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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 current"><a class="current reference internal" href="#">2. Resource Requirements</a><ul>
<li class="toctree-l2"><a class="reference internal" href="#hardware-requirements">2.1. Hardware Requirements</a></li>
<li class="toctree-l2"><a class="reference internal" href="#cpu-requirements">2.2. CPU Requirements</a></li>
<li class="toctree-l2"><a class="reference internal" href="#memory-requirements">2.3. Memory Requirements</a></li>
<li class="toctree-l2"><a class="reference internal" href="#name-server-intensive-environment-issues">2.4. Name Server-Intensive Environment Issues</a></li>
<li class="toctree-l2"><a class="reference internal" href="#supported-platforms">2.5. Supported Platforms</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#regularly-tested-platforms">2.5.1. Regularly Tested Platforms</a></li>
<li class="toctree-l3"><a class="reference internal" href="#best-effort">2.5.2. Best-Effort</a></li>
<li class="toctree-l3"><a class="reference internal" href="#community-maintained">2.5.3. Community-Maintained</a></li>
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<li class="toctree-l2"><a class="reference internal" href="#unsupported-platforms">2.6. Unsupported Platforms</a></li>
<li class="toctree-l2"><a class="reference internal" href="#installing-bind-9">2.7. Installing BIND 9</a></li>
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<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"><a class="reference internal" href="reference.html">8. Configuration Reference</a></li>
<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>
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<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>
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<section id="resource-requirements">
<span id="requirements"></span><h1><span class="section-number">2. </span>Resource Requirements<a class="headerlink" href="#resource-requirements" title="Link to this heading"></a></h1>
<section id="hardware-requirements">
<span id="hw-req"></span><h2><span class="section-number">2.1. </span>Hardware Requirements<a class="headerlink" href="#hardware-requirements" title="Link to this heading"></a></h2>
<p>DNS hardware requirements have traditionally been quite modest. For many
installations, servers that have been retired from active duty
have performed admirably as DNS servers.</p>
<p>However, the DNSSEC features of BIND 9 may be quite CPU-intensive,
so organizations that make heavy use of these features may wish
to consider larger systems for these applications. BIND 9 is fully
multithreaded, allowing full utilization of multiprocessor systems for
installations that need it.</p>
</section>
<section id="cpu-requirements">
<span id="cpu-req"></span><h2><span class="section-number">2.2. </span>CPU Requirements<a class="headerlink" href="#cpu-requirements" title="Link to this heading"></a></h2>
<p>CPU requirements for BIND 9 range from i386-class machines, for serving
static zones without caching, to enterprise-class machines
to process many dynamic updates and DNSSEC-signed zones, serving
many thousands of queries per second.</p>
</section>
<section id="memory-requirements">
<span id="mem-req"></span><h2><span class="section-number">2.3. </span>Memory Requirements<a class="headerlink" href="#memory-requirements" title="Link to this heading"></a></h2>
<p>Server memory must be sufficient to hold both the cache and the
zones loaded from disk. The <a class="reference internal" href="reference.html#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> option can
limit the amount of memory used by the cache, at the expense of reducing
cache hit rates and causing more DNS traffic. It is still good practice
to have enough memory to load all zone and cache data into memory;
unfortunately, the best way to determine this for a given installation
is to watch the name server in operation. After a few weeks, the server
process should reach a relatively stable size where entries are expiring
from the cache as fast as they are being inserted.</p>
</section>
<section id="name-server-intensive-environment-issues">
<span id="intensive-env"></span><h2><span class="section-number">2.4. </span>Name Server-Intensive Environment Issues<a class="headerlink" href="#name-server-intensive-environment-issues" title="Link to this heading"></a></h2>
<p>For name server-intensive environments, there are two
configurations that may be used. The first is one where clients and any
second-level internal name servers query the main name server, which has
enough memory to build a large cache; this approach minimizes the
bandwidth used by external name lookups. The second alternative is to
set up second-level internal name servers to make queries independently.
In this configuration, none of the individual machines need to have as
much memory or CPU power as in the first alternative, but this has the
disadvantage of making many more external queries, as none of the name
servers share their cached data.</p>
</section>
<section id="supported-platforms">
<span id="supported-os"></span><h2><span class="section-number">2.5. </span>Supported Platforms<a class="headerlink" href="#supported-platforms" title="Link to this heading"></a></h2>
<p>The current support status of BIND 9 versions across various platforms can be
found in the ISC Knowledgebase:</p>
<p><a class="reference external" href="https://kb.isc.org/docs/supported-platforms">https://kb.isc.org/docs/supported-platforms</a></p>
<p>In general, this version of BIND will build and run on any
POSIX-compliant system with a C11-compliant C compiler, BSD-style
sockets with RFC-compliant IPv6 support, POSIX-compliant threads, and
the <a class="reference internal" href="chapter10.html#build-dependencies"><span class="std std-ref">required libraries</span></a>.</p>
<p>The following C11 features are used in BIND 9:</p>
<ul class="simple">
<li><p>Atomic operations support, either in the form of C11 atomics or
<strong>__atomic</strong> builtin operations.</p></li>
<li><p>Thread Local Storage support, either in the form of C11
<strong>_Thread_local</strong>/<strong>thread_local</strong>, or the <strong>__thread</strong> GCC
extension.</p></li>
</ul>
<p>The C11 variants are preferred.</p>
<p>ISC regularly tests BIND on many operating systems and architectures,
but lacks the resources to test all of them. Consequently, ISC is only
able to offer support on a “best-effort” basis for some.</p>
<section id="regularly-tested-platforms">
<h3><span class="section-number">2.5.1. </span>Regularly Tested Platforms<a class="headerlink" href="#regularly-tested-platforms" title="Link to this heading"></a></h3>
<p>Current versions of BIND 9 are fully supported and regularly tested on the
following systems:</p>
<ul class="simple">
<li><p>Debian 12</p></li>
<li><p>Ubuntu LTS 22.04, 24.04</p></li>
<li><p>Fedora 42</p></li>
<li><p>Red Hat Enterprise Linux / CentOS / AlmaLinux 8, 9, 10</p></li>
<li><p>FreeBSD 13.4, 14.2</p></li>
<li><p>Alpine Linux 3.22</p></li>
</ul>
<p>The amd64 CPU architecture is fully supported and regularly tested.</p>
</section>
<section id="best-effort">
<h3><span class="section-number">2.5.2. </span>Best-Effort<a class="headerlink" href="#best-effort" title="Link to this heading"></a></h3>
<p>The following are platforms on which BIND is known to build and run. ISC
makes every effort to fix bugs on these platforms, but may be unable to
do so quickly due to lack of hardware, less familiarity on the part of
engineering staff, and other constraints. None of these are tested
regularly by ISC.</p>
<ul class="simple">
<li><p>macOS 10.12+</p></li>
<li><p>Solaris 11</p></li>
<li><p>NetBSD</p></li>
<li><p>OpenBSD</p></li>
<li><p>Other Linux distributions still supported by their vendors, such as:</p>
<ul>
<li><p>Ubuntu 20.10+</p></li>
<li><p>Gentoo</p></li>
<li><p>Arch Linux</p></li>
</ul>
</li>
<li><p>OpenWRT/LEDE 17.01+</p></li>
<li><p>Other CPU architectures (arm, arm64, mips64, ppc64, s390x)</p></li>
</ul>
</section>
<section id="community-maintained">
<h3><span class="section-number">2.5.3. </span>Community-Maintained<a class="headerlink" href="#community-maintained" title="Link to this heading"></a></h3>
<p>These systems may not all have the required dependencies for building
BIND easily available, although it is possible in many cases to
compile those directly from source. The community and interested parties
may wish to help with maintenance, and we welcome patch contributions,
although we cannot guarantee that we will accept them. All contributions
will be assessed against the risk of adverse effect on officially
supported platforms.</p>
<ul class="simple">
<li><p>Platforms past or close to their respective EOL dates, such as:</p>
<ul>
<li><p>Ubuntu 14.04, 16.04, 18.04, 20.04 (Ubuntu ESM releases are not supported)</p></li>
<li><p>CentOS 6</p></li>
<li><p>Debian 8 Jessie, 9 Stretch, 10 Buster, 11 Bullseye</p></li>
<li><p>Red Hat Enterprise Linux / CentOS / Oracle Linux 6, 7</p></li>
<li><p>Debian 8 Jessie, 9 Stretch, 10 Buster</p></li>
<li><p>FreeBSD 10.x, 11.x, 12.x</p></li>
</ul>
</li>
<li><p>Less common CPU architectures (i386, i686, mips, mipsel, sparc, ppc, and others)</p></li>
</ul>
</section>
</section>
<section id="unsupported-platforms">
<h2><span class="section-number">2.6. </span>Unsupported Platforms<a class="headerlink" href="#unsupported-platforms" title="Link to this heading"></a></h2>
<p>These are platforms on which current versions of BIND 9 are known <em>not</em> to build or run:</p>
<ul class="simple">
<li><p>Platforms without at least OpenSSL 1.0.2</p></li>
<li><p>Windows</p></li>
<li><p>Solaris 10 and older</p></li>
<li><p>Platforms that do not support IPv6 Advanced Socket API (RFC 3542)</p></li>
<li><p>Platforms that do not support atomic operations (via compiler or
library)</p></li>
<li><p>Linux without NPTL (Native POSIX Thread Library)</p></li>
<li><p>Platforms on which <strong>libuv</strong> cannot be compiled</p></li>
</ul>
</section>
<section id="installing-bind-9">
<h2><span class="section-number">2.7. </span>Installing BIND 9<a class="headerlink" href="#installing-bind-9" title="Link to this heading"></a></h2>
<p><a class="reference internal" href="chapter10.html#build-bind"><span class="std std-ref">Building BIND 9</span></a> contains complete instructions for how to build BIND 9.</p>
<p>The ISC <a class="reference external" href="https://kb.isc.org/">Knowledgebase</a> contains many useful articles about installing
BIND 9 on specific platforms.</p>
</section>
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