Bv9ARM.ch05.html revision 5d564da348e890e42f63eebf2dced9a05b41f4fb
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - Copyright (C) 2004-2015 Internet Systems Consortium, Inc. ("ISC")
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - Copyright (C) 2000-2003 Internet Software Consortium.
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - Permission to use, copy, modify, and/or distribute this software for any
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - purpose with or without fee is hereby granted, provided that the above
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - copyright notice and this permission notice appear in all copies.
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync - PERFORMANCE OF THIS SOFTWARE.
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<!-- $Id$ -->
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<title>Chapter�5.�The BIND 9 Lightweight Resolver</title>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<meta name="generator" content="DocBook XSL Stylesheets V1.71.1">
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<link rel="start" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual">
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<link rel="up" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual">
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<link rel="prev" href="Bv9ARM.ch04.html" title="Chapter�4.�Advanced DNS Features">
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<link rel="next" href="Bv9ARM.ch06.html" title="Chapter�6.�BIND 9 Configuration Reference">
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<tr><th colspan="3" align="center">Chapter�5.�The <acronym class="acronym">BIND</acronym> 9 Lightweight Resolver</th></tr>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<a accesskey="p" href="Bv9ARM.ch04.html">Prev</a>�</td>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<td width="20%" align="right">�<a accesskey="n" href="Bv9ARM.ch06.html">Next</a>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<a name="Bv9ARM.ch05"></a>Chapter�5.�The <acronym class="acronym">BIND</acronym> 9 Lightweight Resolver</h2></div></div></div>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<dt><span class="sect1"><a href="Bv9ARM.ch05.html#id2571844">The Lightweight Resolver Library</a></span></dt>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<dt><span class="sect1"><a href="Bv9ARM.ch05.html#lwresd">Running a Resolver Daemon</a></span></dt>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<div class="titlepage"><div><div><h2 class="title" style="clear: both">
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<a name="id2571844"></a>The Lightweight Resolver Library</h2></div></div></div>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync Traditionally applications have been linked with a stub resolver
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync library that sends recursive DNS queries to a local caching name
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync IPv6 once introduced new complexity into the resolution process,
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync such as following A6 chains and DNAME records, and simultaneous
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync lookup of IPv4 and IPv6 addresses. Though most of the complexity was
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync then removed, these are hard or impossible
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync to implement in a traditional stub resolver.
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync <acronym class="acronym">BIND</acronym> 9 therefore can also provide resolution
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync services to local clients
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync using a combination of a lightweight resolver library and a resolver
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync daemon process running on the local host. These communicate using
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync a simple UDP-based protocol, the "lightweight resolver protocol"
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync that is distinct from and simpler than the full DNS protocol.
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<div class="titlepage"><div><div><h2 class="title" style="clear: both">
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<a name="lwresd"></a>Running a Resolver Daemon</h2></div></div></div>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync To use the lightweight resolver interface, the system must
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync run the resolver daemon <span><strong class="command">lwresd</strong></span> or a
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync name server configured with a <span><strong class="command">lwres</strong></span>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync By default, applications using the lightweight resolver library will
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync UDP requests to the IPv4 loopback address (127.0.0.1) on port 921.
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync address can be overridden by <span><strong class="command">lwserver</strong></span>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync The daemon currently only looks in the DNS, but in the future
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync it may use other sources such as <code class="filename">/etc/hosts</code>,
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync The <span><strong class="command">lwresd</strong></span> daemon is essentially a
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync caching-only name server that responds to requests using the
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync lightweight
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync resolver protocol rather than the DNS protocol. Because it needs
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync to run on each host, it is designed to require no or minimal
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync configuration.
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync Unless configured otherwise, it uses the name servers listed on
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync <span><strong class="command">nameserver</strong></span> lines in <code class="filename">/etc/resolv.conf</code>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync as forwarders, but is also capable of doing the resolution
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync autonomously if
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync none are specified.
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync The <span><strong class="command">lwresd</strong></span> daemon may also be
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync configured with a
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync <code class="filename">named.conf</code> style configuration file,
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync <code class="filename">/etc/lwresd.conf</code> by default. A name
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync server may also
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync be configured to act as a lightweight resolver daemon using the
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync <span><strong class="command">lwres</strong></span> statement in <code class="filename">named.conf</code>.
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync The number of client queries that the <span><strong class="command">lwresd</strong></span>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync daemon is able to serve can be set using the
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync <code class="option">lwres-tasks</code> and <code class="option">lwres-clients</code>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync statements in the configuration.
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<a accesskey="p" href="Bv9ARM.ch04.html">Prev</a>�</td>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<td width="40%" align="right">�<a accesskey="n" href="Bv9ARM.ch06.html">Next</a>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<td width="40%" align="left" valign="top">Chapter�4.�Advanced DNS Features�</td>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<td width="40%" align="right" valign="top">�Chapter�6.�<acronym class="acronym">BIND</acronym> 9 Configuration Reference</td>
19a258565a4d24e5a0af62f626943ac9b898d957vboxsync<p style="text-align: center;">BIND 9.11.0pre-alpha</p>