statement-fstrm-set-output-queue-model">fstrm-set-output-queue-model</a></span></td>
<td><p><p>Sets the queuing semantics to use for queue objects.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-output-queue-size" title="namedconf-statement-fstrm-set-output-queue-size">fstrm-set-output-queue-size</a></span></td>
<td><p><p>Sets the number of queue entries allocated for each output queue.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fstrm-set-reopen-interval" title="namedconf-statement-fstrm-set-reopen-interval">fstrm-set-reopen-interval</a></span></td>
<td><p><p>Sets the number of seconds to wait between attempts to reopen a closed output stream.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-log-only" title="namedconf-statement-log-only">log-only</a></span></td>
<td><p><p>Tests rate-limiting parameters without actually dropping any requests.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-logging" title="namedconf-statement-logging">logging</a></span></td>
<td><p><p>Configures logging options for the name server.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-memstatistics" title="namedconf-statement-memstatistics">memstatistics</a></span></td>
<td><p><p>Controls whether memory statistics are written to the file specified by <a class="reference internal" href="#namedconf-statement-memstatistics-file" title="namedconf-statement-memstatistics-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">memstatistics-file</span></code></a> at exit.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-memstatistics-file" title="namedconf-statement-memstatistics-file">memstatistics-file</a></span></td>
<td><p><p>Sets the pathname of the file where the server writes memory usage statistics on exit.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-null" title="namedconf-statement-null">null</a></span></td>
<td><p><p>Causes all messages sent to the logging channel to be discarded.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-print-category" title="namedconf-statement-print-category">print-category</a></span></td>
<td><p><p>Includes the category in log messages.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-print-severity" title="namedconf-statement-print-severity">print-severity</a></span></td>
<td><p><p>Includes the severity in log messages.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-print-time" title="namedconf-statement-print-time">print-time</a></span></td>
<td><p><p>Specifies the time format for log messages.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-querylog" title="namedconf-statement-querylog">querylog</a></span></td>
<td><p><p>Specifies whether query logging should be active when <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> first starts.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-severity" title="namedconf-statement-severity">severity</a></span></td>
<td><p><p>Defines the priority level of log messages.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-statistics-channels" title="namedconf-statement-statistics-channels">statistics-channels</a></span></td>
<td><p><p>Specifies the communication channels to be used by system administrators to access statistics information on the name server.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-statistics-file" title="namedconf-statement-statistics-file">statistics-file</a></span></td>
<td><p><p>Specifies the pathname of the file where the server appends statistics, when using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-stats"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">stats</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-stderr" title="namedconf-statement-stderr">stderr</a></span></td>
<td><p><p>Directs the logging channel output to the server's standard error stream.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-syslog" title="namedconf-statement-syslog">syslog</a></span></td>
<td><p><p>Directs the logging channel to the system log.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-zone-statistics" title="namedconf-statement-zone-statistics">zone-statistics</a></span></td>
<td><p><p>Controls the level of statistics gathered for all zones.</p>
</p></td>
</tr>
</tbody>
</table>
</section>
<section id="query-tag-statements">
<span id="id19"></span><h3><span class="section-number">8.4.3. </span>Query Tag Statements<a class="headerlink" href="#query-tag-statements" title="Link to this heading"></a></h3>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Statement</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-all-per-second" title="namedconf-statement-all-per-second">all-per-second</a></span></td>
<td><p><p>Limits UDP responses of all kinds.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-query" title="namedconf-statement-allow-query">allow-query</a></span></td>
<td><p><p>Specifies which hosts (an IP address list) are allowed to send queries to this resolver.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-query-cache" title="namedconf-statement-allow-query-cache">allow-query-cache</a></span></td>
<td><p><p>Specifies which hosts (an IP address list) can access this server's cache and thus effectively controls recursion.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-query-cache-on" title="namedconf-statement-allow-query-cache-on">allow-query-cache-on</a></span></td>
<td><p><p>Specifies which hosts (an IP address list) can access this server's cache. Used on servers with multiple interfaces.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-query-on" title="namedconf-statement-allow-query-on">allow-query-on</a></span></td>
<td><p><p>Specifies which local addresses (an IP address list) are allowed to send queries to this resolver. Used in multi-homed configurations.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-recursion" title="namedconf-statement-allow-recursion">allow-recursion</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of clients that are allowed to perform recursive queries.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-recursion-on" title="namedconf-statement-allow-recursion-on">allow-recursion-on</a></span></td>
<td><p><p>Specifies which local addresses can accept recursive queries.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-answer-cookie" title="namedconf-statement-answer-cookie">answer-cookie</a></span></td>
<td><p><p>Controls whether COOKIE EDNS replies are sent in response to client queries.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-auth-nxdomain" title="namedconf-statement-auth-nxdomain">auth-nxdomain</a></span></td>
<td><p><p>Controls whether BIND, acting as a resolver, provides authoritative NXDOMAIN (domain does not exist) answers.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-blackhole" title="namedconf-statement-blackhole">blackhole</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts to ignore. The server will neither respond to queries from nor send queries to these addresses.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-break-dnssec" title="namedconf-statement-break-dnssec">break-dnssec</a></span></td>
<td><p><p>Enables <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> synthesis even if the validated result would cause a DNSSEC validation failure.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-check-dup-records" title="namedconf-statement-check-dup-records">check-dup-records</a></span></td>
<td><p><p>Checks primary zones for records that are treated as different by DNSSEC but are semantically equal in plain DNS.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-check-names" title="namedconf-statement-check-names">check-names</a></span></td>
<td><p><p>Restricts the character set and syntax of certain domain names in primary files and/or DNS responses received from the network.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-clients" title="namedconf-statement-clients">clients</a></span></td>
<td><p><p>Specifies an access control list (ACL) of clients that are affected by a given <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> directive.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-deny-answer-addresses" title="namedconf-statement-deny-answer-addresses">deny-answer-addresses</a></span></td>
<td><p><p>Rejects A or AAAA records if the corresponding IPv4 or IPv6 addresses match a given <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-deny-answer-aliases" title="namedconf-statement-deny-answer-aliases">deny-answer-aliases</a></span></td>
<td><p><p>Rejects CNAME or DNAME records if the "alias" name matches a given list of <a class="reference internal" href="#term-domain_name"><code class="xref any std std-term docutils literal notranslate"><span class="pre">domain_name</span></code></a> elements.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64">dns64</a></span></td>
<td><p><p>Instructs <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> to return mapped IPv4 addresses to AAAA queries when there are no AAAA records.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dscp" title="namedconf-statement-dscp">dscp</a></span></td>
<td><p><p>Sets the Differentiated Services Code Point (DSCP) value (obsolete).</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-edns-udp-size" title="namedconf-statement-edns-udp-size">edns-udp-size</a></span></td>
<td><p><p>Sets the maximum advertised EDNS UDP buffer size to control the size of packets received from authoritative servers in response to recursive queries.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-endpoints" title="namedconf-statement-endpoints">endpoints</a></span></td>
<td><p><p>Specifies a list of HTTP query paths on which to listen.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-exclude" title="namedconf-statement-exclude">exclude</a></span></td>
<td><p><p>Allows a list of IPv6 addresses to be ignored if they appear in a domain name's AAAA records in <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-exempt-clients" title="namedconf-statement-exempt-clients">exempt-clients</a></span></td>
<td><p><p>Exempts specific clients or client groups from rate limiting.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fetch-quota-params" title="namedconf-statement-fetch-quota-params">fetch-quota-params</a></span></td>
<td><p><p>Sets the parameters for dynamic resizing of the <a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-server</span></code></a> quota in response to detected congestion.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server">fetches-per-server</a></span></td>
<td><p><p>Sets the maximum number of simultaneous iterative queries allowed to be sent by a server to an upstream name server before the server blocks additional queries.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fetches-per-zone" title="namedconf-statement-fetches-per-zone">fetches-per-zone</a></span></td>
<td><p><p>Sets the maximum number of simultaneous iterative queries allowed to any one domain before the server blocks new queries for data in or beneath that zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-forward" title="namedconf-statement-forward">forward</a></span></td>
<td><p><p>Allows or disallows fallback to recursion if forwarding has failed; it is always used in conjunction with the <a class="reference internal" href="#namedconf-statement-forwarders" title="namedconf-statement-forwarders"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">forwarders</span></code></a> statement.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-forwarders" title="namedconf-statement-forwarders">forwarders</a></span></td>
<td><p><p>Defines one or more hosts to which queries are forwarded.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http">http</a></span></td>
<td><p><p>Configures HTTP endpoints on which to listen for DNS-over-HTTPS (DoH) queries.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-http-port" title="namedconf-statement-http-port">http-port</a></span></td>
<td><p><p>Specifies the TCP port number the server uses to receive and send unencrypted DNS traffic via HTTP.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-https-port" title="namedconf-statement-https-port">https-port</a></span></td>
<td><p><p>Specifies the TCP port number the server uses to receive and send DNS-over-HTTPS protocol traffic.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-ipv4only-enable" title="namedconf-statement-ipv4only-enable">ipv4only-enable</a></span></td>
<td><p><p>Enables automatic IPv4 zones if a <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> block is configured.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ipv4only-server" title="namedconf-statement-ipv4only-server">ipv4only-server</a></span></td>
<td><p><p>Specifies the name of the server for the IPV4ONLY.ARPA zone created by <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-listener-clients" title="namedconf-statement-listener-clients">listener-clients</a></span></td>
<td><p><p>Specifies a per-listener quota for active connections.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-log-only" title="namedconf-statement-log-only">log-only</a></span></td>
<td><p><p>Tests rate-limiting parameters without actually dropping any requests.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-mapped" title="namedconf-statement-mapped">mapped</a></span></td>
<td><p><p>Specifies an access control list (ACL) of IPv4 addresses that are to be mapped to the corresponding A RRset in <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-query-count" title="namedconf-statement-max-query-count">max-query-count</a></span></td>
<td><p><p>Sets the maximum number of iterative queries while servicing a recursive query.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-query-restarts" title="namedconf-statement-max-query-restarts">max-query-restarts</a></span></td>
<td><p><p>Sets the maximum number of chained CNAMEs to follow</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-recursion-queries" title="namedconf-statement-max-recursion-queries">max-recursion-queries</a></span></td>
<td><p><p>Sets the maximum number of iterative queries while servicing a recursive query.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-rsa-exponent-size" title="namedconf-statement-max-rsa-exponent-size">max-rsa-exponent-size</a></span></td>
<td><p><p>Sets the maximum RSA exponent size (in bits) when validating.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-udp-size" title="namedconf-statement-max-udp-size">max-udp-size</a></span></td>
<td><p><p>Sets the maximum EDNS UDP message size sent by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl">max-zone-ttl</a></span></td>
<td><p><p>Specifies a maximum permissible time-to-live (TTL) value, in seconds.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-message-compression" title="namedconf-statement-message-compression">message-compression</a></span></td>
<td><p><p>Controls whether DNS name compression is used in responses to regular queries.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-min-table-size" title="namedconf-statement-min-table-size">min-table-size</a></span></td>
<td><p><p>Sets the minimum size of the table used to track requests and rate-limit responses.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-minimal-any" title="namedconf-statement-minimal-any">minimal-any</a></span></td>
<td><p><p>Controls whether the server replies with only one of the RRsets for a query name, when generating a positive response to a query of type ANY over UDP.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-minimal-responses" title="namedconf-statement-minimal-responses">minimal-responses</a></span></td>
<td><p><p>Controls whether the server only adds records to the authority and additional data sections when they are required (e.g. delegations, negative responses). This improves server performance.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-nocookie-udp-size" title="namedconf-statement-nocookie-udp-size">nocookie-udp-size</a></span></td>
<td><p><p>Sets the maximum size of UDP responses that are sent to queries without a valid server COOKIE.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-nodata-per-second" title="namedconf-statement-nodata-per-second">nodata-per-second</a></span></td>
<td><p><p>Limits the number of empty (NODATA) responses for a valid domain name.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-nxdomain-redirect" title="namedconf-statement-nxdomain-redirect">nxdomain-redirect</a></span></td>
<td><p><p>Appends the specified suffix to the original query name, when replacing an NXDOMAIN with a redirect namespace.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-nxdomains-per-second" title="namedconf-statement-nxdomains-per-second">nxdomains-per-second</a></span></td>
<td><p><p>Limits the number of undefined subdomains for a valid domain name.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-port" title="namedconf-statement-port">port</a></span></td>
<td><p><p>Specifies the UDP/TCP port number the server uses to receive and send DNS protocol traffic.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-preferred-glue" title="namedconf-statement-preferred-glue">preferred-glue</a></span></td>
<td><p><p>Controls the order of glue records in an A or AAAA response.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-prefetch" title="namedconf-statement-prefetch">prefetch</a></span></td>
<td><p><p>Specifies the "trigger" time-to-live (TTL) value at which prefetch of the current query takes place.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-qname-minimization" title="namedconf-statement-qname-minimization">qname-minimization</a></span></td>
<td><p><p>Controls QNAME minimization behavior in the BIND 9 resolver.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-qps-scale" title="namedconf-statement-qps-scale">qps-scale</a></span></td>
<td><p><p>Tightens defenses during DNS attacks by scaling back the ratio of the current query-per-second rate.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-query-source" title="namedconf-statement-query-source">query-source</a></span></td>
<td><p><p>Controls the IPv4 address from which queries are issued.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-query-source-v6" title="namedconf-statement-query-source-v6">query-source-v6</a></span></td>
<td><p><p>Controls the IPv6 address from which queries are issued.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-rate-limit" title="namedconf-statement-rate-limit">rate-limit</a></span></td>
<td><p><p>Controls excessive UDP responses, to prevent BIND 9 from being used to amplify reflection denial-of-service (DoS) attacks.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-recursion" title="namedconf-statement-recursion">recursion</a></span></td>
<td><p><p>Defines whether recursion and caching are allowed.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-recursive-clients" title="namedconf-statement-recursive-clients">recursive-clients</a></span></td>
<td><p><p>Specifies the maximum number of concurrent recursive queries the server can perform.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-recursive-only" title="namedconf-statement-recursive-only">recursive-only</a></span></td>
<td><p><p>Toggles whether <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> synthesis occurs only for recursive queries.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-referrals-per-second" title="namedconf-statement-referrals-per-second">referrals-per-second</a></span></td>
<td><p><p>Limits the number of referrals or delegations to a server for a given domain.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-request-expire" title="namedconf-statement-request-expire">request-expire</a></span></td>
<td><p><p>Specifies whether the local server requests the EDNS EXPIRE value, when acting as a secondary.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-request-nsid" title="namedconf-statement-request-nsid">request-nsid</a></span></td>
<td><p><p>Controls whether an empty EDNS(0) NSID (Name Server Identifier) option is sent with all queries to authoritative name servers during iterative resolution.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-require-server-cookie" title="namedconf-statement-require-server-cookie">require-server-cookie</a></span></td>
<td><p><p>Controls whether a valid server cookie is required before sending a full response to a UDP request.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-resolver-query-timeout" title="namedconf-statement-resolver-query-timeout">resolver-query-timeout</a></span></td>
<td><p><p>Specifies the length of time, in milliseconds, that a resolver attempts to resolve a recursive query before failing.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-response-padding" title="namedconf-statement-response-padding">response-padding</a></span></td>
<td><p><p>Adds an EDNS Padding option to encrypted messages, to reduce the chance of guessing the contents based on size.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-response-policy" title="namedconf-statement-response-policy">response-policy</a></span></td>
<td><p><p>Specifies response policy zones for the view or among global options.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-responses-per-second" title="namedconf-statement-responses-per-second">responses-per-second</a></span></td>
<td><p><p>Limits the number of non-empty responses for a valid domain name and record type.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-rrset-order" title="namedconf-statement-rrset-order">rrset-order</a></span></td>
<td><p><p>Defines the order in which equal RRs (RRsets) are returned.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="chapter6.html#namedconf-statement-search" title="namedconf-statement-search">search</a></span></td>
<td><p><p>Specifies whether a Dynamically Loadable Zone (DLZ) module is queried for an answer to a query name.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-send-cookie" title="namedconf-statement-send-cookie">send-cookie</a></span></td>
<td><p><p>Controls whether a COOKIE EDNS option is sent along with a query.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-server-addresses" title="namedconf-statement-server-addresses">server-addresses</a></span></td>
<td><p><p>Specifies a list of IP addresses to which queries should be sent in recursive resolution for a static-stub zone.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-slip" title="namedconf-statement-slip">slip</a></span></td>
<td><p><p>Sets the number of "slipped" responses to minimize the use of forged source addresses for an attack.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-sortlist" title="namedconf-statement-sortlist">sortlist</a></span></td>
<td><p><p>Controls the ordering of RRs returned to the client, based on the client's IP address.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-stale-answer-client-timeout" title="namedconf-statement-stale-answer-client-timeout">stale-answer-client-timeout</a></span></td>
<td><p><p>Defines the amount of time (in milliseconds) that <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> waits before attempting to answer a query with a stale RRset from cache.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-stale-answer-enable" title="namedconf-statement-stale-answer-enable">stale-answer-enable</a></span></td>
<td><p><p>Enables the returning of "stale" cached answers when the name servers for a zone are not answering.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-stale-answer-ttl" title="namedconf-statement-stale-answer-ttl">stale-answer-ttl</a></span></td>
<td><p><p>Specifies the time to live (TTL) to be returned on stale answers, in seconds.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-stale-cache-enable" title="namedconf-statement-stale-cache-enable">stale-cache-enable</a></span></td>
<td><p><p>Enables the retention of "stale" cached answers.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-stale-refresh-time" title="namedconf-statement-stale-refresh-time">stale-refresh-time</a></span></td>
<td><p><p>Sets the time window for the return of "stale" cached answers before the next attempt to contact, if the name servers for a given zone are not responding.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-streams-per-connection" title="namedconf-statement-streams-per-connection">streams-per-connection</a></span></td>
<td><p><p>Specifies the maximum number of concurrent HTTP/2 streams over an HTTP/2 connection.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-suffix" title="namedconf-statement-suffix">suffix</a></span></td>
<td><p><p>Defines trailing bits for mapped IPv4 address bits in <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tcp-advertised-timeout" title="namedconf-statement-tcp-advertised-timeout">tcp-advertised-timeout</a></span></td>
<td><p><p>Sets the timeout value (in milliseconds) that the server sends in responses containing the EDNS TCP keepalive option.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tcp-idle-timeout" title="namedconf-statement-tcp-idle-timeout">tcp-idle-timeout</a></span></td>
<td><p><p>Sets the amount of time (in milliseconds) that the server waits on an idle TCP connection before closing it, if the EDNS TCP keepalive option is not in use.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tcp-initial-timeout" title="namedconf-statement-tcp-initial-timeout">tcp-initial-timeout</a></span></td>
<td><p><p>Sets the amount of time (in milliseconds) that the server waits on a new TCP connection for the first message from the client.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tcp-keepalive-timeout" title="namedconf-statement-tcp-keepalive-timeout">tcp-keepalive-timeout</a></span></td>
<td><p><p>Sets the amount of time (in milliseconds) that the server waits on an idle TCP connection before closing it, if the EDNS TCP keepalive option is in use.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tls-port" title="namedconf-statement-tls-port">tls-port</a></span></td>
<td><p><p>Specifies the TCP port number the server uses to receive and send DNS-over-TLS protocol traffic.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-v6-bias" title="namedconf-statement-v6-bias">v6-bias</a></span></td>
<td><p><p>Indicates the number of milliseconds of preference to give to IPv6 name servers.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-window" title="namedconf-statement-window">window</a></span></td>
<td><p><p>Specifies the length of time during which responses are tracked.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-zero-no-soa-ttl" title="namedconf-statement-zero-no-soa-ttl">zero-no-soa-ttl</a></span></td>
<td><p><p>Specifies whether to set the time to live (TTL) of the SOA record to zero, when returning authoritative negative responses to SOA queries.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-zero-no-soa-ttl-cache" title="namedconf-statement-zero-no-soa-ttl-cache">zero-no-soa-ttl-cache</a></span></td>
<td><p><p>Sets the time to live (TTL) to zero when caching a negative response to an SOA query.</p>
</p></td>
</tr>
</tbody>
</table>
</section>
<section id="security-tag-statements">
<span id="id20"></span><h3><span class="section-number">8.4.4. </span>Security Tag Statements<a class="headerlink" href="#security-tag-statements" title="Link to this heading"></a></h3>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Statement</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-algorithm" title="namedconf-statement-algorithm">algorithm</a></span></td>
<td><p><p>Defines the algorithm to be used in a key clause.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ca-file" title="namedconf-statement-ca-file">ca-file</a></span></td>
<td><p><p>Specifies the path to a file containing TLS certificates for trusted CA authorities, used to verify remote peer certificates.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-cert-file" title="namedconf-statement-cert-file">cert-file</a></span></td>
<td><p><p>Specifies the path to a file containing the TLS certificate for a connection.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ciphers" title="namedconf-statement-ciphers">ciphers</a></span></td>
<td><p><p>Specifies a list of allowed ciphers.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dhparam-file" title="namedconf-statement-dhparam-file">dhparam-file</a></span></td>
<td><p><p>Specifies the path to a file containing Diffie-Hellman parameters, for enabling cipher suites.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnsrps-enable" title="namedconf-statement-dnsrps-enable">dnsrps-enable</a></span></td>
<td><p><p>Turns on the DNS Response Policy Service (DNSRPS) interface.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnsrps-options" title="namedconf-statement-dnsrps-options">dnsrps-options</a></span></td>
<td><p><p>Provides additional RPZ configuration settings, which are passed to the DNS Response Policy Service (DNSRPS) provider library.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-key" title="namedconf-statement-key">key</a></span></td>
<td><p><p>Defines a shared secret key for use with <a class="reference internal" href="chapter7.html#tsig"><span class="std std-ref">TSIG</span></a> or the command channel.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-key-file" title="namedconf-statement-key-file">key-file</a></span></td>
<td><p><p>Specifies the path to a file containing the private TLS key for a connection.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-keys" title="namedconf-statement-keys">keys</a></span></td>
<td><p><p>Specifies one or more <a class="reference internal" href="#term-server_key"><code class="xref any std std-term docutils literal notranslate"><span class="pre">server_key</span></code></a> s to be used with a remote server.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-prefer-server-ciphers" title="namedconf-statement-prefer-server-ciphers">prefer-server-ciphers</a></span></td>
<td><p><p>Specifies that server ciphers should be preferred over client ones.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-protocols" title="namedconf-statement-protocols">protocols</a></span></td>
<td><p><p>Specifies the allowed versions of the TLS protocol.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-remote-hostname" title="namedconf-statement-remote-hostname">remote-hostname</a></span></td>
<td><p><p>Specifies the expected hostname in the TLS certificate of the remote server.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-response-policy" title="namedconf-statement-response-policy">response-policy</a></span></td>
<td><p><p>Specifies response policy zones for the view or among global options.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-secret" title="namedconf-statement-secret">secret</a></span></td>
<td><p><p>Defines a Base64-encoded string to be used as the secret by the algorithm.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-session-keyalg" title="namedconf-statement-session-keyalg">session-keyalg</a></span></td>
<td><p><p>Specifies the algorithm to use for the TSIG session key.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-session-keyfile" title="namedconf-statement-session-keyfile">session-keyfile</a></span></td>
<td><p><p>Specifies the pathname of the file where a TSIG session key is written, when generated by <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> for use by <code class="docutils literal notranslate"><span class="pre">nsupdate</span> <span class="pre">-l</span></code>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-session-keyname" title="namedconf-statement-session-keyname">session-keyname</a></span></td>
<td><p><p>Specifies the key name for the TSIG session key.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-session-tickets" title="namedconf-statement-session-tickets">session-tickets</a></span></td>
<td><p><p>Enables or disables session resumption through TLS session tickets.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tkey-domain" title="namedconf-statement-tkey-domain">tkey-domain</a></span></td>
<td><p><p>Sets the domain appended to the names of all shared keys generated with <code class="docutils literal notranslate"><span class="pre">TKEY</span></code>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tkey-gssapi-credential" title="namedconf-statement-tkey-gssapi-credential">tkey-gssapi-credential</a></span></td>
<td><p><p>Sets the security credential for authentication keys requested by the GSS-TSIG protocol.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tkey-gssapi-keytab" title="namedconf-statement-tkey-gssapi-keytab">tkey-gssapi-keytab</a></span></td>
<td><p><p>Sets the KRB5 keytab file to use for GSS-TSIG updates.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tls" title="namedconf-statement-tls">tls</a></span></td>
<td><p><p>Configures a TLS connection.</p>
</p></td>
</tr>
</tbody>
</table>
</section>
<section id="server-tag-statements">
<span id="id21"></span><h3><span class="section-number">8.4.5. </span>Server Tag Statements<a class="headerlink" href="#server-tag-statements" title="Link to this heading"></a></h3>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Statement</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-acl" title="namedconf-statement-acl">acl</a></span></td>
<td><p><p>Assigns a symbolic name to an address match list.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-new-zones" title="namedconf-statement-allow-new-zones">allow-new-zones</a></span></td>
<td><p><p>Controls the ability to add zones at runtime via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-addzone"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">addzone</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-recursion-on" title="namedconf-statement-allow-recursion-on">allow-recursion-on</a></span></td>
<td><p><p>Specifies which local addresses can accept recursive queries.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-automatic-interface-scan" title="namedconf-statement-automatic-interface-scan">automatic-interface-scan</a></span></td>
<td><p><p>Controls the automatic rescanning of network interfaces when addresses are added or removed.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-bogus" title="namedconf-statement-bogus">bogus</a></span></td>
<td><p><p>Allows a remote server to be ignored.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ca-file" title="namedconf-statement-ca-file">ca-file</a></span></td>
<td><p><p>Specifies the path to a file containing TLS certificates for trusted CA authorities, used to verify remote peer certificates.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-cert-file" title="namedconf-statement-cert-file">cert-file</a></span></td>
<td><p><p>Specifies the path to a file containing the TLS certificate for a connection.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-check-names" title="namedconf-statement-check-names">check-names</a></span></td>
<td><p><p>Restricts the character set and syntax of certain domain names in primary files and/or DNS responses received from the network.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-clients-per-query" title="namedconf-statement-clients-per-query">clients-per-query</a></span></td>
<td><p><p>Sets the initial minimum number of simultaneous recursive clients accepted by the server for any given query before the server drops additional clients.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-controls" title="namedconf-statement-controls">controls</a></span></td>
<td><p><p>Specifies control channels to be used to manage the name server.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-cookie-algorithm" title="namedconf-statement-cookie-algorithm">cookie-algorithm</a></span></td>
<td><p><p>Sets the algorithm to be used when generating a server cookie.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-cookie-secret" title="namedconf-statement-cookie-secret">cookie-secret</a></span></td>
<td><p><p>Specifies a shared secret used for generating and verifying EDNS COOKIE options within an anycast cluster.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dhparam-file" title="namedconf-statement-dhparam-file">dhparam-file</a></span></td>
<td><p><p>Specifies the path to a file containing Diffie-Hellman parameters, for enabling cipher suites.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-directory" title="namedconf-statement-directory">directory</a></span></td>
<td><p><p>Sets the server's working directory.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-disable-empty-zone" title="namedconf-statement-disable-empty-zone">disable-empty-zone</a></span></td>
<td><p><p>Disables individual empty zones.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dns64-contact" title="namedconf-statement-dns64-contact">dns64-contact</a></span></td>
<td><p><p>Specifies the name of the contact for <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> zones.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dns64-server" title="namedconf-statement-dns64-server">dns64-server</a></span></td>
<td><p><p>Specifies the name of the server for <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a> zones.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dnsrps-enable" title="namedconf-statement-dnsrps-enable">dnsrps-enable</a></span></td>
<td><p><p>Turns on the DNS Response Policy Service (DNSRPS) interface.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnsrps-options" title="namedconf-statement-dnsrps-options">dnsrps-options</a></span></td>
<td><p><p>Provides additional RPZ configuration settings, which are passed to the DNS Response Policy Service (DNSRPS) provider library.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dscp" title="namedconf-statement-dscp">dscp</a></span></td>
<td><p><p>Sets the Differentiated Services Code Point (DSCP) value (obsolete).</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dual-stack-servers" title="namedconf-statement-dual-stack-servers">dual-stack-servers</a></span></td>
<td><p><p>Specifies host names or addresses of machines with access to both IPv4 and IPv6 transports.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-edns" title="namedconf-statement-edns">edns</a></span></td>
<td><p><p>Controls the use of the EDNS0 (<span class="target" id="index-26"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc2671.html"><strong>RFC 2671</strong></a>) feature.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-edns-version" title="namedconf-statement-edns-version">edns-version</a></span></td>
<td><p><p>Sets the maximum EDNS VERSION that is sent to the server(s) by the resolver.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-empty-contact" title="namedconf-statement-empty-contact">empty-contact</a></span></td>
<td><p><p>Specifies the contact name in the returned SOA record for empty zones.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-empty-server" title="namedconf-statement-empty-server">empty-server</a></span></td>
<td><p><p>Specifies the server name in the returned SOA record for empty zones.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-empty-zones-enable" title="namedconf-statement-empty-zones-enable">empty-zones-enable</a></span></td>
<td><p><p>Enables or disables all empty zones.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-endpoints" title="namedconf-statement-endpoints">endpoints</a></span></td>
<td><p><p>Specifies a list of HTTP query paths on which to listen.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-errors-per-second" title="namedconf-statement-errors-per-second">errors-per-second</a></span></td>
<td><p><p>Limits the number of errors for a valid domain name and record type.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fetch-quota-params" title="namedconf-statement-fetch-quota-params">fetch-quota-params</a></span></td>
<td><p><p>Sets the parameters for dynamic resizing of the <a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-server</span></code></a> quota in response to detected congestion.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server">fetches-per-server</a></span></td>
<td><p><p>Sets the maximum number of simultaneous iterative queries allowed to be sent by a server to an upstream name server before the server blocks additional queries.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-fetches-per-zone" title="namedconf-statement-fetches-per-zone">fetches-per-zone</a></span></td>
<td><p><p>Sets the maximum number of simultaneous iterative queries allowed to any one domain before the server blocks new queries for data in or beneath that zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-geoip-directory" title="namedconf-statement-geoip-directory">geoip-directory</a></span></td>
<td><p><p>Specifies the directory containing GeoIP database files.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-hostname" title="namedconf-statement-hostname">hostname</a></span></td>
<td><p><p>Specifies the hostname of the server to return in response to a <code class="docutils literal notranslate"><span class="pre">hostname.bind</span></code> query.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-http" title="namedconf-statement-http">http</a></span></td>
<td><p><p>Configures HTTP endpoints on which to listen for DNS-over-HTTPS (DoH) queries.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-http-listener-clients" title="namedconf-statement-http-listener-clients">http-listener-clients</a></span></td>
<td><p><p>Limits the number of active concurrent connections on a per-listener basis.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-http-port" title="namedconf-statement-http-port">http-port</a></span></td>
<td><p><p>Specifies the TCP port number the server uses to receive and send unencrypted DNS traffic via HTTP.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-http-streams-per-connection" title="namedconf-statement-http-streams-per-connection">http-streams-per-connection</a></span></td>
<td><p><p>Limits the number of active concurrent HTTP/2 streams on a per-connection basis.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-https-port" title="namedconf-statement-https-port">https-port</a></span></td>
<td><p><p>Specifies the TCP port number the server uses to receive and send DNS-over-HTTPS protocol traffic.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-inet" title="namedconf-statement-inet">inet</a></span></td>
<td><p><p>Specifies a TCP socket as a control channel.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-interface-interval" title="namedconf-statement-interface-interval">interface-interval</a></span></td>
<td><p><p>Sets the interval at which the server scans the network interface list.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-ipv4-prefix-length" title="namedconf-statement-ipv4-prefix-length">ipv4-prefix-length</a></span></td>
<td><p><p>Specifies the prefix lengths of IPv4 address blocks.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ipv4only-contact" title="namedconf-statement-ipv4only-contact">ipv4only-contact</a></span></td>
<td><p><p>Specifies the contact for the IPV4ONLY.ARPA zone created by <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-ipv4only-server" title="namedconf-statement-ipv4only-server">ipv4only-server</a></span></td>
<td><p><p>Specifies the name of the server for the IPV4ONLY.ARPA zone created by <a class="reference internal" href="#namedconf-statement-dns64" title="namedconf-statement-dns64"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dns64</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ipv6-prefix-length" title="namedconf-statement-ipv6-prefix-length">ipv6-prefix-length</a></span></td>
<td><p><p>Specifies the prefix lengths of IPv6 address blocks.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-keep-response-order" title="namedconf-statement-keep-response-order">keep-response-order</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of addresses which do not accept reordered answers within a single TCP stream.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-key-file" title="namedconf-statement-key-file">key-file</a></span></td>
<td><p><p>Specifies the path to a file containing the private TLS key for a connection.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-keys" title="namedconf-statement-keys">keys</a></span></td>
<td><p><p>Specifies one or more <a class="reference internal" href="#term-server_key"><code class="xref any std std-term docutils literal notranslate"><span class="pre">server_key</span></code></a> s to be used with a remote server.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-lame-ttl" title="namedconf-statement-lame-ttl">lame-ttl</a></span></td>
<td><p><p>Sets the resolver's lame cache.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-listen-on" title="namedconf-statement-listen-on">listen-on</a></span></td>
<td><p><p>Specifies the IPv4 addresses on which a server listens for DNS queries.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-listen-on-v6" title="namedconf-statement-listen-on-v6">listen-on-v6</a></span></td>
<td><p><p>Specifies the IPv6 addresses on which a server listens for DNS queries.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-listener-clients" title="namedconf-statement-listener-clients">listener-clients</a></span></td>
<td><p><p>Specifies a per-listener quota for active connections.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-lmdb-mapsize" title="namedconf-statement-lmdb-mapsize">lmdb-mapsize</a></span></td>
<td><p><p>Sets a maximum size for the memory map of the new-zone database in LMDB database format.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-lock-file" title="namedconf-statement-lock-file">lock-file</a></span></td>
<td><p><p>Sets the pathname of the file on which <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> attempts to acquire a file lock when starting for the first time.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format">masterfile-format</a></span></td>
<td><p><p>Specifies the file format of zone files.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-masterfile-style" title="namedconf-statement-masterfile-style">masterfile-style</a></span></td>
<td><p><p>Specifies the format of zone files during a dump, when the <a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">masterfile-format</span></code></a> is <code class="docutils literal notranslate"><span class="pre">text</span></code>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-match-mapped-addresses" title="namedconf-statement-match-mapped-addresses">match-mapped-addresses</a></span></td>
<td><p><p>Allows IPv4-mapped IPv6 addresses to match address-match list entries for corresponding IPv4 addresses.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-cache-size" title="namedconf-statement-max-cache-size">max-cache-size</a></span></td>
<td><p><p>Sets the maximum amount of memory to use for an individual cache database and its associated metadata.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-cache-ttl" title="namedconf-statement-max-cache-ttl">max-cache-ttl</a></span></td>
<td><p><p>Specifies the maximum time (in seconds) that the server caches ordinary (positive) answers.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-clients-per-query" title="namedconf-statement-max-clients-per-query">max-clients-per-query</a></span></td>
<td><p><p>Sets the maximum number of simultaneous recursive clients accepted by the server for any given query before the server drops additional clients.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-ncache-ttl" title="namedconf-statement-max-ncache-ttl">max-ncache-ttl</a></span></td>
<td><p><p>Specifies the maximum retention time (in seconds) for storage of negative answers in the server's cache.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-query-count" title="namedconf-statement-max-query-count">max-query-count</a></span></td>
<td><p><p>Sets the maximum number of iterative queries while servicing a recursive query.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-query-restarts" title="namedconf-statement-max-query-restarts">max-query-restarts</a></span></td>
<td><p><p>Sets the maximum number of chained CNAMEs to follow</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-records" title="namedconf-statement-max-records">max-records</a></span></td>
<td><p><p>Sets the maximum number of records permitted in a zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-records-per-type" title="namedconf-statement-max-records-per-type">max-records-per-type</a></span></td>
<td><p><p>Sets the maximum number of records that can be stored in an RRset.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-recursion-depth" title="namedconf-statement-max-recursion-depth">max-recursion-depth</a></span></td>
<td><p><p>Sets the maximum number of levels of recursion permitted at any one time while servicing a recursive query.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-recursion-queries" title="namedconf-statement-max-recursion-queries">max-recursion-queries</a></span></td>
<td><p><p>Sets the maximum number of iterative queries while servicing a recursive query.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-stale-ttl" title="namedconf-statement-max-stale-ttl">max-stale-ttl</a></span></td>
<td><p><p>Specifies the maximum time that the server retains records past their normal expiry, to return them as stale records.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-table-size" title="namedconf-statement-max-table-size">max-table-size</a></span></td>
<td><p><p>Sets the maximum size of the table used to track requests and rate-limit responses.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-types-per-name" title="namedconf-statement-max-types-per-name">max-types-per-name</a></span></td>
<td><p><p>Sets the maximum number of RR types that can be stored for an owner name.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-memstatistics" title="namedconf-statement-memstatistics">memstatistics</a></span></td>
<td><p><p>Controls whether memory statistics are written to the file specified by <a class="reference internal" href="#namedconf-statement-memstatistics-file" title="namedconf-statement-memstatistics-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">memstatistics-file</span></code></a> at exit.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-min-cache-ttl" title="namedconf-statement-min-cache-ttl">min-cache-ttl</a></span></td>
<td><p><p>Specifies the minimum time (in seconds) that the server caches ordinary (positive) answers.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-min-ncache-ttl" title="namedconf-statement-min-ncache-ttl">min-ncache-ttl</a></span></td>
<td><p><p>Specifies the minimum retention time (in seconds) for storage of negative answers in the server's cache.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-no-case-compress" title="namedconf-statement-no-case-compress">no-case-compress</a></span></td>
<td><p><p>Specifies a list of addresses that require case-insensitive compression in responses.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options">options</a></span></td>
<td><p><p>Defines global options to be used by BIND 9.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-padding" title="namedconf-statement-padding">padding</a></span></td>
<td><p><p>Adds EDNS Padding options to outgoing messages to increase the packet size.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-pid-file" title="namedconf-statement-pid-file">pid-file</a></span></td>
<td><p><p>Specifies the pathname of the file where the server writes its process ID.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="chapter4.html#namedconf-statement-plugin" title="namedconf-statement-plugin">plugin</a></span></td>
<td><p><p>Configures plugins in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-port" title="namedconf-statement-port">port</a></span></td>
<td><p><p>Specifies the UDP/TCP port number the server uses to receive and send DNS protocol traffic.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-prefer-server-ciphers" title="namedconf-statement-prefer-server-ciphers">prefer-server-ciphers</a></span></td>
<td><p><p>Specifies that server ciphers should be preferred over client ones.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-querylog" title="namedconf-statement-querylog">querylog</a></span></td>
<td><p><p>Specifies whether query logging should be active when <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> first starts.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-recursing-file" title="namedconf-statement-recursing-file">recursing-file</a></span></td>
<td><p><p>Specifies the pathname of the file where the server dumps queries that are currently recursing via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-recursing"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">recursing</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-response-policy" title="namedconf-statement-response-policy">response-policy</a></span></td>
<td><p><p>Specifies response policy zones for the view or among global options.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-reuseport" title="namedconf-statement-reuseport">reuseport</a></span></td>
<td><p><p>Enables kernel load-balancing of sockets.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-root-key-sentinel" title="namedconf-statement-root-key-sentinel">root-key-sentinel</a></span></td>
<td><p><p>Controls whether BIND 9 responds to root key sentinel probes.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-server" title="namedconf-statement-server">server</a></span></td>
<td><p><p>Defines characteristics to be associated with a remote name server.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-server-id" title="namedconf-statement-server-id">server-id</a></span></td>
<td><p><p>Specifies the ID of the server to return in response to a <code class="docutils literal notranslate"><span class="pre">ID.SERVER</span></code> query.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-servfail-ttl" title="namedconf-statement-servfail-ttl">servfail-ttl</a></span></td>
<td><p><p>Sets the length of time (in seconds) that a SERVFAIL response is cached.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-stale-answer-client-timeout" title="namedconf-statement-stale-answer-client-timeout">stale-answer-client-timeout</a></span></td>
<td><p><p>Defines the amount of time (in milliseconds) that <a class="reference internal" href="manpages.html#std-iscman-named"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named</span></code></a> waits before attempting to answer a query with a stale RRset from cache.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-stale-answer-enable" title="namedconf-statement-stale-answer-enable">stale-answer-enable</a></span></td>
<td><p><p>Enables the returning of "stale" cached answers when the name servers for a zone are not answering.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-stale-cache-enable" title="namedconf-statement-stale-cache-enable">stale-cache-enable</a></span></td>
<td><p><p>Enables the retention of "stale" cached answers.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-stale-refresh-time" title="namedconf-statement-stale-refresh-time">stale-refresh-time</a></span></td>
<td><p><p>Sets the time window for the return of "stale" cached answers before the next attempt to contact, if the name servers for a given zone are not responding.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-statistics-file" title="namedconf-statement-statistics-file">statistics-file</a></span></td>
<td><p><p>Specifies the pathname of the file where the server appends statistics, when using <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-stats"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">stats</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-streams-per-connection" title="namedconf-statement-streams-per-connection">streams-per-connection</a></span></td>
<td><p><p>Specifies the maximum number of concurrent HTTP/2 streams over an HTTP/2 connection.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tcp-clients" title="namedconf-statement-tcp-clients">tcp-clients</a></span></td>
<td><p><p>Specifies the maximum number of simultaneous client TCP connections accepted by the server.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tcp-initial-timeout" title="namedconf-statement-tcp-initial-timeout">tcp-initial-timeout</a></span></td>
<td><p><p>Sets the amount of time (in milliseconds) that the server waits on a new TCP connection for the first message from the client.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tcp-keepalive" title="namedconf-statement-tcp-keepalive">tcp-keepalive</a></span></td>
<td><p><p>Adds EDNS TCP keepalive to messages sent over TCP.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tcp-listen-queue" title="namedconf-statement-tcp-listen-queue">tcp-listen-queue</a></span></td>
<td><p><p>Sets the listen-queue depth.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tcp-only" title="namedconf-statement-tcp-only">tcp-only</a></span></td>
<td><p><p>Sets the transport protocol to TCP.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tcp-receive-buffer" title="namedconf-statement-tcp-receive-buffer">tcp-receive-buffer</a></span></td>
<td><p><p>Sets the operating system's receive buffer size for TCP sockets.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tcp-send-buffer" title="namedconf-statement-tcp-send-buffer">tcp-send-buffer</a></span></td>
<td><p><p>Sets the operating system's send buffer size for TCP sockets.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-tls-port" title="namedconf-statement-tls-port">tls-port</a></span></td>
<td><p><p>Specifies the TCP port number the server uses to receive and send DNS-over-TLS protocol traffic.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-transfers" title="namedconf-statement-transfers">transfers</a></span></td>
<td><p><p>Limits the number of concurrent inbound zone transfers from a server.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-udp-receive-buffer" title="namedconf-statement-udp-receive-buffer">udp-receive-buffer</a></span></td>
<td><p><p>Sets the operating system's receive buffer size for UDP sockets.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-udp-send-buffer" title="namedconf-statement-udp-send-buffer">udp-send-buffer</a></span></td>
<td><p><p>Sets the operating system's send buffer size for UDP sockets.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-unix" title="namedconf-statement-unix">unix</a></span></td>
<td><p><p>Specifies a Unix domain socket as a control channel.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-update-quota" title="namedconf-statement-update-quota">update-quota</a></span></td>
<td><p><p>Specifies the maximum number of concurrent DNS UPDATE messages that can be processed by the server.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-v6-bias" title="namedconf-statement-v6-bias">v6-bias</a></span></td>
<td><p><p>Indicates the number of milliseconds of preference to give to IPv6 name servers.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-version" title="namedconf-statement-version">version</a></span></td>
<td><p><p>Specifies the version number of the server to return in response to a <code class="docutils literal notranslate"><span class="pre">version.bind</span></code> query.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-zero-no-soa-ttl" title="namedconf-statement-zero-no-soa-ttl">zero-no-soa-ttl</a></span></td>
<td><p><p>Specifies whether to set the time to live (TTL) of the SOA record to zero, when returning authoritative negative responses to SOA queries.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-zero-no-soa-ttl-cache" title="namedconf-statement-zero-no-soa-ttl-cache">zero-no-soa-ttl-cache</a></span></td>
<td><p><p>Sets the time to live (TTL) to zero when caching a negative response to an SOA query.</p>
</p></td>
</tr>
</tbody>
</table>
</section>
<section id="transfer-tag-statements">
<span id="id22"></span><h3><span class="section-number">8.4.6. </span>Transfer Tag Statements<a class="headerlink" href="#transfer-tag-statements" title="Link to this heading"></a></h3>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Statement</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-notify" title="namedconf-statement-allow-notify">allow-notify</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> that is allowed to send <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages for the zone, in addition to addresses defined in the <a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">primaries</span></code></a> option for the zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-transfer" title="namedconf-statement-allow-transfer">allow-transfer</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts that are allowed to transfer the zone information from this server.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-update" title="namedconf-statement-allow-update">allow-update</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts that are allowed to submit dynamic updates for primary zones.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-allow-update-forwarding" title="namedconf-statement-allow-update-forwarding">allow-update-forwarding</a></span></td>
<td><p><p>Defines an <a class="reference internal" href="#term-address_match_list"><code class="xref any std std-term docutils literal notranslate"><span class="pre">address_match_list</span></code></a> of hosts that are allowed to submit dynamic updates to a secondary server for transmission to a primary.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-also-notify" title="namedconf-statement-also-notify">also-notify</a></span></td>
<td><p><p>Defines one or more hosts that are sent <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages when zone changes occur.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-ixfr-from-differences" title="namedconf-statement-ixfr-from-differences">ixfr-from-differences</a></span></td>
<td><p><p>Controls how IXFR transfers are calculated.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-ixfr-ratio" title="namedconf-statement-max-ixfr-ratio">max-ixfr-ratio</a></span></td>
<td><p><p>Sets the maximum size for IXFR responses to zone transfer requests.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-journal-size" title="namedconf-statement-max-journal-size">max-journal-size</a></span></td>
<td><p><p>Controls the size of journal files.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-refresh-time" title="namedconf-statement-max-refresh-time">max-refresh-time</a></span></td>
<td><p><p>Limits the zone refresh interval to no less often than the specified value, in seconds.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-retry-time" title="namedconf-statement-max-retry-time">max-retry-time</a></span></td>
<td><p><p>Limits the zone refresh retry interval to no less often than the specified value, in seconds.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-transfer-idle-in" title="namedconf-statement-max-transfer-idle-in">max-transfer-idle-in</a></span></td>
<td><p><p>Specifies the number of minutes after which inbound zone transfers making no progress are terminated.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-transfer-idle-out" title="namedconf-statement-max-transfer-idle-out">max-transfer-idle-out</a></span></td>
<td><p><p>Specifies the number of minutes after which outbound zone transfers making no progress are terminated.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-transfer-time-in" title="namedconf-statement-max-transfer-time-in">max-transfer-time-in</a></span></td>
<td><p><p>Specifies the number of minutes after which inbound zone transfers are terminated.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-transfer-time-out" title="namedconf-statement-max-transfer-time-out">max-transfer-time-out</a></span></td>
<td><p><p>Specifies the number of minutes after which outbound zone transfers are terminated.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-min-refresh-time" title="namedconf-statement-min-refresh-time">min-refresh-time</a></span></td>
<td><p><p>Limits the zone refresh interval to no more often than the specified value, in seconds.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-min-retry-time" title="namedconf-statement-min-retry-time">min-retry-time</a></span></td>
<td><p><p>Limits the zone refresh retry interval to no more often than the specified value, in seconds.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-multi-master" title="namedconf-statement-multi-master">multi-master</a></span></td>
<td><p><p>Controls whether serial number mismatch errors are logged.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-notify" title="namedconf-statement-notify">notify</a></span></td>
<td><p><p>Controls whether <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages are sent on zone changes.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-notify-delay" title="namedconf-statement-notify-delay">notify-delay</a></span></td>
<td><p><p>Sets the delay (in seconds) between sending sets of NOTIFY messages for a zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-notify-rate" title="namedconf-statement-notify-rate">notify-rate</a></span></td>
<td><p><p>Specifies the rate at which NOTIFY requests are sent during normal zone maintenance operations.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-notify-source" title="namedconf-statement-notify-source">notify-source</a></span></td>
<td><p><p>Defines the IPv4 address (and optional port) to be used for outgoing <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-notify-source-v6" title="namedconf-statement-notify-source-v6">notify-source-v6</a></span></td>
<td><p><p>Defines the IPv6 address (and optional port) to be used for outgoing <code class="docutils literal notranslate"><span class="pre">NOTIFY</span></code> messages.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-notify-to-soa" title="namedconf-statement-notify-to-soa">notify-to-soa</a></span></td>
<td><p><p>Controls whether the name servers in the NS RRset are checked against the SOA MNAME.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-provide-ixfr" title="namedconf-statement-provide-ixfr">provide-ixfr</a></span></td>
<td><p><p>Controls whether a primary responds to an incremental zone request (IXFR) or only responds with a full zone transfer (AXFR).</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-request-expire" title="namedconf-statement-request-expire">request-expire</a></span></td>
<td><p><p>Specifies whether the local server requests the EDNS EXPIRE value, when acting as a secondary.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-request-ixfr" title="namedconf-statement-request-ixfr">request-ixfr</a></span></td>
<td><p><p>Controls whether a secondary requests an incremental zone transfer (IXFR) or a full zone transfer (AXFR).</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-serial-query-rate" title="namedconf-statement-serial-query-rate">serial-query-rate</a></span></td>
<td><p><p>Defines an upper limit on the number of queries per second issued by the server, when querying the SOA RRs used for zone transfers.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-startup-notify-rate" title="namedconf-statement-startup-notify-rate">startup-notify-rate</a></span></td>
<td><p><p>Specifies the rate at which NOTIFY requests are sent when the name server is first starting, or when new zones have been added.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-transfer-format" title="namedconf-statement-transfer-format">transfer-format</a></span></td>
<td><p><p>Controls whether multiple records can be packed into a message during zone transfers.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-transfer-message-size" title="namedconf-statement-transfer-message-size">transfer-message-size</a></span></td>
<td><p><p>Limits the uncompressed size of DNS messages used in zone transfers over TCP.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source">transfer-source</a></span></td>
<td><p><p>Defines which local IPv4 address(es) are bound to TCP connections used to fetch zones transferred inbound by the server.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-transfer-source-v6" title="namedconf-statement-transfer-source-v6">transfer-source-v6</a></span></td>
<td><p><p>Defines which local IPv6 address(es) are bound to TCP connections used to fetch zones transferred inbound by the server.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-transfers-in" title="namedconf-statement-transfers-in">transfers-in</a></span></td>
<td><p><p>Limits the number of concurrent inbound zone transfers.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-transfers-out" title="namedconf-statement-transfers-out">transfers-out</a></span></td>
<td><p><p>Limits the number of concurrent outbound zone transfers.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-transfers-per-ns" title="namedconf-statement-transfers-per-ns">transfers-per-ns</a></span></td>
<td><p><p>Limits the number of concurrent inbound zone transfers from a remote server.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-try-tcp-refresh" title="namedconf-statement-try-tcp-refresh">try-tcp-refresh</a></span></td>
<td><p><p>Specifies that BIND 9 should attempt to refresh a zone using TCP if UDP queries fail.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-update-policy" title="namedconf-statement-update-policy">update-policy</a></span></td>
<td><p><p>Sets fine-grained rules to allow or deny dynamic updates (DDNS), based on requester identity, updated content, etc.</p>
</p></td>
</tr>
</tbody>
</table>
</section>
<section id="view-tag-statements">
<span id="id23"></span><h3><span class="section-number">8.4.7. </span>View Tag Statements<a class="headerlink" href="#view-tag-statements" title="Link to this heading"></a></h3>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Statement</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-attach-cache" title="namedconf-statement-attach-cache">attach-cache</a></span></td>
<td><p><p>Allows multiple views to share a single cache database.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-in-view" title="namedconf-statement-in-view">in-view</a></span></td>
<td><p><p>Specifies the view in which a given zone is defined.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-match-clients" title="namedconf-statement-match-clients">match-clients</a></span></td>
<td><p><p>Specifies a view of DNS namespace for a given subset of client IP addresses.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-match-destinations" title="namedconf-statement-match-destinations">match-destinations</a></span></td>
<td><p><p>Specifies a view of DNS namespace for a given subset of destination IP addresses.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-match-recursive-only" title="namedconf-statement-match-recursive-only">match-recursive-only</a></span></td>
<td><p><p>Specifies that only recursive requests can match this view of the DNS namespace.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-view" title="namedconf-statement-view">view</a></span></td>
<td><p><p>Allows a name server to answer a DNS query differently depending on who is asking.</p>
</p></td>
</tr>
</tbody>
</table>
</section>
<section id="zone-tag-statements">
<span id="id24"></span><h3><span class="section-number">8.4.8. </span>Zone Tag Statements<a class="headerlink" href="#zone-tag-statements" title="Link to this heading"></a></h3>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Statement</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-allow-new-zones" title="namedconf-statement-allow-new-zones">allow-new-zones</a></span></td>
<td><p><p>Controls the ability to add zones at runtime via <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-addzone"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">addzone</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="chapter6.html#namedconf-statement-catalog-zones" title="namedconf-statement-catalog-zones">catalog-zones</a></span></td>
<td><p><p>Configures catalog zones in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-check-integrity" title="namedconf-statement-check-integrity">check-integrity</a></span></td>
<td><p><p>Performs post-load zone integrity checks on primary zones.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-check-mx" title="namedconf-statement-check-mx">check-mx</a></span></td>
<td><p><p>Checks whether an MX record appears to refer to an IP address.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-check-mx-cname" title="namedconf-statement-check-mx-cname">check-mx-cname</a></span></td>
<td><p><p>Sets the response to MX records that refer to CNAMEs.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-check-sibling" title="namedconf-statement-check-sibling">check-sibling</a></span></td>
<td><p><p>Specifies whether to check for sibling glue when performing integrity checks.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-check-spf" title="namedconf-statement-check-spf">check-spf</a></span></td>
<td><p><p>Specifies whether to check for a TXT Sender Policy Framework record, if an SPF record is present.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-check-srv-cname" title="namedconf-statement-check-srv-cname">check-srv-cname</a></span></td>
<td><p><p>Sets the response to SRV records that refer to CNAMEs.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-check-wildcard" title="namedconf-statement-check-wildcard">check-wildcard</a></span></td>
<td><p><p>Checks for non-terminal wildcards.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-database" title="namedconf-statement-database">database</a></span></td>
<td><p><p>Specifies the type of database to be used to store zone data.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-disable-ds-digests" title="namedconf-statement-disable-ds-digests">disable-ds-digests</a></span></td>
<td><p><p>Disables DS digest types from a specified zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-disable-empty-zone" title="namedconf-statement-disable-empty-zone">disable-empty-zone</a></span></td>
<td><p><p>Disables individual empty zones.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="chapter6.html#namedconf-statement-dlz" title="namedconf-statement-dlz">dlz</a></span></td>
<td><p><p>Configures a Dynamically Loadable Zone (DLZ) database in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="chapter6.html#namedconf-statement-dyndb" title="namedconf-statement-dyndb">dyndb</a></span></td>
<td><p><p>Configures a DynDB database in <a class="reference internal" href="manpages.html#std-iscman-named.conf"><code class="xref std std-iscman docutils literal notranslate"><span class="pre">named.conf</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-empty-contact" title="namedconf-statement-empty-contact">empty-contact</a></span></td>
<td><p><p>Specifies the contact name in the returned SOA record for empty zones.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-empty-server" title="namedconf-statement-empty-server">empty-server</a></span></td>
<td><p><p>Specifies the server name in the returned SOA record for empty zones.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-empty-zones-enable" title="namedconf-statement-empty-zones-enable">empty-zones-enable</a></span></td>
<td><p><p>Enables or disables all empty zones.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-file" title="namedconf-statement-file">file</a></span></td>
<td><p><p>Specifies the zone's filename.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-flush-zones-on-shutdown" title="namedconf-statement-flush-zones-on-shutdown">flush-zones-on-shutdown</a></span></td>
<td><p><p>Controls whether pending zone writes are flushed when the name server exits.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-in-view" title="namedconf-statement-in-view">in-view</a></span></td>
<td><p><p>Specifies the view in which a given zone is defined.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-inline-signing" title="namedconf-statement-inline-signing">inline-signing</a></span></td>
<td><p><p>Specifies whether BIND 9 maintains a separate signed version of a zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-journal" title="namedconf-statement-journal">journal</a></span></td>
<td><p><p>Allows the default journal's filename to be overridden.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-masterfile-format" title="namedconf-statement-masterfile-format">masterfile-format</a></span></td>
<td><p><p>Specifies the file format of zone files.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-max-records" title="namedconf-statement-max-records">max-records</a></span></td>
<td><p><p>Sets the maximum number of records permitted in a zone.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-max-zone-ttl" title="namedconf-statement-max-zone-ttl">max-zone-ttl</a></span></td>
<td><p><p>Specifies a maximum permissible time-to-live (TTL) value, in seconds.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-new-zones-directory" title="namedconf-statement-new-zones-directory">new-zones-directory</a></span></td>
<td><p><p>Specifies the directory where configuration parameters are stored for zones added by <a class="reference internal" href="manpages.html#cmdoption-rndc-arg-addzone"><code class="xref std std-option docutils literal notranslate"><span class="pre">rndc</span> <span class="pre">addzone</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-notify-delay" title="namedconf-statement-notify-delay">notify-delay</a></span></td>
<td><p><p>Sets the delay (in seconds) between sending sets of NOTIFY messages for a zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-notify-rate" title="namedconf-statement-notify-rate">notify-rate</a></span></td>
<td><p><p>Specifies the rate at which NOTIFY requests are sent during normal zone maintenance operations.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-parent-propagation-delay" title="namedconf-statement-parent-propagation-delay">parent-propagation-delay</a></span></td>
<td><p><p>Sets the propagation delay from the time the parent zone is updated to when the new version is served by all of the parent zone's name servers.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-parental-agents" title="namedconf-statement-parental-agents">parental-agents</a></span></td>
<td><p><p>Defines a list of delegation agents to be used by primary and secondary zones.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-primaries" title="namedconf-statement-primaries">primaries</a></span></td>
<td><p><p>Defines one or more primary servers for a zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-response-policy" title="namedconf-statement-response-policy">response-policy</a></span></td>
<td><p><p>Specifies response policy zones for the view or among global options.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-serial-update-method" title="namedconf-statement-serial-update-method">serial-update-method</a></span></td>
<td><p><p>Specifies the update method to be used for the zone serial number in the SOA record.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-server-addresses" title="namedconf-statement-server-addresses">server-addresses</a></span></td>
<td><p><p>Specifies a list of IP addresses to which queries should be sent in recursive resolution for a static-stub zone.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-server-names" title="namedconf-statement-server-names">server-names</a></span></td>
<td><p><p>Specifies a list of domain names of name servers that act as authoritative servers of a static-stub zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-startup-notify-rate" title="namedconf-statement-startup-notify-rate">startup-notify-rate</a></span></td>
<td><p><p>Specifies the rate at which NOTIFY requests are sent when the name server is first starting, or when new zones have been added.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-type" title="namedconf-statement-type">type</a></span></td>
<td><p><p>Specifies the kind of zone in a given configuration.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-type forward" title="namedconf-statement-type forward">type forward</a></span></td>
<td><p><p>Contains forwarding statements that apply to queries within a given domain.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-type hint" title="namedconf-statement-type hint">type hint</a></span></td>
<td><p><p>Contains the initial set of root name servers to be used at BIND 9 startup.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-type mirror" title="namedconf-statement-type mirror">type mirror</a></span></td>
<td><p><p>Contains a DNSSEC-validated duplicate of the main data for a zone.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-type primary" title="namedconf-statement-type primary">type primary</a></span></td>
<td><p><p>Contains the main copy of the data for a zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-type redirect" title="namedconf-statement-type redirect">type redirect</a></span></td>
<td><p><p>Contains information to answer queries when normal resolution would return NXDOMAIN.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-type secondary" title="namedconf-statement-type secondary">type secondary</a></span></td>
<td><p><p>Contains a duplicate of the data for a zone that has been transferred from a primary server.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-type static-stub" title="namedconf-statement-type static-stub">type static-stub</a></span></td>
<td><p><p>Contains a duplicate of the NS records of a primary zone, but statically configured rather than transferred from a primary server.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-type stub" title="namedconf-statement-type stub">type stub</a></span></td>
<td><p><p>Contains a duplicate of the NS records of a primary zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-update-check-ksk" title="namedconf-statement-update-check-ksk">update-check-ksk</a></span></td>
<td><p><p>Specifies whether to check the KSK bit to determine how a key should be used, when generating RRSIGs for a secure zone.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-zero-no-soa-ttl" title="namedconf-statement-zero-no-soa-ttl">zero-no-soa-ttl</a></span></td>
<td><p><p>Specifies whether to set the time to live (TTL) of the SOA record to zero, when returning authoritative negative responses to SOA queries.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-zero-no-soa-ttl-cache" title="namedconf-statement-zero-no-soa-ttl-cache">zero-no-soa-ttl-cache</a></span></td>
<td><p><p>Sets the time to live (TTL) to zero when caching a negative response to an SOA query.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-zone" title="namedconf-statement-zone">zone</a></span></td>
<td><p><p>Specifies the zone in a BIND 9 configuration.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-zone-propagation-delay" title="namedconf-statement-zone-propagation-delay">zone-propagation-delay</a></span></td>
<td><p><p>Sets the propagation delay from the time a zone is first updated to when the new version of the zone is served by all secondary servers.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-zone-statistics" title="namedconf-statement-zone-statistics">zone-statistics</a></span></td>
<td><p><p>Controls the level of statistics gathered for all zones.</p>
</p></td>
</tr>
</tbody>
</table>
</section>
<section id="deprecated-tag-statements">
<span id="id25"></span><h3><span class="section-number">8.4.9. </span>Deprecated Tag Statements<a class="headerlink" href="#deprecated-tag-statements" title="Link to this heading"></a></h3>
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head"><p>Statement</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-alt-transfer-source" title="namedconf-statement-alt-transfer-source">alt-transfer-source</a></span></td>
<td><p><p>Defines alternate local IPv4 address(es) to be used by the server for inbound zone transfers, if the address(es) defined by <a class="reference internal" href="#namedconf-statement-transfer-source" title="namedconf-statement-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">transfer-source</span></code></a> fail and <a class="reference internal" href="#namedconf-statement-use-alt-transfer-source" title="namedconf-statement-use-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">use-alt-transfer-source</span></code></a> is enabled.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-alt-transfer-source-v6" title="namedconf-statement-alt-transfer-source-v6">alt-transfer-source-v6</a></span></td>
<td><p><p>Defines alternate local IPv6 address(es) to be used by the server for inbound zone transfers.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-avoid-v4-udp-ports" title="namedconf-statement-avoid-v4-udp-ports">avoid-v4-udp-ports</a></span></td>
<td><p><p>Specifies the range(s) of ports to be excluded from use as sources for UDP/IPv4 messages.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-avoid-v6-udp-ports" title="namedconf-statement-avoid-v6-udp-ports">avoid-v6-udp-ports</a></span></td>
<td><p><p>Specifies the range(s) of ports to be excluded from use as sources for UDP/IPv6 messages.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-coresize" title="namedconf-statement-coresize">coresize</a></span></td>
<td><p><p>Sets the maximum size of a core dump.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-datasize" title="namedconf-statement-datasize">datasize</a></span></td>
<td><p><p>Sets the maximum amount of data memory that can be used by the server.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-delegation-only" title="namedconf-statement-delegation-only">delegation-only</a></span></td>
<td><p><p>Indicates that a forward, hint, or stub zone is to be treated as a delegation-only type zone.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-dialup" title="namedconf-statement-dialup">dialup</a></span></td>
<td><p><p>Concentrates zone maintenance so that all transfers take place once every <a class="reference internal" href="#namedconf-statement-heartbeat-interval" title="namedconf-statement-heartbeat-interval"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">heartbeat-interval</span></code></a>, ideally during a single call.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-dnssec-must-be-secure" title="namedconf-statement-dnssec-must-be-secure">dnssec-must-be-secure</a></span></td>
<td><p><p>Defines hierarchies that must or may not be secure (signed and validated).</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-files" title="namedconf-statement-files">files</a></span></td>
<td><p><p>Sets the maximum number of files the server may have open concurrently.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-glue-cache" title="namedconf-statement-glue-cache">glue-cache</a></span></td>
<td><p><p>Deprecated.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-heartbeat-interval" title="namedconf-statement-heartbeat-interval">heartbeat-interval</a></span></td>
<td><p><p>Sets the interval at which the server performs zone maintenance tasks for all zones marked as <a class="reference internal" href="#namedconf-statement-dialup" title="namedconf-statement-dialup"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">dialup</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-managed-keys" title="namedconf-statement-managed-keys">managed-keys</a></span></td>
<td><p><p>Deprecated, use <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-reserved-sockets" title="namedconf-statement-reserved-sockets">reserved-sockets</a></span></td>
<td><p><p>Deprecated.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-resolver-retry-interval" title="namedconf-statement-resolver-retry-interval">resolver-retry-interval</a></span></td>
<td><p><p>Sets the base retry interval (in milliseconds).</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-root-delegation-only" title="namedconf-statement-root-delegation-only">root-delegation-only</a></span></td>
<td><p><p>Turns on enforcement of delegation-only in top-level domains (TLDs) and root zones with an optional exclude list.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-stacksize" title="namedconf-statement-stacksize">stacksize</a></span></td>
<td><p><p>Sets the maximum amount of stack memory that can be used by the server.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-tkey-dhkey" title="namedconf-statement-tkey-dhkey">tkey-dhkey</a></span></td>
<td><p><p>Sets the Diffie-Hellman key used by the server to generate shared keys.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-trusted-keys" title="namedconf-statement-trusted-keys">trusted-keys</a></span></td>
<td><p><p>Deprecated, use <a class="reference internal" href="#namedconf-statement-trust-anchors" title="namedconf-statement-trust-anchors"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">trust-anchors</span></code></a>.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-type delegation-only" title="namedconf-statement-type delegation-only">type delegation-only</a></span></td>
<td><p><p>Enforces the delegation-only status of infrastructure zones (COM, NET, ORG, etc.).</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-use-alt-transfer-source" title="namedconf-statement-use-alt-transfer-source">use-alt-transfer-source</a></span></td>
<td><p><p>Indicates whether <a class="reference internal" href="#namedconf-statement-alt-transfer-source" title="namedconf-statement-alt-transfer-source"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">alt-transfer-source</span></code></a> and <a class="reference internal" href="#namedconf-statement-alt-transfer-source-v6" title="namedconf-statement-alt-transfer-source-v6"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">alt-transfer-source-v6</span></code></a> can be used.</p>
</p></td>
</tr>
<tr class="row-odd"><td><span><a class="reference internal" href="#namedconf-statement-use-v4-udp-ports" title="namedconf-statement-use-v4-udp-ports">use-v4-udp-ports</a></span></td>
<td><p><p>Specifies a list of ports that are valid sources for UDP/IPv4 messages.</p>
</p></td>
</tr>
<tr class="row-even"><td><span><a class="reference internal" href="#namedconf-statement-use-v6-udp-ports" title="namedconf-statement-use-v6-udp-ports">use-v6-udp-ports</a></span></td>
<td><p><p>Specifies a list of ports that are valid sources for UDP/IPv6 messages.</p>
</p></td>
</tr>
</tbody>
</table>
</section>
</section>
<section id="bind-9-statistics">
<span id="statistics"></span><h2><span class="section-number">8.5. </span>BIND 9 Statistics<a class="headerlink" href="#bind-9-statistics" title="Link to this heading"></a></h2>
<p>BIND 9 maintains lots of statistics information and provides several
interfaces for users to access those statistics. The available
statistics include all statistics counters that are meaningful in BIND 9,
and other information that is considered useful.</p>
<p>The statistics information is categorized into the following sections:</p>
<dl>
<dt>Incoming Requests</dt><dd><p>The number of incoming DNS requests for each OPCODE.</p>
</dd>
<dt>Incoming Queries</dt><dd><p>The number of incoming queries for each RR type.</p>
</dd>
<dt>Outgoing Queries</dt><dd><p>The number of outgoing queries for each RR type sent from the internal
resolver, maintained per view.</p>
</dd>
<dt>Name Server Statistics</dt><dd><p>Statistics counters for incoming request processing.</p>
</dd>
<dt>Zone Maintenance Statistics</dt><dd><p>Statistics counters regarding zone maintenance operations, such as zone
transfers.</p>
</dd>
<dt>Resolver Statistics</dt><dd><p>Statistics counters for name resolutions performed in the internal resolver,
maintained per view.</p>
</dd>
<dt>Cache DB RRsets</dt><dd><p>Statistics counters related to cache contents, maintained per view.</p>
<p>The “NXDOMAIN” counter is the number of names that have been cached as
nonexistent. Counters named for RR types indicate the number of active
RRsets for each type in the cache database.</p>
<p>If an RR type name is preceded by an exclamation point (!), it represents the
number of records in the cache which indicate that the type does not exist
for a particular name; this is also known as “NXRRSET”. If an RR type name
is preceded by a hash mark (#), it represents the number of RRsets for this
type that are present in the cache but whose TTLs have expired; these RRsets
may only be used if stale answers are enabled. If an RR type name is
preceded by a tilde (~), it represents the number of RRsets for this type
that are present in the cache database but are marked for garbage collection;
these RRsets cannot be used.</p>
</dd>
<dt>Socket I/O Statistics</dt><dd><p>Statistics counters for network-related events.</p>
</dd>
</dl>
<p>A subset of Name Server Statistics is collected and shown per zone for
which the server has the authority, when <a class="reference internal" href="#namedconf-statement-zone-statistics" title="namedconf-statement-zone-statistics"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone-statistics</span></code></a> is set to
<code class="docutils literal notranslate"><span class="pre">full</span></code> (or <code class="docutils literal notranslate"><span class="pre">yes</span></code>), for backward compatibility. See the description of
<a class="reference internal" href="#namedconf-statement-zone-statistics" title="namedconf-statement-zone-statistics"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">zone-statistics</span></code></a> in <a class="reference internal" href="#namedconf-statement-options" title="namedconf-statement-options"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">options</span></code></a> for further details.</p>
<p>These statistics counters are shown with their zone and view names. The
view name is omitted when the server is not configured with explicit
views.</p>
<p>There are currently two user interfaces to get access to the statistics.
One is in plain-text format, dumped to the file specified by the
<a class="reference internal" href="#namedconf-statement-statistics-file" title="namedconf-statement-statistics-file"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">statistics-file</span></code></a> configuration option; the other is remotely
accessible via a statistics channel when the <a class="reference internal" href="#namedconf-statement-statistics-channels" title="namedconf-statement-statistics-channels"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">statistics-channels</span></code></a>
statement is specified in the configuration file.</p>
<section id="the-statistics-file">
<span id="statsfile"></span><h3><span class="section-number">8.5.1. </span>The Statistics File<a class="headerlink" href="#the-statistics-file" title="Link to this heading"></a></h3>
<p>The text format statistics dump begins with a line, like:</p>
<p><code class="docutils literal notranslate"><span class="pre">+++</span> <span class="pre">Statistics</span> <span class="pre">Dump</span> <span class="pre">+++</span> <span class="pre">(973798949)</span></code></p>
<p>The number in parentheses is a standard Unix-style timestamp, measured
in seconds since January 1, 1970. Following that line is a set of
statistics information, which is categorized as described above. Each
section begins with a line, like:</p>
<p><code class="docutils literal notranslate"><span class="pre">++</span> <span class="pre">Name</span> <span class="pre">Server</span> <span class="pre">Statistics</span> <span class="pre">++</span></code></p>
<p>Each section consists of lines, each containing the statistics counter
value followed by its textual description; see below for available
counters. For brevity, counters that have a value of 0 are not shown in
the statistics file.</p>
<p>The statistics dump ends with the line where the number is identical to
the number in the beginning line; for example:</p>
<p><code class="docutils literal notranslate"><span class="pre">---</span> <span class="pre">Statistics</span> <span class="pre">Dump</span> <span class="pre">---</span> <span class="pre">(973798949)</span></code></p>
</section>
<section id="statistics-counters">
<span id="id26"></span><h3><span class="section-number">8.5.2. </span>Statistics Counters<a class="headerlink" href="#statistics-counters" title="Link to this heading"></a></h3>
<p>The following lists summarize the statistics counters that BIND 9 provides.
For each counter, the abbreviated
symbol name is given; these symbols are shown in the statistics
information accessed via an HTTP statistics channel.
The description of the counter is also shown in the
statistics file but, in this document, may be slightly
modified for better readability.</p>
<section id="name-server-statistics-counters">
<span id="stats-counters"></span><h4><span class="section-number">8.5.2.1. </span>Name Server Statistics Counters<a class="headerlink" href="#name-server-statistics-counters" title="Link to this heading"></a></h4>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">Requestv4</span></code></dt><dd><p>This indicates the number of IPv4 requests received. Note: this also counts non-query requests.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Requestv6</span></code></dt><dd><p>This indicates the number of IPv6 requests received. Note: this also counts non-query requests.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ReqEdns0</span></code></dt><dd><p>This indicates the number of requests received with EDNS(0).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ReqBadEDN</span> <span class="pre">SVer</span></code></dt><dd><p>This indicates the number of requests received with an unsupported EDNS version.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ReqTSIG</span></code></dt><dd><p>This indicates the number of requests received with TSIG.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ReqSIG0</span></code></dt><dd><p>This indicates the number of requests received with SIG(0).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ReqBadSIG</span></code></dt><dd><p>This indicates the number of requests received with an invalid (TSIG or SIG(0)) signature.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ReqTCP</span></code></dt><dd><p>This indicates the number of TCP requests received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">AuthQryRej</span></code></dt><dd><p>This indicates the number of rejected authoritative (non-recursive) queries.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">RecQryRej</span></code></dt><dd><p>This indicates the number of rejected recursive queries.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">XfrRej</span></code></dt><dd><p>This indicates the number of rejected zone transfer requests.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">UpdateRej</span></code></dt><dd><p>This indicates the number of rejected dynamic update requests.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Response</span></code></dt><dd><p>This indicates the number of responses sent.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">RespTruncated</span></code></dt><dd><p>This indicates the number of truncated responses sent.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">RespEDNS0</span></code></dt><dd><p>This indicates the number of responses sent with EDNS(0).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">RespTSIG</span></code></dt><dd><p>This indicates the number of responses sent with TSIG.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">RespSIG0</span></code></dt><dd><p>This indicates the number of responses sent with SIG(0).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QrySuccess</span></code></dt><dd><p>This indicates the number of queries that resulted in a successful answer, meaning queries which return a NOERROR response with at least one answer RR. This corresponds to the <code class="docutils literal notranslate"><span class="pre">success</span></code> counter of previous versions of BIND 9.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryAuthAns</span></code></dt><dd><p>This indicates the number of queries that resulted in an authoritative answer.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryNoauthAns</span></code></dt><dd><p>This indicates the number of queries that resulted in a non-authoritative answer.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryReferral</span></code></dt><dd><p>This indicates the number of queries that resulted in a referral answer. This corresponds to the <code class="docutils literal notranslate"><span class="pre">referral</span></code> counter of previous versions of BIND 9.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryNxrrset</span></code></dt><dd><p>This indicates the number of queries that resulted in NOERROR responses with no data. This corresponds to the <code class="docutils literal notranslate"><span class="pre">nxrrset</span></code> counter of previous versions of BIND 9.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QrySERVFAIL</span></code></dt><dd><p>This indicates the number of queries that resulted in SERVFAIL.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryFORMERR</span></code></dt><dd><p>This indicates the number of queries that resulted in FORMERR.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryNXDOMAIN</span></code></dt><dd><p>This indicates the number of queries that resulted in NXDOMAIN. This corresponds to the <code class="docutils literal notranslate"><span class="pre">nxdomain</span></code> counter of previous versions of BIND 9.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryRecursion</span></code></dt><dd><p>This indicates the number of queries that caused the server to perform recursion in order to find the final answer. This corresponds to the <a class="reference internal" href="#namedconf-statement-recursion" title="namedconf-statement-recursion"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">recursion</span></code></a> counter of previous versions of BIND 9.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryDuplicate</span></code></dt><dd><p>This indicates the number of queries which the server attempted to recurse but for which it discovered an existing query with the same IP address, port, query ID, name, type, and class already being processed. This corresponds to the <code class="docutils literal notranslate"><span class="pre">duplicate</span></code> counter of previous versions of BIND 9.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryDropped</span></code></dt><dd><p>This indicates the number of recursive queries dropped by the server as a result of configured limits. These limits include the settings of the <a class="reference internal" href="#namedconf-statement-fetches-per-zone" title="namedconf-statement-fetches-per-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-zone</span></code></a>, <a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-server</span></code></a>, <a class="reference internal" href="#namedconf-statement-clients-per-query" title="namedconf-statement-clients-per-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">clients-per-query</span></code></a>, and <a class="reference internal" href="#namedconf-statement-max-clients-per-query" title="namedconf-statement-max-clients-per-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">max-clients-per-query</span></code></a> options, as well as the <a class="reference internal" href="#namedconf-statement-rate-limit" title="namedconf-statement-rate-limit"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">rate-limit</span></code></a> option. This corresponds to the <code class="docutils literal notranslate"><span class="pre">dropped</span></code> counter of previous versions of BIND 9.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryFailure</span></code></dt><dd><p>This indicates the number of query failures. This corresponds to the <code class="docutils literal notranslate"><span class="pre">failure</span></code> counter of previous versions of BIND 9. Note: this counter is provided mainly for backward compatibility with previous versions; normally, more fine-grained counters such as <code class="docutils literal notranslate"><span class="pre">AuthQryRej</span></code> and <code class="docutils literal notranslate"><span class="pre">RecQryRej</span></code> that would also fall into this counter are provided, so this counter is not of much interest in practice.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryNXRedir</span></code></dt><dd><p>This indicates the number of queries that resulted in NXDOMAIN that were redirected.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryNXRedirRLookup</span></code></dt><dd><p>This indicates the number of queries that resulted in NXDOMAIN that were redirected and resulted in a successful remote lookup.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">XfrReqDone</span></code></dt><dd><p>This indicates the number of requested and completed zone transfers.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">UpdateReqFwd</span></code></dt><dd><p>This indicates the number of forwarded update requests.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">UpdateRespFwd</span></code></dt><dd><p>This indicates the number of forwarded update responses.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">UpdateFwdFail</span></code></dt><dd><p>This indicates the number of forwarded dynamic updates that failed.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">UpdateDone</span></code></dt><dd><p>This indicates the number of completed dynamic updates.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">UpdateFail</span></code></dt><dd><p>This indicates the number of failed dynamic updates.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">UpdateBadPrereq</span></code></dt><dd><p>This indicates the number of dynamic updates rejected due to a prerequisite failure.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">UpdateQuota</span></code></dt><dd><p>This indicates the number of times a dynamic update or update
forwarding request was rejected because the number of pending
requests exceeded <a class="reference internal" href="#namedconf-statement-update-quota" title="namedconf-statement-update-quota"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">update-quota</span></code></a>.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">RateDropped</span></code></dt><dd><p>This indicates the number of responses dropped due to rate limits.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">RateSlipped</span></code></dt><dd><p>This indicates the number of responses truncated by rate limits.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">RPZRewrites</span></code></dt><dd><p>This indicates the number of response policy zone rewrites.</p>
</dd>
</dl>
</section>
<section id="zone-maintenance-statistics-counters">
<span id="zone-stats"></span><h4><span class="section-number">8.5.2.2. </span>Zone Maintenance Statistics Counters<a class="headerlink" href="#zone-maintenance-statistics-counters" title="Link to this heading"></a></h4>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">NotifyOutv4</span></code></dt><dd><p>This indicates the number of IPv4 notifies sent.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">NotifyOutv6</span></code></dt><dd><p>This indicates the number of IPv6 notifies sent.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">NotifyInv4</span></code></dt><dd><p>This indicates the number of IPv4 notifies received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">NotifyInv6</span></code></dt><dd><p>This indicates the number of IPv6 notifies received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">NotifyRej</span></code></dt><dd><p>This indicates the number of incoming notifies rejected.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">SOAOutv4</span></code></dt><dd><p>This indicates the number of IPv4 SOA queries sent.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">SOAOutv6</span></code></dt><dd><p>This indicates the number of IPv6 SOA queries sent.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">AXFRReqv4</span></code></dt><dd><p>This indicates the number of requested IPv4 AXFRs.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">AXFRReqv6</span></code></dt><dd><p>This indicates the number of requested IPv6 AXFRs.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">IXFRReqv4</span></code></dt><dd><p>This indicates the number of requested IPv4 IXFRs.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">IXFRReqv6</span></code></dt><dd><p>This indicates the number of requested IPv6 IXFRs.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">XfrSuccess</span></code></dt><dd><p>This indicates the number of successful zone transfer requests.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">XfrFail</span></code></dt><dd><p>This indicates the number of failed zone transfer requests.</p>
</dd>
</dl>
</section>
<section id="resolver-statistics-counters">
<span id="resolver-stats"></span><h4><span class="section-number">8.5.2.3. </span>Resolver Statistics Counters<a class="headerlink" href="#resolver-statistics-counters" title="Link to this heading"></a></h4>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">Queryv4</span></code></dt><dd><p>This indicates the number of IPv4 queries sent.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Queryv6</span></code></dt><dd><p>This indicates the number of IPv6 queries sent.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Responsev4</span></code></dt><dd><p>This indicates the number of IPv4 responses received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Responsev6</span></code></dt><dd><p>This indicates the number of IPv6 responses received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">NXDOMAIN</span></code></dt><dd><p>This indicates the number of NXDOMAINs received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">SERVFAIL</span></code></dt><dd><p>This indicates the number of SERVFAILs received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">FORMERR</span></code></dt><dd><p>This indicates the number of FORMERRs received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">OtherError</span></code></dt><dd><p>This indicates the number of other errors received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">EDNS0Fail</span></code></dt><dd><p>This indicates the number of EDNS(0) query failures.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Mismatch</span></code></dt><dd><p>This indicates the number of mismatched responses received, meaning the DNS ID, response’s source address, and/or the response’s source port does not match what was expected. (The port must be 53 or as defined by the <a class="reference internal" href="#namedconf-statement-port" title="namedconf-statement-port"><code class="xref namedconf namedconf-ref docutils literal notranslate"><span class="pre">port</span></code></a> option.) This may be an indication of a cache poisoning attempt.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Truncated</span></code></dt><dd><p>This indicates the number of truncated responses received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Lame</span></code></dt><dd><p>This indicates the number of lame delegations received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Retry</span></code></dt><dd><p>This indicates the number of query retries performed.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QueryAbort</span></code></dt><dd><p>This indicates the number of queries aborted due to quota control.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QuerySockFail</span></code></dt><dd><p>This indicates the number of failures in opening query sockets. One common reason for such failures is due to a limitation on file descriptors.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QueryCurUDP</span></code></dt><dd><p>This indicates the number of UDP queries in progress.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QueryCurTCP</span></code></dt><dd><p>This indicates the number of TCP queries in progress.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QueryTimeout</span></code></dt><dd><p>This indicates the number of query timeouts.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">GlueFetchv4</span></code></dt><dd><p>This indicates the number of IPv4 NS address fetches invoked.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">GlueFetchv6</span></code></dt><dd><p>This indicates the number of IPv6 NS address fetches invoked.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">GlueFetchv4Fail</span></code></dt><dd><p>This indicates the number of failed IPv4 NS address fetches.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">GlueFetchv6Fail</span></code></dt><dd><p>This indicates the number of failed IPv6 NS address fetches.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ValAttempt</span></code></dt><dd><p>This indicates the number of attempted DNSSEC validations.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ValOk</span></code></dt><dd><p>This indicates the number of successful DNSSEC validations.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ValNegOk</span></code></dt><dd><p>This indicates the number of successful DNSSEC validations on negative information.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ValFail</span></code></dt><dd><p>This indicates the number of failed DNSSEC validations.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">QryRTTnn</span></code></dt><dd><p>This provides a frequency table on query round-trip times (RTTs). Each <code class="docutils literal notranslate"><span class="pre">nn</span></code> specifies the corresponding frequency. In the sequence of <code class="docutils literal notranslate"><span class="pre">nn_1</span></code>, <code class="docutils literal notranslate"><span class="pre">nn_2</span></code>, …, <code class="docutils literal notranslate"><span class="pre">nn_m</span></code>, the value of <code class="docutils literal notranslate"><span class="pre">nn_i</span></code> is the number of queries whose RTTs are between <code class="docutils literal notranslate"><span class="pre">nn_(i-1)</span></code> (inclusive) and <code class="docutils literal notranslate"><span class="pre">nn_i</span></code> (exclusive) milliseconds. For the sake of convenience, we define <code class="docutils literal notranslate"><span class="pre">nn_0</span></code> to be 0. The last entry should be represented as <code class="docutils literal notranslate"><span class="pre">nn_m+</span></code>, which means the number of queries whose RTTs are equal to or greater than <code class="docutils literal notranslate"><span class="pre">nn_m</span></code> milliseconds.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">NumFetch</span></code></dt><dd><p>This indicates the number of active fetches.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">BucketSize</span></code></dt><dd><p>This indicates the number of the resolver’s internal buckets (a static number).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">REFUSED</span></code></dt><dd><p>This indicates the number of REFUSED responses received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ClientCookieOut</span></code></dt><dd><p>This indicates the number of COOKIE messages sent to an authoritative server with only a client cookie.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ServerCookieOut</span></code></dt><dd><p>This indicates the number of COOKIE messages sent to an authoritative server with both a client and a cached server cookie.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">CookieIn</span></code></dt><dd><p>This indicates the number of COOKIE replies received from an authoritative server.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">CookieClientOk</span></code></dt><dd><p>This indicates the number of correctly formed COOKIE client responses received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">BadEDNSVersion</span></code></dt><dd><p>This indicates the number of bad EDNS version replies received.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">BadCookieRcode</span></code></dt><dd><p>This indicates the number of BADCOOKIE response codes received from an authoritative server.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ZoneQuota</span></code></dt><dd><p>This indicates the number of queries spilled for exceeding the <a class="reference internal" href="#namedconf-statement-fetches-per-zone" title="namedconf-statement-fetches-per-zone"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-zone</span></code></a> quota.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ServerQuota</span></code></dt><dd><p>This indicates the number of queries spilled for exceeding the <a class="reference internal" href="#namedconf-statement-fetches-per-server" title="namedconf-statement-fetches-per-server"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">fetches-per-server</span></code></a> quota.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">ClientQuota</span></code></dt><dd><p>This indicates the number of queries spilled for exceeding the <a class="reference internal" href="#namedconf-statement-clients-per-query" title="namedconf-statement-clients-per-query"><code class="xref any namedconf namedconf-ref docutils literal notranslate"><span class="pre">clients-per-query</span></code></a> quota.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">NextItem</span></code></dt><dd><p>This indicates the number of times the server waited for the next item after receiving an invalid response.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">Priming</span></code></dt><dd><p>This indicates the number of priming fetches performed by the resolver.</p>
</dd>
</dl>
</section>
<section id="socket-i-o-statistics-counters">
<span id="socket-stats"></span><h4><span class="section-number">8.5.2.4. </span>Socket I/O Statistics Counters<a class="headerlink" href="#socket-i-o-statistics-counters" title="Link to this heading"></a></h4>
<p>Socket I/O statistics counters are defined per socket type, which are
<code class="docutils literal notranslate"><span class="pre">UDP4</span></code> (UDP/IPv4), <code class="docutils literal notranslate"><span class="pre">UDP6</span></code> (UDP/IPv6), <code class="docutils literal notranslate"><span class="pre">TCP4</span></code> (TCP/IPv4), <code class="docutils literal notranslate"><span class="pre">TCP6</span></code>
(TCP/IPv6), <code class="docutils literal notranslate"><span class="pre">Unix</span></code> (Unix Domain), and <code class="docutils literal notranslate"><span class="pre">FDwatch</span></code> (sockets opened
outside the socket module). In the following list, <code class="docutils literal notranslate"><span class="pre"><TYPE></span></code> represents
a socket type. Not all counters are available for all socket types;
exceptions are noted in the descriptions.</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre"><TYPE>Open</span></code></dt><dd><p>This indicates the number of sockets opened successfully. This counter does not apply to the <code class="docutils literal notranslate"><span class="pre">FDwatch</span></code> type.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre"><TYPE>OpenFail</span></code></dt><dd><p>This indicates the number of failures to open sockets. This counter does not apply to the <code class="docutils literal notranslate"><span class="pre">FDwatch</span></code> type.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre"><TYPE>Close</span></code></dt><dd><p>This indicates the number of closed sockets.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre"><TYPE>BindFail</span></code></dt><dd><p>This indicates the number of failures to bind sockets.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre"><TYPE>ConnFail</span></code></dt><dd><p>This indicates the number of failures to connect sockets.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre"><TYPE>Conn</span></code></dt><dd><p>This indicates the number of connections established successfully.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre"><TYPE>AcceptFail</span></code></dt><dd><p>This indicates the number of failures to accept incoming connection requests. This counter does not apply to the <code class="docutils literal notranslate"><span class="pre">UDP</span></code> and <code class="docutils literal notranslate"><span class="pre">FDwatch</span></code> types.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre"><TYPE>Accept</span></code></dt><dd><p>This indicates the number of incoming connections successfully accepted. This counter does not apply to the <code class="docutils literal notranslate"><span class="pre">UDP</span></code> and <code class="docutils literal notranslate"><span class="pre">FDwatch</span></code> types.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre"><TYPE>SendErr</span></code></dt><dd><p>This indicates the number of errors in socket send operations.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre"><TYPE>RecvErr</span></code></dt><dd><p>This indicates the number of errors in socket receive operations, including errors of send operations on a connected UDP socket, notified by an ICMP error message.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">TCP4Clients</span></code>/<code class="docutils literal notranslate"><span class="pre">TCP6Clients</span></code></dt><dd><p>This indicates the number of IPv4/IPv6 clients currently connected over TCP.</p>
</dd>
</dl>
</section>
</section>
</section>
</section>
</div>
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