Bv9ARM.ch01.html revision 92554adb458c7b336e5390c5c9fbf2fcc1276524
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - Copyright (C) 2004-2007 Internet Systems Consortium, Inc. ("ISC")
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - Copyright (C) 2000-2003 Internet Software Consortium.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - Permission to use, copy, modify, and distribute this software for any
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - purpose with or without fee is hereby granted, provided that the above
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - copyright notice and this permission notice appear in all copies.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster - PERFORMANCE OF THIS SOFTWARE.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<!-- $Id: Bv9ARM.ch01.html,v 1.38 2007/11/26 01:35:18 marka Exp $ -->
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8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<link rel="next" href="Bv9ARM.ch02.html" title="Chapter�2.�BIND Resource Requirements">
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8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<table width="100%" summary="Navigation header">
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<tr><th colspan="3" align="center">Chapter�1.�Introduction</th></tr>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<a accesskey="p" href="Bv9ARM.html">Prev</a>�</td>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<td width="20%" align="right">�<a accesskey="n" href="Bv9ARM.ch02.html">Next</a>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<div class="titlepage"><div><div><h2 class="title">
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<a name="Bv9ARM.ch01"></a>Chapter�1.�Introduction</h2></div></div></div>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<dt><span class="sect1"><a href="Bv9ARM.ch01.html#id2564106">Scope of Document</a></span></dt>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<dt><span class="sect1"><a href="Bv9ARM.ch01.html#id2564130">Organization of This Document</a></span></dt>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<dt><span class="sect1"><a href="Bv9ARM.ch01.html#id2563470">Conventions Used in This Document</a></span></dt>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<dt><span class="sect1"><a href="Bv9ARM.ch01.html#id2564812">The Domain Name System (<acronym class="acronym">DNS</acronym>)</a></span></dt>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<dt><span class="sect2"><a href="Bv9ARM.ch01.html#id2564834">DNS Fundamentals</a></span></dt>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<dt><span class="sect2"><a href="Bv9ARM.ch01.html#id2564868">Domains and Domain Names</a></span></dt>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<dt><span class="sect2"><a href="Bv9ARM.ch01.html#id2567205">Zones</a></span></dt>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<dt><span class="sect2"><a href="Bv9ARM.ch01.html#id2567282">Authoritative Name Servers</a></span></dt>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<dt><span class="sect2"><a href="Bv9ARM.ch01.html#id2567523">Caching Name Servers</a></span></dt>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<dt><span class="sect2"><a href="Bv9ARM.ch01.html#id2567585">Name Servers in Multiple Roles</a></span></dt>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster The Internet Domain Name System (<acronym class="acronym">DNS</acronym>)
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster consists of the syntax
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster to specify the names of entities in the Internet in a hierarchical
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster manner, the rules used for delegating authority over names, and the
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster system implementation that actually maps names to Internet
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster addresses. <acronym class="acronym">DNS</acronym> data is maintained in a
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster group of distributed
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster hierarchical databases.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<div class="titlepage"><div><div><h2 class="title" style="clear: both">
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<a name="id2564106"></a>Scope of Document</h2></div></div></div>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster The Berkeley Internet Name Domain
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster (<acronym class="acronym">BIND</acronym>) implements a
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster domain name server for a number of operating systems. This
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster document provides basic information about the installation and
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster care of the Internet Systems Consortium (<acronym class="acronym">ISC</acronym>)
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <acronym class="acronym">BIND</acronym> version 9 software package for
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster system administrators.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster This version of the manual corresponds to BIND version 9.4.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<div class="titlepage"><div><div><h2 class="title" style="clear: both">
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<a name="id2564130"></a>Organization of This Document</h2></div></div></div>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster In this document, <span class="emphasis"><em>Section 1</em></span> introduces
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster the basic <acronym class="acronym">DNS</acronym> and <acronym class="acronym">BIND</acronym> concepts. <span class="emphasis"><em>Section 2</em></span>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster describes resource requirements for running <acronym class="acronym">BIND</acronym> in various
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster environments. Information in <span class="emphasis"><em>Section 3</em></span> is
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <span class="emphasis"><em>task-oriented</em></span> in its presentation and is
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster organized functionally, to aid in the process of installing the
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <acronym class="acronym">BIND</acronym> 9 software. The task-oriented
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster section is followed by
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <span class="emphasis"><em>Section 4</em></span>, which contains more advanced
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster concepts that the system administrator may need for implementing
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster certain options. <span class="emphasis"><em>Section 5</em></span>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster describes the <acronym class="acronym">BIND</acronym> 9 lightweight
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster resolver. The contents of <span class="emphasis"><em>Section 6</em></span> are
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster organized as in a reference manual to aid in the ongoing
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster maintenance of the software. <span class="emphasis"><em>Section 7</em></span> addresses
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster security considerations, and
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <span class="emphasis"><em>Section 8</em></span> contains troubleshooting help. The
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster main body of the document is followed by several
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <span class="emphasis"><em>appendices</em></span> which contain useful reference
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster information, such as a <span class="emphasis"><em>bibliography</em></span> and
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster historic information related to <acronym class="acronym">BIND</acronym>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster and the Domain Name
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<div class="titlepage"><div><div><h2 class="title" style="clear: both">
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<a name="id2563470"></a>Conventions Used in This Document</h2></div></div></div>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster In this document, we use the following general typographic
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster conventions:
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <span class="emphasis"><em>To describe:</em></span>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <span class="emphasis"><em>We use the style:</em></span>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster a pathname, filename, URL, hostname,
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster mailing list name, or new term or concept
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster literal user
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <strong class="userinput"><code>Fixed Width Bold</code></strong>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster program output
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <code class="computeroutput">Fixed Width</code>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster The following conventions are used in descriptions of the
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <acronym class="acronym">BIND</acronym> configuration file:</p>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <span class="emphasis"><em>To describe:</em></span>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <span class="emphasis"><em>We use the style:</em></span>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster Optional input
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster [<span class="optional">Text is enclosed in square brackets</span>]
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<div class="titlepage"><div><div><h2 class="title" style="clear: both">
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<a name="id2564812"></a>The Domain Name System (<acronym class="acronym">DNS</acronym>)</h2></div></div></div>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster The purpose of this document is to explain the installation
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster and upkeep of the <acronym class="acronym">BIND</acronym> (Berkeley Internet
bee2440354b4bc8796e1de0b6cbd60e1f68deba0Phill Cunnington Name Domain) software package, and we
bee2440354b4bc8796e1de0b6cbd60e1f68deba0Phill Cunnington begin by reviewing the fundamentals of the Domain Name System
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster (<acronym class="acronym">DNS</acronym>) as they relate to <acronym class="acronym">BIND</acronym>.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<div class="titlepage"><div><div><h3 class="title">
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<a name="id2564834"></a>DNS Fundamentals</h3></div></div></div>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster The Domain Name System (DNS) is a hierarchical, distributed
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster database. It stores information for mapping Internet host names to
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster addresses and vice versa, mail routing information, and other data
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster used by Internet applications.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster Clients look up information in the DNS by calling a
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <span class="emphasis"><em>resolver</em></span> library, which sends queries to one or
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster more <span class="emphasis"><em>name servers</em></span> and interprets the responses.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster The <acronym class="acronym">BIND</acronym> 9 software distribution
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster name server, <span><strong class="command">named</strong></span>, and two resolver
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster libraries, <span><strong class="command">liblwres</strong></span> and <span><strong class="command">libbind</strong></span>.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<div class="titlepage"><div><div><h3 class="title">
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster<a name="id2564868"></a>Domains and Domain Names</h3></div></div></div>
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster The data stored in the DNS is identified by <span class="emphasis"><em>domain names</em></span> that are organized as a tree according to
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster organizational or administrative boundaries. Each node of the tree,
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster called a <span class="emphasis"><em>domain</em></span>, is given a label. The domain
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster node is the concatenation of all the labels on the path from the
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster node to the <span class="emphasis"><em>root</em></span> node. This is represented
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster in written form as a string of labels listed from right to left and
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster separated by dots. A label need only be unique within its parent
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster For example, a domain name for a host at the
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster company <span class="emphasis"><em>Example, Inc.</em></span> could be
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <code class="literal">ourhost.example.com</code>,
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster top level domain to which
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <code class="literal">ourhost.example.com</code> belongs,
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster a subdomain of <code class="literal">com</code>, and
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster name of the host.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster For administrative purposes, the name space is partitioned into
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster areas called <span class="emphasis"><em>zones</em></span>, each starting at a node and
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster extending down to the leaf nodes or to nodes where other zones
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster The data for each zone is stored in a <span class="emphasis"><em>name server</em></span>, which answers queries about the zone using the
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <span class="emphasis"><em>DNS protocol</em></span>.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster The data associated with each domain name is stored in the
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster form of <span class="emphasis"><em>resource records</em></span> (<acronym class="acronym">RR</acronym>s).
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster Some of the supported resource record types are described in
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster <a href="Bv9ARM.ch06.html#types_of_resource_records_and_when_to_use_them" title="Types of Resource Records and When to Use Them">the section called “Types of Resource Records and When to Use Them”</a>.
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster For more detailed information about the design of the DNS and
8af80418ba1ec431c8027fa9668e5678658d3611Allan Foster the DNS protocol, please refer to the standards documents listed in
<a href="Bv9ARM.ch09.html#rfcs" title="Request for Comments (RFCs)">the section called “Request for Comments (RFCs)”</a>.
<span><strong class="command">dig</strong></span> (<a href="Bv9ARM.ch03.html#diagnostic_tools" title="Diagnostic Tools">the section called “Diagnostic Tools”</a>).
at the <span class="emphasis"><em>top level</em></span> or <span class="emphasis"><em>apex</em></span>
that can do it, and that server would query the Internet <acronym class="acronym">DNS</acronym> servers