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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-05 18:37:14 +0000
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Adding upstream version 1:9.11.5.P4+dfsg.upstream/1%9.11.5.P4+dfsgupstream
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+<html lang="en">
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
+<title>Chapter 6. BIND 9 Configuration Reference</title>
+<meta name="generator" content="DocBook XSL Stylesheets V1.78.1">
+<link rel="home" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual">
+<link rel="up" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual">
+<link rel="prev" href="Bv9ARM.ch05.html" title="Chapter 5. The BIND 9 Lightweight Resolver">
+<link rel="next" href="Bv9ARM.ch07.html" title="Chapter 7. BIND 9 Security Considerations">
+</head>
+<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
+<div class="navheader">
+<table width="100%" summary="Navigation header">
+<tr><th colspan="3" align="center">Chapter 6. <acronym class="acronym">BIND</acronym> 9 Configuration Reference</th></tr>
+<tr>
+<td width="20%" align="left">
+<a accesskey="p" href="Bv9ARM.ch05.html">Prev</a> </td>
+<th width="60%" align="center"> </th>
+<td width="20%" align="right"> <a accesskey="n" href="Bv9ARM.ch07.html">Next</a>
+</td>
+</tr>
+</table>
+<hr>
+</div>
+<div class="chapter">
+<div class="titlepage"><div><div><h1 class="title">
+<a name="Bv9ARM.ch06"></a>Chapter 6. <acronym class="acronym">BIND</acronym> 9 Configuration Reference</h1></div></div></div>
+<div class="toc">
+<p><b>Table of Contents</b></p>
+<dl class="toc">
+<dt><span class="section"><a href="Bv9ARM.ch06.html#configuration_file_elements">Configuration File Elements</a></span></dt>
+<dd><dl>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#address_match_lists">Address Match Lists</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#comment_syntax">Comment Syntax</a></span></dt>
+</dl></dd>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#Configuration_File_Grammar">Configuration File Grammar</a></span></dt>
+<dd><dl>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#acl_grammar"><span class="command"><strong>acl</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#acl"><span class="command"><strong>acl</strong></span> Statement Definition and
+ Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#controls_grammar"><span class="command"><strong>controls</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#controls_statement_definition_and_usage"><span class="command"><strong>controls</strong></span> Statement Definition and
+ Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#include_grammar"><span class="command"><strong>include</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#include_statement"><span class="command"><strong>include</strong></span> Statement Definition and Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#key_grammar"><span class="command"><strong>key</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#key_statement"><span class="command"><strong>key</strong></span> Statement Definition and Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#logging_grammar"><span class="command"><strong>logging</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#logging_statement"><span class="command"><strong>logging</strong></span> Statement Definition and Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#lwres_grammar"><span class="command"><strong>lwres</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#lwres_statement"><span class="command"><strong>lwres</strong></span> Statement Definition and Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#masters_grammar"><span class="command"><strong>masters</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#masters_statement"><span class="command"><strong>masters</strong></span> Statement Definition and
+ Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#options_grammar"><span class="command"><strong>options</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#options"><span class="command"><strong>options</strong></span> Statement Definition and
+ Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#server_statement_grammar"><span class="command"><strong>server</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#server_statement_definition_and_usage"><span class="command"><strong>server</strong></span> Statement Definition and
+ Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#statschannels"><span class="command"><strong>statistics-channels</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#statistics_channels"><span class="command"><strong>statistics-channels</strong></span> Statement Definition and
+ Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#trusted-keys"><span class="command"><strong>trusted-keys</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#trusted_keys"><span class="command"><strong>trusted-keys</strong></span> Statement Definition
+ and Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#managed_keys"><span class="command"><strong>managed-keys</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#managed-keys"><span class="command"><strong>managed-keys</strong></span> Statement Definition
+ and Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#view_statement_grammar"><span class="command"><strong>view</strong></span> Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#view_statement"><span class="command"><strong>view</strong></span> Statement Definition and Usage</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#zone_statement_grammar"><span class="command"><strong>zone</strong></span>
+ Statement Grammar</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#zone_statement"><span class="command"><strong>zone</strong></span> Statement Definition and Usage</a></span></dt>
+</dl></dd>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#zone_file">Zone File</a></span></dt>
+<dd><dl>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#types_of_resource_records_and_when_to_use_them">Types of Resource Records and When to Use Them</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#mx_records">Discussion of MX Records</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#Setting_TTLs">Setting TTLs</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#ipv4_reverse">Inverse Mapping in IPv4</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#zone_directives">Other Zone File Directives</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#generate_directive"><acronym class="acronym">BIND</acronym> Master File Extension: the <span class="command"><strong>$GENERATE</strong></span> Directive</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#zonefile_format">Additional File Formats</a></span></dt>
+</dl></dd>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#statistics">BIND9 Statistics</a></span></dt>
+<dd><dl>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#statsfile">The Statistics File</a></span></dt>
+<dt><span class="section"><a href="Bv9ARM.ch06.html#statistics_counters">Statistics Counters</a></span></dt>
+</dl></dd>
+</dl>
+</div>
+
+ <p>
+ <acronym class="acronym">BIND</acronym> 9 configuration is broadly similar
+ to <acronym class="acronym">BIND</acronym> 8; however, there are a few new
+ areas
+ of configuration, such as views. <acronym class="acronym">BIND</acronym>
+ 8 configuration files should work with few alterations in <acronym class="acronym">BIND</acronym>
+ 9, although more complex configurations should be reviewed to check
+ if they can be more efficiently implemented using the new features
+ found in <acronym class="acronym">BIND</acronym> 9.
+ </p>
+
+ <p>
+ <acronym class="acronym">BIND</acronym> 4 configuration files can be
+ converted to the new format
+ using the shell script
+ <code class="filename">contrib/named-bootconf/named-bootconf.sh</code>.
+ </p>
+ <div class="section">
+<div class="titlepage"><div><div><h2 class="title" style="clear: both">
+<a name="configuration_file_elements"></a>Configuration File Elements</h2></div></div></div>
+
+ <p>
+ Following is a list of elements used throughout the <acronym class="acronym">BIND</acronym> configuration
+ file documentation:
+ </p>
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.855in" class="1">
+<col width="3.770in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ <code class="varname">acl_name</code>
+ </p>
+ </td>
+<td>
+ <p>
+ The name of an <code class="varname">address_match_list</code> as
+ defined by the <span class="command"><strong>acl</strong></span> statement.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">address_match_list</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A list of one or more
+ <code class="varname">ip_addr</code>,
+ <code class="varname">ip_prefix</code>, <code class="varname">key_id</code>,
+ or <code class="varname">acl_name</code> elements, see
+ <a class="xref" href="Bv9ARM.ch06.html#address_match_lists" title="Address Match Lists">the section called &#8220;Address Match Lists&#8221;</a>.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">masters_list</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A named list of one or more <code class="varname">ip_addr</code>
+ with optional <code class="varname">key_id</code> and/or
+ <code class="varname">ip_port</code>.
+ A <code class="varname">masters_list</code> may include other
+ <code class="varname">masters_lists</code>.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">domain_name</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A quoted string which will be used as
+ a DNS name, for example "<code class="literal">my.test.domain</code>".
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">namelist</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A list of one or more <code class="varname">domain_name</code>
+ elements.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">dotted_decimal</code>
+ </p>
+ </td>
+<td>
+ <p>
+ One to four integers valued 0 through
+ 255 separated by dots (`.'), such as <span class="command"><strong>123</strong></span>,
+ <span class="command"><strong>45.67</strong></span> or <span class="command"><strong>89.123.45.67</strong></span>.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">ip4_addr</code>
+ </p>
+ </td>
+<td>
+ <p>
+ An IPv4 address with exactly four elements
+ in <code class="varname">dotted_decimal</code> notation.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">ip6_addr</code>
+ </p>
+ </td>
+<td>
+ <p>
+ An IPv6 address, such as <span class="command"><strong>2001:db8::1234</strong></span>.
+ IPv6 scoped addresses that have ambiguity on their
+ scope zones must be disambiguated by an appropriate
+ zone ID with the percent character (`%') as
+ delimiter. It is strongly recommended to use
+ string zone names rather than numeric identifiers,
+ in order to be robust against system configuration
+ changes. However, since there is no standard
+ mapping for such names and identifier values,
+ currently only interface names as link identifiers
+ are supported, assuming one-to-one mapping between
+ interfaces and links. For example, a link-local
+ address <span class="command"><strong>fe80::1</strong></span> on the link
+ attached to the interface <span class="command"><strong>ne0</strong></span>
+ can be specified as <span class="command"><strong>fe80::1%ne0</strong></span>.
+ Note that on most systems link-local addresses
+ always have the ambiguity, and need to be
+ disambiguated.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">ip_addr</code>
+ </p>
+ </td>
+<td>
+ <p>
+ An <code class="varname">ip4_addr</code> or <code class="varname">ip6_addr</code>.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">ip_dscp</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A <code class="varname">number</code> between 0 and 63, used
+ to select a differentiated services code point (DSCP)
+ value for use with outgoing traffic on operating systems
+ that support DSCP.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">ip_port</code>
+ </p>
+ </td>
+<td>
+ <p>
+ An IP port <code class="varname">number</code>.
+ The <code class="varname">number</code> is limited to 0
+ through 65535, with values
+ below 1024 typically restricted to use by processes running
+ as root.
+ In some cases, an asterisk (`*') character can be used as a
+ placeholder to
+ select a random high-numbered port.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">ip_prefix</code>
+ </p>
+ </td>
+<td>
+ <p>
+ An IP network specified as an <code class="varname">ip_addr</code>,
+ followed by a slash (`/') and then the number of bits in the
+ netmask.
+ Trailing zeros in a <code class="varname">ip_addr</code>
+ may omitted.
+ For example, <span class="command"><strong>127/8</strong></span> is the
+ network <span class="command"><strong>127.0.0.0</strong></span> with
+ netmask <span class="command"><strong>255.0.0.0</strong></span> and <span class="command"><strong>1.2.3.0/28</strong></span> is
+ network <span class="command"><strong>1.2.3.0</strong></span> with netmask <span class="command"><strong>255.255.255.240</strong></span>.
+ </p>
+ <p>
+ When specifying a prefix involving a IPv6 scoped address
+ the scope may be omitted. In that case the prefix will
+ match packets from any scope.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">key_id</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A <code class="varname">domain_name</code> representing
+ the name of a shared key, to be used for transaction
+ security.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">key_list</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A list of one or more
+ <code class="varname">key_id</code>s,
+ separated by semicolons and ending with a semicolon.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">number</code>
+ </p>
+ </td>
+<td>
+ <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>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">fixedpoint</code>
+ </p>
+ </td>
+<td>
+ <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
+ context in which it is used.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">path_name</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A quoted string which will be used as
+ a pathname, such as <code class="filename">zones/master/my.test.domain</code>.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">port_list</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A list of an <code class="varname">ip_port</code> or a port
+ range.
+ A port range is specified in the form of
+ <strong class="userinput"><code>range</code></strong> followed by
+ two <code class="varname">ip_port</code>s,
+ <code class="varname">port_low</code> and
+ <code class="varname">port_high</code>, which represents
+ port numbers from <code class="varname">port_low</code> through
+ <code class="varname">port_high</code>, inclusive.
+ <code class="varname">port_low</code> must not be larger than
+ <code class="varname">port_high</code>.
+ For example,
+ <strong class="userinput"><code>range 1024 65535</code></strong> represents
+ ports from 1024 through 65535.
+ In either case an asterisk (`*') character is not
+ allowed as a valid <code class="varname">ip_port</code>.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">size_spec</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A 64-bit unsigned integer, or the keywords
+ <strong class="userinput"><code>unlimited</code></strong> or
+ <strong class="userinput"><code>default</code></strong>.
+ </p>
+ <p>
+ Integers may take values
+ 0 &lt;= value &lt;= 18446744073709551615, though
+ certain parameters
+ (such as <span class="command"><strong>max-journal-size</strong></span>) 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="varname">size_spec</code>
+ for details on how they interpret its use.
+ </p>
+ <p>
+ Numeric values can optionally be followed by a
+ scaling factor:
+ <strong class="userinput"><code>K</code></strong> or <strong class="userinput"><code>k</code></strong>
+ for kilobytes,
+ <strong class="userinput"><code>M</code></strong> or <strong class="userinput"><code>m</code></strong>
+ for megabytes, and
+ <strong class="userinput"><code>G</code></strong> or <strong class="userinput"><code>g</code></strong>
+ for gigabytes, which scale by 1024, 1024*1024, and
+ 1024*1024*1024 respectively.
+ </p>
+ <p>
+ <code class="varname">unlimited</code> generally means
+ "as big as possible", and is usually the best
+ way to safely set a very large number.
+ </p>
+ <p>
+ <code class="varname">default</code>
+ uses the limit that was in force when the server was started.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">size_or_percent</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="varname">size_spec</code> or integer value
+ followed by '%' to represent percents.
+ </p>
+ <p>
+ The behavior is exactly the same as
+ <code class="varname">size_spec</code>, but
+ <code class="varname">size_or_percent</code> allows also
+ to specify a positive integer value followed by
+ '%' sign to represent percents.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">yes_or_no</code>
+ </p>
+ </td>
+<td>
+ <p>
+ Either <strong class="userinput"><code>yes</code></strong> or <strong class="userinput"><code>no</code></strong>.
+ The words <strong class="userinput"><code>true</code></strong> and <strong class="userinput"><code>false</code></strong> are
+ also accepted, as are the numbers <strong class="userinput"><code>1</code></strong>
+ and <strong class="userinput"><code>0</code></strong>.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">dialup_option</code>
+ </p>
+ </td>
+<td>
+ <p>
+ One of <strong class="userinput"><code>yes</code></strong>,
+ <strong class="userinput"><code>no</code></strong>, <strong class="userinput"><code>notify</code></strong>,
+ <strong class="userinput"><code>notify-passive</code></strong>, <strong class="userinput"><code>refresh</code></strong> or
+ <strong class="userinput"><code>passive</code></strong>.
+ When used in a zone, <strong class="userinput"><code>notify-passive</code></strong>,
+ <strong class="userinput"><code>refresh</code></strong>, and <strong class="userinput"><code>passive</code></strong>
+ are restricted to slave and stub zones.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="address_match_lists"></a>Address Match Lists</h3></div></div></div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="id-1.7.4.4.2"></a>Syntax</h4></div></div></div>
+
+<pre class="programlisting"><em class="replaceable"><code>address_match_list</code></em> = <em class="replaceable"><code>address_match_list_element</code></em> <span class="command"><strong>;</strong></span> ...
+
+<em class="replaceable"><code>address_match_list_element</code></em> = [ <span class="command"><strong>!</strong></span> ] ( <em class="replaceable"><code>ip_address</code></em> | <em class="replaceable"><code>ip_prefix</code></em> |
+ <span class="command"><strong>key</strong></span> <em class="replaceable"><code>key_id</code></em> | <em class="replaceable"><code>acl_name</code></em> | <span class="command"><strong>{</strong></span> <em class="replaceable"><code>address_match_list</code></em> <span class="command"><strong>}</strong></span> )
+</pre>
+
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="id-1.7.4.4.3"></a>Definition and Usage</h4></div></div></div>
+
+ <p>
+ Address match lists are primarily used to determine access
+ control for various server operations. They are also used in
+ the <span class="command"><strong>listen-on</strong></span> and <span class="command"><strong>sortlist</strong></span>
+ statements. The elements which constitute an address match
+ list can be any of the following:
+ </p>
+ <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
+<li class="listitem">
+ an IP address (IPv4 or IPv6)
+ </li>
+<li class="listitem">
+ an IP prefix (in `/' notation)
+ </li>
+<li class="listitem">
+
+ a key ID, as defined by the <span class="command"><strong>key</strong></span>
+ statement
+
+ </li>
+<li class="listitem">
+ the name of an address match list defined with
+ the <span class="command"><strong>acl</strong></span> statement
+
+ </li>
+<li class="listitem">
+ a nested address match list enclosed in braces
+ </li>
+</ul></div>
+
+ <p>
+ Elements can be negated with a leading exclamation mark (`!'),
+ 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 acl 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 <span class="command"><strong>listen-on</strong></span> ports, or in a
+ <span class="command"><strong>sortlist</strong></span>, 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
+ <span class="command"><strong>allow-notify</strong></span>,
+ <span class="command"><strong>allow-recursion</strong></span>,
+ <span class="command"><strong>allow-recursion-on</strong></span>,
+ <span class="command"><strong>allow-query</strong></span>,
+ <span class="command"><strong>allow-query-on</strong></span>,
+ <span class="command"><strong>allow-query-cache</strong></span>,
+ <span class="command"><strong>allow-query-cache-on</strong></span>,
+ <span class="command"><strong>allow-transfer</strong></span>,
+ <span class="command"><strong>allow-update</strong></span>,
+ <span class="command"><strong>allow-update-forwarding</strong></span>,
+ <span class="command"><strong>blackhole</strong></span>, and
+ <span class="command"><strong>keep-response-order</strong></span> all use address match
+ lists. Similarly, the <span class="command"><strong>listen-on</strong></span> option will cause 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 will be given to the one that came
+ <span class="emphasis"><em>first</em></span> 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
+ <span class="command"><strong>1.2.3/24; ! 1.2.3.13;</strong></span>
+ the 1.2.3.13 element is completely useless because the
+ algorithm will match any lookup for 1.2.3.13 to the 1.2.3/24
+ element. Using <span class="command"><strong>! 1.2.3.13; 1.2.3/24</strong></span> fixes
+ that problem by having 1.2.3.13 blocked by the negation, but
+ all other 1.2.3.* hosts fall through.
+ </p>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="comment_syntax"></a>Comment Syntax</h3></div></div></div>
+
+ <p>
+ The <acronym class="acronym">BIND</acronym> 9 comment syntax allows for
+ comments to appear
+ anywhere that whitespace may appear in a <acronym class="acronym">BIND</acronym> configuration
+ file. To appeal to programmers of all kinds, they can be written
+ in the C, C++, or shell/perl style.
+ </p>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="id-1.7.4.5.3"></a>Syntax</h4></div></div></div>
+
+ <p>
+ </p>
+<pre class="programlisting">/* This is a <acronym class="acronym">BIND</acronym> comment as in C */</pre>
+<p>
+ </p>
+<pre class="programlisting">// This is a <acronym class="acronym">BIND</acronym> comment as in C++</pre>
+<p>
+ </p>
+<pre class="programlisting"># This is a <acronym class="acronym">BIND</acronym> comment as in common UNIX shells
+# and perl</pre>
+<p>
+ </p>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="id-1.7.4.5.4"></a>Definition and Usage</h4></div></div></div>
+
+ <p>
+ Comments may appear anywhere that whitespace may appear in
+ a <acronym class="acronym">BIND</acronym> 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>
+ <p>
+
+</p>
+<pre class="programlisting">/* 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>
+<p>
+
+ </p>
+
+ <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>
+ <p>
+
+</p>
+<pre class="programlisting">// 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>
+<p>
+
+ </p>
+ <p>
+ Shell-style (or perl-style, if you prefer) comments start
+ with the character <code class="literal">#</code> (number sign)
+ and continue to the end of the
+ physical line, as in C++ comments.
+ For example:
+ </p>
+
+ <p>
+
+</p>
+<pre class="programlisting"># 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>
+<p>
+
+ </p>
+
+ <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Warning</h3>
+ <p>
+ You cannot use the semicolon (`;') character
+ to start a comment such as you would in a zone file. The
+ semicolon indicates the end of a configuration
+ statement.
+ </p>
+ </div>
+ </div>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h2 class="title" style="clear: both">
+<a name="Configuration_File_Grammar"></a>Configuration File Grammar</h2></div></div></div>
+
+ <p>
+ A <acronym class="acronym">BIND</acronym> 9 configuration consists of
+ statements and comments.
+ Statements end with a semicolon. Statements and comments are the
+ only elements that can appear without enclosing braces. Many
+ statements contain a block of sub-statements, which are also
+ terminated with a semicolon.
+ </p>
+
+ <p>
+ The following statements are supported:
+ </p>
+
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.336in" class="1">
+<col width="3.778in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p><span class="command"><strong>acl</strong></span></p>
+ </td>
+<td>
+ <p>
+ defines a named IP address
+ matching list, for access control and other uses.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>controls</strong></span></p>
+ </td>
+<td>
+ <p>
+ declares control channels to be used
+ by the <span class="command"><strong>rndc</strong></span> utility.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>include</strong></span></p>
+ </td>
+<td>
+ <p>
+ includes a file.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>key</strong></span></p>
+ </td>
+<td>
+ <p>
+ specifies key information for use in
+ authentication and authorization using TSIG.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>logging</strong></span></p>
+ </td>
+<td>
+ <p>
+ specifies what the server logs, and where
+ the log messages are sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>lwres</strong></span></p>
+ </td>
+<td>
+ <p>
+ configures <span class="command"><strong>named</strong></span> to
+ also act as a light-weight resolver daemon (<span class="command"><strong>lwresd</strong></span>).
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>masters</strong></span></p>
+ </td>
+<td>
+ <p>
+ defines a named masters list for
+ inclusion in stub and slave zones'
+ <span class="command"><strong>masters</strong></span> or
+ <span class="command"><strong>also-notify</strong></span> lists.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>options</strong></span></p>
+ </td>
+<td>
+ <p>
+ controls global server configuration
+ options and sets defaults for other statements.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>server</strong></span></p>
+ </td>
+<td>
+ <p>
+ sets certain configuration options on
+ a per-server basis.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>statistics-channels</strong></span></p>
+ </td>
+<td>
+ <p>
+ declares communication channels to get access to
+ <span class="command"><strong>named</strong></span> statistics.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>trusted-keys</strong></span></p>
+ </td>
+<td>
+ <p>
+ defines trusted DNSSEC keys.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>managed-keys</strong></span></p>
+ </td>
+<td>
+ <p>
+ lists DNSSEC keys to be kept up to date
+ using RFC 5011 trust anchor maintenance.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>view</strong></span></p>
+ </td>
+<td>
+ <p>
+ defines a view.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>zone</strong></span></p>
+ </td>
+<td>
+ <p>
+ defines a zone.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+
+ <p>
+ The <span class="command"><strong>logging</strong></span> and
+ <span class="command"><strong>options</strong></span> statements may only occur once
+ per
+ configuration.
+ </p>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="acl_grammar"></a><span class="command"><strong>acl</strong></span> Statement Grammar</h3></div></div></div>
+ <pre class="programlisting">
+<span class="command"><strong>acl</strong></span> <em class="replaceable"><code>string</code></em> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+</pre>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="acl"></a><span class="command"><strong>acl</strong></span> Statement Definition and
+ Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>acl</strong></span> statement assigns a symbolic
+ name to an address match list. It gets its name from a primary
+ use of address match lists: Access Control Lists (ACLs).
+ </p>
+
+ <p>
+ The following ACLs are built-in:
+ </p>
+
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.130in" class="1">
+<col width="4.000in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p><span class="command"><strong>any</strong></span></p>
+ </td>
+<td>
+ <p>
+ Matches all hosts.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>none</strong></span></p>
+ </td>
+<td>
+ <p>
+ Matches no hosts.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>localhost</strong></span></p>
+ </td>
+<td>
+ <p>
+ Matches the IPv4 and IPv6 addresses of all network
+ interfaces on the system. When addresses are
+ added or removed, the <span class="command"><strong>localhost</strong></span>
+ ACL element is updated to reflect the changes.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>localnets</strong></span></p>
+ </td>
+<td>
+ <p>
+ Matches any host on an IPv4 or IPv6 network
+ for which the system has an interface.
+ When addresses are added or removed,
+ the <span class="command"><strong>localnets</strong></span>
+ 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 a case, <span class="command"><strong>localnets</strong></span>
+ only matches the local
+ IPv6 addresses, just like <span class="command"><strong>localhost</strong></span>.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="controls_grammar"></a><span class="command"><strong>controls</strong></span> Statement Grammar</h3></div></div></div>
+ <pre class="programlisting">
+<span class="command"><strong>controls</strong></span> {
+ <span class="command"><strong>inet</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | <em class="replaceable"><code>ipv6_address</code></em> |
+ * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] allow
+ { <em class="replaceable"><code>address_match_element</code></em>; ... } [
+ <span class="command"><strong>keys</strong></span> { <em class="replaceable"><code>string</code></em>; ... } ] [ read-only
+ <em class="replaceable"><code>boolean</code></em> ];
+ <span class="command"><strong>unix</strong></span> <em class="replaceable"><code>quoted_string</code></em> perm <em class="replaceable"><code>integer</code></em>
+ <span class="command"><strong>owner</strong></span> <em class="replaceable"><code>integer</code></em> group <em class="replaceable"><code>integer</code></em> [
+ <span class="command"><strong>keys</strong></span> { <em class="replaceable"><code>string</code></em>; ... } ] [ read-only
+ <em class="replaceable"><code>boolean</code></em> ];
+};
+</pre>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="controls_statement_definition_and_usage"></a><span class="command"><strong>controls</strong></span> Statement Definition and
+ Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>controls</strong></span> statement declares control
+ channels to be used by system administrators to control the
+ operation of the name server. These control channels are
+ used by the <span class="command"><strong>rndc</strong></span> utility to send
+ commands to and retrieve non-DNS results from a name server.
+ </p>
+
+ <p>
+ An <span class="command"><strong>inet</strong></span> control channel is a TCP socket
+ listening at the specified <span class="command"><strong>ip_port</strong></span> on the
+ specified <span class="command"><strong>ip_addr</strong></span>, which can be an IPv4 or IPv6
+ address. An <span class="command"><strong>ip_addr</strong></span> of <code class="literal">*</code> (asterisk) is
+ interpreted as the IPv4 wildcard address; connections will be
+ accepted on any of the system's IPv4 addresses.
+ To listen on the IPv6 wildcard address,
+ use an <span class="command"><strong>ip_addr</strong></span> of <code class="literal">::</code>.
+ If you will only use <span class="command"><strong>rndc</strong></span> on the local host,
+ using the loopback address (<code class="literal">127.0.0.1</code>
+ or <code class="literal">::1</code>) is recommended for maximum security.
+ </p>
+
+ <p>
+ If no port is specified, port 953 is used. The asterisk
+ "<code class="literal">*</code>" cannot be used for <span class="command"><strong>ip_port</strong></span>.
+ </p>
+
+ <p>
+ The ability to issue commands over the control channel is
+ restricted by the <span class="command"><strong>allow</strong></span> and
+ <span class="command"><strong>keys</strong></span> clauses.
+ Connections to the control channel are permitted based on the
+ <span class="command"><strong>address_match_list</strong></span>. This is for simple
+ IP address based filtering only; any <span class="command"><strong>key_id</strong></span>
+ elements of the <span class="command"><strong>address_match_list</strong></span>
+ are ignored.
+ </p>
+
+ <p>
+ A <span class="command"><strong>unix</strong></span> control channel is a UNIX domain
+ socket listening at the specified path in the file system.
+ Access to the socket is specified by the <span class="command"><strong>perm</strong></span>,
+ <span class="command"><strong>owner</strong></span> and <span class="command"><strong>group</strong></span> clauses.
+ Note on some platforms (SunOS and Solaris) the permissions
+ (<span class="command"><strong>perm</strong></span>) are applied to the parent directory
+ as the permissions on the socket itself are ignored.
+ </p>
+
+ <p>
+ The primary authorization mechanism of the command
+ channel is the <span class="command"><strong>key_list</strong></span>, which
+ contains a list of <span class="command"><strong>key_id</strong></span>s.
+ Each <span class="command"><strong>key_id</strong></span> in the <span class="command"><strong>key_list</strong></span>
+ is authorized to execute commands over the control channel.
+ See <a class="xref" href="Bv9ARM.ch03.html#rndc">Remote Name Daemon Control application</a> in <a class="xref" href="Bv9ARM.ch03.html#admin_tools" title="Administrative Tools">the section called &#8220;Administrative Tools&#8221;</a>)
+ for information about configuring keys in <span class="command"><strong>rndc</strong></span>.
+ </p>
+
+ <p>
+ If the <span class="command"><strong>read-only</strong></span> clause is enabled, the
+ control channel is limited to the following set of read-only
+ commands: <span class="command"><strong>nta -dump</strong></span>,
+ <span class="command"><strong>null</strong></span>, <span class="command"><strong>status</strong></span>,
+ <span class="command"><strong>showzone</strong></span>, <span class="command"><strong>testgen</strong></span>, and
+ <span class="command"><strong>zonestatus</strong></span>. By default,
+ <span class="command"><strong>read-only</strong></span> is not enabled and the control
+ channel allows read-write access.
+ </p>
+
+ <p>
+ If no <span class="command"><strong>controls</strong></span> statement is present,
+ <span class="command"><strong>named</strong></span> will set 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 <span class="command"><strong>controls</strong></span> statement
+ is present but does not have a <span class="command"><strong>keys</strong></span> clause,
+ <span class="command"><strong>named</strong></span> will attempt to load the command channel key
+ from the file <code class="filename">rndc.key</code> in
+ <code class="filename">/etc</code> (or whatever <code class="varname">sysconfdir</code>
+ was specified as when <acronym class="acronym">BIND</acronym> was built).
+ To create a <code class="filename">rndc.key</code> file, run
+ <strong class="userinput"><code>rndc-confgen -a</code></strong>.
+ </p>
+
+ <p>
+ The <code class="filename">rndc.key</code> feature was created to
+ ease the transition of systems from <acronym class="acronym">BIND</acronym> 8,
+ which did not have digital signatures on its command channel
+ messages and thus did not have a <span class="command"><strong>keys</strong></span> clause.
+
+ It makes it possible to use an existing <acronym class="acronym">BIND</acronym> 8
+ configuration file in <acronym class="acronym">BIND</acronym> 9 unchanged,
+ and still have <span class="command"><strong>rndc</strong></span> work the same way
+ <span class="command"><strong>ndc</strong></span> worked in BIND 8, simply by executing the
+ command <strong class="userinput"><code>rndc-confgen -a</code></strong> after BIND 9 is
+ installed.
+ </p>
+
+ <p>
+ Since the <code class="filename">rndc.key</code> feature
+ is only intended to allow the backward-compatible usage of
+ <acronym class="acronym">BIND</acronym> 8 configuration files, this
+ feature does not
+ have a high degree of configurability. You cannot easily change
+ the key name or the size of the secret, so you should make a
+ <code class="filename">rndc.conf</code> with your own key if you
+ wish to change
+ those things. The <code class="filename">rndc.key</code> file
+ also has its
+ permissions set such that only the owner of the file (the user that
+ <span class="command"><strong>named</strong></span> is running as) can access it.
+ If you
+ desire greater flexibility in allowing other users to access
+ <span class="command"><strong>rndc</strong></span> commands, then you need to create
+ a
+ <code class="filename">rndc.conf</code> file and make it group
+ readable by a group
+ that contains the users who should have access.
+ </p>
+
+ <p>
+ To disable the command channel, use an empty
+ <span class="command"><strong>controls</strong></span> statement:
+ <span class="command"><strong>controls { };</strong></span>.
+ </p>
+
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="include_grammar"></a><span class="command"><strong>include</strong></span> Statement Grammar</h3></div></div></div>
+
+ <pre class="programlisting"><span class="command"><strong>include</strong></span> <em class="replaceable"><code>filename</code></em><span class="command"><strong>;</strong></span></pre>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="include_statement"></a><span class="command"><strong>include</strong></span> Statement Definition and Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>include</strong></span> statement inserts the
+ specified file at the point where the <span class="command"><strong>include</strong></span>
+ statement is encountered. The <span class="command"><strong>include</strong></span>
+ statement 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>
+
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="key_grammar"></a><span class="command"><strong>key</strong></span> Statement Grammar</h3></div></div></div>
+ <pre class="programlisting">
+<span class="command"><strong>key</strong></span> <em class="replaceable"><code>string</code></em> {
+ <span class="command"><strong>algorithm</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>secret</strong></span> <em class="replaceable"><code>string</code></em>;
+};
+</pre>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="key_statement"></a><span class="command"><strong>key</strong></span> Statement Definition and Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>key</strong></span> statement defines a shared
+ secret key for use with TSIG (see <a class="xref" href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called &#8220;TSIG&#8221;</a>)
+ or the command channel
+ (see <a class="xref" href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and Usage">the section called &#8220;<span class="command"><strong>controls</strong></span> Statement Definition and
+ Usage&#8221;</a>).
+ </p>
+
+ <p>
+ The <span class="command"><strong>key</strong></span> statement can occur at the
+ top level
+ of the configuration file or inside a <span class="command"><strong>view</strong></span>
+ statement. Keys defined in top-level <span class="command"><strong>key</strong></span>
+ statements can be used in all views. Keys intended for use in
+ a <span class="command"><strong>controls</strong></span> statement
+ (see <a class="xref" href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and Usage">the section called &#8220;<span class="command"><strong>controls</strong></span> Statement Definition and
+ Usage&#8221;</a>)
+ must be defined at the top level.
+ </p>
+
+ <p>
+ The <em class="replaceable"><code>key_id</code></em>, also known as the
+ key name, is a domain name uniquely identifying the key. It can
+ be used in a <span class="command"><strong>server</strong></span>
+ 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>
+
+ <p>
+ The <em class="replaceable"><code>algorithm_id</code></em> is a string
+ that specifies a security/authentication algorithm. The
+ <span class="command"><strong>named</strong></span> server supports <code class="literal">hmac-md5</code>,
+ <code class="literal">hmac-sha1</code>, <code class="literal">hmac-sha224</code>,
+ <code class="literal">hmac-sha256</code>, <code class="literal">hmac-sha384</code>
+ and <code class="literal">hmac-sha512</code> TSIG authentication.
+ Truncated hashes are supported by appending the minimum
+ number of required bits preceded by a dash, e.g.
+ <code class="literal">hmac-sha1-80</code>. The
+ <em class="replaceable"><code>secret_string</code></em> is the secret
+ to be used by the algorithm, and is treated as a Base64
+ encoded string.
+ </p>
+
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="logging_grammar"></a><span class="command"><strong>logging</strong></span> Statement Grammar</h3></div></div></div>
+ <pre class="programlisting">
+<span class="command"><strong>logging</strong></span> {
+ <span class="command"><strong>category</strong></span> <em class="replaceable"><code>string</code></em> { <em class="replaceable"><code>string</code></em>; ... };
+ <span class="command"><strong>channel</strong></span> <em class="replaceable"><code>string</code></em> {
+ <span class="command"><strong>buffered</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>file</strong></span> <em class="replaceable"><code>quoted_string</code></em> [ versions ( "unlimited" | <em class="replaceable"><code>integer</code></em> )
+ ] [ size <em class="replaceable"><code>size</code></em> ];
+ <span class="command"><strong>null</strong></span>;
+ <span class="command"><strong>print-category</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>print-severity</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>print-time</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>severity</strong></span> <em class="replaceable"><code>log_severity</code></em>;
+ <span class="command"><strong>stderr</strong></span>;
+ <span class="command"><strong>syslog</strong></span> [ <em class="replaceable"><code>syslog_facility</code></em> ];
+ };
+};
+</pre>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="logging_statement"></a><span class="command"><strong>logging</strong></span> Statement Definition and Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>logging</strong></span> statement configures a
+ wide
+ variety of logging options for the name server. Its <span class="command"><strong>channel</strong></span> phrase
+ associates output methods, format options and severity levels with
+ a name that can then be used with the <span class="command"><strong>category</strong></span> phrase
+ to select how various classes of messages are logged.
+ </p>
+ <p>
+ Only one <span class="command"><strong>logging</strong></span> statement is used to
+ define
+ as many channels and categories as are wanted. If there is no <span class="command"><strong>logging</strong></span> statement,
+ the logging configuration will be:
+ </p>
+
+<pre class="programlisting">logging {
+ category default { default_syslog; default_debug; };
+ category unmatched { null; };
+};
+</pre>
+
+ <p>
+ If <span class="command"><strong>named</strong></span> is started with the
+ <code class="option">-L</code> option, it logs to the specified file
+ at startup, instead of using syslog. In this case the logging
+ configuration will be:
+ </p>
+
+<pre class="programlisting">logging {
+ category default { default_logfile; default_debug; };
+ category unmatched { null; };
+};
+</pre>
+
+ <p>
+ In <acronym class="acronym">BIND</acronym> 9, the logging configuration
+ is only established when
+ the entire configuration file has been parsed. In <acronym class="acronym">BIND</acronym> 8, it was
+ established as soon as the <span class="command"><strong>logging</strong></span>
+ statement
+ was parsed. When the server is starting up, all logging messages
+ regarding syntax errors in the configuration file go to the default
+ channels, or to standard error if the <code class="option">-g</code> option
+ was specified.
+ </p>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="channel"></a>The <span class="command"><strong>channel</strong></span> Phrase</h4></div></div></div>
+
+ <p>
+ All log output goes to one or more <span class="emphasis"><em>channels</em></span>;
+ you can make as many of them as you want.
+ </p>
+
+ <p>
+ Every channel definition must include a destination clause that
+ says whether messages selected for the channel go to a file, to a
+ particular syslog facility, to the standard error stream, or are
+ discarded. It can optionally also limit the message severity level
+ that will be accepted by the channel (the default is
+ <span class="command"><strong>info</strong></span>), and whether to include a
+ <span class="command"><strong>named</strong></span>-generated time stamp, the
+ category name
+ and/or severity level (the default is not to include any).
+ </p>
+
+ <p>
+ The <span class="command"><strong>null</strong></span> destination clause
+ causes all messages sent to the channel to be discarded;
+ in that case, other options for the channel are meaningless.
+ </p>
+
+ <p>
+ The <span class="command"><strong>file</strong></span> destination clause directs
+ the channel
+ to a disk file. It can include limitations
+ both on how large the file is allowed to become, and how many
+ versions
+ of the file will be saved each time the file is opened.
+ </p>
+
+ <p>
+ If you use the <span class="command"><strong>versions</strong></span> log file
+ option, then
+ <span class="command"><strong>named</strong></span> will retain that many backup
+ versions of the file by
+ renaming them when opening. For example, if you choose to keep
+ three old versions
+ of the file <code class="filename">lamers.log</code>, then just
+ before it is opened
+ <code class="filename">lamers.log.1</code> is renamed to
+ <code class="filename">lamers.log.2</code>, <code class="filename">lamers.log.0</code> is renamed
+ to <code class="filename">lamers.log.1</code>, and <code class="filename">lamers.log</code> is
+ renamed to <code class="filename">lamers.log.0</code>.
+ You can say <span class="command"><strong>versions unlimited</strong></span> to
+ not limit
+ the number of versions.
+ If a <span class="command"><strong>size</strong></span> option is associated with
+ the log file,
+ then renaming is only done when the file being opened exceeds the
+ indicated size. No backup versions are kept by default; any
+ existing
+ log file is simply appended.
+ </p>
+
+ <p>
+ The <span class="command"><strong>size</strong></span> option for files is used
+ to limit log
+ growth. If the file ever exceeds the size, then <span class="command"><strong>named</strong></span> will
+ stop writing to the file unless it has a <span class="command"><strong>versions</strong></span> option
+ associated with it. If backup versions are kept, the files are
+ rolled as
+ described above and a new one begun. If there is no
+ <span class="command"><strong>versions</strong></span> option, no more data will
+ be 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>
+ Example usage of the <span class="command"><strong>size</strong></span> and
+ <span class="command"><strong>versions</strong></span> options:
+ </p>
+
+<pre class="programlisting">channel an_example_channel {
+ file "example.log" versions 3 size 20m;
+ print-time yes;
+ print-category yes;
+};
+</pre>
+
+ <p>
+ The <span class="command"><strong>syslog</strong></span> destination clause
+ directs the
+ channel to the system log. Its argument is a
+ syslog facility as described in the <span class="command"><strong>syslog</strong></span> man
+ page. Known facilities are <span class="command"><strong>kern</strong></span>, <span class="command"><strong>user</strong></span>,
+ <span class="command"><strong>mail</strong></span>, <span class="command"><strong>daemon</strong></span>, <span class="command"><strong>auth</strong></span>,
+ <span class="command"><strong>syslog</strong></span>, <span class="command"><strong>lpr</strong></span>, <span class="command"><strong>news</strong></span>,
+ <span class="command"><strong>uucp</strong></span>, <span class="command"><strong>cron</strong></span>, <span class="command"><strong>authpriv</strong></span>,
+ <span class="command"><strong>ftp</strong></span>, <span class="command"><strong>local0</strong></span>, <span class="command"><strong>local1</strong></span>,
+ <span class="command"><strong>local2</strong></span>, <span class="command"><strong>local3</strong></span>, <span class="command"><strong>local4</strong></span>,
+ <span class="command"><strong>local5</strong></span>, <span class="command"><strong>local6</strong></span> and
+ <span class="command"><strong>local7</strong></span>, however not all facilities
+ are supported on
+ all operating systems.
+ How <span class="command"><strong>syslog</strong></span> will handle messages
+ sent to
+ this facility is described in the <span class="command"><strong>syslog.conf</strong></span> man
+ page. If you have a system which uses a very old version of <span class="command"><strong>syslog</strong></span> that
+ only uses two arguments to the <span class="command"><strong>openlog()</strong></span> function,
+ then this clause is silently ignored.
+ </p>
+ <p>
+ On Windows machines syslog messages are directed to the EventViewer.
+ </p>
+ <p>
+ The <span class="command"><strong>severity</strong></span> clause works like <span class="command"><strong>syslog</strong></span>'s
+ "priorities", except that they can also be used if you are writing
+ straight to a file rather than using <span class="command"><strong>syslog</strong></span>.
+ Messages which are not at least of the severity level given will
+ not be selected for the channel; messages of higher severity
+ levels
+ will be accepted.
+ </p>
+ <p>
+ If you are using <span class="command"><strong>syslog</strong></span>, then the <span class="command"><strong>syslog.conf</strong></span> priorities
+ will also determine what eventually passes through. For example,
+ defining a channel facility and severity as <span class="command"><strong>daemon</strong></span> and <span class="command"><strong>debug</strong></span> but
+ only logging <span class="command"><strong>daemon.warning</strong></span> via <span class="command"><strong>syslog.conf</strong></span> will
+ cause messages of severity <span class="command"><strong>info</strong></span> and
+ <span class="command"><strong>notice</strong></span> to
+ be dropped. If the situation were reversed, with <span class="command"><strong>named</strong></span> writing
+ messages of only <span class="command"><strong>warning</strong></span> or higher,
+ then <span class="command"><strong>syslogd</strong></span> would
+ print all messages it received from the channel.
+ </p>
+
+ <p>
+ The <span class="command"><strong>stderr</strong></span> 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, for
+ example
+ when debugging a configuration.
+ </p>
+
+ <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, then debugging mode will be active. The global debug
+ level is set either by starting the <span class="command"><strong>named</strong></span> server
+ with the <code class="option">-d</code> flag followed by a positive integer,
+ or by running <span class="command"><strong>rndc trace</strong></span>.
+ The global debug level
+ can be set to zero, and debugging mode turned off, by running <span class="command"><strong>rndc
+notrace</strong></span>. All debugging messages in the server have a debug
+ level, and higher debug levels give more detailed output. Channels
+ that specify a specific debug severity, for example:
+ </p>
+
+<pre class="programlisting">channel specific_debug_level {
+ file "foo";
+ severity debug 3;
+};
+</pre>
+
+ <p>
+ will get debugging output of level 3 or less any time the
+ server is in debugging mode, regardless of the global debugging
+ level. Channels with <span class="command"><strong>dynamic</strong></span>
+ severity use the
+ server's global debug level to determine what messages to print.
+ </p>
+ <p>
+ If <span class="command"><strong>print-time</strong></span> has been turned on,
+ then
+ the date and time will be logged. <span class="command"><strong>print-time</strong></span> may
+ be specified for a <span class="command"><strong>syslog</strong></span> channel,
+ but is usually
+ pointless since <span class="command"><strong>syslog</strong></span> also logs
+ the date and
+ time. If <span class="command"><strong>print-category</strong></span> is
+ requested, then the
+ category of the message will be logged as well. Finally, if <span class="command"><strong>print-severity</strong></span> is
+ on, then the severity level of the message will be logged. The <span class="command"><strong>print-</strong></span> options may
+ be used in any combination, and will always be printed in the
+ following
+ order: time, category, severity. Here is an example where all
+ three <span class="command"><strong>print-</strong></span> options
+ are on:
+ </p>
+
+ <p>
+ <code class="computeroutput">28-Feb-2000 15:05:32.863 general: notice: running</code>
+ </p>
+
+ <p>
+ If <span class="command"><strong>buffered</strong></span> has been turned on the output
+ to files will not be flushed after each log entry. By default
+ all log messages are flushed.
+ </p>
+
+ <p>
+ There are four predefined channels that are used for
+ <span class="command"><strong>named</strong></span>'s default logging as follows.
+ If <span class="command"><strong>named</strong></span> is started with the
+ <code class="option">-L</code> then a
+ fifth channel <span class="command"><strong>default_logfile</strong></span> is added.
+ How they are
+ used is described in <a class="xref" href="Bv9ARM.ch06.html#the_category_phrase" title="The category Phrase">the section called &#8220;The <span class="command"><strong>category</strong></span> Phrase&#8221;</a>.
+ </p>
+
+<pre class="programlisting">channel default_syslog {
+ // send to syslog's daemon facility
+ syslog daemon;
+ // only send priority info and higher
+ severity info;
+};
+
+channel default_debug {
+ // write to named.run in the working directory
+ // Note: stderr is used instead of "named.run" if
+ // the server is started with the '-g' option.
+ file "named.run";
+ // log at the server's current debug level
+ severity dynamic;
+};
+
+channel default_stderr {
+ // writes to stderr
+ stderr;
+ // only send priority info and higher
+ severity info;
+};
+
+channel null {
+ // toss anything sent to this channel
+ null;
+};
+
+channel default_logfile {
+ // this channel is only present if named is
+ // started with the -L option, whose argument
+ // provides the file name
+ file "...";
+ // log at the server's current debug level
+ severity dynamic;
+};
+</pre>
+
+ <p>
+ The <span class="command"><strong>default_debug</strong></span> channel has the
+ special
+ property that it only produces output when the server's debug
+ level is
+ nonzero. It normally writes to a file called <code class="filename">named.run</code>
+ in the server's working directory.
+ </p>
+
+ <p>
+ For security reasons, when the <code class="option">-u</code>
+ command line option is used, the <code class="filename">named.run</code> file
+ is created only after <span class="command"><strong>named</strong></span> has
+ changed to the
+ new UID, and any debug output generated while <span class="command"><strong>named</strong></span> is
+ starting up and still running as root is discarded. If you need
+ to capture this output, you must run the server with the <code class="option">-L</code>
+ option to specify a default logfile, or the <code class="option">-g</code>
+ option to log to standard error which you can redirect to a file.
+ </p>
+
+ <p>
+ Once a channel is defined, it cannot be redefined. Thus you
+ cannot alter the built-in channels directly, but you can modify
+ the default logging by pointing categories at channels you have
+ defined.
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="the_category_phrase"></a>The <span class="command"><strong>category</strong></span> Phrase</h4></div></div></div>
+
+ <p>
+ There are many categories, so you can send the logs you want
+ to see wherever you want, without seeing logs you don't want. If
+ you don't specify a list of channels for a category, then log
+ messages
+ in that category will be sent to the <span class="command"><strong>default</strong></span> category
+ instead. If you don't specify a default category, the following
+ "default default" is used:
+ </p>
+
+<pre class="programlisting">category default { default_syslog; default_debug; };
+</pre>
+
+ <p>
+ If you start <span class="command"><strong>named</strong></span> with the
+ <code class="option">-L</code> option then the default category is:
+ </p>
+
+<pre class="programlisting">category default { default_logfile; default_debug; };
+</pre>
+
+ <p>
+ As an example, let's say you want to log security events to
+ a file, but you also want keep the default logging behavior. You'd
+ specify the following:
+ </p>
+
+<pre class="programlisting">channel my_security_channel {
+ file "my_security_file";
+ severity info;
+};
+category security {
+ my_security_channel;
+ default_syslog;
+ default_debug;
+};</pre>
+
+ <p>
+ To discard all messages in a category, specify the <span class="command"><strong>null</strong></span> channel:
+ </p>
+
+<pre class="programlisting">category xfer-out { null; };
+category notify { null; };
+</pre>
+
+ <p>
+ Following are the available categories and brief descriptions
+ of the types of log information they contain. More
+ categories may be added in future <acronym class="acronym">BIND</acronym> releases.
+ </p>
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.150in" class="1">
+<col width="3.350in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p><span class="command"><strong>client</strong></span></p>
+ </td>
+<td>
+ <p>
+ Processing of client requests.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>cname</strong></span></p>
+ </td>
+<td>
+ <p>
+ Logs nameservers that are skipped due to them being
+ a CNAME rather than A / AAAA records.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>config</strong></span></p>
+ </td>
+<td>
+ <p>
+ Configuration file parsing and processing.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>database</strong></span></p>
+ </td>
+<td>
+ <p>
+ Messages relating to the databases used
+ internally by the name server to store zone and cache
+ data.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>default</strong></span></p>
+ </td>
+<td>
+ <p>
+ The default category defines the logging
+ options for those categories where no specific
+ configuration has been
+ defined.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>delegation-only</strong></span></p>
+ </td>
+<td>
+ <p>
+ Delegation only. Logs queries that have been
+ forced to NXDOMAIN as the result of a
+ delegation-only zone or a
+ <span class="command"><strong>delegation-only</strong></span> in a
+ forward, hint or stub zone declaration.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>dispatch</strong></span></p>
+ </td>
+<td>
+ <p>
+ Dispatching of incoming packets to the
+ server modules where they are to be processed.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>dnssec</strong></span></p>
+ </td>
+<td>
+ <p>
+ DNSSEC and TSIG protocol processing.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>dnstap</strong></span></p>
+ </td>
+<td>
+ <p>
+ The "dnstap" DNS traffic capture system.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>edns-disabled</strong></span></p>
+ </td>
+<td>
+ <p>
+ Log queries that have been forced to use plain
+ DNS due to timeouts. This is often due to
+ the remote servers not being RFC 1034 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-RFC 1034 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 <span class="command"><strong>named</strong></span> will have to stop
+ treating such timeouts as due to RFC 1034 non
+ compliance and start treating it as plain
+ packet loss. Falsely classifying packet
+ loss as due to RFC 1034 non compliance impacts
+ on DNSSEC validation which requires EDNS for
+ the DNSSEC records to be returned.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>general</strong></span></p>
+ </td>
+<td>
+ <p>
+ The catch-all. Many things still aren't
+ classified into categories, and they all end up here.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>lame-servers</strong></span></p>
+ </td>
+<td>
+ <p>
+ Lame servers. These are misconfigurations
+ in remote servers, discovered by BIND 9 when trying to
+ query those servers during resolution.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>network</strong></span></p>
+ </td>
+<td>
+ <p>
+ Network operations.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>notify</strong></span></p>
+ </td>
+<td>
+ <p>
+ The NOTIFY protocol.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>queries</strong></span></p>
+ </td>
+<td>
+ <p>
+ Specify where queries should be logged to.
+ </p>
+ <p>
+ At startup, specifying the category <span class="command"><strong>queries</strong></span> will also
+ enable query logging unless <span class="command"><strong>querylog</strong></span> option has been
+ specified.
+ </p>
+
+ <p>
+ The query log entry first reports a client object
+ identifier in @0x&lt;hexadecimal-number&gt;
+ 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), if the query was signed (S),
+ EDNS was in used along with the EDNS version
+ number (E(#)), if TCP was used (T), if DO
+ (DNSSEC Ok) was set (D), if CD (Checking
+ Disabled) was set (C), if a valid DNS Server
+ COOKIE was received (V), or if a DNS COOKIE
+ option without a valid Server COOKIE was
+ present (K). After this the destination
+ address the query was sent to is reported.
+ </p>
+
+ <p>
+ <code class="computeroutput">client 127.0.0.1#62536 (www.example.com): query: www.example.com IN AAAA +SE</code>
+ </p>
+ <p>
+ <code class="computeroutput">client ::1#62537 (www.example.net): query: www.example.net IN AAAA -SE</code>
+ </p>
+ <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>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>query-errors</strong></span></p>
+ </td>
+<td>
+ <p>
+ Information about queries that resulted in some
+ failure.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>rate-limit</strong></span></p>
+ </td>
+<td>
+ <p>
+ The start, periodic, and final notices of the
+ rate limiting of a stream of responses are logged at
+ <span class="command"><strong>info</strong></span> 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 limit stops.
+ A lack of memory can hurry the final notice,
+ in which case it starts with an asterisk (*).
+ Various internal events are logged at debug 1 level
+ and higher.
+ </p>
+ <p>
+ Rate limiting of individual requests
+ is logged in the <span class="command"><strong>query-errors</strong></span> category.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>resolver</strong></span></p>
+ </td>
+<td>
+ <p>
+ DNS resolution, such as the recursive
+ lookups performed on behalf of clients by a caching name
+ server.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>rpz</strong></span></p>
+ </td>
+<td>
+ <p>
+ Information about errors in response policy zone files,
+ rewritten responses, and at the highest
+ <span class="command"><strong>debug</strong></span> levels, mere rewriting
+ attempts.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>security</strong></span></p>
+ </td>
+<td>
+ <p>
+ Approval and denial of requests.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>spill</strong></span></p>
+ </td>
+<td>
+ <p>
+ Logs queries that have been terminated, either by dropping
+ or responding with SERVFAIL, as a result of a fetchlimit
+ quota being exceeded.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>trust-anchor-telemetry</strong></span></p>
+ </td>
+<td>
+ <p>
+ Logs trust-anchor-telemetry requests received by named.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>unmatched</strong></span></p>
+ </td>
+<td>
+ <p>
+ Messages that <span class="command"><strong>named</strong></span> was unable to determine the
+ class of or for which there was no matching <span class="command"><strong>view</strong></span>.
+ A one line summary is also logged to the <span class="command"><strong>client</strong></span> category.
+ This category is best sent to a file or stderr, by
+ default it is sent to
+ the <span class="command"><strong>null</strong></span> channel.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>update</strong></span></p>
+ </td>
+<td>
+ <p>
+ Dynamic updates.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>update-security</strong></span></p>
+ </td>
+<td>
+ <p>
+ Approval and denial of update requests.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>xfer-in</strong></span></p>
+ </td>
+<td>
+ <p>
+ Zone transfers the server is receiving.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>xfer-out</strong></span></p>
+ </td>
+<td>
+ <p>
+ Zone transfers the server is sending.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+</div>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="query_errors"></a>The <span class="command"><strong>query-errors</strong></span> Category</h4></div></div></div>
+ <p>
+ The <span class="command"><strong>query-errors</strong></span> category is
+ specifically intended for debugging purposes: To identify
+ why and how specific queries result in responses which
+ indicate an error.
+ Messages of this category are therefore only logged
+ with <span class="command"><strong>debug</strong></span> levels.
+ </p>
+
+ <p>
+ At the debug levels of 1 or higher, each response with the
+ rcode of SERVFAIL is logged as follows:
+ </p>
+ <p>
+ <code class="computeroutput">client 127.0.0.1#61502: query failed (SERVFAIL) for www.example.com/IN/AAAA at query.c:3880</code>
+ </p>
+ <p>
+ This means an error resulting in SERVFAIL was
+ detected at line 3880 of source file
+ <code class="filename">query.c</code>.
+ Log messages of this level will particularly
+ help identify the cause of SERVFAIL for an
+ authoritative server.
+ </p>
+ <p>
+ At the debug levels of 2 or higher, detailed context
+ information of recursive resolutions that resulted in
+ SERVFAIL is logged.
+ The log message will look like as follows:
+ </p>
+ <p>
+
+ </p>
+<pre class="programlisting">
+fetch completed at resolver.c:2970 for www.example.com/A
+in 30.000183: timed out/success [domain:example.com,
+referral:2,restart:7,qrysent:8,timeout:5,lame:0,neterr:0,
+badresp:1,adberr:0,findfail:0,valfail:0]
+ </pre>
+<p>
+ </p>
+ <p>
+ The first part before the colon shows that a recursive
+ resolution for AAAA records of www.example.com completed
+ in 30.000183 seconds and the final result that led to the
+ SERVFAIL was determined at line 2970 of source file
+ <code class="filename">resolver.c</code>.
+ </p>
+ <p>
+ The following part shows the detected final result and the
+ latest result of DNSSEC validation.
+ The latter is always success when no validation attempt
+ is made.
+ In this example, this query resulted in SERVFAIL probably
+ because all name servers are down or unreachable, leading
+ to a timeout in 30 seconds.
+ DNSSEC validation was probably not attempted.
+ </p>
+ <p>
+ The last part enclosed in square brackets shows statistics
+ information collected for this particular resolution
+ attempt.
+ The <code class="varname">domain</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 table.
+ </p>
+
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.150in" class="1">
+<col width="3.350in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p><code class="varname">referral</code></p>
+ </td>
+<td>
+ <p>
+ The number of referrals the resolver received
+ throughout the resolution process.
+ In the above example this is 2, which are most
+ likely com and example.com.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><code class="varname">restart</code></p>
+ </td>
+<td>
+ <p>
+ The number of cycles that the resolver tried
+ remote servers at the <code class="varname">domain</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="varname">domain</code> zone.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><code class="varname">qrysent</code></p>
+ </td>
+<td>
+ <p>
+ The number of queries the resolver sent at the
+ <code class="varname">domain</code> zone.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><code class="varname">timeout</code></p>
+ </td>
+<td>
+ <p>
+ The number of timeouts since the resolver
+ received the last response.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><code class="varname">lame</code></p>
+ </td>
+<td>
+ <p>
+ The number of lame servers the resolver detected
+ at the <code class="varname">domain</code> zone.
+ A server is detected to be lame either by an
+ invalid response or as a result of lookup in
+ BIND9's address database (ADB), where lame
+ servers are cached.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><code class="varname">neterr</code></p>
+ </td>
+<td>
+ <p>
+ The number of erroneous results that the
+ resolver encountered in sending queries
+ at the <code class="varname">domain</code> zone.
+ One common case is the remote server is
+ unreachable and the resolver receives an ICMP
+ unreachable error message.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><code class="varname">badresp</code></p>
+ </td>
+<td>
+ <p>
+ The number of unexpected responses (other than
+ <code class="varname">lame</code>) to queries sent by the
+ resolver at the <code class="varname">domain</code> zone.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><code class="varname">adberr</code></p>
+ </td>
+<td>
+ <p>
+ Failures in finding remote server addresses
+ of the <code class="varname">domain</code> zone in the ADB.
+ One common case of this is that the remote
+ server's name does not have any address records.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><code class="varname">findfail</code></p>
+ </td>
+<td>
+ <p>
+ Failures of resolving remote server addresses.
+ This is a total number of failures throughout
+ the resolution process.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><code class="varname">valfail</code></p>
+ </td>
+<td>
+ <p>
+ Failures of DNSSEC validation.
+ Validation failures are counted throughout
+ the resolution process (not limited to
+ the <code class="varname">domain</code> zone), but should
+ only happen in <code class="varname">domain</code>.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ <p>
+ At the debug levels of 3 or higher, the same messages
+ as those at the debug 1 level are logged for other errors
+ than SERVFAIL.
+ Note that negative responses such as NXDOMAIN are not
+ regarded as errors here.
+ </p>
+ <p>
+ At the debug levels of 4 or higher, the same messages
+ as those at the debug 2 level are logged for other errors
+ than SERVFAIL.
+ Unlike the above case of level 3, messages are logged for
+ negative responses.
+ This is because any unexpected results can be difficult to
+ debug in the recursion case.
+ </p>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="lwres_grammar"></a><span class="command"><strong>lwres</strong></span> Statement Grammar</h3></div></div></div>
+
+ <p>
+ This is the grammar of the <span class="command"><strong>lwres</strong></span>
+ statement in the <code class="filename">named.conf</code> file:
+ </p>
+
+<pre class="programlisting"><span class="command"><strong>lwres {</strong></span>
+ [ <span class="command"><strong>listen-on {</strong></span>
+ ( <em class="replaceable"><code>ip_addr</code></em> [ <span class="command"><strong>port</strong></span> <em class="replaceable"><code>ip_port</code></em> ] [ <span class="command"><strong>dscp</strong></span> <em class="replaceable"><code>ip_dscp</code></em> ] <span class="command"><strong>;</strong></span> )
+ ...
+ <span class="command"><strong>};</strong></span> ]
+ [ <span class="command"><strong>view</strong></span> <em class="replaceable"><code>view_name</code></em><span class="command"><strong>;</strong></span> ]
+ [ <span class="command"><strong>search {</strong></span> <em class="replaceable"><code>domain_name</code></em> <span class="command"><strong>;</strong></span> ... <span class="command"><strong>};</strong></span> ]
+ [ <span class="command"><strong>ndots</strong></span> <em class="replaceable"><code>number</code></em><span class="command"><strong>;</strong></span> ]
+ [ <span class="command"><strong>lwres-tasks</strong></span> <em class="replaceable"><code>number</code></em><span class="command"><strong>;</strong></span> ]
+ [ <span class="command"><strong>lwres-clients</strong></span> <em class="replaceable"><code>number</code></em><span class="command"><strong>;</strong></span> ]
+<span class="command"><strong>};</strong></span>
+</pre>
+
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="lwres_statement"></a><span class="command"><strong>lwres</strong></span> Statement Definition and Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>lwres</strong></span> statement configures the
+ name
+ server to also act as a lightweight resolver server. (See
+ <a class="xref" href="Bv9ARM.ch05.html#lwresd" title="Running a Resolver Daemon">the section called &#8220;Running a Resolver Daemon&#8221;</a>.) There may be multiple
+ <span class="command"><strong>lwres</strong></span> statements configuring
+ lightweight resolver servers with different properties.
+ </p>
+
+ <p>
+ The <span class="command"><strong>listen-on</strong></span> statement specifies a
+ list of
+ IPv4 addresses (and ports) that this instance of a lightweight
+ resolver daemon
+ should accept requests on. If no port is specified, port 921 is
+ used.
+ If this statement is omitted, requests will be accepted on
+ 127.0.0.1,
+ port 921.
+ </p>
+
+ <p>
+ The <span class="command"><strong>view</strong></span> statement binds this
+ instance of a
+ lightweight resolver daemon to a view in the DNS namespace, so that
+ the
+ response will be constructed in the same manner as a normal DNS
+ query
+ matching this view. If this statement is omitted, the default view
+ is
+ used, and if there is no default view, an error is triggered.
+ </p>
+
+ <p>
+ The <span class="command"><strong>search</strong></span> statement is equivalent to
+ the
+ <span class="command"><strong>search</strong></span> statement in
+ <code class="filename">/etc/resolv.conf</code>. It provides a
+ list of domains
+ which are appended to relative names in queries.
+ </p>
+
+ <p>
+ The <span class="command"><strong>ndots</strong></span> statement is equivalent to
+ the
+ <span class="command"><strong>ndots</strong></span> statement in
+ <code class="filename">/etc/resolv.conf</code>. It indicates the
+ minimum
+ number of dots in a relative domain name that should result in an
+ exact match lookup before search path elements are appended.
+ </p>
+ <p>
+ The <code class="option">lwres-tasks</code> statement specifies the number
+ of worker threads the lightweight resolver will dedicate to serving
+ clients. By default the number is the same as the number of CPUs on
+ the system; this can be overridden using the <code class="option">-n</code>
+ command line option when starting the server.
+ </p>
+ <p>
+ The <code class="option">lwres-clients</code> specifies
+ the number of client objects per thread the lightweight
+ resolver should create to serve client queries.
+ By default, if the lightweight resolver runs as a part
+ of <span class="command"><strong>named</strong></span>, 256 client objects are
+ created for each task; if it runs as <span class="command"><strong>lwresd</strong></span>,
+ 1024 client objects are created for each thread. The maximum
+ value is 32768; higher values will be silently ignored and
+ the maximum will be used instead.
+ Note that setting too high a value may overconsume
+ system resources.
+ </p>
+ <p>
+ The maximum number of client queries that the lightweight
+ resolver can handle at any one time equals
+ <code class="option">lwres-tasks</code> times <code class="option">lwres-clients</code>.
+ </p>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="masters_grammar"></a><span class="command"><strong>masters</strong></span> Statement Grammar</h3></div></div></div>
+ <pre class="programlisting">
+<span class="command"><strong>masters</strong></span> <em class="replaceable"><code>string</code></em> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp
+ <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>masters</code></em> | <em class="replaceable"><code>ipv4_address</code></em> [
+ <span class="command"><strong>port</strong></span> <em class="replaceable"><code>integer</code></em> ] | <em class="replaceable"><code>ipv6_address</code></em> [ port
+ <em class="replaceable"><code>integer</code></em> ] ) [ key <em class="replaceable"><code>string</code></em> ]; ... };
+</pre>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="masters_statement"></a><span class="command"><strong>masters</strong></span> Statement Definition and
+ Usage</h3></div></div></div>
+
+ <p><span class="command"><strong>masters</strong></span>
+ lists allow for a common set of masters to be easily used by
+ multiple stub and slave zones in their <span class="command"><strong>masters</strong></span>
+ or <span class="command"><strong>also-notify</strong></span> lists.
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="options_grammar"></a><span class="command"><strong>options</strong></span> Statement Grammar</h3></div></div></div>
+
+ <p>
+ This is the grammar of the <span class="command"><strong>options</strong></span>
+ statement in the <code class="filename">named.conf</code> file:
+ </p>
+ <pre class="programlisting">
+<span class="command"><strong>options</strong></span> {
+ <span class="command"><strong>acache-cleaning-interval</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>acache-enable</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>additional-from-auth</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>additional-from-cache</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>allow-new-zones</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>allow-notify</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-query</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-query-cache</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-query-cache-on</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-query-on</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-recursion</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-recursion-on</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-transfer</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-update</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-update-forwarding</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>also-notify</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>masters</code></em> |
+ <em class="replaceable"><code>ipv4_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] | <em class="replaceable"><code>ipv6_address</code></em> [ port
+ <em class="replaceable"><code>integer</code></em> ] ) [ key <em class="replaceable"><code>string</code></em> ]; ... };
+ <span class="command"><strong>alt-transfer-source</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * )
+ ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>alt-transfer-source-v6</strong></span> ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> |
+ * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>answer-cookie</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>attach-cache</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>auth-nxdomain</strong></span> <em class="replaceable"><code>boolean</code></em>; // default changed
+ <span class="command"><strong>auto-dnssec</strong></span> ( allow | maintain | off );
+ <span class="command"><strong>automatic-interface-scan</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>avoid-v4-udp-ports</strong></span> { <em class="replaceable"><code>portrange</code></em>; ... };
+ <span class="command"><strong>avoid-v6-udp-ports</strong></span> { <em class="replaceable"><code>portrange</code></em>; ... };
+ <span class="command"><strong>bindkeys-file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>blackhole</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>cache-file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>catalog-zones</strong></span> { zone <em class="replaceable"><code>quoted_string</code></em> [ default-masters [ port
+ <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>masters</code></em> | <em class="replaceable"><code>ipv4_address</code></em> [
+ <span class="command"><strong>port</strong></span> <em class="replaceable"><code>integer</code></em> ] | <em class="replaceable"><code>ipv6_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] ) [ key
+ <em class="replaceable"><code>string</code></em> ]; ... } ] [ zone-directory <em class="replaceable"><code>quoted_string</code></em> ] [
+ <span class="command"><strong>in-memory</strong></span> <em class="replaceable"><code>boolean</code></em> ] [ min-update-interval <em class="replaceable"><code>integer</code></em> ]; ... };
+ <span class="command"><strong>check-dup-records</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>check-integrity</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>check-mx</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>check-mx-cname</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>check-names</strong></span> ( master | slave | response
+ ) ( fail | warn | ignore );
+ <span class="command"><strong>check-sibling</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>check-spf</strong></span> ( warn | ignore );
+ <span class="command"><strong>check-srv-cname</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>check-wildcard</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>cleaning-interval</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>clients-per-query</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>cookie-algorithm</strong></span> ( aes | sha1 | sha256 );
+ <span class="command"><strong>cookie-secret</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>coresize</strong></span> ( default | unlimited | <em class="replaceable"><code>sizeval</code></em> );
+ <span class="command"><strong>datasize</strong></span> ( default | unlimited | <em class="replaceable"><code>sizeval</code></em> );
+ <span class="command"><strong>deny-answer-addresses</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... } [
+ <span class="command"><strong>except-from</strong></span> { <em class="replaceable"><code>quoted_string</code></em>; ... } ];
+ <span class="command"><strong>deny-answer-aliases</strong></span> { <em class="replaceable"><code>quoted_string</code></em>; ... } [ except-from {
+ <em class="replaceable"><code>quoted_string</code></em>; ... } ];
+ <span class="command"><strong>dialup</strong></span> ( notify | notify-passive | passive | refresh | <em class="replaceable"><code>boolean</code></em> );
+ <span class="command"><strong>directory</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>disable-algorithms</strong></span> <em class="replaceable"><code>string</code></em> { <em class="replaceable"><code>string</code></em>;
+ ... };
+ <span class="command"><strong>disable-ds-digests</strong></span> <em class="replaceable"><code>string</code></em> { <em class="replaceable"><code>string</code></em>;
+ ... };
+ <span class="command"><strong>disable-empty-zone</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>dns64</strong></span> <em class="replaceable"><code>netprefix</code></em> {
+ <span class="command"><strong>break-dnssec</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>clients</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>exclude</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>mapped</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>recursive-only</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>suffix</strong></span> <em class="replaceable"><code>ipv6_address</code></em>;
+ };
+ <span class="command"><strong>dns64-contact</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>dns64-server</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>dnssec-accept-expired</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>dnssec-dnskey-kskonly</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>dnssec-enable</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>dnssec-loadkeys-interval</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>dnssec-lookaside</strong></span> ( <em class="replaceable"><code>string</code></em> trust-anchor
+ <em class="replaceable"><code>string</code></em> | auto | no );
+ <span class="command"><strong>dnssec-must-be-secure</strong></span> <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>dnssec-secure-to-insecure</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>dnssec-update-mode</strong></span> ( maintain | no-resign );
+ <span class="command"><strong>dnssec-validation</strong></span> ( yes | no | auto );
+ <span class="command"><strong>dnstap</strong></span> { ( all | auth | client | forwarder |
+ <span class="command"><strong>resolver</strong></span> ) [ ( query | response ) ]; ... };
+ <span class="command"><strong>dnstap-identity</strong></span> ( <em class="replaceable"><code>quoted_string</code></em> | none |
+ <span class="command"><strong>hostname</strong></span> );
+ <span class="command"><strong>dnstap-output</strong></span> ( file | unix ) <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>dnstap-version</strong></span> ( <em class="replaceable"><code>quoted_string</code></em> | none );
+ <span class="command"><strong>dscp</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>dual-stack-servers</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>quoted_string</code></em> [ port
+ <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] | <em class="replaceable"><code>ipv4_address</code></em> [ port
+ <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] | <em class="replaceable"><code>ipv6_address</code></em> [ port
+ <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] ); ... };
+ <span class="command"><strong>dump-file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>edns-udp-size</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>empty-contact</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>empty-server</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>empty-zones-enable</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>fetch-quota-params</strong></span> <em class="replaceable"><code>integer</code></em> <em class="replaceable"><code>fixedpoint</code></em> <em class="replaceable"><code>fixedpoint</code></em> <em class="replaceable"><code>fixedpoint</code></em>;
+ <span class="command"><strong>fetches-per-server</strong></span> <em class="replaceable"><code>integer</code></em> [ ( drop | fail ) ];
+ <span class="command"><strong>fetches-per-zone</strong></span> <em class="replaceable"><code>integer</code></em> [ ( drop | fail ) ];
+ <span class="command"><strong>files</strong></span> ( default | unlimited | <em class="replaceable"><code>sizeval</code></em> );
+ <span class="command"><strong>filter-aaaa</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>filter-aaaa-on-v4</strong></span> ( break-dnssec | <em class="replaceable"><code>boolean</code></em> );
+ <span class="command"><strong>filter-aaaa-on-v6</strong></span> ( break-dnssec | <em class="replaceable"><code>boolean</code></em> );
+ <span class="command"><strong>flush-zones-on-shutdown</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>forward</strong></span> ( first | only );
+ <span class="command"><strong>forwarders</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>ipv4_address</code></em>
+ | <em class="replaceable"><code>ipv6_address</code></em> ) [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ]; ... };
+ <span class="command"><strong>fstrm-set-buffer-hint</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>fstrm-set-flush-timeout</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>fstrm-set-input-queue-size</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>fstrm-set-output-notify-threshold</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>fstrm-set-output-queue-model</strong></span> ( mpsc | spsc );
+ <span class="command"><strong>fstrm-set-output-queue-size</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>fstrm-set-reopen-interval</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>geoip-directory</strong></span> ( <em class="replaceable"><code>quoted_string</code></em> | none );
+ <span class="command"><strong>geoip-use-ecs</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>heartbeat-interval</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>hostname</strong></span> ( <em class="replaceable"><code>quoted_string</code></em> | none );
+ <span class="command"><strong>inline-signing</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>interface-interval</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>ixfr-from-differences</strong></span> ( master | slave | <em class="replaceable"><code>boolean</code></em> );
+ <span class="command"><strong>keep-response-order</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>key-directory</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>lame-ttl</strong></span> <em class="replaceable"><code>ttlval</code></em>;
+ <span class="command"><strong>listen-on</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp
+ <em class="replaceable"><code>integer</code></em> ] {
+ <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>listen-on-v6</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp
+ <em class="replaceable"><code>integer</code></em> ] {
+ <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>lmdb-mapsize</strong></span> <em class="replaceable"><code>sizeval</code></em>;
+ <span class="command"><strong>lock-file</strong></span> ( <em class="replaceable"><code>quoted_string</code></em> | none );
+ <span class="command"><strong>managed-keys-directory</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>masterfile-format</strong></span> ( map | raw | text );
+ <span class="command"><strong>masterfile-style</strong></span> ( full | relative );
+ <span class="command"><strong>match-mapped-addresses</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>max-acache-size</strong></span> ( unlimited | <em class="replaceable"><code>sizeval</code></em> );
+ <span class="command"><strong>max-cache-size</strong></span> ( default | unlimited | <em class="replaceable"><code>sizeval</code></em> | <em class="replaceable"><code>percentage</code></em> );
+ <span class="command"><strong>max-cache-ttl</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-clients-per-query</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-journal-size</strong></span> ( unlimited | <em class="replaceable"><code>sizeval</code></em> );
+ <span class="command"><strong>max-ncache-ttl</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-records</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-recursion-depth</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-recursion-queries</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-refresh-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-retry-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-rsa-exponent-size</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-idle-in</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-idle-out</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-time-in</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-time-out</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-udp-size</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-zone-ttl</strong></span> ( unlimited | <em class="replaceable"><code>ttlval</code></em> );
+ <span class="command"><strong>memstatistics</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>memstatistics-file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>message-compression</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>min-refresh-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>min-retry-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>minimal-any</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>minimal-responses</strong></span> ( no-auth | no-auth-recursive | <em class="replaceable"><code>boolean</code></em> );
+ <span class="command"><strong>multi-master</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>no-case-compress</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>nocookie-udp-size</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>notify</strong></span> ( explicit | master-only | <em class="replaceable"><code>boolean</code></em> );
+ <span class="command"><strong>notify-delay</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>notify-rate</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>notify-source</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [
+ <span class="command"><strong>dscp</strong></span> <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>notify-source-v6</strong></span> ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ]
+ [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>notify-to-soa</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>nta-lifetime</strong></span> <em class="replaceable"><code>ttlval</code></em>;
+ <span class="command"><strong>nta-recheck</strong></span> <em class="replaceable"><code>ttlval</code></em>;
+ <span class="command"><strong>nxdomain-redirect</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>pid-file</strong></span> ( <em class="replaceable"><code>quoted_string</code></em> | none );
+ <span class="command"><strong>port</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>preferred-glue</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>prefetch</strong></span> <em class="replaceable"><code>integer</code></em> [ <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>provide-ixfr</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>query-source</strong></span> ( ( [ address ] ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port (
+ <em class="replaceable"><code>integer</code></em> | * ) ] ) | ( [ [ address ] ( <em class="replaceable"><code>ipv4_address</code></em> | * ) ]
+ <span class="command"><strong>port</strong></span> ( <em class="replaceable"><code>integer</code></em> | * ) ) ) [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>query-source-v6</strong></span> ( ( [ address ] ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port (
+ <em class="replaceable"><code>integer</code></em> | * ) ] ) | ( [ [ address ] ( <em class="replaceable"><code>ipv6_address</code></em> | * ) ]
+ <span class="command"><strong>port</strong></span> ( <em class="replaceable"><code>integer</code></em> | * ) ) ) [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>querylog</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>random-device</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>rate-limit</strong></span> {
+ <span class="command"><strong>all-per-second</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>errors-per-second</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>exempt-clients</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>ipv4-prefix-length</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>ipv6-prefix-length</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>log-only</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>max-table-size</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>min-table-size</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>nodata-per-second</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>nxdomains-per-second</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>qps-scale</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>referrals-per-second</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>responses-per-second</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>slip</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>window</strong></span> <em class="replaceable"><code>integer</code></em>;
+ };
+ <span class="command"><strong>recursing-file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>recursion</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>recursive-clients</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>request-expire</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>request-ixfr</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>request-nsid</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>require-server-cookie</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>reserved-sockets</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>resolver-query-timeout</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>response-policy</strong></span> { zone <em class="replaceable"><code>quoted_string</code></em> [ log <em class="replaceable"><code>boolean</code></em> ] [
+ <span class="command"><strong>max-policy-ttl</strong></span> <em class="replaceable"><code>integer</code></em> ] [ policy ( cname | disabled | drop |
+ <span class="command"><strong>given</strong></span> | no-op | nodata | nxdomain | passthru | tcp-only
+ <em class="replaceable"><code>quoted_string</code></em> ) ] [ recursive-only <em class="replaceable"><code>boolean</code></em> ]; ... } [
+ <span class="command"><strong>break-dnssec</strong></span> <em class="replaceable"><code>boolean</code></em> ] [ max-policy-ttl <em class="replaceable"><code>integer</code></em> ] [
+ <span class="command"><strong>min-ns-dots</strong></span> <em class="replaceable"><code>integer</code></em> ] [ nsip-wait-recurse <em class="replaceable"><code>boolean</code></em> ] [
+ <span class="command"><strong>qname-wait-recurse</strong></span> <em class="replaceable"><code>boolean</code></em> ] [ recursive-only <em class="replaceable"><code>boolean</code></em> ];
+ <span class="command"><strong>root-delegation-only</strong></span> [ exclude { <em class="replaceable"><code>quoted_string</code></em>; ... } ];
+ <span class="command"><strong>root-key-sentinel</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>rrset-order</strong></span> { [ class <em class="replaceable"><code>string</code></em> ] [ type <em class="replaceable"><code>string</code></em> ] [ name
+ <em class="replaceable"><code>quoted_string</code></em> ] <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>string</code></em>; ... };
+ <span class="command"><strong>secroots-file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>send-cookie</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>serial-query-rate</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>serial-update-method</strong></span> ( date | increment | unixtime );
+ <span class="command"><strong>server-id</strong></span> ( <em class="replaceable"><code>quoted_string</code></em> | none | hostname );
+ <span class="command"><strong>servfail-ttl</strong></span> <em class="replaceable"><code>ttlval</code></em>;
+ <span class="command"><strong>session-keyalg</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>session-keyfile</strong></span> ( <em class="replaceable"><code>quoted_string</code></em> | none );
+ <span class="command"><strong>session-keyname</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>sig-signing-nodes</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>sig-signing-signatures</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>sig-signing-type</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>sig-validity-interval</strong></span> <em class="replaceable"><code>integer</code></em> [ <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>sortlist</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>stacksize</strong></span> ( default | unlimited | <em class="replaceable"><code>sizeval</code></em> );
+ <span class="command"><strong>startup-notify-rate</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>statistics-file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>tcp-clients</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>tcp-listen-queue</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>tkey-dhkey</strong></span> <em class="replaceable"><code>quoted_string</code></em> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>tkey-domain</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>tkey-gssapi-credential</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>tkey-gssapi-keytab</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>transfer-format</strong></span> ( many-answers | one-answer );
+ <span class="command"><strong>transfer-message-size</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>transfer-source</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [
+ <span class="command"><strong>dscp</strong></span> <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>transfer-source-v6</strong></span> ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * )
+ ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>transfers-in</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>transfers-out</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>transfers-per-ns</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>trust-anchor-telemetry</strong></span> <em class="replaceable"><code>boolean</code></em>; // experimental
+ <span class="command"><strong>try-tcp-refresh</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>update-check-ksk</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>use-alt-transfer-source</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>use-v4-udp-ports</strong></span> { <em class="replaceable"><code>portrange</code></em>; ... };
+ <span class="command"><strong>use-v6-udp-ports</strong></span> { <em class="replaceable"><code>portrange</code></em>; ... };
+ <span class="command"><strong>v6-bias</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>version</strong></span> ( <em class="replaceable"><code>quoted_string</code></em> | none );
+ <span class="command"><strong>zero-no-soa-ttl</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>zero-no-soa-ttl-cache</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>zone-statistics</strong></span> ( full | terse | none | <em class="replaceable"><code>boolean</code></em> );
+};
+</pre>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="options"></a><span class="command"><strong>options</strong></span> Statement Definition and
+ Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>options</strong></span> statement sets up global
+ options
+ to be used by <acronym class="acronym">BIND</acronym>. This statement
+ may appear only
+ once in a configuration file. If there is no <span class="command"><strong>options</strong></span>
+ statement, an options block with each option set to its default will
+ be used.
+ </p>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>attach-cache</strong></span></span></dt>
+<dd>
+ <p>
+ 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 <span class="command"><strong>attach-cache</strong></span> option
+ may also be specified in <span class="command"><strong>view</strong></span>
+ statements, in which case it overrides the
+ global <span class="command"><strong>attach-cache</strong></span> option.
+ </p>
+
+ <p>
+ The <em class="replaceable"><code>cache_name</code></em> specifies
+ the cache to be shared.
+ When the <span class="command"><strong>named</strong></span> 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 will simply refer to the
+ already created cache.
+ </p>
+
+ <p>
+ One common configuration to share a cache would be to
+ allow all views to share a single cache.
+ This can be done by specifying
+ the <span class="command"><strong>attach-cache</strong></span> 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 to
+ 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
+ <span class="command"><strong>attach-cache</strong></span> option as a view A (or
+ B)'s option, referring to the other view name:
+ </p>
+
+<pre class="programlisting">
+ view "A" {
+ // this view has its own cache
+ ...
+ };
+ view "B" {
+ // this view refers to A's cache
+ attach-cache "A";
+ };
+ view "C" {
+ // this view has its own cache
+ ...
+ };
+</pre>
+
+ <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:
+ <span class="command"><strong>check-names</strong></span>,
+ <span class="command"><strong>cleaning-interval</strong></span>,
+ <span class="command"><strong>dnssec-accept-expired</strong></span>,
+ <span class="command"><strong>dnssec-validation</strong></span>,
+ <span class="command"><strong>max-cache-ttl</strong></span>,
+ <span class="command"><strong>max-ncache-ttl</strong></span>,
+ <span class="command"><strong>max-cache-size</strong></span>, and
+ <span class="command"><strong>zero-no-soa-ttl</strong></span>.
+ </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 administrator's responsibility to ensure
+ configuration differences in different views do
+ not cause disruption with a shared cache.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>directory</strong></span></span></dt>
+<dd>
+ <p>
+ The working directory of the server.
+ Any non-absolute pathnames in the configuration file will
+ be taken as relative to this directory. The default
+ location for most server output files
+ (e.g. <code class="filename">named.run</code>) is this directory.
+ If a directory is not specified, the working directory
+ defaults to `<code class="filename">.</code>', the directory from
+ which the server was started. The directory specified
+ should be an absolute path. It is
+ <span class="emphasis"><em>strongly recommended</em></span>
+ that the directory be writable by the effective user
+ ID of the <span class="command"><strong>named</strong></span> process.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnstap</strong></span></span></dt>
+<dd>
+ <p>
+ <span class="command"><strong>dnstap</strong></span> 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, <span class="command"><strong>dnstap</strong></span>
+ uses
+ <span class="command"><strong>libfstrm</strong></span> (a lightweight high-speed
+ framing library, see
+ <a class="link" href="https://github.com/farsightsec/fstrm" target="_top">https://github.com/farsightsec/fstrm</a>) to send
+ event payloads which are encoded using Protocol Buffers
+ (<span class="command"><strong>libprotobuf-c</strong></span>, a mechanism for
+ serializing structured data developed
+ by Google, Inc.; see
+ <a class="link" href="https://developers.google.com/protocol-buffers/" target="_top">https://developers.google.com/protocol-buffers</a>).
+ </p>
+ <p>
+ To enable <span class="command"><strong>dnstap</strong></span> at compile time,
+ the <span class="command"><strong>fstrm</strong></span> and <span class="command"><strong>protobuf-c</strong></span>
+ libraries must be available, and BIND must be configured with
+ <code class="option">--enable-dnstap</code>.
+ </p>
+ <p>
+ The <span class="command"><strong>dnstap</strong></span> option is a bracketed list
+ of message types to be logged. These may be set differently
+ for each view. Supported types are <code class="literal">client</code>,
+ <code class="literal">auth</code>, <code class="literal">resolver</code>, and
+ <code class="literal">forwarder</code>. Specifying type
+ <code class="literal">all</code> will cause all <span class="command"><strong>dnstap</strong></span>
+ messages to be logged, regardless of type.
+ </p>
+ <p>
+ Each type may take an additional argument to indicate whether
+ to log <code class="literal">query</code> messages or
+ <code class="literal">response</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>
+<pre class="programlisting">dnstap {
+ auth;
+ client response;
+ resolver query;
+};
+</pre>
+<p>
+ </p>
+ <p>
+ Logged <span class="command"><strong>dnstap</strong></span> messages can be parsed
+ using the <span class="command"><strong>dnstap-read</strong></span> utility (see
+ <a class="xref" href="man.dnstap-read.html" title="dnstap-read"><span class="refentrytitle"><span class="application">dnstap-read</span></span>(1)</a> for details).
+ </p>
+ <p>
+ For more information on <span class="command"><strong>dnstap</strong></span>, see
+ <a class="link" href="http://dnstap.info" target="_top">http://dnstap.info</a>.
+ </p>
+ <p>
+ The fstrm library has a number of tunables that are exposed
+ in <code class="filename">named.conf</code>, and can be modified
+ if necessary to improve performance or prevent loss of data.
+ These are:
+ </p>
+ <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
+<li class="listitem">
+
+ <span class="command"><strong>fstrm-set-buffer-hint</strong></span>: 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.
+
+ </li>
+<li class="listitem">
+
+ <span class="command"><strong>fstrm-set-flush-timeout</strong></span>: 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.
+
+ </li>
+<li class="listitem">
+
+ <span class="command"><strong>fstrm-set-output-notify-threshold</strong></span>:
+ 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.
+
+ </li>
+<li class="listitem">
+
+ <span class="command"><strong>fstrm-set-output-queue-model</strong></span>:
+ Controls the queuing semantics to use for queue
+ objects. The default is <code class="literal">mpsc</code>
+ (multiple producer, single consumer); the other
+ option is <code class="literal">spsc</code> (single producer,
+ single consumer).
+
+ </li>
+<li class="listitem">
+
+ <span class="command"><strong>fstrm-set-input-queue-size</strong></span>: 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.
+
+ </li>
+<li class="listitem">
+
+ <span class="command"><strong>fstrm-set-output-queue-size</strong></span>:
+ 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="option">IOV_MAX</code>,
+ and the default is 64.
+
+ </li>
+<li class="listitem">
+
+ <span class="command"><strong>fstrm-set-reopen-interval</strong></span>:
+ 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.
+
+ </li>
+</ul></div>
+ <p>
+ Note that all of the above minimum, maximum, and default
+ values are set by the <span class="command"><strong>libfstrm</strong></span> library,
+ and may be subject to change in future versions of the
+ library. See the <span class="command"><strong>libfstrm</strong></span> documentation
+ for more information.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnstap-output</strong></span></span></dt>
+<dd>
+ <p>
+ Configures the path to which the <span class="command"><strong>dnstap</strong></span>
+ frame stream will be sent if <span class="command"><strong>dnstap</strong></span>
+ is enabled at compile time and active.
+ </p>
+ <p>
+ The first argument is either <code class="literal">file</code> or
+ <code class="literal">unix</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, <span class="command"><strong>dnstap</strong></span> messages will
+ only be sent if another process such as
+ <span class="command"><strong>fstrm_capture</strong></span>
+ (provided with <span class="command"><strong>libfstrm</strong></span>) is listening on
+ the socket.)
+ </p>
+ <p>
+ <span class="command"><strong>dnstap-output</strong></span> can only be set globally
+ in <span class="command"><strong>options</strong></span>. Currently, it can only be
+ set once while <span class="command"><strong>named</strong></span> is running;
+ once set, it cannot be changed by
+ <span class="command"><strong>rndc reload</strong></span> or
+ <span class="command"><strong>rndc reconfig</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnstap-identity</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies an <span class="command"><strong>identity</strong></span> string to send in
+ <span class="command"><strong>dnstap</strong></span> messages. If set to
+ <code class="literal">hostname</code>, which is the default, the
+ server's hostname will be sent. If set to
+ <code class="literal">none</code>, no identity string will be sent.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnstap-version</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies a <span class="command"><strong>version</strong></span> string to send in
+ <span class="command"><strong>dnstap</strong></span> messages. The default is the
+ version number of the BIND release. If set to
+ <code class="literal">none</code>, no version string will be sent.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>geoip-directory</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies the directory containing GeoIP
+ <code class="filename">.dat</code> database files for GeoIP
+ initialization. By default, this option is unset
+ and the GeoIP support will use libGeoIP's
+ built-in directory.
+ (For details, see <a class="xref" href="Bv9ARM.ch06.html#acl" title="acl Statement Definition and Usage">the section called &#8220;<span class="command"><strong>acl</strong></span> Statement Definition and
+ Usage&#8221;</a> about the
+ <span class="command"><strong>geoip</strong></span> ACL.)
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>key-directory</strong></span></span></dt>
+<dd>
+ <p>
+ When performing dynamic update of secure zones, the
+ directory where the public and private DNSSEC key files
+ should be found, 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="filename">bind.keys</code>,
+ <code class="filename">rndc.key</code> or
+ <code class="filename">session.key</code>.)
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>lmdb-mapsize</strong></span></span></dt>
+<dd>
+ <p>
+ When <span class="command"><strong>named</strong></span> 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 <span class="command"><strong>rndc addzone</strong></span>.
+ 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 named process. The
+ default of 32 megabytes was chosen to be usable with
+ 32-bit <span class="command"><strong>named</strong></span> 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>
+<dt><span class="term"><span class="command"><strong>managed-keys-directory</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies the directory in which to store the files that
+ track managed DNSSEC keys. By default, this is the working
+ directory. The directory <span class="emphasis"><em>must</em></span>
+ be writable by the effective user ID of the
+ <span class="command"><strong>named</strong></span> process.
+ </p>
+ <p>
+ If <span class="command"><strong>named</strong></span> is not configured to use views,
+ then managed keys for the server will be tracked in a single
+ file called <code class="filename">managed-keys.bind</code>.
+ Otherwise, managed keys will be tracked in separate files,
+ one file per view; each file name will be 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="filename">.mkeys</code>.
+ </p>
+ <p>
+ (Note: in previous releases, file names for views
+ always used the SHA256 hash of the view name. To ensure
+ compatibility after upgrade, if a file using the old
+ name format is found to exist, it will be used instead
+ of the new format.)
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>named-xfer</strong></span></span></dt>
+<dd>
+ <p>
+ <span class="emphasis"><em>This option is obsolete.</em></span> It
+ was used in <acronym class="acronym">BIND</acronym> 8 to specify
+ the pathname to the <span class="command"><strong>named-xfer</strong></span>
+ program. In <acronym class="acronym">BIND</acronym> 9, no separate
+ <span class="command"><strong>named-xfer</strong></span> program is needed;
+ its functionality is built into the name server.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>tkey-gssapi-keytab</strong></span></span></dt>
+<dd>
+ <p>
+ The KRB5 keytab file to use for GSS-TSIG updates. If
+ this option is set and tkey-gssapi-credential is not
+ set, then updates will be allowed with any key
+ matching a principal in the specified keytab.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>tkey-gssapi-credential</strong></span></span></dt>
+<dd>
+ <p>
+ The security credential with which the server should
+ authenticate keys requested by the GSS-TSIG protocol.
+ Currently only Kerberos 5 authentication is available
+ and the credential is a Kerberos principal which the
+ server can acquire through the default system key
+ file, normally <code class="filename">/etc/krb5.keytab</code>.
+ The location keytab file can be overridden using the
+ tkey-gssapi-keytab option. Normally this principal is
+ of the form "<strong class="userinput"><code>DNS/</code></strong><code class="varname">server.domain</code>".
+ To use GSS-TSIG, <span class="command"><strong>tkey-domain</strong></span> must
+ also be set if a specific keytab is not set with
+ tkey-gssapi-keytab.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>tkey-domain</strong></span></span></dt>
+<dd>
+ <p>
+ The domain appended to the names of all shared keys
+ generated with <span class="command"><strong>TKEY</strong></span>. When a
+ client requests a <span class="command"><strong>TKEY</strong></span> exchange,
+ it may or may not specify the desired name for the
+ key. If present, the name of the shared key will
+ be <code class="varname">client specified part</code> +
+ <code class="varname">tkey-domain</code>. Otherwise, the
+ name of the shared key will be <code class="varname">random hex
+ digits</code> + <code class="varname">tkey-domain</code>.
+ In most cases, the <span class="command"><strong>domainname</strong></span>
+ should be the server's domain name, or an otherwise
+ non-existent subdomain like
+ "_tkey.<code class="varname">domainname</code>". If you are
+ using GSS-TSIG, this variable must be defined, unless
+ you specify a specific keytab using tkey-gssapi-keytab.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>tkey-dhkey</strong></span></span></dt>
+<dd>
+ <p>
+ The Diffie-Hellman key used by the server
+ to generate shared keys with clients using the Diffie-Hellman
+ mode
+ of <span class="command"><strong>TKEY</strong></span>. The server must be
+ able to load the
+ public and private keys from files in the working directory.
+ In
+ most cases, the <code class="varname">key_name</code> should be the server's host name.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>cache-file</strong></span></span></dt>
+<dd>
+ <p>
+ This is for testing only. Do not use.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dump-file</strong></span></span></dt>
+<dd>
+ <p>
+ The pathname of the file the server dumps
+ the database to when instructed to do so with
+ <span class="command"><strong>rndc dumpdb</strong></span>.
+ If not specified, the default is <code class="filename">named_dump.db</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>memstatistics-file</strong></span></span></dt>
+<dd>
+ <p>
+ The pathname of the file the server writes memory
+ usage statistics to on exit. If not specified,
+ the default is <code class="filename">named.memstats</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>lock-file</strong></span></span></dt>
+<dd>
+ <p>
+ The pathname of a file on which <span class="command"><strong>named</strong></span> will
+ attempt to acquire a file lock when starting up for
+ the first time; if unsuccessful, the server will
+ will terminate, under the assumption that another
+ server is already running. If not specified, the default is
+ <code class="filename">/var/run/named/named.lock</code>.
+ </p>
+ <p>
+ Specifying <span class="command"><strong>lock-file none</strong></span> disables the
+ use of a lock file. <span class="command"><strong>lock-file</strong></span> is
+ ignored if <span class="command"><strong>named</strong></span> was run using the <code class="option">-X</code>
+ option, which overrides it. Changes to
+ <span class="command"><strong>lock-file</strong></span> are ignored if
+ <span class="command"><strong>named</strong></span> is being reloaded or
+ reconfigured; it is only effective when the server is
+ first started up.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>pid-file</strong></span></span></dt>
+<dd>
+ <p>
+ The pathname of the file the server writes its process ID
+ in. If not specified, the default is
+ <code class="filename">/var/run/named/named.pid</code>.
+ The PID file is used by programs that want to send signals to
+ the running
+ name server. Specifying <span class="command"><strong>pid-file none</strong></span> disables the
+ use of a PID file &#8212; no file will be written and any
+ existing one will be removed. Note that <span class="command"><strong>none</strong></span>
+ is a keyword, not a filename, and therefore is not enclosed
+ in
+ double quotes.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>recursing-file</strong></span></span></dt>
+<dd>
+ <p>
+ The pathname of the file the server dumps
+ the queries that are currently recursing when instructed
+ to do so with <span class="command"><strong>rndc recursing</strong></span>.
+ If not specified, the default is <code class="filename">named.recursing</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>statistics-file</strong></span></span></dt>
+<dd>
+ <p>
+ The pathname of the file the server appends statistics
+ to when instructed to do so using <span class="command"><strong>rndc stats</strong></span>.
+ If not specified, the default is <code class="filename">named.stats</code> in the
+ server's current directory. The format of the file is
+ described
+ in <a class="xref" href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called &#8220;The Statistics File&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>bindkeys-file</strong></span></span></dt>
+<dd>
+ <p>
+ The pathname of a file to override the built-in trusted
+ keys provided by <span class="command"><strong>named</strong></span>.
+ See the discussion of <span class="command"><strong>dnssec-validation</strong></span>
+ for details. If not specified, the default is
+ <code class="filename">/etc/bind.keys</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>secroots-file</strong></span></span></dt>
+<dd>
+ <p>
+ The pathname of the file the server dumps
+ security roots to when instructed to do so with
+ <span class="command"><strong>rndc secroots</strong></span>.
+ If not specified, the default is
+ <code class="filename">named.secroots</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>session-keyfile</strong></span></span></dt>
+<dd>
+ <p>
+ The pathname of the file into which to write a TSIG
+ session key generated by <span class="command"><strong>named</strong></span> for use by
+ <span class="command"><strong>nsupdate -l</strong></span>. If not specified, the
+ default is <code class="filename">/var/run/named/session.key</code>.
+ (See <a class="xref" href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called &#8220;Dynamic Update Policies&#8221;</a>, and in
+ particular the discussion of the
+ <span class="command"><strong>update-policy</strong></span> statement's
+ <strong class="userinput"><code>local</code></strong> option for more
+ information about this feature.)
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>session-keyname</strong></span></span></dt>
+<dd>
+ <p>
+ The key name to use for the TSIG session key.
+ If not specified, the default is "local-ddns".
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>session-keyalg</strong></span></span></dt>
+<dd>
+ <p>
+ 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>
+<dt><span class="term"><span class="command"><strong>port</strong></span></span></dt>
+<dd>
+ <p>
+ The UDP/TCP port number the server uses for
+ receiving and sending DNS protocol traffic.
+ The default is 53. This option is mainly intended for server
+ testing;
+ a server using a port other than 53 will not be able to
+ communicate with
+ the global DNS.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dscp</strong></span></span></dt>
+<dd>
+ <p>
+ The global Differentiated Services Code Point (DSCP)
+ value to classify outgoing DNS traffic on operating
+ systems that support DSCP. Valid values are 0 through 63.
+ It is not configured by default.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>random-device</strong></span></span></dt>
+<dd>
+ <p>
+ The source of entropy to be used by the server. Entropy is
+ primarily needed
+ for DNSSEC operations, such as TKEY transactions and dynamic
+ update of signed
+ zones. This options specifies the device (or file) from which
+ to read
+ entropy. If this is a file, operations requiring entropy will
+ fail when the
+ file has been exhausted. If not specified, the default value
+ is
+ <code class="filename">/dev/random</code>
+ (or equivalent) when present, and none otherwise. The
+ <span class="command"><strong>random-device</strong></span> option takes
+ effect during
+ the initial configuration load at server startup time and
+ is ignored on subsequent reloads.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>preferred-glue</strong></span></span></dt>
+<dd>
+ <p>
+ If specified, the listed type (A or AAAA) will be 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>
+<dt>
+<a name="root_delegation_only"></a><span class="term"><span class="command"><strong>root-delegation-only</strong></span></span>
+</dt>
+<dd>
+ <p>
+ Turn on enforcement of delegation-only in TLDs
+ (top level domains) 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
+ if they are signed by a child zone or not. The
+ authority section is also 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 ANY.
+ </p>
+ <p>
+ Note some TLDs are not delegation only (e.g. "DE", "LV",
+ "US" and "MUSEUM"). This list is not exhaustive.
+ </p>
+
+<pre class="programlisting">
+options {
+ root-delegation-only exclude { "de"; "lv"; "us"; "museum"; };
+};
+</pre>
+
+ </dd>
+<dt><span class="term"><span class="command"><strong>disable-algorithms</strong></span></span></dt>
+<dd>
+ <p>
+ Disable the specified DNSSEC algorithms at and below the
+ specified name.
+ Multiple <span class="command"><strong>disable-algorithms</strong></span>
+ statements are allowed.
+ Only the best match <span class="command"><strong>disable-algorithms</strong></span>
+ clause will be used to determine which algorithms are used.
+ </p>
+ <p>
+ If all supported algorithms are disabled, the zones covered
+ by the <span class="command"><strong>disable-algorithms</strong></span> will be treated
+ as insecure.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>disable-ds-digests</strong></span></span></dt>
+<dd>
+ <p>
+ Disable the specified DS/DLV digest types at and below the
+ specified name.
+ Multiple <span class="command"><strong>disable-ds-digests</strong></span>
+ statements are allowed.
+ Only the best match <span class="command"><strong>disable-ds-digests</strong></span>
+ clause will be used to determine which digest types are used.
+ </p>
+ <p>
+ If all supported digest types are disabled, the zones covered
+ by the <span class="command"><strong>disable-ds-digests</strong></span> will be treated
+ as insecure.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-lookaside</strong></span></span></dt>
+<dd>
+ <p>
+ When set, <span class="command"><strong>dnssec-lookaside</strong></span> provides the
+ validator with an alternate method to validate DNSKEY
+ records at the top of a zone. When a DNSKEY is at or
+ below a domain specified by the deepest
+ <span class="command"><strong>dnssec-lookaside</strong></span>, and the normal DNSSEC
+ validation has left the key untrusted, the trust-anchor
+ will be appended to the key name and a DLV record will be
+ looked up to see if it can validate the key. If the DLV
+ record validates a DNSKEY (similarly to the way a DS
+ record does) the DNSKEY RRset is deemed to be trusted.
+ </p>
+ <p>
+ If <span class="command"><strong>dnssec-lookaside</strong></span> is set to
+ <strong class="userinput"><code>no</code></strong>, then dnssec-lookaside
+ is not used.
+ </p>
+ <p>
+ NOTE: The ISC-provided DLV service at
+ <code class="literal">dlv.isc.org</code>, has been shut down.
+ The <span class="command"><strong>dnssec-lookaside auto;</strong></span>
+ configuration option, which set <span class="command"><strong>named</strong></span>
+ up to use ISC DLV with minimal configuration, has
+ accordingly been removed.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-must-be-secure</strong></span></span></dt>
+<dd>
+ <p>
+ Specify hierarchies which must be or may not be secure
+ (signed and validated). If <strong class="userinput"><code>yes</code></strong>,
+ then <span class="command"><strong>named</strong></span> will only accept answers if
+ they are secure. If <strong class="userinput"><code>no</code></strong>, then normal
+ DNSSEC validation applies allowing for insecure answers to
+ be accepted. The specified domain must be under a
+ <span class="command"><strong>trusted-keys</strong></span> or
+ <span class="command"><strong>managed-keys</strong></span> statement, or
+ <span class="command"><strong>dnssec-validation auto</strong></span> must be active.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dns64</strong></span></span></dt>
+<dd>
+ <p>
+ This directive instructs <span class="command"><strong>named</strong></span> 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
+ <span class="command"><strong>dns64</strong></span> 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 as per RFC 6052.
+ </p>
+ <p>
+ Additionally a reverse IP6.ARPA zone will be created for
+ the prefix to provide a mapping from the IP6.ARPA names
+ to the corresponding IN-ADDR.ARPA names using synthesized
+ CNAMEs. <span class="command"><strong>dns64-server</strong></span> and
+ <span class="command"><strong>dns64-contact</strong></span> can be used to specify
+ the name of the server and contact for the zones. These
+ are settable at the view / options level. These are
+ not settable on a per-prefix basis.
+ </p>
+ <p>
+ Each <span class="command"><strong>dns64</strong></span> supports an optional
+ <span class="command"><strong>clients</strong></span> ACL that determines which
+ clients are affected by this directive. If not defined,
+ it defaults to <strong class="userinput"><code>any;</code></strong>.
+ </p>
+ <p>
+ Each <span class="command"><strong>dns64</strong></span> supports an optional
+ <span class="command"><strong>mapped</strong></span> ACL that selects which
+ IPv4 addresses are to be mapped in the corresponding
+ A RRset. If not defined it defaults to
+ <strong class="userinput"><code>any;</code></strong>.
+ </p>
+ <p>
+ Normally, DNS64 won't apply to a domain name that
+ owns one or more AAAA records; these records will
+ simply be returned. The optional
+ <span class="command"><strong>exclude</strong></span> ACL allows specification
+ of a list of IPv6 addresses that will be ignored
+ if they appear in a domain name's AAAA records, and
+ DNS64 will be applied to any A records the domain
+ name owns. If not defined, <span class="command"><strong>exclude</strong></span>
+ defaults to ::ffff:0.0.0.0/96.
+ </p>
+ <p>
+ A optional <span class="command"><strong>suffix</strong></span> can also
+ be defined to set the bits trailing the mapped
+ IPv4 address bits. By default these bits are
+ set to <strong class="userinput"><code>::</code></strong>. The bits
+ matching the prefix and mapped IPv4 address
+ must be zero.
+ </p>
+ <p>
+ If <span class="command"><strong>recursive-only</strong></span> is set to
+ <span class="command"><strong>yes</strong></span> the DNS64 synthesis will
+ only happen for recursive queries. The default
+ is <span class="command"><strong>no</strong></span>.
+ </p>
+ <p>
+ If <span class="command"><strong>break-dnssec</strong></span> is set to
+ <span class="command"><strong>yes</strong></span> the DNS64 synthesis will
+ happen even if the result, if validated, would
+ cause a DNSSEC validation failure. If this option
+ is set to <span class="command"><strong>no</strong></span> (the default), the DO
+ is set on the incoming query, and there are RRSIGs on
+ the applicable records, then synthesis will not happen.
+ </p>
+<pre class="programlisting">
+ 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>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-loadkeys-interval</strong></span></span></dt>
+<dd>
+ <p>
+ When a zone is configured with <span class="command"><strong>auto-dnssec
+ maintain;</strong></span> 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="xref" href="man.dnssec-keygen.html" title="dnssec-keygen"><span class="refentrytitle"><span class="application">dnssec-keygen</span></span>(8)</a> and
+ <a class="xref" href="man.dnssec-settime.html" title="dnssec-settime"><span class="refentrytitle"><span class="application">dnssec-settime</span></span>(8)</a>). The
+ <span class="command"><strong>dnssec-loadkeys-interval</strong></span> option
+ sets the frequency of automatic repository checks, in
+ minutes. The default is <code class="literal">60</code> (1 hour),
+ the minimum is <code class="literal">1</code> (1 minute), and the
+ maximum is <code class="literal">1440</code> (24 hours); any higher
+ value is silently reduced.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-update-mode</strong></span></span></dt>
+<dd>
+ <p>
+ If this option is set to its default value of
+ <code class="literal">maintain</code> in a zone of type
+ <code class="literal">master</code> which is DNSSEC-signed
+ and configured to allow dynamic updates (see
+ <a class="xref" href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called &#8220;Dynamic Update Policies&#8221;</a>), and
+ if <span class="command"><strong>named</strong></span> has access to the
+ private signing key(s) for the zone, then
+ <span class="command"><strong>named</strong></span> will automatically sign all new
+ or changed records and maintain signatures for the zone
+ by regenerating RRSIG records whenever they approach
+ their expiration date.
+ </p>
+ <p>
+ If the option is changed to <code class="literal">no-resign</code>,
+ then <span class="command"><strong>named</strong></span> will sign all new or
+ changed records, but scheduled maintenance of
+ signatures is disabled.
+ </p>
+ <p>
+ With either of these settings, <span class="command"><strong>named</strong></span>
+ will reject updates to a DNSSEC-signed zone when the
+ signing keys are inactive or unavailable to
+ <span class="command"><strong>named</strong></span>. (A planned third option,
+ <code class="literal">external</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>
+<dt><span class="term"><span class="command"><strong>nta-lifetime</strong></span></span></dt>
+<dd>
+ <p>
+ Species the default lifetime, in seconds,
+ that will be used for negative trust anchors added
+ via <span class="command"><strong>rndc nta</strong></span>.
+ </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), <span class="command"><strong>named</strong></span> will
+ abort the DNSSEC validation process and treat the data as
+ insecure rather than bogus. This continues until the
+ NTA's lifetime is elapsed. NTAs persist
+ across <span class="command"><strong>named</strong></span> restarts.
+ </p>
+ <p>
+ For convenience, TTL-style time unit suffixes can be
+ used to specify the NTA lifetime in seconds, minutes
+ or hours. <code class="option">nta-lifetime</code> defaults to
+ one hour. It cannot exceed one week.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>nta-recheck</strong></span></span></dt>
+<dd>
+ <p>
+ Species how often to check whether negative
+ trust anchors added via <span class="command"><strong>rndc nta</strong></span>
+ 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,
+ <span class="command"><strong>named</strong></span> will periodically send 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 <span class="command"><strong>rndc nta -f</strong></span>, or
+ for all NTAs by setting <code class="option">nta-recheck</code>
+ 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. The default is five minutes. It
+ cannot be longer than <code class="option">nta-lifetime</code>
+ (which cannot be longer than a week).
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-zone-ttl</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies a maximum permissible TTL value in seconds.
+ For convenience, TTL-style time unit suffixes may be
+ used to specify the maximum value.
+ When loading a zone file using a
+ <code class="option">masterfile-format</code> of
+ <code class="constant">text</code> or <code class="constant">raw</code>,
+ any record encountered with a TTL higher than
+ <code class="option">max-zone-ttl</code> will cause the zone to
+ be rejected.
+ </p>
+ <p>
+ This is useful in DNSSEC-signed zones because when
+ rolling to a new DNSKEY, the old key needs to remain
+ available until RRSIG records have expired from
+ caches. The <code class="option">max-zone-ttl</code> option guarantees
+ that the largest TTL in the zone will be no higher
+ than the set value.
+ </p>
+ <p>
+ (NOTE: Because <code class="constant">map</code>-format files
+ load directly into memory, this option cannot be
+ used with them.)
+ </p>
+ <p>
+ The default value is <code class="constant">unlimited</code>.
+ A <code class="option">max-zone-ttl</code> of zero is treated as
+ <code class="constant">unlimited</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>serial-update-method</strong></span></span></dt>
+<dd>
+ <p>
+ Zones configured for dynamic DNS may use this
+ option to set the update method that will be used for
+ the zone serial number in the SOA record.
+ </p>
+ <p>
+ With the default setting of
+ <span class="command"><strong>serial-update-method increment;</strong></span>, the
+ SOA serial number will be incremented by one each time
+ the zone is updated.
+ </p>
+ <p>
+ When set to
+ <span class="command"><strong>serial-update-method unixtime;</strong></span>, the
+ SOA serial number will be 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
+ <span class="command"><strong>serial-update-method date;</strong></span>, the
+ new SOA serial number will be 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>
+<dt><span class="term"><span class="command"><strong>zone-statistics</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>full</code></strong>, the server will collect
+ statistical data on all zones (unless specifically
+ turned off on a per-zone basis by specifying
+ <span class="command"><strong>zone-statistics terse</strong></span> or
+ <span class="command"><strong>zone-statistics none</strong></span>
+ in the <span class="command"><strong>zone</strong></span> statement).
+ The default is <strong class="userinput"><code>terse</code></strong>, 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
+ <span class="command"><strong>statistics-channel</strong></span> or
+ using <span class="command"><strong>rndc stats</strong></span>, which
+ will dump them to the file listed
+ in the <span class="command"><strong>statistics-file</strong></span>. See
+ also <a class="xref" href="Bv9ARM.ch06.html#statsfile" title="The Statistics File">the section called &#8220;The Statistics File&#8221;</a>.
+ </p>
+ <p>
+ For backward compatibility with earlier versions
+ of BIND 9, the <span class="command"><strong>zone-statistics</strong></span>
+ option can also accept <strong class="userinput"><code>yes</code></strong>
+ or <strong class="userinput"><code>no</code></strong>; <strong class="userinput"><code>yes</code></strong>
+ has the same meaning as <strong class="userinput"><code>full</code></strong>.
+ As of <acronym class="acronym">BIND</acronym> 9.10,
+ <strong class="userinput"><code>no</code></strong> has the same meaning
+ as <strong class="userinput"><code>none</code></strong>; previously, it
+ was the same as <strong class="userinput"><code>terse</code></strong>.
+ </p>
+ </dd>
+</dl></div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="boolean_options"></a>Boolean Options</h4></div></div></div>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>automatic-interface-scan</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong> and supported by the OS,
+ automatically rescan network interfaces when the interface
+ addresses are added or removed. The default is
+ <strong class="userinput"><code>yes</code></strong>.
+ </p>
+ <p>
+ Currently the OS needs to support routing sockets for
+ <span class="command"><strong>automatic-interface-scan</strong></span> to be
+ supported.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-new-zones</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong>, then zones can be
+ added at runtime via <span class="command"><strong>rndc addzone</strong></span>.
+ The default is <strong class="userinput"><code>no</code></strong>.
+ </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="filename"><em class="replaceable"><code>viewname</code></em>.nzf</code>
+ (or, if <span class="command"><strong>named</strong></span> is compiled with
+ liblmdb, in an LMDB database file called
+ <code class="filename"><em class="replaceable"><code>viewname</code></em>.nzd</code>).
+ <em class="replaceable"><code>viewname</code></em> 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>
+ Zones added at runtime will have their configuration
+ stored either in a new-zone file (NZF) or a new-zone
+ database (NZD) depending on whether
+ <span class="command"><strong>named</strong></span> was linked with
+ liblmdb at compile time.
+ See <a class="xref" href="man.rndc.html" title="rndc"><span class="refentrytitle"><span class="application">rndc</span></span>(8)</a> for further details
+ about <span class="command"><strong>rndc addzone</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>auth-nxdomain</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong>, then the <span class="command"><strong>AA</strong></span> bit
+ is always set on NXDOMAIN responses, even if the server is
+ not actually
+ authoritative. The default is <strong class="userinput"><code>no</code></strong>;
+ this is
+ a change from <acronym class="acronym">BIND</acronym> 8. If you
+ are using very old DNS software, you
+ may need to set it to <strong class="userinput"><code>yes</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>deallocate-on-exit</strong></span></span></dt>
+<dd>
+ <p>
+ This option was used in <acronym class="acronym">BIND</acronym>
+ 8 to enable checking
+ for memory leaks on exit. <acronym class="acronym">BIND</acronym> 9 ignores the option and always performs
+ the checks.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>memstatistics</strong></span></span></dt>
+<dd>
+ <p>
+ Write memory statistics to the file specified by
+ <span class="command"><strong>memstatistics-file</strong></span> at exit.
+ The default is <strong class="userinput"><code>no</code></strong> unless
+ '-m record' is specified on the command line in
+ which case it is <strong class="userinput"><code>yes</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dialup</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong>, 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. This has different effects
+ according
+ to zone type and concentrates the zone maintenance so that
+ it all
+ happens in a short interval, once every <span class="command"><strong>heartbeat-interval</strong></span> and
+ hopefully during the one call. It also suppresses some of
+ the normal
+ zone maintenance traffic. The default is <strong class="userinput"><code>no</code></strong>.
+ </p>
+ <p>
+ The <span class="command"><strong>dialup</strong></span> option
+ may also be specified in the <span class="command"><strong>view</strong></span> and
+ <span class="command"><strong>zone</strong></span> statements,
+ in which case it overrides the global <span class="command"><strong>dialup</strong></span>
+ option.
+ </p>
+ <p>
+ If the zone is a master zone, then the server will send out a
+ NOTIFY
+ request to all the slaves (default). This should trigger the
+ zone serial
+ number check in the slave (providing it supports NOTIFY)
+ allowing the slave
+ to verify the zone while the connection is active.
+ The set of servers to which NOTIFY is sent can be controlled
+ by
+ <span class="command"><strong>notify</strong></span> and <span class="command"><strong>also-notify</strong></span>.
+ </p>
+ <p>
+ If the
+ zone is a slave or stub zone, then the server will suppress
+ the regular
+ "zone up to date" (refresh) queries and only perform them
+ when the
+ <span class="command"><strong>heartbeat-interval</strong></span> expires in
+ addition to sending
+ NOTIFY requests.
+ </p>
+ <p>
+ Finer control can be achieved by using
+ <strong class="userinput"><code>notify</code></strong> which only sends NOTIFY
+ messages,
+ <strong class="userinput"><code>notify-passive</code></strong> which sends NOTIFY
+ messages and
+ suppresses the normal refresh queries, <strong class="userinput"><code>refresh</code></strong>
+ which suppresses normal refresh processing and sends refresh
+ queries
+ when the <span class="command"><strong>heartbeat-interval</strong></span>
+ expires, and
+ <strong class="userinput"><code>passive</code></strong> which just disables normal
+ refresh
+ processing.
+ </p>
+
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.150in" class="1">
+<col width="1.150in" class="2">
+<col width="1.150in" class="3">
+<col width="1.150in" class="4">
+</colgroup>
+<tbody>
+<tr>
+<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>
+<td>
+ <p><span class="command"><strong>no</strong></span> (default)</p>
+ </td>
+<td>
+ <p>
+ yes
+ </p>
+ </td>
+<td>
+ <p>
+ no
+ </p>
+ </td>
+<td>
+ <p>
+ no
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>yes</strong></span></p>
+ </td>
+<td>
+ <p>
+ no
+ </p>
+ </td>
+<td>
+ <p>
+ yes
+ </p>
+ </td>
+<td>
+ <p>
+ yes
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>notify</strong></span></p>
+ </td>
+<td>
+ <p>
+ yes
+ </p>
+ </td>
+<td>
+ <p>
+ no
+ </p>
+ </td>
+<td>
+ <p>
+ yes
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>refresh</strong></span></p>
+ </td>
+<td>
+ <p>
+ no
+ </p>
+ </td>
+<td>
+ <p>
+ yes
+ </p>
+ </td>
+<td>
+ <p>
+ no
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>passive</strong></span></p>
+ </td>
+<td>
+ <p>
+ no
+ </p>
+ </td>
+<td>
+ <p>
+ no
+ </p>
+ </td>
+<td>
+ <p>
+ no
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>notify-passive</strong></span></p>
+ </td>
+<td>
+ <p>
+ no
+ </p>
+ </td>
+<td>
+ <p>
+ no
+ </p>
+ </td>
+<td>
+ <p>
+ yes
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+
+ <p>
+ Note that normal NOTIFY processing is not affected by
+ <span class="command"><strong>dialup</strong></span>.
+ </p>
+
+ </dd>
+<dt><span class="term"><span class="command"><strong>fake-iquery</strong></span></span></dt>
+<dd>
+ <p>
+ In <acronym class="acronym">BIND</acronym> 8, this option
+ enabled simulating the obsolete DNS query type
+ IQUERY. <acronym class="acronym">BIND</acronym> 9 never does
+ IQUERY simulation.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>fetch-glue</strong></span></span></dt>
+<dd>
+ <p>
+ This option is obsolete.
+ In BIND 8, <strong class="userinput"><code>fetch-glue yes</code></strong>
+ caused the server to attempt to fetch glue resource records
+ it
+ didn't have when constructing the additional
+ data section of a response. This is now considered a bad
+ idea
+ and BIND 9 never does it.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>flush-zones-on-shutdown</strong></span></span></dt>
+<dd>
+ <p>
+ When the nameserver exits due receiving SIGTERM,
+ flush or do not flush any pending zone writes. The default
+ is
+ <span class="command"><strong>flush-zones-on-shutdown</strong></span> <strong class="userinput"><code>no</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>geoip-use-ecs</strong></span></span></dt>
+<dd>
+ <p>
+ When BIND is compiled with GeoIP support and configured
+ with "geoip" ACL elements, this option indicates whether
+ the EDNS Client Subnet option, if present in a request,
+ should be used for matching against the GeoIP database.
+ The default is
+ <span class="command"><strong>geoip-use-ecs</strong></span> <strong class="userinput"><code>yes</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>has-old-clients</strong></span></span></dt>
+<dd>
+ <p>
+ This option was incorrectly implemented
+ in <acronym class="acronym">BIND</acronym> 8, and is ignored by <acronym class="acronym">BIND</acronym> 9.
+ To achieve the intended effect
+ of
+ <span class="command"><strong>has-old-clients</strong></span> <strong class="userinput"><code>yes</code></strong>, specify
+ the two separate options <span class="command"><strong>auth-nxdomain</strong></span> <strong class="userinput"><code>yes</code></strong>
+ and <span class="command"><strong>rfc2308-type1</strong></span> <strong class="userinput"><code>no</code></strong> instead.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>host-statistics</strong></span></span></dt>
+<dd>
+ <p>
+ In BIND 8, this enabled keeping of
+ statistics for every host that the name server interacts
+ with.
+ Not implemented in BIND 9.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>root-key-sentinel</strong></span></span></dt>
+<dd>
+ <p>
+ Respond to root key sentinel probes as described in
+ draft-ietf-dnsop-kskroll-sentinel-08. The default is
+ <strong class="userinput"><code>yes</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>maintain-ixfr-base</strong></span></span></dt>
+<dd>
+ <p>
+ <span class="emphasis"><em>This option is obsolete</em></span>.
+ It was used in <acronym class="acronym">BIND</acronym> 8 to
+ determine whether a transaction log was
+ kept for Incremental Zone Transfer. <acronym class="acronym">BIND</acronym> 9 maintains a transaction
+ log whenever possible. If you need to disable outgoing
+ incremental zone
+ transfers, use <span class="command"><strong>provide-ixfr</strong></span> <strong class="userinput"><code>no</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>message-compression</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong>, DNS name compression is
+ used in responses to regular queries (not including
+ AXFR or IXFR, which always uses compression). Setting
+ this option to <strong class="userinput"><code>no</code></strong> 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 RFC 1123 Section
+ 6.1.3.2. The default is <strong class="userinput"><code>yes</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>minimal-responses</strong></span></span></dt>
+<dd>
+ <p>
+ If set to <strong class="userinput"><code>yes</code></strong>, then when generating
+ responses the server will only add records to the authority
+ and additional data sections when they are required (e.g.
+ delegations, negative responses). This may improve the
+ performance of the server.
+ </p>
+ <p>
+ When set to <strong class="userinput"><code>no-auth</code></strong>, the
+ server will omit records from the authority section
+ unless they are required, but it may still add
+ records to the additional section. When set to
+ <strong class="userinput"><code>no-auth-recursive</code></strong>, this
+ is only done if the query is recursive. These
+ settings are useful when answering stub clients,
+ which usually ignore the authority section.
+ <strong class="userinput"><code>no-auth-recursive</code></strong> is
+ designed for mixed-mode servers which handle
+ both authoritative and recursive queries.
+ </p>
+ <p>
+ The default is <strong class="userinput"><code>no</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>minimal-any</strong></span></span></dt>
+<dd>
+ <p>
+ If set to <strong class="userinput"><code>yes</code></strong>, then when
+ generating a positive response to a query of type
+ ANY over UDP, the server will reply with only one
+ of the RRsets for the query name, and its covering
+ RRSIGs if any, instead of replying with all known
+ RRsets for the name. Similarly, a query for type
+ RRSIG will be 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, <code class="option">minimal-responses</code> is
+ turned on for these queries, so no unnecessary records
+ will be added to the authority or additional sections.
+ The default is <strong class="userinput"><code>no</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>multiple-cnames</strong></span></span></dt>
+<dd>
+ <p>
+ This option was used in <acronym class="acronym">BIND</acronym> 8 to allow
+ a domain name to have multiple CNAME records in violation of
+ the DNS standards. <acronym class="acronym">BIND</acronym> 9.2 onwards
+ always strictly enforces the CNAME rules both in master
+ files and dynamic updates.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>notify</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong> (the default),
+ DNS NOTIFY messages are sent when a zone the server is
+ authoritative for
+ changes, see <a class="xref" href="Bv9ARM.ch04.html#notify" title="Notify">the section called &#8220;Notify&#8221;</a>. The messages are
+ sent to the
+ servers listed in the zone's NS records (except the master
+ server identified
+ in the SOA MNAME field), and to any servers listed in the
+ <span class="command"><strong>also-notify</strong></span> option.
+ </p>
+ <p>
+ If <strong class="userinput"><code>master-only</code></strong>, notifies are only
+ sent
+ for master zones.
+ If <strong class="userinput"><code>explicit</code></strong>, notifies are sent only
+ to
+ servers explicitly listed using <span class="command"><strong>also-notify</strong></span>.
+ If <strong class="userinput"><code>no</code></strong>, no notifies are sent.
+ </p>
+ <p>
+ The <span class="command"><strong>notify</strong></span> option may also be
+ specified in the <span class="command"><strong>zone</strong></span>
+ statement,
+ in which case it overrides the <span class="command"><strong>options notify</strong></span> statement.
+ It would only be necessary to turn off this option if it
+ caused slaves
+ to crash.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>notify-to-soa</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong> do not check the nameservers
+ 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 master.
+ Sometimes, however, a slave is listed as the SOA MNAME in
+ hidden master configurations and in that case you would
+ want the ultimate master to still send NOTIFY messages to
+ all the nameservers listed in the NS RRset.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>recursion</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong>, and a
+ DNS query requests recursion, then the server will attempt
+ to do
+ all the work required to answer the query. If recursion is
+ off
+ and the server does not already know the answer, it will
+ return a
+ referral response. The default is
+ <strong class="userinput"><code>yes</code></strong>.
+ Note that setting <span class="command"><strong>recursion no</strong></span> 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 the server's internal
+ operation, such as NOTIFY address lookups.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>request-nsid</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong>, 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 <span class="command"><strong>resolver</strong></span> category at level
+ <span class="command"><strong>info</strong></span>.
+ The default is <strong class="userinput"><code>no</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>request-sit</strong></span></span></dt>
+<dd>
+ <p>
+ This experimental option is obsolete.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>require-server-cookie</strong></span></span></dt>
+<dd>
+ <p>
+ 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 no existent
+ server cookie.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>answer-cookie</strong></span></span></dt>
+<dd>
+ <p>
+ When set to the default value of <strong class="userinput"><code>yes</code></strong>,
+ COOKIE EDNS options will be sent when applicable in
+ replies to client queries. If set to
+ <strong class="userinput"><code>no</code></strong>, COOKIE EDNS options will not
+ be sent in replies. This can only be set at the global
+ options level, not per-view.
+ </p>
+ <p>
+ <span class="command"><strong>answer-cookie no</strong></span> is only intended as a
+ temporary measure, for use when <span class="command"><strong>named</strong></span>
+ 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>
+<dt><span class="term"><span class="command"><strong>send-cookie</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong>, then a COOKIE EDNS
+ option is sent along with the query. If the
+ resolver has previously talked to 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
+ <span class="command"><strong>nocookie-udp-size</strong></span> option.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>nocookie-udp-size</strong></span></span></dt>
+<dd>
+ <p>
+ Sets the maximum size of UDP responses that will be
+ sent to queries without a valid server COOKIE. A value
+ below 128 will be silently raised to 128. The default
+ value is 4096, but the <span class="command"><strong>max-udp-size</strong></span>
+ option may further limit the response size.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>sit-secret</strong></span></span></dt>
+<dd>
+ <p>
+ This experimental option is obsolete.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>cookie-algorithm</strong></span></span></dt>
+<dd>
+ <p>
+ Set the algorithm to be used when generating the
+ server cookie. One of "aes", "sha1" or "sha256".
+ The default is "aes" if supported by the cryptographic
+ library or otherwise "sha256".
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>cookie-secret</strong></span></span></dt>
+<dd>
+ <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
+ will generate a random secret at startup. The
+ shared secret is encoded as a hex string and needs
+ to be 128 bits for AES128, 160 bits for SHA1 and
+ 256 bits for SHA256.
+ </p>
+ <p>
+ If there are multiple secrets specified, the first
+ one listed in <code class="filename">named.conf</code> is
+ used to generate new server cookies. The others
+ will only be used to verify returned cookies.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>rfc2308-type1</strong></span></span></dt>
+<dd>
+ <p>
+ Setting this to <strong class="userinput"><code>yes</code></strong> will
+ cause the server to send NS records along with the SOA
+ record for negative
+ answers. The default is <strong class="userinput"><code>no</code></strong>.
+ </p>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ Not yet implemented in <acronym class="acronym">BIND</acronym>
+ 9.
+ </p>
+ </div>
+ </dd>
+<dt><span class="term"><span class="command"><strong>trust-anchor-telemetry</strong></span></span></dt>
+<dd>
+ <p>
+ Causes <span class="command"><strong>named</strong></span> to send specially-formed
+ queries once per day to domains for which trust anchors
+ have been configured via <span class="command"><strong>trusted-keys</strong></span>,
+ <span class="command"><strong>managed-keys</strong></span>, or
+ <span class="command"><strong>dnssec-validation auto</strong></span>.
+ </p>
+ <p>
+ The query name used for these queries has the
+ form "_ta-xxxx(-xxxx)(...)".&lt;domain&gt;, 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 will
+ be 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 <strong class="userinput"><code>yes</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>use-id-pool</strong></span></span></dt>
+<dd>
+ <p>
+ <span class="emphasis"><em>This option is obsolete</em></span>.
+ <acronym class="acronym">BIND</acronym> 9 always allocates query
+ IDs from a pool.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>use-ixfr</strong></span></span></dt>
+<dd>
+ <p>
+ <span class="emphasis"><em>This option is obsolete</em></span>.
+ If you need to disable IXFR to a particular server or
+ servers, see
+ the information on the <span class="command"><strong>provide-ixfr</strong></span> option
+ in <a class="xref" href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and Usage">the section called &#8220;<span class="command"><strong>server</strong></span> Statement Definition and
+ Usage&#8221;</a>.
+ See also
+ <a class="xref" href="Bv9ARM.ch04.html#incremental_zone_transfers" title="Incremental Zone Transfers (IXFR)">the section called &#8220;Incremental Zone Transfers (IXFR)&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>provide-ixfr</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>provide-ixfr</strong></span> in
+ <a class="xref" href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and Usage">the section called &#8220;<span class="command"><strong>server</strong></span> Statement Definition and
+ Usage&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>request-ixfr</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>request-ixfr</strong></span> in
+ <a class="xref" href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and Usage">the section called &#8220;<span class="command"><strong>server</strong></span> Statement Definition and
+ Usage&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>request-expire</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>request-expire</strong></span> in
+ <a class="xref" href="Bv9ARM.ch06.html#server_statement_definition_and_usage" title="server Statement Definition and Usage">the section called &#8220;<span class="command"><strong>server</strong></span> Statement Definition and
+ Usage&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>treat-cr-as-space</strong></span></span></dt>
+<dd>
+ <p>
+ This option was used in <acronym class="acronym">BIND</acronym>
+ 8 to make
+ the server treat carriage return ("<span class="command"><strong>\r</strong></span>") characters the same way
+ as a space or tab character,
+ to facilitate loading of zone files on a UNIX system that
+ were generated
+ on an NT or DOS machine. In <acronym class="acronym">BIND</acronym> 9, both UNIX "<span class="command"><strong>\n</strong></span>"
+ and NT/DOS "<span class="command"><strong>\r\n</strong></span>" newlines
+ are always accepted,
+ and the option is ignored.
+ </p>
+ </dd>
+<dt>
+<span class="term"><span class="command"><strong>additional-from-auth</strong></span>, </span><span class="term"><span class="command"><strong>additional-from-cache</strong></span></span>
+</dt>
+<dd>
+
+ <p>
+ These options control the behavior of an authoritative
+ server when
+ answering queries which have additional data, or when
+ following CNAME
+ and DNAME chains.
+ </p>
+
+ <p>
+ When both of these options are set to <strong class="userinput"><code>yes</code></strong>
+ (the default) and a
+ query is being answered from authoritative data (a zone
+ configured into the server), the additional data section of
+ the
+ reply will be filled in using data from other authoritative
+ zones
+ and from the cache. In some situations this is undesirable,
+ such
+ as when there is concern over the correctness of the cache,
+ or
+ in servers where slave zones may be added and modified by
+ untrusted third parties. Also, avoiding
+ the search for this additional data will speed up server
+ operations
+ at the possible expense of additional queries to resolve
+ what would
+ otherwise be provided in the additional section.
+ </p>
+
+ <p>
+ For example, if a query asks for an MX record for host <code class="literal">foo.example.com</code>,
+ and the record found is "<code class="literal">MX 10 mail.example.net</code>", normally the address
+ records (A and AAAA) for <code class="literal">mail.example.net</code> will be provided as well,
+ if known, even though they are not in the example.com zone.
+ Setting these options to <span class="command"><strong>no</strong></span>
+ disables this behavior and makes
+ the server only search for additional data in the zone it
+ answers from.
+ </p>
+
+ <p>
+ These options are intended for use in authoritative-only
+ servers, or in authoritative-only views. Attempts to set
+ them to <span class="command"><strong>no</strong></span> without also
+ specifying
+ <span class="command"><strong>recursion no</strong></span> will cause the
+ server to
+ ignore the options and log a warning message.
+ </p>
+
+ <p>
+ Specifying <span class="command"><strong>additional-from-cache no</strong></span> actually
+ disables the use of the cache not only for additional data
+ lookups
+ but also when looking up the answer. This is usually the
+ desired
+ behavior in an authoritative-only server where the
+ correctness of
+ the cached data is an issue.
+ </p>
+
+ <p>
+ When a name server is non-recursively queried for a name
+ that is not
+ below the apex of any served zone, it normally answers with
+ an
+ "upwards referral" to the root servers or the servers of
+ some other
+ known parent of the query name. Since the data in an
+ upwards referral
+ comes from the cache, the server will not be able to provide
+ upwards
+ referrals when <span class="command"><strong>additional-from-cache no</strong></span>
+ has been specified. Instead, it will respond to such
+ queries
+ with REFUSED. This should not cause any problems since
+ upwards referrals are not required for the resolution
+ process.
+ </p>
+
+ </dd>
+<dt><span class="term"><span class="command"><strong>match-mapped-addresses</strong></span></span></dt>
+<dd>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong>, then an
+ IPv4-mapped IPv6 address will match 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,
+ <span class="command"><strong>named</strong></span> now solves this problem
+ internally. The use of this option is discouraged.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>filter-aaaa-on-v4</strong></span></span></dt>
+<dd>
+ <p>
+ This option is only available when
+ <acronym class="acronym">BIND</acronym> 9 is compiled with the
+ <strong class="userinput"><code>--enable-filter-aaaa</code></strong> option on the
+ "configure" command line. It is intended to help the
+ transition from IPv4 to IPv6 by not giving IPv6 addresses
+ to DNS clients unless they have connections to the IPv6
+ Internet. This is not recommended unless absolutely
+ necessary. The default is <strong class="userinput"><code>no</code></strong>.
+ The <span class="command"><strong>filter-aaaa-on-v4</strong></span> option
+ may also be specified in <span class="command"><strong>view</strong></span> statements
+ to override the global <span class="command"><strong>filter-aaaa-on-v4</strong></span>
+ option.
+ </p>
+ <p>
+ If <strong class="userinput"><code>yes</code></strong>,
+ the DNS client is at an IPv4 address, in <span class="command"><strong>filter-aaaa</strong></span>,
+ and if the response does not include DNSSEC signatures,
+ then all AAAA records are deleted from the response.
+ This filtering applies to all responses and not only
+ authoritative responses.
+ </p>
+ <p>
+ If <strong class="userinput"><code>break-dnssec</code></strong>,
+ then AAAA records are deleted even when DNSSEC is enabled.
+ As suggested by the name, this makes the response not verify,
+ because the DNSSEC protocol is designed detect deletions.
+ </p>
+ <p>
+ This mechanism can erroneously cause other servers to
+ not give AAAA records to their clients.
+ A recursing server with both IPv6 and IPv4 network connections
+ that queries an authoritative server using this mechanism
+ via IPv4 will be denied AAAA records even if its client is
+ using IPv6.
+ </p>
+ <p>
+ This mechanism is applied to authoritative as well as
+ non-authoritative records.
+ A client using IPv4 that is not allowed recursion can
+ erroneously be given AAAA records because the server is not
+ allowed to check for A records.
+ </p>
+ <p>
+ Some AAAA records are given to IPv4 clients in glue records.
+ IPv4 clients that are servers can then erroneously
+ answer requests for AAAA records received via IPv4.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>filter-aaaa-on-v6</strong></span></span></dt>
+<dd>
+ <p>
+ Identical to <span class="command"><strong>filter-aaaa-on-v4</strong></span>,
+ except it filters AAAA responses to queries from IPv6
+ clients instead of IPv4 clients. To filter all
+ responses, set both options to <strong class="userinput"><code>yes</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>ixfr-from-differences</strong></span></span></dt>
+<dd>
+ <p>
+ When <strong class="userinput"><code>yes</code></strong> and the server loads a new
+ version of a master zone from its zone file or receives a
+ new version of a slave file via zone transfer, it will
+ compare the new version to the previous one and calculate
+ a set of differences. The differences are then logged in
+ the zone's journal file such that the changes can be
+ transmitted to downstream slaves 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
+ master.
+ In particular, if the new version of a zone is completely
+ different from the previous one, the set of differences
+ will be of a size comparable to the combined size of the
+ old and new zone version, and the server will need to
+ temporarily allocate memory to hold this complete
+ difference set.
+ </p>
+ <p><span class="command"><strong>ixfr-from-differences</strong></span>
+ also accepts <span class="command"><strong>master</strong></span> and
+ <span class="command"><strong>slave</strong></span> at the view and options
+ levels which causes
+ <span class="command"><strong>ixfr-from-differences</strong></span> to be enabled for
+ all <span class="command"><strong>master</strong></span> or
+ <span class="command"><strong>slave</strong></span> zones respectively.
+ It is off by default.
+ </p>
+ <p>
+ Note: if inline signing is enabled for a zone, the
+ user-provided <span class="command"><strong>ixfr-from-differences</strong></span>
+ setting is ignored for that zone.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>multi-master</strong></span></span></dt>
+<dd>
+ <p>
+ This should be set when you have multiple masters for a zone
+ and the
+ addresses refer to different machines. If <strong class="userinput"><code>yes</code></strong>, <span class="command"><strong>named</strong></span> will
+ not log
+ when the serial number on the master is less than what <span class="command"><strong>named</strong></span>
+ currently
+ has. The default is <strong class="userinput"><code>no</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>auto-dnssec</strong></span></span></dt>
+<dd>
+ <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>
+ <span class="command"><strong>auto-dnssec allow;</strong></span> permits
+ keys to be updated and the zone fully re-signed
+ whenever the user issues the command <span class="command"><strong>rndc sign
+ <em class="replaceable"><code>zonename</code></em></strong></span>.
+ </p>
+ <p>
+ <span class="command"><strong>auto-dnssec maintain;</strong></span> includes the
+ above, but also automatically adjusts the zone's DNSSEC
+ keys on schedule, according to the keys' timing metadata
+ (see <a class="xref" href="man.dnssec-keygen.html" title="dnssec-keygen"><span class="refentrytitle"><span class="application">dnssec-keygen</span></span>(8)</a> and
+ <a class="xref" href="man.dnssec-settime.html" title="dnssec-settime"><span class="refentrytitle"><span class="application">dnssec-settime</span></span>(8)</a>). The command
+ <span class="command"><strong>rndc sign
+ <em class="replaceable"><code>zonename</code></em></strong></span> causes
+ <span class="command"><strong>named</strong></span> to load keys from the key
+ repository and sign the zone with all keys that are
+ active.
+ <span class="command"><strong>rndc loadkeys
+ <em class="replaceable"><code>zonename</code></em></strong></span> causes
+ <span class="command"><strong>named</strong></span> 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 will be searched
+ for changes periodically, regardless of whether
+ <span class="command"><strong>rndc loadkeys</strong></span> is used. The recheck
+ interval is defined by
+ <span class="command"><strong>dnssec-loadkeys-interval</strong></span>.)
+ </p>
+ <p>
+ The default setting is <span class="command"><strong>auto-dnssec off</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-enable</strong></span></span></dt>
+<dd>
+ <p>
+ This indicates whether DNSSEC-related resource
+ records are to be returned by <span class="command"><strong>named</strong></span>.
+ If set to <strong class="userinput"><code>no</code></strong>,
+ <span class="command"><strong>named</strong></span> will not return DNSSEC-related
+ resource records unless specifically queried for.
+ The default is <strong class="userinput"><code>yes</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-validation</strong></span></span></dt>
+<dd>
+ <p>
+ Enable DNSSEC validation in <span class="command"><strong>named</strong></span>.
+ Note <span class="command"><strong>dnssec-enable</strong></span> also needs to be
+ set to <strong class="userinput"><code>yes</code></strong> to be effective.
+ If set to <strong class="userinput"><code>no</code></strong>, DNSSEC validation
+ is disabled.
+ </p>
+ <p>
+ If set to <strong class="userinput"><code>auto</code></strong>, DNSSEC validation
+ is enabled, and a default trust anchor for the DNS root
+ zone is used. If set to <strong class="userinput"><code>yes</code></strong>,
+ DNSSEC validation is enabled, but a trust anchor must be
+ manually configured using a <span class="command"><strong>trusted-keys</strong></span>
+ or <span class="command"><strong>managed-keys</strong></span> statement. The default
+ is <strong class="userinput"><code>yes</code></strong>.
+ </p>
+ <p>
+ The default root trust anchor is stored in the file
+ <code class="filename">bind.keys</code>.
+ <span class="command"><strong>named</strong></span> will load that key at
+ startup if <span class="command"><strong>dnssec-validation</strong></span> is
+ set to <code class="constant">auto</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="filename">bind.keys</code> can be downloaded
+ from <a class="link" href="https://www.isc.org/bind-keys" target="_top">https://www.isc.org/bind-keys</a>.
+ </p>
+ <p>
+ To prevent problems if <code class="filename">bind.keys</code> is
+ not found, the current trust anchor is also compiled in
+ to <span class="command"><strong>named</strong></span>. Relying on this is not
+ recommended, however, as it requires <span class="command"><strong>named</strong></span>
+ to be recompiled with a new key when the root key expires.)
+ </p>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ <span class="command"><strong>named</strong></span> <span class="emphasis"><em>only</em></span>
+ loads the root key from <code class="filename">bind.keys</code>.
+ The file cannot be used to store keys for other zones.
+ The root key in <code class="filename">bind.keys</code> is ignored
+ if <span class="command"><strong>dnssec-validation auto</strong></span> 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
+ <span class="command"><strong>dnssec-validation</strong></span> is off.
+ </p>
+ </div>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-accept-expired</strong></span></span></dt>
+<dd>
+ <p>
+ Accept expired signatures when verifying DNSSEC signatures.
+ The default is <strong class="userinput"><code>no</code></strong>.
+ Setting this option to <strong class="userinput"><code>yes</code></strong>
+ leaves <span class="command"><strong>named</strong></span> vulnerable to
+ replay attacks.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>querylog</strong></span></span></dt>
+<dd>
+ <p>
+ Specify whether query logging should be started when <span class="command"><strong>named</strong></span>
+ starts.
+ If <span class="command"><strong>querylog</strong></span> is not specified,
+ then the query logging
+ is determined by the presence of the logging category <span class="command"><strong>queries</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-names</strong></span></span></dt>
+<dd>
+ <p>
+ This option is used to restrict the character set and syntax
+ of
+ certain domain names in master files and/or DNS responses
+ received
+ from the network. The default varies according to usage
+ area. For
+ <span class="command"><strong>master</strong></span> zones the default is <span class="command"><strong>fail</strong></span>.
+ For <span class="command"><strong>slave</strong></span> zones the default
+ is <span class="command"><strong>warn</strong></span>.
+ For answers received from the network (<span class="command"><strong>response</strong></span>)
+ the default is <span class="command"><strong>ignore</strong></span>.
+ </p>
+ <p>
+ The rules for legal hostnames and mail domains are derived
+ from RFC 952 and RFC 821 as modified by RFC 1123.
+ </p>
+ <p><span class="command"><strong>check-names</strong></span>
+ 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 also applies to the RDATA of PTR records where the owner
+ name indicated that it is a reverse lookup of a hostname
+ (the owner name ends in IN-ADDR.ARPA, IP6.ARPA, or IP6.INT).
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-dup-records</strong></span></span></dt>
+<dd>
+ <p>
+ Check master zones for records that are treated as different
+ by DNSSEC but are semantically equal in plain DNS. The
+ default is to <span class="command"><strong>warn</strong></span>. Other possible
+ values are <span class="command"><strong>fail</strong></span> and
+ <span class="command"><strong>ignore</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-mx</strong></span></span></dt>
+<dd>
+ <p>
+ Check whether the MX record appears to refer to a IP address.
+ The default is to <span class="command"><strong>warn</strong></span>. Other possible
+ values are <span class="command"><strong>fail</strong></span> and
+ <span class="command"><strong>ignore</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-wildcard</strong></span></span></dt>
+<dd>
+ <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 failure
+ to understand the wildcard matching algorithm (RFC 1034).
+ This option
+ affects master zones. The default (<span class="command"><strong>yes</strong></span>) is to check
+ for non-terminal wildcards and issue a warning.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-integrity</strong></span></span></dt>
+<dd>
+ <p>
+ Perform post load zone integrity checks on master
+ zones. This 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
+ <span class="command"><strong>named-checkzone</strong></span>).
+ For NS records only names below top of zone are
+ checked (for out-of-zone names and glue consistency
+ checks use <span class="command"><strong>named-checkzone</strong></span>).
+ The default is <span class="command"><strong>yes</strong></span>.
+ </p>
+ <p>
+ The use of the SPF record for publishing 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 and can be suppressed with
+ <span class="command"><strong>check-spf</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-mx-cname</strong></span></span></dt>
+<dd>
+ <p>
+ If <span class="command"><strong>check-integrity</strong></span> is set then
+ fail, warn or ignore MX records that refer
+ to CNAMES. The default is to <span class="command"><strong>warn</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-srv-cname</strong></span></span></dt>
+<dd>
+ <p>
+ If <span class="command"><strong>check-integrity</strong></span> is set then
+ fail, warn or ignore SRV records that refer
+ to CNAMES. The default is to <span class="command"><strong>warn</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-sibling</strong></span></span></dt>
+<dd>
+ <p>
+ When performing integrity checks, also check that
+ sibling glue exists. The default is <span class="command"><strong>yes</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-spf</strong></span></span></dt>
+<dd>
+ <p>
+ If <span class="command"><strong>check-integrity</strong></span> is set then
+ 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
+ <span class="command"><strong>warn</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>zero-no-soa-ttl</strong></span></span></dt>
+<dd>
+ <p>
+ 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 <span class="command"><strong>yes</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>zero-no-soa-ttl-cache</strong></span></span></dt>
+<dd>
+ <p>
+ When caching a negative response to a SOA query
+ set the TTL to zero.
+ The default is <span class="command"><strong>no</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>update-check-ksk</strong></span></span></dt>
+<dd>
+ <p>
+ When set to the default value of <code class="literal">yes</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="literal">no</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 <span class="command"><strong>dnssec-signzone -z</strong></span>
+ command line option.
+ </p>
+ <p>
+ When this option is set to <code class="literal">yes</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 will be ignored
+ for that algorithm.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-dnskey-kskonly</strong></span></span></dt>
+<dd>
+ <p>
+ When this option and <span class="command"><strong>update-check-ksk</strong></span>
+ are both set to <code class="literal">yes</code>, only key-signing
+ keys (that is, keys with the KSK bit set) will be used
+ to sign the DNSKEY RRset at the zone apex. Zone-signing
+ keys (keys without the KSK bit set) will be used to sign
+ the remainder of the zone, but not the DNSKEY RRset.
+ This is similar to the
+ <span class="command"><strong>dnssec-signzone -x</strong></span> command line option.
+ </p>
+ <p>
+ The default is <span class="command"><strong>no</strong></span>. If
+ <span class="command"><strong>update-check-ksk</strong></span> is set to
+ <code class="literal">no</code>, this option is ignored.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>try-tcp-refresh</strong></span></span></dt>
+<dd>
+ <p>
+ Try to refresh the zone using TCP if UDP queries fail.
+ For BIND 8 compatibility, the default is
+ <span class="command"><strong>yes</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-secure-to-insecure</strong></span></span></dt>
+<dd>
+ <p>
+ Allow a dynamic zone to transition from secure to
+ insecure (i.e., signed to unsigned) by deleting all
+ of the DNSKEY records. The default is <span class="command"><strong>no</strong></span>.
+ If set to <span class="command"><strong>yes</strong></span>, and if the DNSKEY RRset
+ at the zone apex is deleted, all RRSIG and NSEC records
+ will be removed from the zone as well.
+ </p>
+ <p>
+ If the zone uses NSEC3, then it is also necessary to
+ delete the NSEC3PARAM RRset from the zone apex; this will
+ cause 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
+ <span class="command"><strong>auto-dnssec maintain</strong></span> and the
+ private keys remain accessible in the key repository,
+ then the zone will be automatically signed again the
+ next time <span class="command"><strong>named</strong></span> is started.
+ </p>
+ </dd>
+</dl></div>
+
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="forwarding"></a>Forwarding</h4></div></div></div>
+
+ <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>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>forward</strong></span></span></dt>
+<dd>
+ <p>
+ This option is only meaningful if the
+ forwarders list is not empty. A value of <code class="varname">first</code>,
+ the default, causes the server to query the forwarders
+ first &#8212; and
+ if that doesn't answer the question, the server will then
+ look for
+ the answer itself. If <code class="varname">only</code> is
+ specified, the
+ server will only query the forwarders.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>forwarders</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies the IP addresses to be used
+ for forwarding. The default is the empty list (no
+ forwarding).
+ </p>
+ </dd>
+</dl></div>
+
+ <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. You can set particular domains to use different
+ forwarders,
+ or have a different <span class="command"><strong>forward only/first</strong></span> behavior,
+ or not forward at all, see <a class="xref" href="Bv9ARM.ch06.html#zone_statement_grammar" title="zone Statement Grammar">the section called &#8220;<span class="command"><strong>zone</strong></span>
+ Statement Grammar&#8221;</a>.
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="dual_stack"></a>Dual-stack Servers</h4></div></div></div>
+
+ <p>
+ Dual-stack servers are used as servers of last resort to work
+ around
+ problems in reachability due the lack of support for either IPv4
+ or IPv6
+ on the host machine.
+ </p>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>dual-stack-servers</strong></span></span></dt>
+<dd>
+ <p>
+ 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, then the <span class="command"><strong>dual-stack-servers</strong></span> have no effect unless
+ access to a transport has been disabled on the command line
+ (e.g. <span class="command"><strong>named -4</strong></span>).
+ </p>
+ </dd>
+</dl></div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="access_control"></a>Access Control</h4></div></div></div>
+
+
+ <p>
+ Access to the server can be restricted based on the IP address
+ of the requesting system. See <a class="xref" href="Bv9ARM.ch06.html#address_match_lists" title="Address Match Lists">the section called &#8220;Address Match Lists&#8221;</a> for
+ details on how to specify IP address lists.
+ </p>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>allow-notify</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies which hosts are allowed to
+ notify this server, a slave, of zone changes in addition
+ to the zone masters.
+ <span class="command"><strong>allow-notify</strong></span> may also be
+ specified in the
+ <span class="command"><strong>zone</strong></span> statement, in which case
+ it overrides the
+ <span class="command"><strong>options allow-notify</strong></span>
+ statement. It is only meaningful
+ for a slave zone. If not specified, the default is to
+ process notify messages
+ only from a zone's master.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-query</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies which hosts are allowed to ask ordinary
+ DNS questions. <span class="command"><strong>allow-query</strong></span> may
+ also be specified in the <span class="command"><strong>zone</strong></span>
+ statement, in which case it overrides the
+ <span class="command"><strong>options allow-query</strong></span> statement.
+ If not specified, the default is to allow queries
+ from all hosts.
+ </p>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ <span class="command"><strong>allow-query-cache</strong></span> is now
+ used to specify access to the cache.
+ </p>
+ </div>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-query-on</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies which local addresses can accept ordinary
+ DNS questions. 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 <span class="command"><strong>allow-query-on</strong></span> is only
+ checked for queries that are permitted by
+ <span class="command"><strong>allow-query</strong></span>. A query must be
+ allowed by both ACLs, or it will be refused.
+ </p>
+ <p>
+ <span class="command"><strong>allow-query-on</strong></span> may
+ also be specified in the <span class="command"><strong>zone</strong></span>
+ statement, in which case it overrides the
+ <span class="command"><strong>options allow-query-on</strong></span> statement.
+ </p>
+ <p>
+ If not specified, the default is to allow queries
+ on all addresses.
+ </p>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ <span class="command"><strong>allow-query-cache</strong></span> is
+ used to specify access to the cache.
+ </p>
+ </div>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-query-cache</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies which hosts are allowed to get answers
+ from the cache. If <span class="command"><strong>allow-query-cache</strong></span>
+ is not set then <span class="command"><strong>allow-recursion</strong></span>
+ is used if set, otherwise <span class="command"><strong>allow-query</strong></span>
+ is used if set unless <span class="command"><strong>recursion no;</strong></span> is
+ set in which case <span class="command"><strong>none;</strong></span> is used,
+ otherwise the default (<span class="command"><strong>localnets;</strong></span>
+ <span class="command"><strong>localhost;</strong></span>) is used.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-query-cache-on</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies which local addresses can give answers
+ from the cache. If not specified, the default is
+ to allow cache queries on any address,
+ <span class="command"><strong>localnets</strong></span> and
+ <span class="command"><strong>localhost</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-recursion</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies which hosts are allowed to make recursive
+ queries through this server. If
+ <span class="command"><strong>allow-recursion</strong></span> is not set
+ then <span class="command"><strong>allow-query-cache</strong></span> is
+ used if set, otherwise <span class="command"><strong>allow-query</strong></span>
+ is used if set, otherwise the default
+ (<span class="command"><strong>localnets;</strong></span>
+ <span class="command"><strong>localhost;</strong></span>) is used.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-recursion-on</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies which local addresses can accept recursive
+ queries. If not specified, the default is to allow
+ recursive queries on all addresses.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-update</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies which hosts are allowed to
+ submit Dynamic DNS updates for master zones. The default is
+ to deny
+ updates from all hosts. Note that allowing updates based
+ on the requestor's IP address is insecure; see
+ <a class="xref" href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called &#8220;Dynamic Update Security&#8221;</a> for details.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-update-forwarding</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies which hosts are allowed to
+ submit Dynamic DNS updates to slave zones to be forwarded to
+ the
+ master. The default is <strong class="userinput"><code>{ none; }</code></strong>,
+ which
+ means that no update forwarding will be performed. To
+ enable
+ update forwarding, specify
+ <strong class="userinput"><code>allow-update-forwarding { any; };</code></strong>.
+ Specifying values other than <strong class="userinput"><code>{ none; }</code></strong> or
+ <strong class="userinput"><code>{ any; }</code></strong> is usually
+ counterproductive, since
+ the responsibility for update access control should rest
+ with the
+ master server, not the slaves.
+ </p>
+ <p>
+ Note that enabling the update forwarding feature on a slave
+ server
+ may expose master servers relying on insecure IP address
+ based
+ access control to attacks; see <a class="xref" href="Bv9ARM.ch07.html#dynamic_update_security" title="Dynamic Update Security">the section called &#8220;Dynamic Update Security&#8221;</a>
+ for more details.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-v6-synthesis</strong></span></span></dt>
+<dd>
+ <p>
+ This option was introduced for the smooth transition from
+ AAAA
+ to A6 and from "nibble labels" to binary labels.
+ However, since both A6 and binary labels were then
+ deprecated,
+ this option was also deprecated.
+ It is now ignored with some warning messages.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-transfer</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies which hosts are allowed to
+ receive zone transfers from the server. <span class="command"><strong>allow-transfer</strong></span> may
+ also be specified in the <span class="command"><strong>zone</strong></span>
+ statement, in which
+ case it overrides the <span class="command"><strong>options allow-transfer</strong></span> statement.
+ If not specified, the default is to allow transfers to all
+ hosts.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>blackhole</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies a list of addresses that the
+ server will not accept queries from or use to resolve a
+ query. Queries
+ from these addresses will not be responded to. The default
+ is <strong class="userinput"><code>none</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>filter-aaaa</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies a list of addresses to which
+ <span class="command"><strong>filter-aaaa-on-v4</strong></span>
+ and <span class="command"><strong>filter-aaaa-on-v6</strong></span>
+ apply. The default is <strong class="userinput"><code>any</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>keep-response-order</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies a list of addresses to which the server
+ will send 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 <strong class="userinput"><code>none</code></strong>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>no-case-compress</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies a list of addresses which require responses
+ to use case-insensitive compression. This ACL can be
+ used when <span class="command"><strong>named</strong></span> needs to work with
+ clients that do not comply with the requirement in RFC
+ 1034 to use case-insensitive name comparisons when
+ checking for matching domain names.
+ </p>
+ <p>
+ If left undefined, the ACL defaults to
+ <span class="command"><strong>none</strong></span>: case-insensitive compression
+ will be used for all clients. If the ACL is defined and
+ matches a client, then case will be 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 would treat
+ 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 matching 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 <span class="emphasis"><em>always</em></span>
+ used in AXFR and IXFR responses, regardless of whether
+ the client matches this ACL.
+ </p>
+ <p>
+ There are circumstances in which <span class="command"><strong>named</strong></span>
+ will 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 will use the <span class="emphasis"><em>first</em></span> 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) will always
+ have their case preserved unless the client matches this
+ ACL.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>resolver-query-timeout</strong></span></span></dt>
+<dd>
+ <p>
+ The amount of time in seconds that the resolver
+ will spend attempting to resolve a recursive
+ query before failing. The default and minimum
+ is <code class="literal">10</code> and the maximum is
+ <code class="literal">30</code>. Setting it to
+ <code class="literal">0</code> will result in the default
+ being used.
+ </p>
+ </dd>
+</dl></div>
+
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="interfaces"></a>Interfaces</h4></div></div></div>
+
+ <p>
+ The interfaces and ports that the server will answer queries
+ from may be specified using the <span class="command"><strong>listen-on</strong></span> option. <span class="command"><strong>listen-on</strong></span> takes
+ an optional port and an <code class="varname">address_match_list</code>
+ of IPv4 addresses. (IPv6 addresses are ignored, with a
+ logged warning.)
+ The server will listen on all interfaces allowed by the address
+ match list. If a port is not specified, port 53 will be used.
+ </p>
+ <p>
+ Multiple <span class="command"><strong>listen-on</strong></span> statements are
+ allowed.
+ For example,
+ </p>
+
+<pre class="programlisting">listen-on { 5.6.7.8; };
+listen-on port 1234 { !1.2.3.4; 1.2/16; };
+</pre>
+
+ <p>
+ will enable the name server on port 53 for 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.
+ </p>
+
+ <p>
+ If no <span class="command"><strong>listen-on</strong></span> is specified, the
+ server will listen on port 53 on all IPv4 interfaces.
+ </p>
+
+ <p>
+ The <span class="command"><strong>listen-on-v6</strong></span> option is used to
+ specify the interfaces and the ports on which the server will
+ listen for incoming queries sent using IPv6. If not specified,
+ the server will listen on port 53 on all IPv6 interfaces.
+ </p>
+
+ <p>
+ When </p>
+<pre class="programlisting">{ any; }</pre>
+<p> is
+ specified
+ as the <code class="varname">address_match_list</code> for the
+ <span class="command"><strong>listen-on-v6</strong></span> option,
+ the server does not bind a separate socket to each IPv6 interface
+ address as it does for IPv4 if the operating system has enough API
+ support for IPv6 (specifically if it conforms to RFC 3493 and RFC
+ 3542).
+ Instead, it listens on the IPv6 wildcard address.
+ If the system only has incomplete API support for IPv6, however,
+ the behavior is the same as that for IPv4.
+ </p>
+
+ <p>
+ A list of particular IPv6 addresses can also be specified, in
+ which case
+ the server listens on a separate socket for each specified
+ address,
+ regardless of whether the desired API is supported by the system.
+ IPv4 addresses specified in <span class="command"><strong>listen-on-v6</strong></span>
+ will be ignored, with a logged warning.
+ </p>
+
+ <p>
+ Multiple <span class="command"><strong>listen-on-v6</strong></span> options can
+ be used.
+ For example,
+ </p>
+
+<pre class="programlisting">listen-on-v6 { any; };
+listen-on-v6 port 1234 { !2001:db8::/32; any; };
+</pre>
+
+ <p>
+ will enable the name server on port 53 for any IPv6 addresses
+ (with a single wildcard socket),
+ and on port 1234 of IPv6 addresses that is not in the prefix
+ 2001:db8::/32 (with separate sockets for each matched address.)
+ </p>
+
+ <p>
+ To make the server not listen on any IPv6 address, use
+ </p>
+
+<pre class="programlisting">listen-on-v6 { none; };
+</pre>
+
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="query_address"></a>Query Address</h4></div></div></div>
+
+ <p>
+ If the server doesn't know the answer to a question, it will
+ query other name servers. <span class="command"><strong>query-source</strong></span> specifies
+ the address and port used for such queries. For queries sent over
+ IPv6, there is a separate <span class="command"><strong>query-source-v6</strong></span> option.
+ If <span class="command"><strong>address</strong></span> is <span class="command"><strong>*</strong></span> (asterisk) or is omitted,
+ a wildcard IP address (<span class="command"><strong>INADDR_ANY</strong></span>)
+ will be used.
+ </p>
+
+ <p>
+ If <span class="command"><strong>port</strong></span> is <span class="command"><strong>*</strong></span> or is omitted,
+ a random port number from a pre-configured
+ range is picked up and will be used for each query.
+ The port range(s) is that specified in
+ the <span class="command"><strong>use-v4-udp-ports</strong></span> (for IPv4)
+ and <span class="command"><strong>use-v6-udp-ports</strong></span> (for IPv6)
+ options, excluding the ranges specified in
+ the <span class="command"><strong>avoid-v4-udp-ports</strong></span>
+ and <span class="command"><strong>avoid-v6-udp-ports</strong></span> options, respectively.
+ </p>
+
+ <p>
+ The defaults of the <span class="command"><strong>query-source</strong></span> and
+ <span class="command"><strong>query-source-v6</strong></span> options
+ are:
+ </p>
+
+<pre class="programlisting">query-source address * port *;
+query-source-v6 address * port *;
+</pre>
+
+ <p>
+ If <span class="command"><strong>use-v4-udp-ports</strong></span> or
+ <span class="command"><strong>use-v6-udp-ports</strong></span> is unspecified,
+ <span class="command"><strong>named</strong></span> will check if the operating
+ system provides a programming interface to retrieve the
+ system's default range for ephemeral ports.
+ If such an interface is available,
+ <span class="command"><strong>named</strong></span> will use the corresponding system
+ default range; otherwise, it will use its own defaults:
+ </p>
+
+<pre class="programlisting">use-v4-udp-ports { range 1024 65535; };
+use-v6-udp-ports { range 1024 65535; };
+</pre>
+
+ <p>
+ Note: make sure the ranges be sufficiently large for
+ security. A desirable size depends on various 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 <span class="command"><strong>named</strong></span> is running; the new
+ range will automatically be applied when <span class="command"><strong>named</strong></span>
+ is reloaded.
+ It is encouraged to
+ configure <span class="command"><strong>use-v4-udp-ports</strong></span> and
+ <span class="command"><strong>use-v6-udp-ports</strong></span> explicitly so that the
+ ranges are sufficiently large and are reasonably
+ independent from the ranges used by other applications.
+ </p>
+
+ <p>
+ Note: the operational configuration
+ where <span class="command"><strong>named</strong></span> runs may prohibit the use
+ of some ports. For example, UNIX systems will not allow
+ <span class="command"><strong>named</strong></span> running without a 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>
+
+ <p>
+ The defaults of the <span class="command"><strong>avoid-v4-udp-ports</strong></span> and
+ <span class="command"><strong>avoid-v6-udp-ports</strong></span> options
+ are:
+ </p>
+
+<pre class="programlisting">avoid-v4-udp-ports {};
+avoid-v6-udp-ports {};
+</pre>
+
+ <p>
+ Note: BIND 9.5.0 introduced
+ the <span class="command"><strong>use-queryport-pool</strong></span>
+ option to support a pool of such random ports, but this
+ option is now obsolete because reusing the same ports in
+ the pool may not be sufficiently secure.
+ For the same reason, it is generally strongly discouraged to
+ specify a particular port for the
+ <span class="command"><strong>query-source</strong></span> or
+ <span class="command"><strong>query-source-v6</strong></span> options;
+ it implicitly disables the use of randomized port numbers.
+ </p>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>use-queryport-pool</strong></span></span></dt>
+<dd>
+ <p>
+ This option is obsolete.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>queryport-pool-ports</strong></span></span></dt>
+<dd>
+ <p>
+ This option is obsolete.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>queryport-pool-updateinterval</strong></span></span></dt>
+<dd>
+ <p>
+ This option is obsolete.
+ </p>
+ </dd>
+</dl></div>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ The address specified in the <span class="command"><strong>query-source</strong></span> 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>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ Solaris 2.5.1 and earlier does not support setting the source
+ address for TCP sockets.
+ </p>
+ </div>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ See also <span class="command"><strong>transfer-source</strong></span> and
+ <span class="command"><strong>notify-source</strong></span>.
+ </p>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="zone_transfers"></a>Zone Transfers</h4></div></div></div>
+
+ <p>
+ <acronym class="acronym">BIND</acronym> 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>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>also-notify</strong></span></span></dt>
+<dd>
+ <p>
+ 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 will
+ quickly converge on stealth servers.
+ Optionally, a port may be specified with each
+ <span class="command"><strong>also-notify</strong></span> 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
+ <span class="command"><strong>masters</strong></span> lists can be used.
+ </p>
+ <p>
+ If an <span class="command"><strong>also-notify</strong></span> list
+ is given in a <span class="command"><strong>zone</strong></span> statement,
+ it will override
+ the <span class="command"><strong>options also-notify</strong></span>
+ statement. When a <span class="command"><strong>zone notify</strong></span>
+ statement
+ is set to <span class="command"><strong>no</strong></span>, the IP
+ addresses in the global <span class="command"><strong>also-notify</strong></span> list will
+ not be sent NOTIFY messages for that zone. The default is
+ the empty
+ list (no global notification list).
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-transfer-time-in</strong></span></span></dt>
+<dd>
+ <p>
+ Inbound zone transfers running longer than
+ this many minutes will be terminated. The default is 120
+ minutes
+ (2 hours). The maximum value is 28 days (40320 minutes).
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-transfer-idle-in</strong></span></span></dt>
+<dd>
+ <p>
+ Inbound zone transfers making no progress
+ in this many minutes will be terminated. The default is 60
+ minutes
+ (1 hour). The maximum value is 28 days (40320 minutes).
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-transfer-time-out</strong></span></span></dt>
+<dd>
+ <p>
+ Outbound zone transfers running longer than
+ this many minutes will be terminated. The default is 120
+ minutes
+ (2 hours). The maximum value is 28 days (40320 minutes).
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-transfer-idle-out</strong></span></span></dt>
+<dd>
+ <p>
+ Outbound zone transfers making no progress
+ in this many minutes will be terminated. The default is 60
+ minutes (1
+ hour). The maximum value is 28 days (40320 minutes).
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>notify-rate</strong></span></span></dt>
+<dd>
+ <p>
+ The rate at which NOTIFY requests will be 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 will be silently raised to one.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>startup-notify-rate</strong></span></span></dt>
+<dd>
+ <p>
+ The rate at which NOTIFY requests will be sent
+ when the name server is first starting up, or when
+ zones have been newly added to the nameserver.
+ The default is 20 per second.
+ The lowest possible rate is one per second; when set
+ to zero, it will be silently raised to one.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>serial-query-rate</strong></span></span></dt>
+<dd>
+ <p>
+ Slave servers will periodically query master
+ servers to find out if zone serial numbers have
+ changed. Each such query uses a minute amount of
+ the slave 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
+ <span class="command"><strong>serial-query-rate</strong></span> 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 will be silently raised to one.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>serial-queries</strong></span></span></dt>
+<dd>
+ <p>
+ In BIND 8, the <span class="command"><strong>serial-queries</strong></span>
+ option
+ set the maximum number of concurrent serial number queries
+ allowed to be outstanding at any given time.
+ BIND 9 does not limit the number of outstanding
+ serial queries and ignores the <span class="command"><strong>serial-queries</strong></span> option.
+ Instead, it limits the rate at which the queries are sent
+ as defined using the <span class="command"><strong>serial-query-rate</strong></span> option.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>transfer-format</strong></span></span></dt>
+<dd>
+
+ <p>
+ Zone transfers can be sent using two different formats,
+ <span class="command"><strong>one-answer</strong></span> and
+ <span class="command"><strong>many-answers</strong></span>.
+ The <span class="command"><strong>transfer-format</strong></span> option is used
+ on the master server to determine which format it sends.
+ <span class="command"><strong>one-answer</strong></span> uses one DNS message per
+ resource record transferred.
+ <span class="command"><strong>many-answers</strong></span> packs as many resource
+ records as possible into a message.
+ <span class="command"><strong>many-answers</strong></span> is more efficient, but is
+ only supported by relatively new slave servers,
+ such as <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
+ 8.x and <acronym class="acronym">BIND</acronym> 4.9.5 onwards.
+ The <span class="command"><strong>many-answers</strong></span> format is also supported by
+ recent Microsoft Windows nameservers.
+ The default is <span class="command"><strong>many-answers</strong></span>.
+ <span class="command"><strong>transfer-format</strong></span> may be overridden on a
+ per-server basis by using the <span class="command"><strong>server</strong></span>
+ statement.
+ </p>
+
+ </dd>
+<dt><span class="term"><span class="command"><strong>transfer-message-size</strong></span></span></dt>
+<dd>
+ <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 will be
+ 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, and any
+ values outside that range will be adjusted to the nearest
+ value within it. The default is <code class="literal">20480</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>
+<dt><span class="term"><span class="command"><strong>transfers-in</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum number of inbound zone transfers
+ that can be running concurrently. The default value is <code class="literal">10</code>.
+ Increasing <span class="command"><strong>transfers-in</strong></span> may
+ speed up the convergence
+ of slave zones, but it also may increase the load on the
+ local system.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>transfers-out</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum number of outbound zone transfers
+ that can be running concurrently. Zone transfer requests in
+ excess
+ of the limit will be refused. The default value is <code class="literal">10</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>transfers-per-ns</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum number of inbound zone transfers
+ that can be concurrently transferring from a given remote
+ name server.
+ The default value is <code class="literal">2</code>.
+ Increasing <span class="command"><strong>transfers-per-ns</strong></span>
+ may
+ speed up the convergence of slave zones, but it also may
+ increase
+ the load on the remote name server. <span class="command"><strong>transfers-per-ns</strong></span> may
+ be overridden on a per-server basis by using the <span class="command"><strong>transfers</strong></span> phrase
+ of the <span class="command"><strong>server</strong></span> statement.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>transfer-source</strong></span></span></dt>
+<dd>
+ <p><span class="command"><strong>transfer-source</strong></span>
+ determines which local address will be 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 will usually be the address
+ of the interface "closest to" the remote end. This
+ address must appear in the remote end's
+ <span class="command"><strong>allow-transfer</strong></span> option for the
+ zone being transferred, if one is specified. This
+ statement sets the
+ <span class="command"><strong>transfer-source</strong></span> for all zones,
+ but can be overridden on a per-view or per-zone
+ basis by including a
+ <span class="command"><strong>transfer-source</strong></span> statement within
+ the <span class="command"><strong>view</strong></span> or
+ <span class="command"><strong>zone</strong></span> block in the configuration
+ file.
+ </p>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ Solaris 2.5.1 and earlier does not support setting the
+ source address for TCP sockets.
+ </p>
+ </div>
+ </dd>
+<dt><span class="term"><span class="command"><strong>transfer-source-v6</strong></span></span></dt>
+<dd>
+ <p>
+ The same as <span class="command"><strong>transfer-source</strong></span>,
+ except zone transfers are performed using IPv6.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>alt-transfer-source</strong></span></span></dt>
+<dd>
+ <p>
+ An alternate transfer source if the one listed in
+ <span class="command"><strong>transfer-source</strong></span> fails and
+ <span class="command"><strong>use-alt-transfer-source</strong></span> is
+ set.
+ </p>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+<p>
+ If you do not wish the alternate transfer source
+ to be used, you should set
+ <span class="command"><strong>use-alt-transfer-source</strong></span>
+ appropriately and you should not depend upon
+ getting an answer back to the first refresh
+ query.
+ </p>
+</div>
+ </dd>
+<dt><span class="term"><span class="command"><strong>alt-transfer-source-v6</strong></span></span></dt>
+<dd>
+ <p>
+ An alternate transfer source if the one listed in
+ <span class="command"><strong>transfer-source-v6</strong></span> fails and
+ <span class="command"><strong>use-alt-transfer-source</strong></span> is
+ set.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>use-alt-transfer-source</strong></span></span></dt>
+<dd>
+ <p>
+ Use the alternate transfer sources or not. If views are
+ specified this defaults to <span class="command"><strong>no</strong></span>
+ otherwise it defaults to
+ <span class="command"><strong>yes</strong></span> (for BIND 8
+ compatibility).
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>notify-source</strong></span></span></dt>
+<dd>
+ <p><span class="command"><strong>notify-source</strong></span>
+ determines which local source address, and
+ optionally UDP port, will be used to send NOTIFY
+ messages. This address must appear in the slave
+ server's <span class="command"><strong>masters</strong></span> zone clause or
+ in an <span class="command"><strong>allow-notify</strong></span> clause. This
+ statement sets the <span class="command"><strong>notify-source</strong></span>
+ for all zones, but can be overridden on a per-zone or
+ per-view basis by including a
+ <span class="command"><strong>notify-source</strong></span> statement within
+ the <span class="command"><strong>zone</strong></span> or
+ <span class="command"><strong>view</strong></span> block in the configuration
+ file.
+ </p>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ Solaris 2.5.1 and earlier does not support setting the
+ source address for TCP sockets.
+ </p>
+ </div>
+ </dd>
+<dt><span class="term"><span class="command"><strong>notify-source-v6</strong></span></span></dt>
+<dd>
+ <p>
+ Like <span class="command"><strong>notify-source</strong></span>,
+ but applies to notify messages sent to IPv6 addresses.
+ </p>
+ </dd>
+</dl></div>
+
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="port_lists"></a>UDP Port Lists</h4></div></div></div>
+
+ <p>
+ <span class="command"><strong>use-v4-udp-ports</strong></span>,
+ <span class="command"><strong>avoid-v4-udp-ports</strong></span>,
+ <span class="command"><strong>use-v6-udp-ports</strong></span>, and
+ <span class="command"><strong>avoid-v6-udp-ports</strong></span>
+ specify a list of IPv4 and IPv6 UDP ports that will be
+ used or not used as source ports for UDP messages.
+ See <a class="xref" href="Bv9ARM.ch06.html#query_address" title="Query Address">the section called &#8220;Query Address&#8221;</a> about how the
+ available ports are determined.
+ For example, with the following configuration
+ </p>
+
+<pre class="programlisting">
+use-v6-udp-ports { range 32768 65535; };
+avoid-v6-udp-ports { 40000; range 50000 60000; };
+</pre>
+
+ <p>
+ UDP ports of IPv6 messages sent
+ from <span class="command"><strong>named</strong></span> will be in one
+ of the following ranges: 32768 to 39999, 40001 to 49999,
+ and 60001 to 65535.
+ </p>
+
+ <p>
+ <span class="command"><strong>avoid-v4-udp-ports</strong></span> and
+ <span class="command"><strong>avoid-v6-udp-ports</strong></span> can be used
+ to prevent <span class="command"><strong>named</strong></span> from choosing as its random source port a
+ port that is blocked by your firewall or a port that is
+ used by other applications;
+ if a query went out with a source port blocked by a
+ firewall, the
+ answer would not get by the firewall and the name server would
+ have to query again.
+ Note: the desired range can also be represented only with
+ <span class="command"><strong>use-v4-udp-ports</strong></span> and
+ <span class="command"><strong>use-v6-udp-ports</strong></span>, and the
+ <span class="command"><strong>avoid-</strong></span> options are redundant in that
+ sense; they are provided for backward compatibility and
+ to possibly simplify the port specification.
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="resource_limits"></a>Operating System Resource Limits</h4></div></div></div>
+
+ <p>
+ The server's usage of many system resources can be limited.
+ Scaled values are allowed when specifying resource limits. For
+ example, <span class="command"><strong>1G</strong></span> can be used instead of
+ <span class="command"><strong>1073741824</strong></span> to specify a limit of
+ one
+ gigabyte. <span class="command"><strong>unlimited</strong></span> requests
+ unlimited use, or the
+ maximum available amount. <span class="command"><strong>default</strong></span>
+ uses the limit
+ that was in force when the server was started. See the description
+ of <span class="command"><strong>size_spec</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#configuration_file_elements" title="Configuration File Elements">the section called &#8220;Configuration File Elements&#8221;</a>.
+ </p>
+
+ <p>
+ The following options set operating system resource limits for
+ the name server process. Some operating systems don't support
+ some or
+ any of the limits. On such systems, a warning will be issued if
+ the
+ unsupported limit is used.
+ </p>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>coresize</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum size of a core dump. The default
+ is <code class="literal">default</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>datasize</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum amount of data memory the server
+ may use. The default is <code class="literal">default</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 of limiting 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. If you wish to limit the amount
+ of memory used by the server, use the
+ <span class="command"><strong>max-cache-size</strong></span> and
+ <span class="command"><strong>recursive-clients</strong></span>
+ options instead.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>files</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum number of files the server
+ may have open concurrently. The default is <code class="literal">unlimited</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>stacksize</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum amount of stack memory the server
+ may use. The default is <code class="literal">default</code>.
+ </p>
+ </dd>
+</dl></div>
+
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="server_resource_limits"></a>Server Resource Limits</h4></div></div></div>
+
+ <p>
+ The following options set limits on the server's
+ resource consumption that are enforced internally by the
+ server rather than the operating system.
+ </p>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>max-ixfr-log-size</strong></span></span></dt>
+<dd>
+ <p>
+ This option is obsolete; it is accepted
+ and ignored for BIND 8 compatibility. The option
+ <span class="command"><strong>max-journal-size</strong></span> performs a
+ similar function in BIND 9.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-journal-size</strong></span></span></dt>
+<dd>
+ <p>
+ Sets a maximum size for each journal file
+ (see <a class="xref" href="Bv9ARM.ch04.html#journal" title="The journal file">the section called &#8220;The journal file&#8221;</a>). When the journal file
+ approaches
+ the specified size, some of the oldest transactions in the
+ journal
+ will be automatically removed. The largest permitted
+ value is 2 gigabytes. The default is
+ <code class="literal">unlimited</code>, which also
+ means 2 gigabytes.
+ This may also be set on a per-zone basis.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-records</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum number of records permitted in a zone.
+ The default is zero which means unlimited.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>host-statistics-max</strong></span></span></dt>
+<dd>
+ <p>
+ In BIND 8, specifies the maximum number of host statistics
+ entries to be kept.
+ Not implemented in BIND 9.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>recursive-clients</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum number ("hard quota") of simultaneous
+ recursive lookups the server will perform on behalf
+ of clients. The default is
+ <code class="literal">1000</code>. Because each recursing
+ client uses a fair
+ bit of memory (on the order of 20 kilobytes), the
+ value of the
+ <span class="command"><strong>recursive-clients</strong></span> option may
+ have to be decreased on hosts with limited memory.
+ </p>
+ <p>
+ <code class="option">recursive-clients</code> defines a "hard
+ quota" limit for pending recursive clients: when more
+ clients than this are pending, new incoming requests
+ will not be accepted, and for each incoming request
+ a previous pending request will also be 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 will be dropped.
+ If <code class="option">recursive-clients</code> is greater than
+ 1000, the soft quota is set to
+ <code class="option">recursive-clients</code> minus 100;
+ otherwise it is set to 90% of
+ <code class="option">recursive-clients</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>tcp-clients</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum number of simultaneous client TCP
+ connections that the server will accept.
+ The default is <code class="literal">150</code>.
+ </p>
+ </dd>
+<dt>
+<a name="clients-per-query"></a><span class="term"><a name="cpq_term"></a><span class="command"><strong>clients-per-query</strong></span>, </span><span class="term"><span class="command"><strong>max-clients-per-query</strong></span></span>
+</dt>
+<dd>
+ <p>These set the
+ initial value (minimum) and maximum number of recursive
+ simultaneous clients for any given query
+ (&lt;qname,qtype,qclass&gt;) that the server will accept
+ before dropping additional clients. <span class="command"><strong>named</strong></span> will attempt to
+ self tune this value and changes will be logged. The
+ default values are 10 and 100.
+ </p>
+ <p>
+ This value should reflect how many queries come in for
+ a given name in the time it takes to resolve that name.
+ If the number of queries exceed this value, <span class="command"><strong>named</strong></span> will
+ assume that it is dealing with a non-responsive zone
+ and will drop additional queries. If it gets a response
+ after dropping queries, it will raise the estimate. The
+ estimate will then be lowered in 20 minutes if it has
+ remained unchanged.
+ </p>
+ <p>
+ If <span class="command"><strong>clients-per-query</strong></span> is set to zero,
+ then there is no limit on the number of clients per query
+ and no queries will be dropped.
+ </p>
+ <p>
+ If <span class="command"><strong>max-clients-per-query</strong></span> is set to zero,
+ then there is no upper bound other than imposed by
+ <span class="command"><strong>recursive-clients</strong></span>.
+ </p>
+ </dd>
+<dt>
+<a name="fetches-per-zone"></a><span class="term"><span class="command"><strong>fetches-per-zone</strong></span></span>
+</dt>
+<dd>
+ <p>
+ The maximum number of simultaneous iterative
+ queries to any one domain that the server will
+ permit 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 <code class="option">recursive-clients</code>.
+ </p>
+ <p>
+ When many clients simultaneously query for the
+ same name and type, the clients will all be attached
+ to the same fetch, up to the
+ <code class="option">max-clients-per-query</code> limit,
+ and only one iterative query will be sent.
+ However, when clients are simultaneously
+ querying for <span class="emphasis"><em>different</em></span> names
+ or types, multiple queries will be sent and
+ <code class="option">max-clients-per-query</code> is not
+ effective as a limit.
+ </p>
+ <p>
+ Optionally, this value may be followed by the keyword
+ <code class="literal">drop</code> or <code class="literal">fail</code>,
+ indicating whether queries which exceed the fetch
+ quota for a zone will be dropped with no response,
+ or answered with SERVFAIL. The default is
+ <code class="literal">drop</code>.
+ </p>
+ <p>
+ If <span class="command"><strong>fetches-per-zone</strong></span> is set to zero,
+ then there is no limit on the number of fetches per query
+ and no queries will be dropped. The default is zero.
+ </p>
+ <p>
+ The current list of active fetches can be dumped by
+ running <span class="command"><strong>rndc recursing</strong></span>. The list
+ includes the number of active fetches for each
+ domain and the number of queries that have been
+ passed or dropped as a result of the
+ <code class="option">fetches-per-zone</code> 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>
+<dt>
+<a name="fetches-per-server"></a><span class="term"><span class="command"><strong>fetches-per-server</strong></span></span>
+</dt>
+<dd>
+ <p>
+ The maximum number of simultaneous iterative
+ queries that the server will allow 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 <code class="option">recursive-clients</code>.
+ </p>
+ <p>
+ Optionally, this value may be followed by the keyword
+ <code class="literal">drop</code> or <code class="literal">fail</code>,
+ indicating whether queries will be 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="literal">fail</code>.
+ </p>
+ <p>
+ If <span class="command"><strong>fetches-per-server</strong></span> is set to zero,
+ then there is no limit on the number of fetches per query
+ and no queries will be dropped. The default is zero.
+ </p>
+ <p>
+ The <span class="command"><strong>fetches-per-server</strong></span> quota is
+ dynamically adjusted in response to detected
+ congestion. As queries are sent to a server
+ and are either 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 <span class="command"><strong>fetches-per-server</strong></span>
+ is reduced for that server. If the timeout ratio
+ drops below a "low" threshold, then
+ <span class="command"><strong>fetches-per-server</strong></span> is increased.
+ The <span class="command"><strong>fetch-quota-params</strong></span> options
+ can be used to adjust the parameters for this
+ calculation.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>fetch-quota-params</strong></span></span></dt>
+<dd>
+ <p>
+ Sets the parameters to use for dynamic resizing of
+ the <code class="option">fetches-per-server</code> 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 we recalculate
+ 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>
+<dt><span class="term"><span class="command"><strong>reserved-sockets</strong></span></span></dt>
+<dd>
+ <p>
+ The number of file descriptors reserved for TCP, stdio,
+ etc. This needs to be big enough to cover the number of
+ interfaces <span class="command"><strong>named</strong></span> listens on, <span class="command"><strong>tcp-clients</strong></span> as well as
+ to provide room for outgoing TCP queries and incoming zone
+ transfers. The default is <code class="literal">512</code>.
+ The minimum value is <code class="literal">128</code> and the
+ maximum value is <code class="literal">128</code> less than
+ maxsockets (-S). This option may be removed in the future.
+ </p>
+ <p>
+ This option has little effect on Windows.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-cache-size</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum amount of memory to use for the
+ server's cache, in bytes or % of total physical memory.
+ When the amount of data in the cache
+ reaches this limit, the server will cause records to
+ expire prematurely based on an LRU based strategy so
+ that the limit is not exceeded.
+ The keyword <strong class="userinput"><code>unlimited</code></strong>,
+ or the value 0, will place no limit on cache size;
+ records will be purged from the cache only when their
+ TTLs expire.
+ Any positive values less than 2MB will be ignored
+ and reset to 2MB.
+ In a server with multiple views, the limit applies
+ separately to the cache of each view.
+ The default is <strong class="userinput"><code>90%</code></strong>.
+ On systems where detection of amount of physical
+ memory is not supported values represented as %
+ fall back to unlimited.
+ Note that the detection of physical memory is done only
+ once at startup, so <span class="command"><strong>named</strong></span> will not
+ adjust the cache size if the amount of physical memory
+ is changed during runtime.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>tcp-listen-queue</strong></span></span></dt>
+<dd>
+ <p>
+ 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 that will be queued in kernel space
+ waiting for
+ some data before being passed to accept. Nonzero values
+ less than 10 will be 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></div>
+
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="intervals"></a>Periodic Task Intervals</h4></div></div></div>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>cleaning-interval</strong></span></span></dt>
+<dd>
+ <p>
+ This interval is effectively obsolete. Previously,
+ the server would remove expired resource records
+ from the cache every <span class="command"><strong>cleaning-interval</strong></span> minutes.
+ <acronym class="acronym">BIND</acronym> 9 now manages cache
+ memory in a more sophisticated manner and does not
+ rely on the periodic cleaning any more.
+ Specifying this option therefore has no effect on
+ the server's behavior.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>heartbeat-interval</strong></span></span></dt>
+<dd>
+ <p>
+ The server will perform zone maintenance tasks
+ for all zones marked as <span class="command"><strong>dialup</strong></span> 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 will occur.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>interface-interval</strong></span></span></dt>
+<dd>
+ <p>
+ The server will scan the network interface list
+ every <span class="command"><strong>interface-interval</strong></span>
+ minutes. The default
+ is 60 minutes. The maximum value is 28 days (40320 minutes).
+ If set to 0, interface scanning will only occur when
+ the configuration file is loaded. After the scan, the
+ server will
+ begin listening for queries on any newly discovered
+ interfaces (provided they are allowed by the
+ <span class="command"><strong>listen-on</strong></span> configuration), and
+ will
+ stop listening on interfaces that have gone away.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>statistics-interval</strong></span></span></dt>
+<dd>
+ <p>
+ Name server statistics will be logged
+ every <span class="command"><strong>statistics-interval</strong></span>
+ minutes. The default is
+ 60. The maximum value is 28 days (40320 minutes).
+ If set to 0, no statistics will be logged.
+ </p>
+<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ Not yet implemented in
+ <acronym class="acronym">BIND</acronym> 9.
+ </p>
+ </div>
+ </dd>
+<dt><span class="term"><span class="command"><strong>topology</strong></span></span></dt>
+<dd>
+ <p>
+ In BIND 8, this option indicated network topology
+ so that preferential treatment could be given to
+ the topologicaly closest name servers when sending
+ queries. It is not implemented in BIND 9.
+ </p>
+ </dd>
+</dl></div>
+
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="the_sortlist_statement"></a>The <span class="command"><strong>sortlist</strong></span> Statement</h4></div></div></div>
+
+ <p>
+ The response to a DNS query may consist of multiple resource
+ records (RRs) forming a resource record set (RRset). The name
+ server will normally return the RRs within the RRset in an
+ indeterminate order (but see the <span class="command"><strong>rrset-order</strong></span>
+ statement in <a class="xref" href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called &#8220;RRset Ordering&#8221;</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>
+
+ <p>
+ The <span class="command"><strong>sortlist</strong></span> statement (see below) takes an
+ <span class="command"><strong>address_match_list</strong></span> and interprets it in a
+ special way. Each top level statement in the
+ <span class="command"><strong>sortlist</strong></span> must itself be an explicit
+ <span class="command"><strong>address_match_list</strong></span> with one or two elements.
+ The first element (which may be an IP address, an IP prefix, an
+ ACL name or a nested <span class="command"><strong>address_match_list</strong></span>) of
+ each top level list is checked against the source address of
+ the query until a match is found.
+ </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 will 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 will 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 will only prefer other addresses on
+ their directly connected networks.
+ </p>
+
+<pre class="programlisting">sortlist {
+ // IF the local host
+ // THEN first fit on the following nets
+ { localhost;
+ { localnets;
+ 192.168.1/24;
+ { 192.168.2/24; 192.168.3/24; }; }; };
+ // IF on class C 192.168.1 THEN use .1, or .2 or .3
+ { 192.168.1/24;
+ { 192.168.1/24;
+ { 192.168.2/24; 192.168.3/24; }; }; };
+ // IF on class C 192.168.2 THEN use .2, or .1 or .3
+ { 192.168.2/24;
+ { 192.168.2/24;
+ { 192.168.1/24; 192.168.3/24; }; }; };
+ // IF on class C 192.168.3 THEN use .3, or .1 or .2
+ { 192.168.3/24;
+ { 192.168.3/24;
+ { 192.168.1/24; 192.168.2/24; }; }; };
+ // IF .4 or .5 THEN prefer that net
+ { { 192.168.4/24; 192.168.5/24; };
+ };
+};</pre>
+
+ <p>
+ The following example will give reasonable behavior for the
+ local host and hosts on directly connected networks. It is
+ similar to the behavior of the address sort in
+ <acronym class="acronym">BIND</acronym> 4.9.x. Responses sent to queries from
+ the local host will favor any of the directly connected
+ networks. Responses sent to queries from any other hosts on a
+ directly connected network will prefer addresses on that same
+ network. Responses to other queries will not be sorted.
+ </p>
+
+<pre class="programlisting">sortlist {
+ { localhost; localnets; };
+ { localnets; };
+};
+</pre>
+
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="rrset_ordering"></a>RRset Ordering</h4></div></div></div>
+
+ <p>
+ When multiple records are returned in an answer it may be
+ useful to configure the order of the records placed into the
+ response.
+ The <span class="command"><strong>rrset-order</strong></span> statement permits
+ configuration
+ of the ordering of the records in a multiple record response.
+ See also the <span class="command"><strong>sortlist</strong></span> statement,
+ <a class="xref" href="Bv9ARM.ch06.html#the_sortlist_statement" title="The sortlist Statement">the section called &#8220;The <span class="command"><strong>sortlist</strong></span> Statement&#8221;</a>.
+ </p>
+
+ <p>
+ An <span class="command"><strong>order_spec</strong></span> is defined as
+ follows:
+ </p>
+ <p>
+ [<span class="optional">class <em class="replaceable"><code>class_name</code></em></span>]
+ [<span class="optional">type <em class="replaceable"><code>type_name</code></em></span>]
+ [<span class="optional">name <em class="replaceable"><code>"domain_name"</code></em></span>]
+ order <em class="replaceable"><code>ordering</code></em>
+ </p>
+ <p>
+ If no class is specified, the default is <span class="command"><strong>ANY</strong></span>.
+ If no type is specified, the default is <span class="command"><strong>ANY</strong></span>.
+ If no name is specified, the default is "<span class="command"><strong>*</strong></span>" (asterisk).
+ </p>
+ <p>
+ The legal values for <span class="command"><strong>ordering</strong></span> are:
+ </p>
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="0.750in" class="1">
+<col width="3.750in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p><span class="command"><strong>fixed</strong></span></p>
+ </td>
+<td>
+ <p>
+ Records are returned in the order they
+ are defined in the zone file.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>random</strong></span></p>
+ </td>
+<td>
+ <p>
+ Records are returned in some random order.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>cyclic</strong></span></p>
+ </td>
+<td>
+ <p>
+ Records are returned in a cyclic round-robin order.
+ </p>
+ <p>
+ If <acronym class="acronym">BIND</acronym> is configured with the
+ "--enable-fixed-rrset" option at compile time, then
+ the initial ordering of the RRset will match the
+ one specified in the zone file.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ <p>
+ For example:
+ </p>
+
+<pre class="programlisting">rrset-order {
+ class IN type A name "host.example.com" order random;
+ order cyclic;
+};
+</pre>
+
+ <p>
+ will cause any responses for type A records in class IN that
+ have "<code class="literal">host.example.com</code>" as a
+ suffix, to always be returned
+ in random order. All other records are returned in cyclic order.
+ </p>
+ <p>
+ If multiple <span class="command"><strong>rrset-order</strong></span> statements
+ appear, they are not combined &#8212; the last one applies.
+ </p>
+ <p>
+ By default, all records are returned in random order.
+ </p>
+
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ In this release of <acronym class="acronym">BIND</acronym> 9, the
+ <span class="command"><strong>rrset-order</strong></span> statement does not support
+ "fixed" ordering by default. Fixed ordering can be enabled
+ at compile time by specifying "--enable-fixed-rrset" on
+ the "configure" command line.
+ </p>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="tuning"></a>Tuning</h4></div></div></div>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>lame-ttl</strong></span></span></dt>
+<dd>
+ <p>
+ Sets the number of seconds to cache a
+ lame server indication. 0 disables caching. (This is
+ <span class="bold"><strong>NOT</strong></span> recommended.)
+ The default is <code class="literal">600</code> (10 minutes) and the
+ maximum value is
+ <code class="literal">1800</code> (30 minutes).
+ </p>
+
+ </dd>
+<dt><span class="term"><span class="command"><strong>servfail-ttl</strong></span></span></dt>
+<dd>
+ <p>
+ 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="literal">0</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="literal">30</code>
+ seconds; any higher value will be silently
+ reduced. The default is <code class="literal">1</code>
+ second.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-ncache-ttl</strong></span></span></dt>
+<dd>
+ <p>
+ To reduce network traffic and increase performance,
+ the server stores negative answers. <span class="command"><strong>max-ncache-ttl</strong></span> is
+ used to set a maximum retention time for these answers in
+ the server
+ in seconds. The default
+ <span class="command"><strong>max-ncache-ttl</strong></span> is <code class="literal">10800</code> seconds (3 hours).
+ <span class="command"><strong>max-ncache-ttl</strong></span> cannot exceed
+ 7 days and will
+ be silently truncated to 7 days if set to a greater value.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-cache-ttl</strong></span></span></dt>
+<dd>
+ <p>
+ Sets the maximum time for which the server will
+ cache ordinary (positive) answers in seconds.
+ The default 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>
+<dt><span class="term"><span class="command"><strong>min-roots</strong></span></span></dt>
+<dd>
+ <p>
+ The minimum number of root servers that
+ is required for a request for the root servers to be
+ accepted. The default
+ is <strong class="userinput"><code>2</code></strong>.
+ </p>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ Not implemented in <acronym class="acronym">BIND</acronym> 9.
+ </p>
+ </div>
+ </dd>
+<dt><span class="term"><span class="command"><strong>sig-validity-interval</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies the number of days into the future when
+ DNSSEC signatures automatically generated as a
+ result of dynamic updates (<a class="xref" href="Bv9ARM.ch04.html#dynamic_update" title="Dynamic Update">the section called &#8220;Dynamic Update&#8221;</a>) will expire. There
+ is an optional second field which specifies how
+ long before expiry that the signatures will be
+ regenerated. If not specified, the signatures will
+ be regenerated at 1/4 of base interval. The second
+ field is specified in days if the base interval is
+ greater than 7 days otherwise it is specified in hours.
+ The default base interval is <code class="literal">30</code> days
+ giving a re-signing interval of 7 1/2 days. The maximum
+ values are 10 years (3660 days).
+ </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 <span class="command"><strong>sig-validity-interval</strong></span>
+ 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>
+<dt><span class="term"><span class="command"><strong>sig-signing-nodes</strong></span></span></dt>
+<dd>
+ <p>
+ Specify the maximum number of nodes to be
+ examined in each quantum when signing a zone with
+ a new DNSKEY. The default is
+ <code class="literal">100</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>sig-signing-signatures</strong></span></span></dt>
+<dd>
+ <p>
+ Specify a threshold number of signatures that
+ will terminate processing a quantum when signing
+ a zone with a new DNSKEY. The default is
+ <code class="literal">10</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>sig-signing-type</strong></span></span></dt>
+<dd>
+ <p>
+ Specify a private RDATA type to be used when generating
+ signing state records. The default is
+ <code class="literal">65534</code>.
+ </p>
+ <p>
+ It is expected that this parameter may be removed
+ in a future version once there is a standard type.
+ </p>
+ <p>
+ Signing state records are used to internally by
+ <span class="command"><strong>named</strong></span> 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
+ <span class="command"><strong>rndc signing -list <em class="replaceable"><code>zone</code></em></strong></span>.
+ Once <span class="command"><strong>named</strong></span> 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
+ <span class="command"><strong>rndc signing -clear <em class="replaceable"><code>keyid/algorithm</code></em> <em class="replaceable"><code>zone</code></em></strong></span>.
+ To clear all of the completed signing state
+ records for a zone, use
+ <span class="command"><strong>rndc signing -clear all <em class="replaceable"><code>zone</code></em></strong></span>.
+ </p>
+ </dd>
+<dt>
+<span class="term"><span class="command"><strong>min-refresh-time</strong></span>, </span><span class="term"><span class="command"><strong>max-refresh-time</strong></span>, </span><span class="term"><span class="command"><strong>min-retry-time</strong></span>, </span><span class="term"><span class="command"><strong>max-retry-time</strong></span></span>
+</dt>
+<dd>
+ <p>
+ These options control the server's behavior on refreshing a
+ zone (querying for SOA changes) or retrying failed
+ transfers. Usually the SOA values for the zone are used,
+ up to a hard-coded maximum expiry of 24 weeks. However,
+ these values are set by the master, giving slave server
+ administrators little control over their contents.
+ </p>
+ <p>
+ These options allow the administrator to set a minimum and
+ maximum refresh and retry time in seconds per-zone,
+ per-view, or globally. These options are valid for
+ slave and stub zones, and clamp the SOA refresh and
+ retry times to the specified values.
+ </p>
+ <p>
+ The following defaults apply.
+ <span class="command"><strong>min-refresh-time</strong></span> 300 seconds,
+ <span class="command"><strong>max-refresh-time</strong></span> 2419200 seconds
+ (4 weeks), <span class="command"><strong>min-retry-time</strong></span> 500 seconds,
+ and <span class="command"><strong>max-retry-time</strong></span> 1209600 seconds
+ (2 weeks).
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>edns-udp-size</strong></span></span></dt>
+<dd>
+ <p>
+ 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
+ will be silently adjusted to the nearest value within
+ it). The default value is 4096.
+ </p>
+ <p>
+ The usual reason for setting
+ <span class="command"><strong>edns-udp-size</strong></span> 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 <span class="command"><strong>named</strong></span> first queries a remote
+ server, it will advertise a UDP buffer size of 512, as
+ this has the greatest chance of success on the first try.
+ </p>
+ <p>
+ If the initial response times out, <span class="command"><strong>named</strong></span>
+ will try again with plain DNS, and if that is successful,
+ it will be taken as evidence that the server does not
+ support EDNS. After enough failures using EDNS and
+ successes using plain DNS, <span class="command"><strong>named</strong></span>
+ will default to plain DNS for future communications
+ with that server. (Periodically, <span class="command"><strong>named</strong></span>
+ will send an EDNS query to see if the situation has
+ improved.)
+ </p>
+ <p>
+ However, if the initial query is successful with
+ EDNS advertising a buffer size of 512, then
+ <span class="command"><strong>named</strong></span> will advertise progressively
+ larger buffer sizes on successive queries, until
+ responses begin timing out or
+ <span class="command"><strong>edns-udp-size</strong></span> is reached.
+ </p>
+ <p>
+ The default buffer sizes used by <span class="command"><strong>named</strong></span>
+ are 512, 1232, 1432, and 4096, but never exceeding
+ <span class="command"><strong>edns-udp-size</strong></span>. (The values 1232 and
+ 1432 are chosen to allow for an IPv4/IPv6 encapsulated
+ UDP message to be sent without fragmentation at the
+ minimum MTU sizes for Ethernet and IPv6 networks.)
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-udp-size</strong></span></span></dt>
+<dd>
+ <p>
+ Sets the maximum EDNS UDP message size
+ <span class="command"><strong>named</strong></span> will send in bytes.
+ Valid values are 512 to 4096 (values outside this
+ range will be silently adjusted to the nearest
+ value within it). The default value is 4096.
+ </p>
+ <p>
+ This value applies to responses sent by a server; to
+ set the advertised buffer size in queries, see
+ <span class="command"><strong>edns-udp-size</strong></span>.
+ </p>
+ <p>
+ The usual reason for setting
+ <span class="command"><strong>max-udp-size</strong></span> to a non-default
+ value is to get 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 (<span class="command"><strong>edns-udp-size</strong></span>).
+ </p>
+ <p>
+ Setting this to a low value will encourage additional
+ TCP traffic to the nameserver.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>masterfile-format</strong></span></span></dt>
+<dd>
+ <p>Specifies
+ the file format of zone files (see
+ <a class="xref" href="Bv9ARM.ch06.html#zonefile_format" title="Additional File Formats">the section called &#8220;Additional File Formats&#8221;</a>).
+ The default value is <code class="constant">text</code>, which is the
+ standard textual representation, except for slave zones,
+ in which the default value is <code class="constant">raw</code>.
+ Files in other formats than <code class="constant">text</code> are
+ typically expected to be generated by the
+ <span class="command"><strong>named-compilezone</strong></span> tool, or dumped by
+ <span class="command"><strong>named</strong></span>.
+ </p>
+ <p>
+ Note that when a zone file in a different format than
+ <code class="constant">text</code> is loaded, <span class="command"><strong>named</strong></span>
+ may omit some of the checks which would be performed for a
+ file in the <code class="constant">text</code> format. In particular,
+ <span class="command"><strong>check-names</strong></span> checks do not apply
+ for the <code class="constant">raw</code> format. This means
+ a zone file in the <code class="constant">raw</code> format
+ must be generated with the same check level as that
+ specified in the <span class="command"><strong>named</strong></span> configuration
+ file. Also, <code class="constant">map</code> format files are
+ loaded directly into memory via memory mapping, with only
+ minimal checking.
+ </p>
+ <p>
+ This statement sets the
+ <span class="command"><strong>masterfile-format</strong></span> for all zones,
+ but can be overridden on a per-zone or per-view basis
+ by including a <span class="command"><strong>masterfile-format</strong></span>
+ statement within the <span class="command"><strong>zone</strong></span> or
+ <span class="command"><strong>view</strong></span> block in the configuration
+ file.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>masterfile-style</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies the formatting of zone files during dump
+ when the <code class="option">masterfile-format</code> is
+ <code class="constant">text</code>. (This option is ignored
+ with any other <code class="option">masterfile-format</code>.)
+ </p>
+ <p>
+ When set to <code class="constant">relative</code>,
+ records are printed in a multi-line format with owner
+ names expressed relative to a shared origin. When set
+ to <code class="constant">full</code>, records are printed in
+ a single-line format with absolute owner names.
+ The <code class="constant">full</code> format is most suitable
+ when a zone file needs to be processed automatically
+ by a script. The <code class="constant">relative</code> format
+ is more human-readable, and is thus suitable when a
+ zone is to be edited by hand. The default is
+ <code class="constant">relative</code>.
+ </p>
+ </dd>
+<dt>
+<a name="max-recursion-depth"></a><span class="term"><span class="command"><strong>max-recursion-depth</strong></span></span>
+</dt>
+<dd>
+ <p>
+ 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 indirections exceeds this value, the recursive
+ query is terminated and returns SERVFAIL. The
+ default is 7.
+ </p>
+ </dd>
+<dt>
+<a name="max-recursion-queries"></a><span class="term"><span class="command"><strong>max-recursion-queries</strong></span></span>
+</dt>
+<dd>
+ <p>
+ Sets the maximum number of iterative queries that
+ may be sent while servicing a recursive query.
+ If more queries are sent, the recursive query
+ is terminated and returns SERVFAIL. Queries to
+ look up top level domains such as "com" and "net"
+ and the DNS root zone are exempt from this limitation.
+ The default is 75.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>notify-delay</strong></span></span></dt>
+<dd>
+ <p>
+ The delay, in seconds, between sending sets of notify
+ messages for a zone. The default is five (5) seconds.
+ </p>
+ <p>
+ The overall rate that NOTIFY messages are sent for all
+ zones is controlled by <span class="command"><strong>serial-query-rate</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-rsa-exponent-size</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum RSA exponent size, in bits, that will
+ be accepted when validating. Valid values are 35
+ to 4096 bits. The default zero (0) is also accepted
+ and is equivalent to 4096.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>prefetch</strong></span></span></dt>
+<dd>
+ <p>
+ When a query is received for cached data which
+ is to expire shortly, <span class="command"><strong>named</strong></span> can
+ refresh the data from the authoritative server
+ immediately, ensuring that the cache always has an
+ answer available.
+ </p>
+ <p>
+ The <code class="option">prefetch</code> specifies the
+ "trigger" TTL value at which prefetch of the current
+ query will take place: when a cache record with a
+ lower TTL value is encountered during query processing,
+ it will be refreshed. Valid trigger TTL values are 1 to
+ 10 seconds. Values larger than 10 seconds will be silently
+ reduced to 10.
+ Setting a trigger TTL to zero (0) causes
+ prefetch to be disabled.
+ The default trigger TTL is <code class="literal">2</code>.
+ </p>
+ <p>
+ An optional second argument specifies the "eligibility"
+ TTL: the smallest <span class="emphasis"><em>original</em></span>
+ TTL value that will be accepted for a record to be
+ eligible for prefetching. The eligibility TTL must
+ be at least six seconds longer than the trigger TTL;
+ if it isn't, <span class="command"><strong>named</strong></span> will silently
+ adjust it upward.
+ The default eligibility TTL is <code class="literal">9</code>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>v6-bias</strong></span></span></dt>
+<dd>
+ <p>
+ When determining the next nameserver to try
+ preference IPv6 nameservers by this many milliseconds.
+ The default is <code class="literal">50</code> milliseconds.
+ </p>
+ </dd>
+</dl></div>
+
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="builtin"></a>Built-in server information zones</h4></div></div></div>
+
+ <p>
+ The server provides some helpful diagnostic information
+ through a number of built-in zones under the
+ pseudo-top-level-domain <code class="literal">bind</code> in the
+ <span class="command"><strong>CHAOS</strong></span> class. These zones are part
+ of a
+ built-in view (see <a class="xref" href="Bv9ARM.ch06.html#view_statement_grammar" title="view Statement Grammar">the section called &#8220;<span class="command"><strong>view</strong></span> Statement Grammar&#8221;</a>) of
+ class
+ <span class="command"><strong>CHAOS</strong></span> which is separate from the
+ default view of class <span class="command"><strong>IN</strong></span>. Most global
+ configuration options (<span class="command"><strong>allow-query</strong></span>,
+ etc) will apply to this view, but some are locally
+ overridden: <span class="command"><strong>notify</strong></span>,
+ <span class="command"><strong>recursion</strong></span> and
+ <span class="command"><strong>allow-new-zones</strong></span> are
+ always set to <strong class="userinput"><code>no</code></strong>, and
+ <span class="command"><strong>rate-limit</strong></span> is set to allow
+ three responses per second.
+ </p>
+ <p>
+ If you need to disable these zones, use the options
+ below, or hide the built-in <span class="command"><strong>CHAOS</strong></span>
+ view by
+ defining an explicit view of class <span class="command"><strong>CHAOS</strong></span>
+ that matches all clients.
+ </p>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>version</strong></span></span></dt>
+<dd>
+ <p>
+ The version the server should report
+ via a query of the name <code class="literal">version.bind</code>
+ with type <span class="command"><strong>TXT</strong></span>, class <span class="command"><strong>CHAOS</strong></span>.
+ The default is the real version number of this server.
+ Specifying <span class="command"><strong>version none</strong></span>
+ disables processing of the queries.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>hostname</strong></span></span></dt>
+<dd>
+ <p>
+ The hostname the server should report via a query of
+ the name <code class="filename">hostname.bind</code>
+ with type <span class="command"><strong>TXT</strong></span>, class <span class="command"><strong>CHAOS</strong></span>.
+ This defaults to the hostname of the machine hosting the
+ name server as
+ found by the gethostname() function. The primary purpose of such queries
+ is to
+ identify which of a group of anycast servers is actually
+ answering your queries. Specifying <span class="command"><strong>hostname none;</strong></span>
+ disables processing of the queries.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>server-id</strong></span></span></dt>
+<dd>
+ <p>
+ The ID the server should report when receiving a Name
+ Server Identifier (NSID) query, or a query of the name
+ <code class="filename">ID.SERVER</code> with type
+ <span class="command"><strong>TXT</strong></span>, class <span class="command"><strong>CHAOS</strong></span>.
+ The primary purpose of such queries is to
+ identify which of a group of anycast servers is actually
+ answering your queries. Specifying <span class="command"><strong>server-id none;</strong></span>
+ disables processing of the queries.
+ Specifying <span class="command"><strong>server-id hostname;</strong></span> will cause <span class="command"><strong>named</strong></span> to
+ use the hostname as found by the gethostname() function.
+ The default <span class="command"><strong>server-id</strong></span> is <span class="command"><strong>none</strong></span>.
+ </p>
+ </dd>
+</dl></div>
+
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="empty"></a>Built-in Empty Zones</h4></div></div></div>
+
+ <p>
+ The <span class="command"><strong>named</strong></span> server has some built-in
+ empty zones (SOA and NS records only).
+ These are for zones that should normally be answered locally
+ and which queries should not be sent to the Internet's root
+ servers. The official servers which cover these namespaces
+ return NXDOMAIN responses to these queries. In particular,
+ these cover the reverse namespaces for addresses from
+ RFC 1918, RFC 4193, RFC 5737 and RFC 6598. They also include the
+ reverse namespace for IPv6 local address (locally assigned),
+ IPv6 link local addresses, the IPv6 loopback address and the
+ IPv6 unknown address.
+ </p>
+ <p>
+ The server will attempt to determine if a built-in zone
+ already exists or is active (covered by a forward-only
+ forwarding declaration) and will not create an empty
+ zone in that case.
+ </p>
+ <p>
+ The current list of empty zones is:
+ </p>
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
+<li class="listitem">10.IN-ADDR.ARPA</li>
+<li class="listitem">16.172.IN-ADDR.ARPA</li>
+<li class="listitem">17.172.IN-ADDR.ARPA</li>
+<li class="listitem">18.172.IN-ADDR.ARPA</li>
+<li class="listitem">19.172.IN-ADDR.ARPA</li>
+<li class="listitem">20.172.IN-ADDR.ARPA</li>
+<li class="listitem">21.172.IN-ADDR.ARPA</li>
+<li class="listitem">22.172.IN-ADDR.ARPA</li>
+<li class="listitem">23.172.IN-ADDR.ARPA</li>
+<li class="listitem">24.172.IN-ADDR.ARPA</li>
+<li class="listitem">25.172.IN-ADDR.ARPA</li>
+<li class="listitem">26.172.IN-ADDR.ARPA</li>
+<li class="listitem">27.172.IN-ADDR.ARPA</li>
+<li class="listitem">28.172.IN-ADDR.ARPA</li>
+<li class="listitem">29.172.IN-ADDR.ARPA</li>
+<li class="listitem">30.172.IN-ADDR.ARPA</li>
+<li class="listitem">31.172.IN-ADDR.ARPA</li>
+<li class="listitem">168.192.IN-ADDR.ARPA</li>
+<li class="listitem">64.100.IN-ADDR.ARPA</li>
+<li class="listitem">65.100.IN-ADDR.ARPA</li>
+<li class="listitem">66.100.IN-ADDR.ARPA</li>
+<li class="listitem">67.100.IN-ADDR.ARPA</li>
+<li class="listitem">68.100.IN-ADDR.ARPA</li>
+<li class="listitem">69.100.IN-ADDR.ARPA</li>
+<li class="listitem">70.100.IN-ADDR.ARPA</li>
+<li class="listitem">71.100.IN-ADDR.ARPA</li>
+<li class="listitem">72.100.IN-ADDR.ARPA</li>
+<li class="listitem">73.100.IN-ADDR.ARPA</li>
+<li class="listitem">74.100.IN-ADDR.ARPA</li>
+<li class="listitem">75.100.IN-ADDR.ARPA</li>
+<li class="listitem">76.100.IN-ADDR.ARPA</li>
+<li class="listitem">77.100.IN-ADDR.ARPA</li>
+<li class="listitem">78.100.IN-ADDR.ARPA</li>
+<li class="listitem">79.100.IN-ADDR.ARPA</li>
+<li class="listitem">80.100.IN-ADDR.ARPA</li>
+<li class="listitem">81.100.IN-ADDR.ARPA</li>
+<li class="listitem">82.100.IN-ADDR.ARPA</li>
+<li class="listitem">83.100.IN-ADDR.ARPA</li>
+<li class="listitem">84.100.IN-ADDR.ARPA</li>
+<li class="listitem">85.100.IN-ADDR.ARPA</li>
+<li class="listitem">86.100.IN-ADDR.ARPA</li>
+<li class="listitem">87.100.IN-ADDR.ARPA</li>
+<li class="listitem">88.100.IN-ADDR.ARPA</li>
+<li class="listitem">89.100.IN-ADDR.ARPA</li>
+<li class="listitem">90.100.IN-ADDR.ARPA</li>
+<li class="listitem">91.100.IN-ADDR.ARPA</li>
+<li class="listitem">92.100.IN-ADDR.ARPA</li>
+<li class="listitem">93.100.IN-ADDR.ARPA</li>
+<li class="listitem">94.100.IN-ADDR.ARPA</li>
+<li class="listitem">95.100.IN-ADDR.ARPA</li>
+<li class="listitem">96.100.IN-ADDR.ARPA</li>
+<li class="listitem">97.100.IN-ADDR.ARPA</li>
+<li class="listitem">98.100.IN-ADDR.ARPA</li>
+<li class="listitem">99.100.IN-ADDR.ARPA</li>
+<li class="listitem">100.100.IN-ADDR.ARPA</li>
+<li class="listitem">101.100.IN-ADDR.ARPA</li>
+<li class="listitem">102.100.IN-ADDR.ARPA</li>
+<li class="listitem">103.100.IN-ADDR.ARPA</li>
+<li class="listitem">104.100.IN-ADDR.ARPA</li>
+<li class="listitem">105.100.IN-ADDR.ARPA</li>
+<li class="listitem">106.100.IN-ADDR.ARPA</li>
+<li class="listitem">107.100.IN-ADDR.ARPA</li>
+<li class="listitem">108.100.IN-ADDR.ARPA</li>
+<li class="listitem">109.100.IN-ADDR.ARPA</li>
+<li class="listitem">110.100.IN-ADDR.ARPA</li>
+<li class="listitem">111.100.IN-ADDR.ARPA</li>
+<li class="listitem">112.100.IN-ADDR.ARPA</li>
+<li class="listitem">113.100.IN-ADDR.ARPA</li>
+<li class="listitem">114.100.IN-ADDR.ARPA</li>
+<li class="listitem">115.100.IN-ADDR.ARPA</li>
+<li class="listitem">116.100.IN-ADDR.ARPA</li>
+<li class="listitem">117.100.IN-ADDR.ARPA</li>
+<li class="listitem">118.100.IN-ADDR.ARPA</li>
+<li class="listitem">119.100.IN-ADDR.ARPA</li>
+<li class="listitem">120.100.IN-ADDR.ARPA</li>
+<li class="listitem">121.100.IN-ADDR.ARPA</li>
+<li class="listitem">122.100.IN-ADDR.ARPA</li>
+<li class="listitem">123.100.IN-ADDR.ARPA</li>
+<li class="listitem">124.100.IN-ADDR.ARPA</li>
+<li class="listitem">125.100.IN-ADDR.ARPA</li>
+<li class="listitem">126.100.IN-ADDR.ARPA</li>
+<li class="listitem">127.100.IN-ADDR.ARPA</li>
+<li class="listitem">0.IN-ADDR.ARPA</li>
+<li class="listitem">127.IN-ADDR.ARPA</li>
+<li class="listitem">254.169.IN-ADDR.ARPA</li>
+<li class="listitem">2.0.192.IN-ADDR.ARPA</li>
+<li class="listitem">100.51.198.IN-ADDR.ARPA</li>
+<li class="listitem">113.0.203.IN-ADDR.ARPA</li>
+<li class="listitem">255.255.255.255.IN-ADDR.ARPA</li>
+<li class="listitem">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</li>
+<li class="listitem">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</li>
+<li class="listitem">8.B.D.0.1.0.0.2.IP6.ARPA</li>
+<li class="listitem">D.F.IP6.ARPA</li>
+<li class="listitem">8.E.F.IP6.ARPA</li>
+<li class="listitem">9.E.F.IP6.ARPA</li>
+<li class="listitem">A.E.F.IP6.ARPA</li>
+<li class="listitem">B.E.F.IP6.ARPA</li>
+<li class="listitem">EMPTY.AS112.ARPA</li>
+<li class="listitem">HOME.ARPA</li>
+</ul></div>
+<p>
+ </p>
+ <p>
+ Empty zones are settable 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, you can disable the root zone at the view level, for example:
+</p>
+<pre class="programlisting">
+ disable-empty-zone ".";
+</pre>
+<p>
+ </p>
+ <p>
+ If you are using the address ranges covered here, you should
+ already have reverse zones covering the addresses you use.
+ 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 were needed
+ to be deployed to channel the query load away from the
+ infrastructure servers.
+ </p>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+<p>
+ The real parent servers for these zones should disable all
+ empty zone under the parent zone they serve. For the real
+ root servers, this is all built-in empty zones. This will
+ enable them to return referrals to deeper in the tree.
+ </p>
+</div>
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>empty-server</strong></span></span></dt>
+<dd>
+ <p>
+ Specify what server name will appear in the returned
+ SOA record for empty zones. If none is specified, then
+ the zone's name will be used.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>empty-contact</strong></span></span></dt>
+<dd>
+ <p>
+ Specify what contact name will appear in the returned
+ SOA record for empty zones. If none is specified, then
+ "." will be used.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>empty-zones-enable</strong></span></span></dt>
+<dd>
+ <p>
+ Enable or disable all empty zones. By default, they
+ are enabled.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>disable-empty-zone</strong></span></span></dt>
+<dd>
+ <p>
+ Disable individual empty zones. By default, none are
+ disabled. This option can be specified multiple times.
+ </p>
+ </dd>
+</dl></div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="acache"></a>Additional Section Caching</h4></div></div></div>
+
+
+ <p>
+ The additional section cache, also called <span class="command"><strong>acache</strong></span>,
+ is an internal cache to improve the response performance of BIND 9.
+ When additional section caching is enabled, BIND 9 will
+ cache an internal short-cut to the additional section content for
+ each answer RR.
+ Note that <span class="command"><strong>acache</strong></span> is an internal caching
+ mechanism of BIND 9, and is not related to the DNS caching
+ server function.
+ </p>
+
+ <p>
+ Additional section caching does not change the
+ response content (except the RRsets ordering of the additional
+ section, see below), but can improve the response performance
+ significantly.
+ It is particularly effective when BIND 9 acts as an authoritative
+ server for a zone that has many delegations with many glue RRs.
+ </p>
+
+ <p>
+ In order to obtain the maximum performance improvement
+ from additional section caching, setting
+ <span class="command"><strong>additional-from-cache</strong></span>
+ to <span class="command"><strong>no</strong></span> is recommended, since the current
+ implementation of <span class="command"><strong>acache</strong></span>
+ does not short-cut of additional section information from the
+ DNS cache data.
+ </p>
+
+ <p>
+ One obvious disadvantage of <span class="command"><strong>acache</strong></span> is
+ that it requires much more
+ memory for the internal cached data.
+ Thus, if the response performance does not matter and memory
+ consumption is much more critical, the
+ <span class="command"><strong>acache</strong></span> mechanism can be
+ disabled by setting <span class="command"><strong>acache-enable</strong></span> to
+ <span class="command"><strong>no</strong></span>.
+ It is also possible to specify the upper limit of memory
+ consumption
+ for acache by using <span class="command"><strong>max-acache-size</strong></span>.
+ </p>
+
+ <p>
+ Additional section caching also has a minor effect on the
+ RRset ordering in the additional section.
+ Without <span class="command"><strong>acache</strong></span>,
+ <span class="command"><strong>cyclic</strong></span> order is effective for the additional
+ section as well as the answer and authority sections.
+ However, additional section caching fixes the ordering when it
+ first caches an RRset for the additional section, and the same
+ ordering will be kept in succeeding responses, regardless of the
+ setting of <span class="command"><strong>rrset-order</strong></span>.
+ The effect of this should be minor, however, since an
+ RRset in the additional section
+ typically only contains a small number of RRs (and in many cases
+ it only contains a single RR), in which case the
+ ordering does not matter much.
+ </p>
+
+ <p>
+ The following is a summary of options related to
+ <span class="command"><strong>acache</strong></span>.
+ </p>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>acache-enable</strong></span></span></dt>
+<dd>
+ <p>
+ If <span class="command"><strong>yes</strong></span>, additional section caching is
+ enabled. The default value is <span class="command"><strong>no</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>acache-cleaning-interval</strong></span></span></dt>
+<dd>
+ <p>
+ The server will remove stale cache entries, based on an LRU
+ based
+ algorithm, every <span class="command"><strong>acache-cleaning-interval</strong></span> minutes.
+ The default is 60 minutes.
+ If set to 0, no periodic cleaning will occur.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-acache-size</strong></span></span></dt>
+<dd>
+ <p>
+ The maximum amount of memory in bytes to use for the server's acache.
+ When the amount of data in the acache reaches this limit,
+ the server
+ will clean more aggressively so that the limit is not
+ exceeded.
+ In a server with multiple views, the limit applies
+ separately to the
+ acache of each view.
+ The default is <code class="literal">16M</code>.
+ </p>
+ </dd>
+</dl></div>
+
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="content_filtering"></a>Content Filtering</h4></div></div></div>
+
+ <p>
+ <acronym class="acronym">BIND</acronym> 9 provides the ability to filter
+ out DNS 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
+ <code class="varname">address_match_list</code> of the
+ <span class="command"><strong>deny-answer-addresses</strong></span> option.
+ 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 <code class="varname">namelist</code> of the
+ <span class="command"><strong>deny-answer-aliases</strong></span> option, where
+ "match" means the alias name is a subdomain of one of
+ the <code class="varname">name_list</code> elements.
+ If the optional <code class="varname">namelist</code> is specified
+ with <span class="command"><strong>except-from</strong></span>, records whose query name
+ matches the list will be accepted regardless of the filter
+ setting.
+ Likewise, if the alias name is a subdomain of the
+ corresponding zone, the <span class="command"><strong>deny-answer-aliases</strong></span>
+ filter will not apply;
+ for example, even if "example.com" is specified for
+ <span class="command"><strong>deny-answer-aliases</strong></span>,
+ </p>
+<pre class="programlisting">www.example.com. CNAME xxx.example.com.</pre>
+
+ <p>
+ returned by an "example.com" server will be accepted.
+ </p>
+
+ <p>
+ In the <code class="varname">address_match_list</code> of the
+ <span class="command"><strong>deny-answer-addresses</strong></span> option, only
+ <code class="varname">ip_addr</code>
+ and <code class="varname">ip_prefix</code>
+ are meaningful;
+ any <code class="varname">key_id</code> will be silently ignored.
+ </p>
+
+ <p>
+ If a response message is rejected due to the filtering,
+ the entire message is discarded without being cached, and
+ a SERVFAIL error will be 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 your own network or
+ an alias name within your 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 your local network
+ that couldn't be externally accessed otherwise.
+ See the paper available at
+ <a class="link" href="http://portal.acm.org/citation.cfm?id=1315245.1315298" target="_top">
+ http://portal.acm.org/citation.cfm?id=1315245.1315298
+ </a>
+ for more details about the attacks.
+ </p>
+
+ <p>
+ For example, if you own a domain named "example.net" and
+ your internal network uses an IPv4 prefix 192.0.2.0/24,
+ you might specify the following rules:
+ </p>
+
+<pre class="programlisting">deny-answer-addresses { 192.0.2.0/24; } except-from { "example.net"; };
+deny-answer-aliases { "example.net"; };
+</pre>
+
+ <p>
+ If an external attacker lets a web browser in your local
+ network look up an IPv4 address of "attacker.example.com",
+ the attacker's DNS server would return a response like this:
+ </p>
+
+<pre class="programlisting">attacker.example.com. A 192.0.2.1</pre>
+
+ <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 will be
+ ignored.
+ </p>
+
+ <p>
+ On the other hand, if the browser looks up a legitimate
+ internal web server "www.example.net" and the
+ following response is returned to
+ the <acronym class="acronym">BIND</acronym> 9 server
+ </p>
+
+<pre class="programlisting">www.example.net. A 192.0.2.2</pre>
+
+ <p>
+ it will be accepted since the owner name "www.example.net"
+ matches the <span class="command"><strong>except-from</strong></span> element,
+ "example.net".
+ </p>
+
+ <p>
+ Note that this is not really an attack on the DNS per se.
+ In fact, there is nothing wrong for an "external" name to
+ be mapped to your "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 is not possible or does not make sense to detect
+ whether the intent of the mapping is legitimate or not
+ 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;
+ it is generally discouraged to turn it on unless you are
+ very sure you have no other choice and the attack is a
+ real threat for your applications.
+ </p>
+
+ <p>
+ Care should be particularly taken if you want to use 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>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="rpz"></a>Response Policy Zone (RPZ) Rewriting</h4></div></div></div>
+
+ <p>
+ <acronym class="acronym">BIND</acronym> 9 includes a limited
+ mechanism to modify DNS responses for requests
+ analogous to email anti-spam DNS blacklists.
+ 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>
+
+ <p>
+ Response policy zones are named in the
+ <span class="command"><strong>response-policy</strong></span> option for the view or among the
+ global options if there is no response-policy 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
+ <span class="command"><strong>allow-query { localhost; };</strong></span>.
+ Note that zones using <span class="command"><strong>masterfile-format map</strong></span>
+ cannot be used as policy zones.
+ </p>
+
+ <p>
+ A <span class="command"><strong>response-policy</strong></span> 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 32 on the number of policy zones
+ in a single <span class="command"><strong>response-policy</strong></span> option; more
+ than that is a configuration error.
+ </p>
+
+ <p>
+ Five policy triggers can be encoded in RPZ records.
+ </p>
+<div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>RPZ-CLIENT-IP</strong></span></span></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
+ <span class="command"><strong>rpz-client-ip</strong></span> relativized to the
+ policy zone origin name
+ and encode an address or address block.
+ IPv4 addresses are represented as
+ <strong class="userinput"><code>prefixlength.B4.B3.B2.B1.rpz-client-ip</code></strong>.
+ 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,
+ <strong class="userinput"><code>prefixlength.W8.W7.W6.W5.W4.W3.W2.W1.rpz-client-ip</code></strong>.
+ 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
+ address 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 <strong class="userinput"><code>.zz.</code></strong>
+ analogous to double colons (::) in standard IPv6 text
+ encodings.
+ The IPv6 prefix length must be between 1 and 128.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>QNAME</strong></span></span></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><span class="term"><span class="command"><strong>RPZ-IP</strong></span></span></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 <span class="command"><strong>rpz-ip</strong></span>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>RPZ-NSDNAME</strong></span></span></dt>
+<dd>
+ <p>
+ NSDNAME triggers match names of authoritative servers
+ for the query name, a parent of the query name, a CNAME for
+ query name, or a parent of a CNAME.
+ They are encoded as subdomains of
+ <span class="command"><strong>rpz-nsdname</strong></span> 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.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>RPZ-NSIP</strong></span></span></dt>
+<dd>
+ <p>
+ NSIP triggers match the IP addresses of authoritative
+ servers. They are enncoded like IP triggers, except as
+ subdomains of <span class="command"><strong>rpz-nsip</strong></span>.
+ NSDNAME and NSIP triggers are checked only for names with at
+ least <span class="command"><strong>min-ns-dots</strong></span> dots.
+ The default value of <span class="command"><strong>min-ns-dots</strong></span> is
+ 1, to exclude top level domains.
+ </p>
+ <p>
+ If a name server's IP address is not yet known,
+ <span class="command"><strong>named</strong></span> will recursively look up
+ the IP address before applying an RPZ-NSIP rule.
+ This can cause a processing delay. To speed up
+ processing at the cost of precision, the
+ <span class="command"><strong>nsip-wait-recurse</strong></span> option
+ can be used: when set to <strong class="userinput"><code>no</code></strong>,
+ RPZ-NSIP rules will only be applied when a name
+ servers's IP address has already been looked up and
+ cached. If a server's IP address is not in the
+ cache, then the RPZ-NSIP rule will be ignored,
+ but the address will be looked up in the
+ background, and the rule will be applied
+ to subsequent queries. The default is
+ <strong class="userinput"><code>yes</code></strong>, meaning RPZ-NSIP
+ rules should always be applied even if an
+ address needs to be looked up first.
+ </p>
+ </dd>
+</dl></div>
+<p>
+ </p>
+
+ <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
+ <span class="command"><strong>DISABLED</strong></span> actions) must be chosen.
+ Triggers or the records that encode them are chosen for the
+ rewriting in the following order:
+ </p>
+<div class="orderedlist"><ol class="orderedlist" type="1">
+<li class="listitem">Choose the triggered record in the zone that appears
+ first in the <span class="command"><strong>response-policy</strong></span> option.
+ </li>
+<li class="listitem">Prefer CLIENT-IP to QNAME to IP to NSDNAME to NSIP
+ triggers in a single zone.
+ </li>
+<li class="listitem">Among NSDNAME triggers, prefer the
+ trigger that matches the smallest name under the DNSSEC ordering.
+ </li>
+<li class="listitem">Among IP or NSIP triggers, prefer the trigger
+ with the longest prefix.
+ </li>
+<li class="listitem">Among triggers with the same prefix length,
+ prefer the IP or NSIP trigger that matches
+ the smallest IP address.
+ </li>
+</ol></div>
+<p>
+ </p>
+
+ <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 <span class="command"><strong>TCP-only</strong></span> policy is
+ commonly used with <span class="command"><strong>client-IP</strong></span> 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>
+<div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>PASSTHRU</strong></span></span></dt>
+<dd>
+ <p>
+ The whitelist policy is specified
+ by a CNAME whose target is <span class="command"><strong>rpz-passthru</strong></span>.
+ It causes the response to not be rewritten
+ and is most often used to "poke holes" in policies for
+ CIDR blocks.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>DROP</strong></span></span></dt>
+<dd>
+ <p>
+ The blacklist policy is specified
+ by a CNAME whose target is <span class="command"><strong>rpz-drop</strong></span>.
+ It causes the response to be discarded.
+ Nothing is sent to the DNS client.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>TCP-Only</strong></span></span></dt>
+<dd>
+ <p>
+ The "slip" policy is specified
+ by a CNAME whose target is <span class="command"><strong>rpz-tcp-only</strong></span>.
+ 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><span class="term"><span class="command"><strong>NXDOMAIN</strong></span></span></dt>
+<dd>
+ <p>
+ The domain undefined response is encoded
+ by a CNAME whose target is the root domain (.)
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>NODATA</strong></span></span></dt>
+<dd>
+ <p>
+ The empty set of resource records is specified by
+ CNAME whose target is the wildcard top-level
+ domain (*.).
+ It rewrites the response to NODATA or ANCOUNT=1.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>Local Data</strong></span></span></dt>
+<dd>
+ <p>
+ A set of ordinary DNS records can be used to answer queries.
+ Queries for record types not 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 were an ordinary CNAME after the asterisk (*)
+ has been replaced with the query name.
+ The purpose for this special form is query logging in the
+ walled garden's authority DNS server.
+ </p>
+ </dd>
+</dl></div>
+<p>
+ </p>
+
+ <p>
+ All of the actions specified in all of the individual records
+ in a policy zone
+ can be overridden with a <span class="command"><strong>policy</strong></span> clause in the
+ <span class="command"><strong>response-policy</strong></span> option.
+ An organization using a policy zone provided by another
+ organization might use this mechanism to redirect domains
+ to its own walled garden.
+ </p>
+<div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>GIVEN</strong></span></span></dt>
+<dd>
+ <p>The placeholder policy says "do not override but
+ perform the action specified in the zone."
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>DISABLED</strong></span></span></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 will be written (or not)
+ according to any triggered policy records that are not
+ disabled.
+ Disabled policy zones should appear first,
+ because they will often not be logged
+ if a higher precedence trigger is found first.
+ </p>
+ </dd>
+<dt>
+<span class="term"><span class="command"><strong>PASSTHRU</strong></span>, </span><span class="term"><span class="command"><strong>DROP</strong></span>, </span><span class="term"><span class="command"><strong>TCP-Only</strong></span>, </span><span class="term"><span class="command"><strong>NXDOMAIN</strong></span>, </span><span class="term"><span class="command"><strong>NODATA</strong></span></span>
+</dt>
+<dd>
+ <p>
+ override with the corresponding per-record policy.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>CNAME domain</strong></span></span></dt>
+<dd>
+ <p>
+ causes all RPZ policy records to act as if they were
+ "cname domain" records.
+ </p>
+ </dd>
+</dl></div>
+<p>
+ </p>
+
+ <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
+ all response policy zones in a view
+ with a <span class="command"><strong>recursive-only no</strong></span> clause.
+ This feature is useful for serving the same zone files
+ both inside and outside an RFC 1918 cloud and using RPZ to
+ delete answers that would otherwise contain RFC 1918 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 request 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
+ <span class="command"><strong>break-dnssec yes</strong></span> 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 default behavior can cost
+ significant time.
+ The <span class="command"><strong>qname-wait-recurse no</strong></span> option
+ overrides that default 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 <span class="command"><strong>break-dnssec yes</strong></span>
+ is in use, because the response would depend on whether or not
+ 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>
+
+ <p>
+ The TTL of a record modified by RPZ policies is set from the
+ TTL of the relevant record in policy zone. It is then limited
+ to a maximum value.
+ The <span class="command"><strong>max-policy-ttl</strong></span> clause changes the
+ maximum seconds from its default of 5.
+ </p>
+
+ <p>
+ For example, you might use this option statement
+ </p>
+<pre class="programlisting"> response-policy { zone "badlist"; };</pre>
+ <p>
+ and this zone statement
+ </p>
+<pre class="programlisting"> zone "badlist" {type master; file "master/badlist"; allow-query {none;}; };</pre>
+ <p>
+ with this zone file
+ </p>
+<pre class="programlisting">$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 .
+
+; blacklist and whitelist 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>
+ <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 <acronym class="acronym">BIND9</acronym> server with adequate memory and one
+ response policy zone with QNAME and IP triggers might achieve a
+ maximum queries-per-second 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
+ <span class="command"><strong>RPZRewrites</strong></span> statistics.
+ </p>
+
+ <p>
+ The <span class="command"><strong>log</strong></span> clause can be used to optionally
+ turn off rewrite logging for a particular response policy
+ zone. By default, all rewrites are logged.
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="rrl"></a>Response Rate Limiting</h4></div></div></div>
+
+ <p>
+ Excessive almost identical UDP <span class="emphasis"><em>responses</em></span>
+ can be controlled by configuring a
+ <span class="command"><strong>rate-limit</strong></span> clause in an
+ <span class="command"><strong>options</strong></span> or <span class="command"><strong>view</strong></span> statement.
+ This mechanism keeps authoritative BIND 9 from being used
+ in amplifying reflection denial of service (DoS) attacks.
+ Short 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 or truncated response
+ by retrying with UDP or with TCP respectively.
+ </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.
+ Responses are tracked within a rolling window of time
+ which defaults to 15 seconds, but can be configured with
+ the <span class="command"><strong>window</strong></span> 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 <span class="command"><strong>window</strong></span>
+ 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>
+
+ <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 addresses blocks are
+ specified with <span class="command"><strong>ipv4-prefix-length</strong></span> (default 24)
+ and <span class="command"><strong>ipv6-prefix-length</strong></span> (default 56).
+ </p>
+
+ <p>
+ All non-empty responses for a valid domain name (qname)
+ and record type (qtype) are identical and have a limit specified
+ with <span class="command"><strong>responses-per-second</strong></span>
+ (default 0 or no limit).
+ All empty (NODATA) responses for a valid domain,
+ regardless of query type, are identical.
+ Responses in the NODATA class are limited by
+ <span class="command"><strong>nodata-per-second</strong></span>
+ (default <span class="command"><strong>responses-per-second</strong></span>).
+ 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 <span class="command"><strong>nxdomains-per-second</strong></span>
+ (default <span class="command"><strong>responses-per-second</strong></span>).
+ 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 blacklists.
+ Referrals or delegations to the server of a given
+ domain are identical and are limited by
+ <span class="command"><strong>referrals-per-second</strong></span>
+ (default <span class="command"><strong>responses-per-second</strong></span>).
+ </p>
+
+ <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.
+ By default the limit on errors is the same as the
+ <span class="command"><strong>responses-per-second</strong></span> value,
+ but it can be set separately with
+ <span class="command"><strong>errors-per-second</strong></span>.
+ </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 <span class="command"><strong>slip</strong></span> to 2 (its default) causes every
+ other UDP request to be answered with a small truncated (TC=1)
+ response.
+ The small size and reduced frequency, and so lack of
+ amplification, of "slipped" responses make them unattractive
+ for reflection DoS attacks.
+ <span class="command"><strong>slip</strong></span> must be between 0 and 10.
+ A value of 0 does not "slip":
+ no truncated responses are sent due to rate limiting,
+ all responses are dropped.
+ A value of 1 causes every response to slip;
+ values between 2 and 10 cause every n'th response to slip.
+ Some error responses including REFUSED and SERVFAIL
+ cannot be replaced with truncated responses and are instead
+ leaked at the <span class="command"><strong>slip</strong></span> 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
+ <span class="command"><strong>slip</strong></span> to 1, causing all rate-limited
+ responses to be truncated rather than dropped. This reduces
+ the effectiveness of rate-limiting against reflection attacks.)
+ </p>
+
+ <p>
+ When the approximate query per second rate exceeds
+ the <span class="command"><strong>qps-scale</strong></span> value,
+ then the <span class="command"><strong>responses-per-second</strong></span>,
+ <span class="command"><strong>errors-per-second</strong></span>,
+ <span class="command"><strong>nxdomains-per-second</strong></span> and
+ <span class="command"><strong>all-per-second</strong></span> values are reduced by the
+ ratio of the current rate to the <span class="command"><strong>qps-scale</strong></span> value.
+ This feature can tighten defenses during attacks.
+ For example, with
+ <span class="command"><strong>qps-scale 250; responses-per-second 20;</strong></span> 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 sent via TCP are not limited
+ but are counted to compute the query per second rate.
+ </p>
+
+ <p>
+ Rate limiters for different name spaces maintain
+ separate counters: If, for example, there is a
+ <span class="command"><strong>rate-limit</strong></span> statement for "com" and
+ another for "example.com", queries matching "example.com"
+ will not be debited against the rate limiter for "com".
+ </p>
+
+ <p>
+ If a <span class="command"><strong>rate-limit</strong></span> statement does not specify a
+ <span class="command"><strong>domain</strong></span>, then it applies to the root domain
+ (".") and thus affects the entire DNS namespace, except those
+ portions covered by other <span class="command"><strong>rate-limit</strong></span>
+ statements.
+ </p>
+
+ <p>
+ Communities of DNS clients can be given their own parameters or no
+ rate limiting by putting
+ <span class="command"><strong>rate-limit</strong></span> statements in <span class="command"><strong>view</strong></span>
+ statements instead of the global <span class="command"><strong>option</strong></span>
+ statement.
+ A <span class="command"><strong>rate-limit</strong></span> statement in a view replaces,
+ rather than supplementing, a <span class="command"><strong>rate-limit</strong></span>
+ statement among the main options.
+ DNS clients within a view can be exempted from rate limits
+ with the <span class="command"><strong>exempt-clients</strong></span> clause.
+ </p>
+
+ <p>
+ UDP responses of all kinds can be limited with the
+ <span class="command"><strong>all-per-second</strong></span> phrase. This rate
+ limiting is unlike the rate limiting provided by
+ <span class="command"><strong>responses-per-second</strong></span>,
+ <span class="command"><strong>errors-per-second</strong></span>, and
+ <span class="command"><strong>nxdomains-per-second</strong></span> 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 <span class="command"><strong>all-per-second</strong></span> limit
+ are always dropped; the <span class="command"><strong>slip</strong></span> value
+ has no effect. An <span class="command"><strong>all-per-second</strong></span>
+ 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 STMP <span class="command"><strong>Mail From</strong></span>
+ command. Web browsers often repeatedly resolve the
+ same names that are repeated in HTML &lt;IMG&gt; tags
+ in a page. <span class="command"><strong>all-per-second</strong></span> is similar
+ to the rate limiting offered by firewalls but 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 make TCP connections
+ or parsing DNS requests, but that rate limiting must
+ be done before the DNS server sees the requests.
+ </p>
+
+ <p>
+ The maximum size of the table used to track requests and
+ rate limit responses is set with <span class="command"><strong>max-table-size</strong></span>.
+ 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,
+ <span class="command"><strong>min-table-size</strong></span> (default 500)
+ can set the minimum table size.
+ Enable <span class="command"><strong>rate-limit</strong></span> category logging to monitor
+ expansions of the table and inform
+ choices for the initial and maximum table size.
+ </p>
+
+ <p>
+ Use <span class="command"><strong>log-only yes</strong></span> to test rate limiting parameters
+ without actually dropping any requests.
+ </p>
+
+ <p>
+ Responses dropped by rate limits are included in the
+ <span class="command"><strong>RateDropped</strong></span> and <span class="command"><strong>QryDropped</strong></span>
+ statistics.
+ Responses that truncated by rate limits are included in
+ <span class="command"><strong>RateSlipped</strong></span> and <span class="command"><strong>RespTruncated</strong></span>.
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"></div>
+ <p>
+ Named supports NXDOMAIN redirection via two methods:
+ </p>
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
+<li class="listitem">Redirect zone <a class="xref" href="Bv9ARM.ch06.html#zone_statement_grammar" title="zone Statement Grammar">the section called &#8220;<span class="command"><strong>zone</strong></span>
+ Statement Grammar&#8221;</a>
+</li>
+<li class="listitem">Redirect namespace</li>
+</ul></div>
+<p>
+ </p>
+ <p>
+ With both methods when named gets a 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 (<span class="command"><strong>zone "." { type redirect; };</strong></span>), 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>
+ <p>
+ With a redirect namespace (<span class="command"><strong>option { nxdomain-redirect
+ &lt;suffix&gt; };</strong></span>) 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 you have the original NXDOMAIN response and
+ the replacement data or a NXDOMAIN indicating that there
+ is no replacement.
+ </p>
+ <p>
+ If both a redirect zone and a redirect namespace are configured,
+ the redirect zone is tried first.
+ </p>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="server_statement_grammar"></a><span class="command"><strong>server</strong></span> Statement Grammar</h3></div></div></div>
+ <pre class="programlisting">
+<span class="command"><strong>server</strong></span> <em class="replaceable"><code>netprefix</code></em> {
+ <span class="command"><strong>bogus</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>edns</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>edns-udp-size</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>edns-version</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>keys</strong></span> <em class="replaceable"><code>server_key</code></em>;
+ <span class="command"><strong>max-udp-size</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>notify-source</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [
+ <span class="command"><strong>dscp</strong></span> <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>notify-source-v6</strong></span> ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ]
+ [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>provide-ixfr</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>query-source</strong></span> ( ( [ address ] ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port (
+ <em class="replaceable"><code>integer</code></em> | * ) ] ) | ( [ [ address ] ( <em class="replaceable"><code>ipv4_address</code></em> | * ) ]
+ <span class="command"><strong>port</strong></span> ( <em class="replaceable"><code>integer</code></em> | * ) ) ) [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>query-source-v6</strong></span> ( ( [ address ] ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port (
+ <em class="replaceable"><code>integer</code></em> | * ) ] ) | ( [ [ address ] ( <em class="replaceable"><code>ipv6_address</code></em> | * ) ]
+ <span class="command"><strong>port</strong></span> ( <em class="replaceable"><code>integer</code></em> | * ) ) ) [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>request-expire</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>request-ixfr</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>request-nsid</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>send-cookie</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>tcp-only</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>transfer-format</strong></span> ( many-answers | one-answer );
+ <span class="command"><strong>transfer-source</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [
+ <span class="command"><strong>dscp</strong></span> <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>transfer-source-v6</strong></span> ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * )
+ ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>transfers</strong></span> <em class="replaceable"><code>integer</code></em>;
+};
+</pre>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="server_statement_definition_and_usage"></a><span class="command"><strong>server</strong></span> Statement Definition and
+ Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>server</strong></span> 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
+ <code class="filename">named.conf</code>.
+ </p>
+
+ <p>
+ The <span class="command"><strong>server</strong></span> statement can occur at
+ the top level of the
+ configuration file or inside a <span class="command"><strong>view</strong></span>
+ statement.
+ If a <span class="command"><strong>view</strong></span> statement contains
+ one or more <span class="command"><strong>server</strong></span> statements, only
+ those
+ apply to the view and any top-level ones are ignored.
+ If a view contains no <span class="command"><strong>server</strong></span>
+ statements,
+ any top-level <span class="command"><strong>server</strong></span> statements are
+ used as
+ defaults.
+ </p>
+
+ <p>
+ If you discover that a remote server is giving out bad data,
+ marking it as bogus will prevent further queries to it. The
+ default
+ value of <span class="command"><strong>bogus</strong></span> is <span class="command"><strong>no</strong></span>.
+ </p>
+ <p>
+ The <span class="command"><strong>provide-ixfr</strong></span> clause determines
+ whether
+ the local server, acting as master, will respond with an
+ incremental
+ zone transfer when the given remote server, a slave, requests it.
+ If set to <span class="command"><strong>yes</strong></span>, incremental transfer
+ will be provided
+ whenever possible. If set to <span class="command"><strong>no</strong></span>,
+ all transfers
+ to the remote server will be non-incremental. If not set, the
+ value
+ of the <span class="command"><strong>provide-ixfr</strong></span> option in the
+ view or
+ global options block is used as a default.
+ </p>
+
+ <p>
+ The <span class="command"><strong>request-ixfr</strong></span> clause determines
+ whether
+ the local server, acting as a slave, will request incremental zone
+ transfers from the given remote server, a master. If not set, the
+ value of the <span class="command"><strong>request-ixfr</strong></span> option in
+ the view or global options block is used as a default. It may
+ also be set in the zone block and, if set there, it will
+ override the global or view setting for that zone.
+ </p>
+
+ <p>
+ IXFR requests to servers that do not support IXFR will
+ 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 <span class="command"><strong>yes</strong></span> should always work.
+ The purpose of the <span class="command"><strong>provide-ixfr</strong></span> and
+ <span class="command"><strong>request-ixfr</strong></span> clauses is
+ to make it possible to disable the use of IXFR even when both
+ master
+ and slave claim to support it, for example if one of the servers
+ is buggy and crashes or corrupts data when IXFR is used.
+ </p>
+
+ <p>
+ The <span class="command"><strong>request-expire</strong></span> clause determines
+ whether the local server, when acting as a slave, will
+ request the EDNS EXPIRE value. The EDNS EXPIRE value
+ indicates the remaining time before the zone data will
+ expire and need to be 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 <span class="command"><strong>yes</strong></span>.
+ </p>
+
+ <p>
+ The <span class="command"><strong>edns</strong></span> clause determines whether
+ the local server will attempt to use EDNS when communicating
+ with the remote server. The default is <span class="command"><strong>yes</strong></span>.
+ </p>
+
+ <p>
+ The <span class="command"><strong>edns-udp-size</strong></span> option sets the
+ EDNS UDP size that is advertised by <span class="command"><strong>named</strong></span>
+ when querying the remote server. Valid values are 512
+ to 4096 bytes (values outside this range will be silently
+ adjusted to the nearest value within it). This option
+ is useful when you wish to advertise a different value
+ to this server than the value you advertise globally,
+ for example, when there is a firewall at the remote
+ site that is blocking large replies. (Note: Currently,
+ this sets a single UDP size for all packets sent to the
+ server; <span class="command"><strong>named</strong></span> will not deviate from
+ this value. This differs from the behavior of
+ <span class="command"><strong>edns-udp-size</strong></span> in <span class="command"><strong>options</strong></span>
+ or <span class="command"><strong>view</strong></span> statements, where it specifies
+ a maximum value. The <span class="command"><strong>server</strong></span> statement
+ behavior may be brought into conformance with the
+ <span class="command"><strong>options/view</strong></span> behavior in future releases.)
+ </p>
+
+ <p>
+ The <span class="command"><strong>edns-version</strong></span> option sets the
+ maximum EDNS VERSION that will be sent to the server(s)
+ by the resolver. The actual EDNS version sent is still
+ subject to normal EDNS version negotiation rules (see
+ RFC 6891), 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 will be silently
+ adjusted. This option will not be needed until higher
+ EDNS versions than 0 are in use.
+ </p>
+
+ <p>
+ The <span class="command"><strong>max-udp-size</strong></span> option sets the
+ maximum EDNS UDP message size <span class="command"><strong>named</strong></span>
+ will send. Valid values are 512 to 4096 bytes (values
+ outside this range will be silently adjusted). This
+ option is useful when you know that there is a firewall
+ that is blocking large replies from <span class="command"><strong>named</strong></span>.
+ </p>
+
+ <p>
+ The <span class="command"><strong>tcp-only</strong></span> 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>
+
+ <p>
+ The server supports two zone transfer methods. The first, <span class="command"><strong>one-answer</strong></span>,
+ uses one DNS message per resource record transferred. <span class="command"><strong>many-answers</strong></span> packs
+ as many resource records as possible into a message. <span class="command"><strong>many-answers</strong></span> is
+ more efficient, but is only known to be understood by <acronym class="acronym">BIND</acronym> 9, <acronym class="acronym">BIND</acronym>
+ 8.x, and patched versions of <acronym class="acronym">BIND</acronym>
+ 4.9.5. You can specify which method
+ to use for a server with the <span class="command"><strong>transfer-format</strong></span> option.
+ If <span class="command"><strong>transfer-format</strong></span> is not
+ specified, the <span class="command"><strong>transfer-format</strong></span>
+ specified
+ by the <span class="command"><strong>options</strong></span> statement will be
+ used.
+ </p>
+
+ <p><span class="command"><strong>transfers</strong></span>
+ is used to limit the number of concurrent inbound zone
+ transfers from the specified server. If no
+ <span class="command"><strong>transfers</strong></span> clause is specified, the
+ limit is set according to the
+ <span class="command"><strong>transfers-per-ns</strong></span> option.
+ </p>
+
+ <p>
+ The <span class="command"><strong>keys</strong></span> clause identifies a
+ <span class="command"><strong>key_id</strong></span> defined by the <span class="command"><strong>key</strong></span> statement,
+ to be used for transaction security (TSIG, <a class="xref" href="Bv9ARM.ch04.html#tsig" title="TSIG">the section called &#8220;TSIG&#8221;</a>)
+ when talking to the remote server.
+ When a request is sent to the remote server, a request signature
+ will be 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>
+
+ <p>
+ The <span class="command"><strong>transfer-source</strong></span> and
+ <span class="command"><strong>transfer-source-v6</strong></span> clauses specify
+ the IPv4 and IPv6 source
+ address to be used for zone transfer with the remote server,
+ respectively.
+ For an IPv4 remote server, only <span class="command"><strong>transfer-source</strong></span> can
+ be specified.
+ Similarly, for an IPv6 remote server, only
+ <span class="command"><strong>transfer-source-v6</strong></span> can be
+ specified.
+ For more details, see the description of
+ <span class="command"><strong>transfer-source</strong></span> and
+ <span class="command"><strong>transfer-source-v6</strong></span> in
+ <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+
+ <p>
+ The <span class="command"><strong>notify-source</strong></span> and
+ <span class="command"><strong>notify-source-v6</strong></span> clauses specify the
+ IPv4 and IPv6 source address to be used for notify
+ messages sent to remote servers, respectively. For an
+ IPv4 remote server, only <span class="command"><strong>notify-source</strong></span>
+ can be specified. Similarly, for an IPv6 remote server,
+ only <span class="command"><strong>notify-source-v6</strong></span> can be specified.
+ </p>
+
+ <p>
+ The <span class="command"><strong>query-source</strong></span> and
+ <span class="command"><strong>query-source-v6</strong></span> clauses specify the
+ IPv4 and IPv6 source address to be used for queries
+ sent to remote servers, respectively. For an IPv4
+ remote server, only <span class="command"><strong>query-source</strong></span> can
+ be specified. Similarly, for an IPv6 remote server,
+ only <span class="command"><strong>query-source-v6</strong></span> can be specified.
+ </p>
+
+ <p>
+ The <span class="command"><strong>request-nsid</strong></span> clause determines
+ whether the local server will add a NSID EDNS option
+ to requests sent to the server. This overrides
+ <span class="command"><strong>request-nsid</strong></span> set at the view or
+ option level.
+ </p>
+
+ <p>
+ The <span class="command"><strong>send-cookie</strong></span> clause determines
+ whether the local server will add a COOKIE EDNS option
+ to requests sent to the server. This overrides
+ <span class="command"><strong>send-cookie</strong></span> set at the view or
+ option level. The <span class="command"><strong>named</strong></span> server may
+ determine that COOKIE is not supported by the remote server
+ and not add a COOKIE EDNS option to requests.
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="statschannels"></a><span class="command"><strong>statistics-channels</strong></span> Statement Grammar</h3></div></div></div>
+ <pre class="programlisting">
+<span class="command"><strong>statistics-channels</strong></span> {
+ <span class="command"><strong>inet</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | <em class="replaceable"><code>ipv6_address</code></em> |
+ * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [
+ <span class="command"><strong>allow</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ...
+ } ];
+};
+</pre>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="statistics_channels"></a><span class="command"><strong>statistics-channels</strong></span> Statement Definition and
+ Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>statistics-channels</strong></span> statement
+ declares communication channels to be used by system
+ administrators to get access to statistics information of
+ the name server.
+ </p>
+
+ <p>
+ This statement intends 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
+ <span class="command"><strong>statistics-channels</strong></span> statement is
+ still accepted even if it is built without the library,
+ but any HTTP access will fail with an error.
+ </p>
+
+ <p>
+ An <span class="command"><strong>inet</strong></span> control channel is a TCP socket
+ listening at the specified <span class="command"><strong>ip_port</strong></span> on the
+ specified <span class="command"><strong>ip_addr</strong></span>, which can be an IPv4 or IPv6
+ address. An <span class="command"><strong>ip_addr</strong></span> of <code class="literal">*</code>
+ (asterisk) is
+ interpreted as the IPv4 wildcard address; connections will be
+ accepted on any of the system's IPv4 addresses.
+ To listen on the IPv6 wildcard address,
+ use an <span class="command"><strong>ip_addr</strong></span> of <code class="literal">::</code>.
+ </p>
+
+ <p>
+ If no port is specified, port 80 is used for HTTP channels.
+ The asterisk "<code class="literal">*</code>" cannot be used for
+ <span class="command"><strong>ip_port</strong></span>.
+ </p>
+
+ <p>
+ The attempt of opening a statistics channel is
+ restricted by the optional <span class="command"><strong>allow</strong></span> clause.
+ Connections to the statistics channel are permitted based on the
+ <span class="command"><strong>address_match_list</strong></span>.
+ If no <span class="command"><strong>allow</strong></span> clause is present,
+ <span class="command"><strong>named</strong></span> accepts connection
+ attempts from any address; since the statistics may
+ contain sensitive internal information, it is highly
+ recommended to restrict the source of connection requests
+ appropriately.
+ </p>
+
+ <p>
+ If no <span class="command"><strong>statistics-channels</strong></span> statement is present,
+ <span class="command"><strong>named</strong></span> will 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="link" href="http://127.0.0.1:8888/" target="_top">http://127.0.0.1:8888/</a> or
+ <a class="link" href="http://127.0.0.1:8888/xml" target="_top">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>
+ Applications that depend on a particular XML schema
+ can request
+ <a class="link" href="http://127.0.0.1:8888/xml/v2" target="_top">http://127.0.0.1:8888/xml/v2</a> for version 2
+ of the statistics XML schema or
+ <a class="link" href="http://127.0.0.1:8888/xml/v3" target="_top">http://127.0.0.1:8888/xml/v3</a> for version 3.
+ If the requested schema is supported by the server, then
+ it will respond; if not, it will return a "page not found"
+ error.
+ </p>
+
+ <p>
+ Broken-out subsets of the statistics can be viewed at
+ <a class="link" href="http://127.0.0.1:8888/xml/v3/status" target="_top">http://127.0.0.1:8888/xml/v3/status</a>
+ (server uptime and last reconfiguration time),
+ <a class="link" href="http://127.0.0.1:8888/xml/v3/server" target="_top">http://127.0.0.1:8888/xml/v3/server</a>
+ (server and resolver statistics),
+ <a class="link" href="http://127.0.0.1:8888/xml/v3/zones" target="_top">http://127.0.0.1:8888/xml/v3/zones</a>
+ (zone statistics),
+ <a class="link" href="http://127.0.0.1:8888/xml/v3/net" target="_top">http://127.0.0.1:8888/xml/v3/net</a>
+ (network status and socket statistics),
+ <a class="link" href="http://127.0.0.1:8888/xml/v3/mem" target="_top">http://127.0.0.1:8888/xml/v3/mem</a>
+ (memory manager statistics),
+ <a class="link" href="http://127.0.0.1:8888/xml/v3/tasks" target="_top">http://127.0.0.1:8888/xml/v3/tasks</a>
+ (task manager statistics), and
+ <a class="link" href="http://127.0.0.1:8888/xml/v3/traffic" target="_top">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="link" href="http://127.0.0.1:8888/json" target="_top">http://127.0.0.1:8888/json</a>,
+ with the broken-out subsets at
+ <a class="link" href="http://127.0.0.1:8888/json/v1/status" target="_top">http://127.0.0.1:8888/json/v1/status</a>
+ (server uptime and last reconfiguration time),
+ <a class="link" href="http://127.0.0.1:8888/json/v1/server" target="_top">http://127.0.0.1:8888/json/v1/server</a>
+ (server and resolver statistics),
+ <a class="link" href="http://127.0.0.1:8888/json/v1/zones" target="_top">http://127.0.0.1:8888/json/v1/zones</a>
+ (zone statistics),
+ <a class="link" href="http://127.0.0.1:8888/json/v1/net" target="_top">http://127.0.0.1:8888/json/v1/net</a>
+ (network status and socket statistics),
+ <a class="link" href="http://127.0.0.1:8888/json/v1/mem" target="_top">http://127.0.0.1:8888/json/v1/mem</a>
+ (memory manager statistics),
+ <a class="link" href="http://127.0.0.1:8888/json/v1/tasks" target="_top">http://127.0.0.1:8888/json/v1/tasks</a>
+ (task manager statistics), and
+ <a class="link" href="http://127.0.0.1:8888/json/v1/traffic" target="_top">http://127.0.0.1:8888/json/v1/traffic</a>
+ (traffic sizes).
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="trusted-keys"></a><span class="command"><strong>trusted-keys</strong></span> Statement Grammar</h3></div></div></div>
+ <pre class="programlisting">
+<span class="command"><strong>trusted-keys</strong></span> { <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>integer</code></em> <em class="replaceable"><code>integer</code></em>
+ <em class="replaceable"><code>integer</code></em> <em class="replaceable"><code>quoted_string</code></em>; ... };
+</pre>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="trusted_keys"></a><span class="command"><strong>trusted-keys</strong></span> Statement Definition
+ and Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>trusted-keys</strong></span> statement defines
+ DNSSEC security roots. DNSSEC is described in <a class="xref" href="Bv9ARM.ch04.html#DNSSEC" title="DNSSEC">the section called &#8220;DNSSEC&#8221;</a>. A security root is defined when the
+ public key 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 has been configured as a trusted
+ key, it is treated as if it had been validated and
+ proven secure. The resolver attempts DNSSEC validation
+ on all DNS data in subdomains of a security root.
+ </p>
+ <p>
+ All keys (and corresponding zones) listed in
+ <span class="command"><strong>trusted-keys</strong></span> are deemed to exist regardless
+ of what parent zones say. Similarly for all keys listed in
+ <span class="command"><strong>trusted-keys</strong></span> only those keys are
+ used to validate the DNSKEY RRset. The parent's DS RRset
+ will not be used.
+ </p>
+ <p>
+ The <span class="command"><strong>trusted-keys</strong></span> statement can contain
+ multiple key entries, each consisting of the key's
+ domain name, flags, protocol, algorithm, and the Base64
+ representation of the key data.
+ Spaces, tabs, newlines and carriage returns are ignored
+ in the key data, so the configuration may be split up into
+ multiple lines.
+ </p>
+ <p>
+ <span class="command"><strong>trusted-keys</strong></span> may be set at the top level
+ of <code class="filename">named.conf</code> or within a view. If it is
+ set in both places, they 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>
+ Validation below specified names can be temporarily disabled
+ by using <span class="command"><strong>rndc nta</strong></span>.
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="managed_keys"></a><span class="command"><strong>managed-keys</strong></span> Statement Grammar</h3></div></div></div>
+ <pre class="programlisting">
+<span class="command"><strong>managed-keys</strong></span> { <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>integer</code></em>
+ <em class="replaceable"><code>integer</code></em> <em class="replaceable"><code>integer</code></em> <em class="replaceable"><code>quoted_string</code></em>; ... };
+</pre>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="managed-keys"></a><span class="command"><strong>managed-keys</strong></span> Statement Definition
+ and Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>managed-keys</strong></span> statement, like
+ <span class="command"><strong>trusted-keys</strong></span>, defines DNSSEC
+ security roots. The difference is that
+ <span class="command"><strong>managed-keys</strong></span> can be kept up to date
+ automatically, without intervention from the resolver
+ operator.
+ </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 old key in a
+ <span class="command"><strong>trusted-keys</strong></span> statement 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
+ <span class="command"><strong>trusted-keys</strong></span> statement with the new key.
+ </p>
+ <p>
+ If, however, the zone were listed in a
+ <span class="command"><strong>managed-keys</strong></span> statement instead, then the
+ zone owner could add a "stand-by" key to the zone in advance.
+ <span class="command"><strong>named</strong></span> would store the stand-by key, and
+ when the original key was revoked, <span class="command"><strong>named</strong></span>
+ 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.
+ </p>
+ <p>
+ A <span class="command"><strong>managed-keys</strong></span> statement contains a list of
+ the keys to be managed, along with information about how the
+ keys are to be initialized for the first time. The only
+ initialization method currently supported is
+ <code class="literal">initial-key</code>.
+ This means the <span class="command"><strong>managed-keys</strong></span> statement must
+ contain a copy of the initializing key. (Future releases may
+ allow keys to be initialized by other methods, eliminating this
+ requirement.)
+ </p>
+ <p>
+ Consequently, a <span class="command"><strong>managed-keys</strong></span> statement
+ appears similar to a <span class="command"><strong>trusted-keys</strong></span>, differing
+ in the presence of the second field, containing the keyword
+ <code class="literal">initial-key</code>. The difference is, whereas the
+ keys listed in a <span class="command"><strong>trusted-keys</strong></span> continue to be
+ trusted until they are removed from
+ <code class="filename">named.conf</code>, an initializing key listed
+ in a <span class="command"><strong>managed-keys</strong></span> statement is only trusted
+ <span class="emphasis"><em>once</em></span>: for as long as it takes to load the
+ managed key database and start the RFC 5011 key maintenance
+ process.
+ </p>
+ <p>
+ The first time <span class="command"><strong>named</strong></span> runs with a managed key
+ configured in <code class="filename">named.conf</code>, it fetches the
+ DNSKEY RRset directly from the zone apex, and validates it
+ using the key specified in the <span class="command"><strong>managed-keys</strong></span>
+ statement. If the DNSKEY RRset is validly signed, then it is
+ used as the basis for a new managed keys database.
+ </p>
+ <p>
+ From that point on, whenever <span class="command"><strong>named</strong></span> runs, it
+ sees the <span class="command"><strong>managed-keys</strong></span> statement, checks to
+ make sure RFC 5011 key maintenance has already been initialized
+ for the specified domain, and if so, it simply moves on. The
+ key specified in the <span class="command"><strong>managed-keys</strong></span>
+ statement is not used to validate answers; it has been
+ superseded by the key or keys stored in the managed keys database.
+ </p>
+ <p>
+ The next time <span class="command"><strong>named</strong></span> runs after a name
+ has been <span class="emphasis"><em>removed</em></span> from the
+ <span class="command"><strong>managed-keys</strong></span> statement, the corresponding
+ zone will be removed from the managed keys database,
+ and RFC 5011 key maintenance will no longer be 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="filename">managed-keys.bind</code>. When views are in
+ use, there will be a separate managed keys database for each
+ view; the filename will be 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="filename">.mkeys</code>.
+ </p>
+ <p>
+ When the key database is changed, the zone is updated.
+ As with any other dynamic zone, changes will be written
+ into a journal file, e.g.,
+ <code class="filename">managed-keys.bind.jnl</code> or
+ <code class="filename">internal.mkeys.jnl</code>.
+ Changes are committed to the master file as soon as
+ possible afterward; this will usually occur within 30
+ seconds. So, whenever <span class="command"><strong>named</strong></span> 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 <span class="command"><strong>named</strong></span>.)
+ </p>
+ <p>
+ If the <span class="command"><strong>dnssec-validation</strong></span> option is
+ set to <strong class="userinput"><code>auto</code></strong>, <span class="command"><strong>named</strong></span>
+ will automatically initialize a managed key for the
+ root zone. The key that is used to initialize the key
+ maintenance process is stored in <code class="filename">bind.keys</code>;
+ the location of this file can be overridden with the
+ <span class="command"><strong>bindkeys-file</strong></span> option. As a fallback
+ in the event no <code class="filename">bind.keys</code> can be
+ found, the initializing key is also compiled directly
+ into <span class="command"><strong>named</strong></span>.
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="view_statement_grammar"></a><span class="command"><strong>view</strong></span> Statement Grammar</h3></div></div></div>
+
+<pre class="programlisting"><span class="command"><strong>view</strong></span> <em class="replaceable"><code>view_name</code></em> [ <em class="replaceable"><code>class</code></em> ] <span class="command"><strong>{</strong></span>
+ <span class="command"><strong>match-clients {</strong></span> <em class="replaceable"><code>address_match_list</code></em> <span class="command"><strong>}</strong></span> ;
+ <span class="command"><strong>match-destinations {</strong></span> <em class="replaceable"><code>address_match_list</code></em> <span class="command"><strong>}</strong></span> ;
+ <span class="command"><strong>match-recursive-only</strong></span> <em class="replaceable"><code>yes_or_no</code></em> ;
+ [ <em class="replaceable"><code>view_option</code></em> ; ... ]
+ [ <em class="replaceable"><code>zone_statement</code></em> ; ... ]
+<span class="command"><strong>} </strong></span>;
+</pre>
+
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="view_statement"></a><span class="command"><strong>view</strong></span> Statement Definition and Usage</h3></div></div></div>
+
+ <p>
+ The <span class="command"><strong>view</strong></span> statement is a powerful
+ feature
+ of <acronym class="acronym">BIND</acronym> 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>
+
+ <p>
+ Each <span class="command"><strong>view</strong></span> statement defines a view
+ of the
+ DNS namespace that will be seen by a subset of clients. A client
+ matches
+ a view if its source IP address matches the
+ <code class="varname">address_match_list</code> of the view's
+ <span class="command"><strong>match-clients</strong></span> clause and its
+ destination IP address matches
+ the <code class="varname">address_match_list</code> of the
+ view's
+ <span class="command"><strong>match-destinations</strong></span> clause. If not
+ specified, both
+ <span class="command"><strong>match-clients</strong></span> and <span class="command"><strong>match-destinations</strong></span>
+ default to matching all addresses. In addition to checking IP
+ addresses
+ <span class="command"><strong>match-clients</strong></span> and <span class="command"><strong>match-destinations</strong></span>
+ can also take <span class="command"><strong>keys</strong></span> which provide an
+ mechanism for the
+ client to select the view. A view can also be specified
+ as <span class="command"><strong>match-recursive-only</strong></span>, which
+ means that only recursive
+ requests from matching clients will match that view.
+ The order of the <span class="command"><strong>view</strong></span> statements is
+ significant &#8212;
+ a client request will be resolved in the context of the first
+ <span class="command"><strong>view</strong></span> that it matches.
+ </p>
+
+ <p>
+ Zones defined within a <span class="command"><strong>view</strong></span>
+ statement will
+ only be accessible to clients that match the <span class="command"><strong>view</strong></span>.
+ 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 <span class="command"><strong>options</strong></span> statement
+ can also be used within a <span class="command"><strong>view</strong></span>
+ statement, and then
+ apply only when resolving queries with that view. When no
+ view-specific
+ value is given, the value in the <span class="command"><strong>options</strong></span> statement
+ is used as a default. Also, zone options can have default values
+ specified
+ in the <span class="command"><strong>view</strong></span> statement; these
+ view-specific defaults
+ take precedence over those in the <span class="command"><strong>options</strong></span> 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 <span class="command"><strong>view</strong></span> statements in
+ the config
+ file, a default view that matches any client is automatically
+ created
+ in class IN. Any <span class="command"><strong>zone</strong></span> statements
+ specified on
+ the top level of the configuration file are considered to be part
+ of
+ this default view, and the <span class="command"><strong>options</strong></span>
+ statement will
+ apply to the default view. If any explicit <span class="command"><strong>view</strong></span>
+ statements are present, all <span class="command"><strong>zone</strong></span>
+ statements must
+ occur inside <span class="command"><strong>view</strong></span> statements.
+ </p>
+
+ <p>
+ Here is an example of a typical split DNS setup implemented
+ using <span class="command"><strong>view</strong></span> statements:
+ </p>
+
+<pre class="programlisting">view "internal" {
+ // This should match our internal networks.
+ match-clients { 10.0.0.0/8; };
+
+ // Provide recursive service to internal
+ // clients only.
+ recursion yes;
+
+ // Provide a complete view of the example.com
+ // zone including addresses of internal hosts.
+ zone "example.com" {
+ type master;
+ file "example-internal.db";
+ };
+};
+
+view "external" {
+ // Match all clients not matched by the
+ // previous view.
+ match-clients { any; };
+
+ // Refuse recursive service to external clients.
+ recursion no;
+
+ // Provide a restricted view of the example.com
+ // zone containing only publicly accessible hosts.
+ zone "example.com" {
+ type master;
+ file "example-external.db";
+ };
+};
+</pre>
+
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="zone_statement_grammar"></a><span class="command"><strong>zone</strong></span>
+ Statement Grammar</h3></div></div></div>
+
+<pre class="programlisting">
+<span class="command"><strong>zone</strong></span> <em class="replaceable"><code>string</code></em> [ <em class="replaceable"><code>class</code></em> ] {
+ <span class="command"><strong>type</strong></span> ( master | primary );
+ <span class="command"><strong>allow-query</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-query-on</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-transfer</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-update</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>also-notify</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>masters</code></em> | <em class="replaceable"><code>ipv4_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] | <em class="replaceable"><code>ipv6_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] ) [ key <em class="replaceable"><code>string</code></em> ]; ... };
+ <span class="command"><strong>alt-transfer-source</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>alt-transfer-source-v6</strong></span> ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>auto-dnssec</strong></span> ( allow | maintain | off );
+ <span class="command"><strong>check-dup-records</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>check-integrity</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>check-mx</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>check-mx-cname</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>check-names</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>check-sibling</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>check-spf</strong></span> ( warn | ignore );
+ <span class="command"><strong>check-srv-cname</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>check-wildcard</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>database</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>dialup</strong></span> ( notify | notify-passive | passive | refresh | <em class="replaceable"><code>boolean</code></em> );
+ <span class="command"><strong>dlz</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>dnssec-dnskey-kskonly</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>dnssec-loadkeys-interval</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>dnssec-secure-to-insecure</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>dnssec-update-mode</strong></span> ( maintain | no-resign );
+ <span class="command"><strong>file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>forward</strong></span> ( first | only );
+ <span class="command"><strong>forwarders</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>ipv4_address</code></em> | <em class="replaceable"><code>ipv6_address</code></em> ) [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ]; ... };
+ <span class="command"><strong>inline-signing</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>ixfr-from-differences</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>journal</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>key-directory</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>masterfile-format</strong></span> ( map | raw | text );
+ <span class="command"><strong>masterfile-style</strong></span> ( full | relative );
+ <span class="command"><strong>max-journal-size</strong></span> ( unlimited | <em class="replaceable"><code>sizeval</code></em> );
+ <span class="command"><strong>max-records</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-idle-out</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-time-out</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-zone-ttl</strong></span> ( unlimited | <em class="replaceable"><code>ttlval</code></em> );
+ <span class="command"><strong>notify</strong></span> ( explicit | master-only | <em class="replaceable"><code>boolean</code></em> );
+ <span class="command"><strong>notify-delay</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>notify-source</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>notify-source-v6</strong></span> ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>notify-to-soa</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>serial-update-method</strong></span> ( date | increment | unixtime );
+ <span class="command"><strong>sig-signing-nodes</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>sig-signing-signatures</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>sig-signing-type</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>sig-validity-interval</strong></span> <em class="replaceable"><code>integer</code></em> [ <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>update-check-ksk</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>update-policy</strong></span> ( local | { ( deny | grant ) <em class="replaceable"><code>string</code></em> ( 6to4-self | external | krb5-self | krb5-selfsub | krb5-subdomain | ms-self | ms-selfsub | ms-subdomain | name | self | selfsub | selfwild | subdomain | tcp-self | wildcard | zonesub ) [ <em class="replaceable"><code>string</code></em> ] <em class="replaceable"><code>rrtypelist</code></em>; ... };
+ <span class="command"><strong>zero-no-soa-ttl</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>zone-statistics</strong></span> ( full | terse | none | <em class="replaceable"><code>boolean</code></em> );
+};
+</pre>
+<pre class="programlisting">
+<span class="command"><strong>zone</strong></span> <em class="replaceable"><code>string</code></em> [ <em class="replaceable"><code>class</code></em> ] {
+ <span class="command"><strong>type</strong></span> ( slave | secondary );
+ <span class="command"><strong>allow-notify</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-query</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-query-on</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-transfer</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-update-forwarding</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>also-notify</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>masters</code></em> | <em class="replaceable"><code>ipv4_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] | <em class="replaceable"><code>ipv6_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] ) [ key <em class="replaceable"><code>string</code></em> ]; ... };
+ <span class="command"><strong>alt-transfer-source</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>alt-transfer-source-v6</strong></span> ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>auto-dnssec</strong></span> ( allow | maintain | off );
+ <span class="command"><strong>check-names</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>database</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>dialup</strong></span> ( notify | notify-passive | passive | refresh | <em class="replaceable"><code>boolean</code></em> );
+ <span class="command"><strong>dlz</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>dnssec-dnskey-kskonly</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>dnssec-loadkeys-interval</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>dnssec-update-mode</strong></span> ( maintain | no-resign );
+ <span class="command"><strong>file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>forward</strong></span> ( first | only );
+ <span class="command"><strong>forwarders</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>ipv4_address</code></em> | <em class="replaceable"><code>ipv6_address</code></em> ) [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ]; ... };
+ <span class="command"><strong>inline-signing</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>ixfr-from-differences</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>journal</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>key-directory</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>masterfile-format</strong></span> ( map | raw | text );
+ <span class="command"><strong>masterfile-style</strong></span> ( full | relative );
+ <span class="command"><strong>masters</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>masters</code></em> | <em class="replaceable"><code>ipv4_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] | <em class="replaceable"><code>ipv6_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] ) [ key <em class="replaceable"><code>string</code></em> ]; ... };
+ <span class="command"><strong>max-journal-size</strong></span> ( unlimited | <em class="replaceable"><code>sizeval</code></em> );
+ <span class="command"><strong>max-records</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-refresh-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-retry-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-idle-in</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-idle-out</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-time-in</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-time-out</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>min-refresh-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>min-retry-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>multi-master</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>notify</strong></span> ( explicit | master-only | <em class="replaceable"><code>boolean</code></em> );
+ <span class="command"><strong>notify-delay</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>notify-source</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>notify-source-v6</strong></span> ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>notify-to-soa</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>request-expire</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>request-ixfr</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>sig-signing-nodes</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>sig-signing-signatures</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>sig-signing-type</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>sig-validity-interval</strong></span> <em class="replaceable"><code>integer</code></em> [ <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>transfer-source</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>transfer-source-v6</strong></span> ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>try-tcp-refresh</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>update-check-ksk</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>use-alt-transfer-source</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>zero-no-soa-ttl</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>zone-statistics</strong></span> ( full | terse | none | <em class="replaceable"><code>boolean</code></em> );
+};
+</pre>
+<pre class="programlisting">
+<span class="command"><strong>zone</strong></span> <em class="replaceable"><code>string</code></em> [ <em class="replaceable"><code>class</code></em> ] {
+ <span class="command"><strong>type</strong></span> hint;
+ <span class="command"><strong>check-names</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>delegation-only</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+};
+</pre>
+<pre class="programlisting">
+<span class="command"><strong>zone</strong></span> <em class="replaceable"><code>string</code></em> [ <em class="replaceable"><code>class</code></em> ] {
+ <span class="command"><strong>type</strong></span> stub;
+ <span class="command"><strong>allow-query</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-query-on</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>check-names</strong></span> ( fail | warn | ignore );
+ <span class="command"><strong>database</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>delegation-only</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>dialup</strong></span> ( notify | notify-passive | passive | refresh | <em class="replaceable"><code>boolean</code></em> );
+ <span class="command"><strong>file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>forward</strong></span> ( first | only );
+ <span class="command"><strong>forwarders</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>ipv4_address</code></em> | <em class="replaceable"><code>ipv6_address</code></em> ) [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ]; ... };
+ <span class="command"><strong>masterfile-format</strong></span> ( map | raw | text );
+ <span class="command"><strong>masterfile-style</strong></span> ( full | relative );
+ <span class="command"><strong>masters</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>masters</code></em> | <em class="replaceable"><code>ipv4_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] | <em class="replaceable"><code>ipv6_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] ) [ key <em class="replaceable"><code>string</code></em> ]; ... };
+ <span class="command"><strong>max-records</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-refresh-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-retry-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-idle-in</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-transfer-time-in</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>min-refresh-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>min-retry-time</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>multi-master</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>transfer-source</strong></span> ( <em class="replaceable"><code>ipv4_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>transfer-source-v6</strong></span> ( <em class="replaceable"><code>ipv6_address</code></em> | * ) [ port ( <em class="replaceable"><code>integer</code></em> | * ) ] [ dscp <em class="replaceable"><code>integer</code></em> ];
+ <span class="command"><strong>use-alt-transfer-source</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>zone-statistics</strong></span> ( full | terse | none | <em class="replaceable"><code>boolean</code></em> );
+};
+</pre>
+<pre class="programlisting">
+<span class="command"><strong>zone</strong></span> <em class="replaceable"><code>string</code></em> [ <em class="replaceable"><code>class</code></em> ] {
+ <span class="command"><strong>type</strong></span> static-stub;
+ <span class="command"><strong>allow-query</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-query-on</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>forward</strong></span> ( first | only );
+ <span class="command"><strong>forwarders</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>ipv4_address</code></em> | <em class="replaceable"><code>ipv6_address</code></em> ) [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ]; ... };
+ <span class="command"><strong>max-records</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>server-addresses</strong></span> { ( <em class="replaceable"><code>ipv4_address</code></em> | <em class="replaceable"><code>ipv6_address</code></em> ) [ port <em class="replaceable"><code>integer</code></em> ]; ... };
+ <span class="command"><strong>server-names</strong></span> { <em class="replaceable"><code>quoted_string</code></em>; ... };
+ <span class="command"><strong>zone-statistics</strong></span> ( full | terse | none | <em class="replaceable"><code>boolean</code></em> );
+};
+</pre>
+<pre class="programlisting">
+<span class="command"><strong>zone</strong></span> <em class="replaceable"><code>string</code></em> [ <em class="replaceable"><code>class</code></em> ] {
+ <span class="command"><strong>type</strong></span> forward;
+ <span class="command"><strong>delegation-only</strong></span> <em class="replaceable"><code>boolean</code></em>;
+ <span class="command"><strong>forward</strong></span> ( first | only );
+ <span class="command"><strong>forwarders</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>ipv4_address</code></em> | <em class="replaceable"><code>ipv6_address</code></em> ) [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ]; ... };
+};
+</pre>
+<pre class="programlisting">
+<span class="command"><strong>zone</strong></span> <em class="replaceable"><code>string</code></em> [ <em class="replaceable"><code>class</code></em> ] {
+ <span class="command"><strong>type</strong></span> redirect;
+ <span class="command"><strong>allow-query</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>allow-query-on</strong></span> { <em class="replaceable"><code>address_match_element</code></em>; ... };
+ <span class="command"><strong>dlz</strong></span> <em class="replaceable"><code>string</code></em>;
+ <span class="command"><strong>file</strong></span> <em class="replaceable"><code>quoted_string</code></em>;
+ <span class="command"><strong>masterfile-format</strong></span> ( map | raw | text );
+ <span class="command"><strong>masterfile-style</strong></span> ( full | relative );
+ <span class="command"><strong>masters</strong></span> [ port <em class="replaceable"><code>integer</code></em> ] [ dscp <em class="replaceable"><code>integer</code></em> ] { ( <em class="replaceable"><code>masters</code></em> | <em class="replaceable"><code>ipv4_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] | <em class="replaceable"><code>ipv6_address</code></em> [ port <em class="replaceable"><code>integer</code></em> ] ) [ key <em class="replaceable"><code>string</code></em> ]; ... };
+ <span class="command"><strong>max-records</strong></span> <em class="replaceable"><code>integer</code></em>;
+ <span class="command"><strong>max-zone-ttl</strong></span> ( unlimited | <em class="replaceable"><code>ttlval</code></em> );
+ <span class="command"><strong>zone-statistics</strong></span> ( full | terse | none | <em class="replaceable"><code>boolean</code></em> );
+};
+</pre>
+<pre class="programlisting">
+<span class="command"><strong>zone</strong></span> <em class="replaceable"><code>string</code></em> [ <em class="replaceable"><code>class</code></em> ] {
+ <span class="command"><strong>type</strong></span> delegation-only;
+};
+</pre>
+<pre class="programlisting">
+<span class="command"><strong>zone</strong></span> <em class="replaceable"><code>string</code></em> [ <em class="replaceable"><code>class</code></em> ] {
+ <span class="command"><strong>in-view</strong></span> <em class="replaceable"><code>string</code></em>;
+};
+</pre>
+
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="zone_statement"></a><span class="command"><strong>zone</strong></span> Statement Definition and Usage</h3></div></div></div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="zone_types"></a>Zone Types</h4></div></div></div>
+ <p>
+ The <span class="command"><strong>type</strong></span> keyword is required
+ for the <span class="command"><strong>zone</strong></span> configuration unless
+ it is an <span class="command"><strong>in-view</strong></span> configuration. Its
+ acceptable values include: <code class="varname">delegation-only</code>,
+ <code class="varname">forward</code>, <code class="varname">hint</code>,
+ <code class="varname">master</code>, <code class="varname">redirect</code>,
+ <code class="varname">slave</code>, <code class="varname">static-stub</code>,
+ and <code class="varname">stub</code>.
+ </p>
+
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col class="1">
+<col width="4.017in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ <code class="varname">master</code>
+ </p>
+ </td>
+<td>
+ <p>
+ The server has a master copy of the data
+ for the zone and will be able to provide authoritative
+ answers for
+ it.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">slave</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A slave zone is a replica of a master
+ zone. The <span class="command"><strong>masters</strong></span> list
+ specifies one or more IP addresses
+ of master servers that the slave contacts to update
+ its copy of the zone.
+ Masters list elements can also be names of other
+ masters 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 master can also be done with
+ per-server TSIG keys.
+ If a file is specified, then the
+ replica will be 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 slave server for the zone <code class="literal">example.com</code> might place
+ the zone contents into a file called
+ <code class="filename">ex/example.com</code> where <code class="filename">ex/</code> is
+ just the first two letters of the zone name. (Most
+ operating systems
+ behave very slowly if you put 100000 files into
+ a single directory.)
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">stub</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A stub zone is similar to a slave zone,
+ except that it replicates only the NS records of a
+ master zone instead
+ of the entire zone. Stub zones are not a standard part
+ of the DNS;
+ they are a feature specific to the <acronym class="acronym">BIND</acronym> implementation.
+ </p>
+
+ <p>
+ Stub zones can be used to eliminate the need for glue
+ NS record
+ in a parent zone at the expense of maintaining a stub
+ zone entry and
+ a set of name server addresses in <code class="filename">named.conf</code>.
+ This usage is not recommended for new configurations,
+ and BIND 9
+ supports it only in a limited way.
+ In <acronym class="acronym">BIND</acronym> 4/8, zone
+ transfers of a parent zone
+ included the NS records from stub children of that
+ zone. This meant
+ that, in some cases, users could get away with
+ configuring child stubs
+ only in the master server for the parent zone. <acronym class="acronym">BIND</acronym>
+ 9 never mixes together zone data from different zones
+ in this
+ way. Therefore, if a <acronym class="acronym">BIND</acronym> 9 master serving a parent
+ zone has child stub zones configured, all the slave
+ 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 of forcing 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
+ RFC1918 addressing may be configured with stub zones
+ for
+ <code class="literal">10.in-addr.arpa</code>
+ to use a set of internal name servers as the
+ authoritative
+ servers for that domain.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">static-stub</code>
+ </p>
+ </td>
+<td>
+ <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 master server;
+ when recursion is necessary for a query that
+ matches a static-stub zone, the locally
+ configured data (nameserver names and glue addresses)
+ is always used even if different authoritative
+ information is cached.
+ </p>
+ <p>
+ Zone data is configured via the
+ <span class="command"><strong>server-addresses</strong></span> and
+ <span class="command"><strong>server-names</strong></span> 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 by <span class="command"><strong>rndc dumpdb -all</strong></span>.
+ 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 will be responded 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
+ will be 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>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">forward</code>
+ </p>
+ </td>
+<td>
+ <p>
+ A "forward zone" is a way to configure
+ forwarding on a per-domain basis. A <span class="command"><strong>zone</strong></span> statement
+ of type <span class="command"><strong>forward</strong></span> can
+ contain a <span class="command"><strong>forward</strong></span>
+ and/or <span class="command"><strong>forwarders</strong></span>
+ statement,
+ which will apply to queries within the domain given by
+ the zone
+ name. If no <span class="command"><strong>forwarders</strong></span>
+ statement is present or
+ an empty list for <span class="command"><strong>forwarders</strong></span> is given, then no
+ forwarding will be done for the domain, canceling the
+ effects of
+ any forwarders in the <span class="command"><strong>options</strong></span> statement. Thus
+ if you want to use this type of zone to change the
+ behavior of the
+ global <span class="command"><strong>forward</strong></span> option
+ (that is, "forward first"
+ to, then "forward only", or vice versa, but want to
+ use the same
+ servers as set globally) you need to re-specify the
+ global forwarders.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">hint</code>
+ </p>
+ </td>
+<td>
+ <p>
+ The initial set of root name servers is
+ specified using a "hint zone". When the server starts
+ up, 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 defaults hints.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">redirect</code>
+ </p>
+ </td>
+<td>
+ <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. <span class="command"><strong>allow-query</strong></span> 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 then no substitution
+ will occur.
+ </p>
+ <p>
+ To redirect all NXDOMAIN responses to
+ 100.100.100.2 and
+ 2001:ffff:ffff::100.100.100.2, one would
+ configure a type redirect zone named ".",
+ with the zone file containing wildcard records
+ that point to the desired addresses:
+ <code class="literal">"*. IN A 100.100.100.2"</code>
+ and
+ <code class="literal">"*. IN AAAA 2001:ffff:ffff::100.100.100.2"</code>.
+ </p>
+ <p>
+ To redirect all Spanish names (under .ES) one
+ would use similar entries but with the names
+ "*.ES." instead of "*.". To redirect all
+ commercial Spanish names (under COM.ES) one
+ would use wildcard entries called "*.COM.ES.".
+ </p>
+ <p>
+ Note that the redirect zone supports all
+ possible types; it is not limited to A and
+ AAAA records.
+ </p>
+ <p>
+ Because redirect zones are not referenced
+ directly by name, they are not kept in the
+ zone lookup table with normal master and slave
+ zones. Consequently, it is not currently possible
+ to use
+ <span class="command"><strong>rndc reload
+ <em class="replaceable"><code>zonename</code></em></strong></span>
+ to reload a redirect zone. However, when using
+ <span class="command"><strong>rndc reload</strong></span> without specifying
+ a zone name, redirect zones will be reloaded along
+ with other zones.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">delegation-only</code>
+ </p>
+ </td>
+<td>
+ <p>
+ This 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 will be treated
+ as NXDOMAIN. This does not apply to the
+ zone apex. This should not be applied to
+ leaf zones.
+ </p>
+ <p>
+ <code class="varname">delegation-only</code> has no
+ effect on answers received from forwarders.
+ </p>
+ <p>
+ See caveats in <a class="xref" href="Bv9ARM.ch06.html#root_delegation_only"><span class="command"><strong>root-delegation-only</strong></span></a>.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="class"></a>Class</h4></div></div></div>
+
+ <p>
+ The zone's name may optionally be followed by a class. If
+ a class is not specified, class <code class="literal">IN</code> (for <code class="varname">Internet</code>),
+ is assumed. This is correct for the vast majority of cases.
+ </p>
+ <p>
+ The <code class="literal">hesiod</code> class is
+ named for an information service from MIT's Project Athena. It
+ is
+ used to share information about various systems databases, such
+ as users, groups, printers and so on. The keyword
+ <code class="literal">HS</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="literal">CHAOS</code> class.
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="zone_options"></a>Zone Options</h4></div></div></div>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>allow-notify</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>allow-notify</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-query</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>allow-query</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-query-on</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>allow-query-on</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-transfer</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of <span class="command"><strong>allow-transfer</strong></span>
+ in <a class="xref" href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-update</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of <span class="command"><strong>allow-update</strong></span>
+ in <a class="xref" href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>update-policy</strong></span></span></dt>
+<dd>
+ <p>
+ Specifies a "Simple Secure Update" policy. See
+ <a class="xref" href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called &#8220;Dynamic Update Policies&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>allow-update-forwarding</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of <span class="command"><strong>allow-update-forwarding</strong></span>
+ in <a class="xref" href="Bv9ARM.ch06.html#access_control" title="Access Control">the section called &#8220;Access Control&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>also-notify</strong></span></span></dt>
+<dd>
+ <p>
+ Only meaningful if <span class="command"><strong>notify</strong></span>
+ is
+ active for this zone. The set of machines that will
+ receive a
+ <code class="literal">DNS NOTIFY</code> message
+ for this zone is made up of all the listed name servers
+ (other than
+ the primary master) for the zone plus any IP addresses
+ specified
+ with <span class="command"><strong>also-notify</strong></span>. A port
+ may be specified
+ with each <span class="command"><strong>also-notify</strong></span>
+ 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="literal">NOTIFY</code> to be signed by the
+ given key.
+ <span class="command"><strong>also-notify</strong></span> is not
+ meaningful for stub zones.
+ The default is the empty list.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-names</strong></span></span></dt>
+<dd>
+ <p>
+ This option is used to restrict the character set and
+ syntax of
+ certain domain names in master files and/or DNS responses
+ received from the
+ network. The default varies according to zone type. For <span class="command"><strong>master</strong></span> zones the default is <span class="command"><strong>fail</strong></span>. For <span class="command"><strong>slave</strong></span>
+ zones the default is <span class="command"><strong>warn</strong></span>.
+ It is not implemented for <span class="command"><strong>hint</strong></span> zones.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-mx</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>check-mx</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-spf</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>check-spf</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-wildcard</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>check-wildcard</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-integrity</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>check-integrity</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>check-sibling</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>check-sibling</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>zero-no-soa-ttl</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>zero-no-soa-ttl</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>update-check-ksk</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>update-check-ksk</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-loadkeys-interval</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>dnssec-loadkeys-interval</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#options" title="options Statement Definition and Usage">the section called &#8220;<span class="command"><strong>options</strong></span> Statement Definition and
+ Usage&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-update-mode</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>dnssec-update-mode</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#options" title="options Statement Definition and Usage">the section called &#8220;<span class="command"><strong>options</strong></span> Statement Definition and
+ Usage&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-dnskey-kskonly</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>dnssec-dnskey-kskonly</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>try-tcp-refresh</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>try-tcp-refresh</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>database</strong></span></span></dt>
+<dd>
+ <p>
+ Specify the type of database to be used for storing the
+ zone data. The string following the <span class="command"><strong>database</strong></span> 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 <strong class="userinput"><code>"rbt"</code></strong>, 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>
+<dt><span class="term"><span class="command"><strong>dialup</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>dialup</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>delegation-only</strong></span></span></dt>
+<dd>
+ <p>
+ The flag only applies to forward, hint and stub
+ zones. If set to <strong class="userinput"><code>yes</code></strong>,
+ then the zone will also be treated as if it is
+ also a delegation-only type zone.
+ </p>
+ <p>
+ See caveats in <a class="xref" href="Bv9ARM.ch06.html#root_delegation_only"><span class="command"><strong>root-delegation-only</strong></span></a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>file</strong></span></span></dt>
+<dd>
+ <p>
+ Set the zone's filename. In <span class="command"><strong>master</strong></span>,
+ <span class="command"><strong>hint</strong></span>, and <span class="command"><strong>redirect</strong></span>
+ zones which do not have <span class="command"><strong>masters</strong></span>
+ defined, zone data is loaded from this file. In
+ <span class="command"><strong>slave</strong></span>, <span class="command"><strong>stub</strong></span>, and
+ <span class="command"><strong>redirect</strong></span> zones which do have
+ <span class="command"><strong>masters</strong></span> defined, zone data is
+ retrieved from another server and saved in this file.
+ This option is not applicable to other zone types.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>forward</strong></span></span></dt>
+<dd>
+ <p>
+ Only meaningful if the zone has a forwarders
+ list. The <span class="command"><strong>only</strong></span> value causes
+ the lookup to fail
+ after trying the forwarders and getting no answer, while <span class="command"><strong>first</strong></span> would
+ allow a normal lookup to be tried.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>forwarders</strong></span></span></dt>
+<dd>
+ <p>
+ Used to override the list of global forwarders.
+ If it is not specified in a zone of type <span class="command"><strong>forward</strong></span>,
+ no forwarding is done for the zone and the global options are
+ not used.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>ixfr-base</strong></span></span></dt>
+<dd>
+ <p>
+ Was used in <acronym class="acronym">BIND</acronym> 8 to
+ specify the name
+ of the transaction log (journal) file for dynamic update
+ and IXFR.
+ <acronym class="acronym">BIND</acronym> 9 ignores the option
+ and constructs the name of the journal
+ file by appending "<code class="filename">.jnl</code>"
+ to the name of the
+ zone file.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>ixfr-tmp-file</strong></span></span></dt>
+<dd>
+ <p>
+ Was an undocumented option in <acronym class="acronym">BIND</acronym> 8.
+ Ignored in <acronym class="acronym">BIND</acronym> 9.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>journal</strong></span></span></dt>
+<dd>
+ <p>
+ Allow the default journal's filename to be overridden.
+ The default is the zone's filename with "<code class="filename">.jnl</code>" appended.
+ This is applicable to <span class="command"><strong>master</strong></span> and <span class="command"><strong>slave</strong></span> zones.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-journal-size</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>max-journal-size</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#server_resource_limits" title="Server Resource Limits">the section called &#8220;Server Resource Limits&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-records</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>max-records</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#server_resource_limits" title="Server Resource Limits">the section called &#8220;Server Resource Limits&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-transfer-time-in</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>max-transfer-time-in</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-transfer-idle-in</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>max-transfer-idle-in</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-transfer-time-out</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>max-transfer-time-out</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-transfer-idle-out</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>max-transfer-idle-out</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>notify</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>notify</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>notify-delay</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>notify-delay</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>notify-to-soa</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>notify-to-soa</strong></span> in
+ <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>pubkey</strong></span></span></dt>
+<dd>
+ <p>
+ In <acronym class="acronym">BIND</acronym> 8, this option was
+ intended for specifying
+ a public zone key for verification of signatures in DNSSEC
+ signed
+ zones when they are loaded from disk. <acronym class="acronym">BIND</acronym> 9 does not verify signatures
+ on load and ignores the option.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>zone-statistics</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>zone-statistics</strong></span> in
+ <a class="xref" href="Bv9ARM.ch06.html#options" title="options Statement Definition and Usage">the section called &#8220;<span class="command"><strong>options</strong></span> Statement Definition and
+ Usage&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>server-addresses</strong></span></span></dt>
+<dd>
+ <p>
+ 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 will internally
+ configure 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 <span class="command"><strong>server-addresses</strong></span> option,
+ the following RRs will be internally configured.
+ </p>
+<pre class="programlisting">example.com. NS example.com.
+example.com. A 192.0.2.1
+example.com. AAAA 2001:db8::1234</pre>
+ <p>
+ These records are internally used 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
+ will initiate recursive resolution and send
+ queries to 192.0.2.1 and/or 2001:db8::1234.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>server-names</strong></span></span></dt>
+<dd>
+ <p>
+ Only meaningful for static-stub zones.
+ This is a list of domain names of nameservers that
+ act as authoritative servers of the static-stub
+ zone.
+ These names will be resolved to IP addresses when
+ <span class="command"><strong>named</strong></span> needs to send queries to
+ these servers.
+ To make this supplemental resolution successful,
+ these names must not be a subdomain of the origin
+ name of 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
+ <span class="command"><strong>server-names</strong></span> option, but
+ "ns.example.net" cannot, and will be rejected by
+ the configuration parser.
+ </p>
+ <p>
+ A non empty list for this option will internally
+ configure 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 <span class="command"><strong>server-names</strong></span> option,
+ the following RRs will be internally configured.
+ </p>
+<pre class="programlisting">example.com. NS ns1.example.net.
+example.com. NS ns2.example.net.
+</pre>
+ <p>
+ These records are internally used 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
+ initiate recursive resolution,
+ resolve "ns1.example.net" and/or
+ "ns2.example.net" to IP addresses, and then send
+ queries to (one or more of) these addresses.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>sig-validity-interval</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>sig-validity-interval</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>sig-signing-nodes</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>sig-signing-nodes</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>sig-signing-signatures</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>sig-signing-signatures</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>sig-signing-type</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>sig-signing-type</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>transfer-source</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>transfer-source</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>transfer-source-v6</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>transfer-source-v6</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>alt-transfer-source</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>alt-transfer-source</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>alt-transfer-source-v6</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>alt-transfer-source-v6</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>use-alt-transfer-source</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>use-alt-transfer-source</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>notify-source</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>notify-source</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>notify-source-v6</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>notify-source-v6</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>.
+ </p>
+ </dd>
+<dt>
+<span class="term"><span class="command"><strong>min-refresh-time</strong></span>, </span><span class="term"><span class="command"><strong>max-refresh-time</strong></span>, </span><span class="term"><span class="command"><strong>min-retry-time</strong></span>, </span><span class="term"><span class="command"><strong>max-retry-time</strong></span></span>
+</dt>
+<dd>
+ <p>
+ See the description in <a class="xref" href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>ixfr-from-differences</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>ixfr-from-differences</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ (Note that the <span class="command"><strong>ixfr-from-differences</strong></span>
+ <strong class="userinput"><code>master</code></strong> and
+ <strong class="userinput"><code>slave</code></strong> choices are not
+ available at the zone level.)
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>key-directory</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>key-directory</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#options" title="options Statement Definition and Usage">the section called &#8220;<span class="command"><strong>options</strong></span> Statement Definition and
+ Usage&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>auto-dnssec</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>auto-dnssec</strong></span> in
+ <a class="xref" href="Bv9ARM.ch06.html#options" title="options Statement Definition and Usage">the section called &#8220;<span class="command"><strong>options</strong></span> Statement Definition and
+ Usage&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>serial-update-method</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>serial-update-method</strong></span> in
+ <a class="xref" href="Bv9ARM.ch06.html#options" title="options Statement Definition and Usage">the section called &#8220;<span class="command"><strong>options</strong></span> Statement Definition and
+ Usage&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>inline-signing</strong></span></span></dt>
+<dd>
+ <p>
+ If <code class="literal">yes</code>, this enables
+ "bump in the wire" signing of a zone, where a
+ unsigned zone is transferred in or loaded from
+ disk and a signed version of the zone is served,
+ with possibly, a different serial number. This
+ behavior is disabled by default.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>multi-master</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of <span class="command"><strong>multi-master</strong></span> in
+ <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>masterfile-format</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of <span class="command"><strong>masterfile-format</strong></span>
+ in <a class="xref" href="Bv9ARM.ch06.html#tuning" title="Tuning">the section called &#8220;Tuning&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>max-zone-ttl</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of <span class="command"><strong>max-zone-ttl</strong></span>
+ in <a class="xref" href="Bv9ARM.ch06.html#options" title="options Statement Definition and Usage">the section called &#8220;<span class="command"><strong>options</strong></span> Statement Definition and
+ Usage&#8221;</a>.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>dnssec-secure-to-insecure</strong></span></span></dt>
+<dd>
+ <p>
+ See the description of
+ <span class="command"><strong>dnssec-secure-to-insecure</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a>.
+ </p>
+ </dd>
+</dl></div>
+
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="dynamic_update_policies"></a>Dynamic Update Policies</h4></div></div></div>
+
+ <p><acronym class="acronym">BIND</acronym> 9 supports two alternative
+ methods of granting clients the right to perform
+ dynamic updates to a zone, configured by the
+ <span class="command"><strong>allow-update</strong></span> and
+ <span class="command"><strong>update-policy</strong></span> option, respectively.
+ </p>
+ <p>
+ The <span class="command"><strong>allow-update</strong></span> clause is a simple
+ access control list. Any client that matches
+ the ACL is granted permission to update any record
+ in the zone.
+ </p>
+ <p>
+ The <span class="command"><strong>update-policy</strong></span> clause
+ allows more fine-grained control over what 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 either TSIG or SIG(0).
+ In most cases, <span class="command"><strong>update-policy</strong></span> rules
+ only apply to key-based identities. There is no way
+ to specify update permissions based on client source
+ address.
+ </p>
+ <p>
+ <span class="command"><strong>update-policy</strong></span> rules are only meaningful
+ for zones of type <span class="command"><strong>master</strong></span>, and are
+ not allowed in any other zone type.
+ It is a configuration error to specify both
+ <span class="command"><strong>allow-update</strong></span> and
+ <span class="command"><strong>update-policy</strong></span> at the same time.
+ </p>
+ <p>
+ A pre-defined <span class="command"><strong>update-policy</strong></span> rule can be
+ switched on with the command
+ <span class="command"><strong>update-policy local;</strong></span>.
+ Using this in a zone causes
+ <span class="command"><strong>named</strong></span> to generate a TSIG session key
+ when starting up and store it in a file; this key can then
+ be used by local clients to update the zone while
+ <span class="command"><strong>named</strong></span> is running.
+ By default, the session key is stored in the file
+ <code class="filename">/var/run/named/session.key</code>, the key name
+ is "local-ddns", and the key algorithm is HMAC-SHA256.
+ These values are configurable with the
+ <span class="command"><strong>session-keyfile</strong></span>,
+ <span class="command"><strong>session-keyname</strong></span> and
+ <span class="command"><strong>session-keyalg</strong></span> 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 will be 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>
+
+ <pre class="programlisting">update-policy { grant local-ddns zonesub any; };
+ </pre>
+
+ <p>
+ ...with the additional restriction that only clients
+ connecting from the local system will be permitted to send
+ updates.
+ </p>
+ <p>
+ Note that only one session key is generated by
+ <span class="command"><strong>named</strong></span>; all zones configured to use
+ <span class="command"><strong>update-policy local</strong></span> will accept the same key.
+ </p>
+ <p>
+ The command <span class="command"><strong>nsupdate -l</strong></span> 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>
+
+<pre class="programlisting">
+( <span class="command"><strong>grant</strong></span> | <span class="command"><strong>deny</strong></span> ) <em class="replaceable"><code>identity</code></em> <em class="replaceable"><code>ruletype</code></em> [<span class="optional"> <em class="replaceable"><code>name</code></em> </span>] [<span class="optional"> <em class="replaceable"><code>types</code></em> </span>]
+</pre>
+
+ <p>
+ Each rule grants or denies privileges. Rules are checked
+ in the order in which they are specified in the
+ <span class="command"><strong>update-policy</strong></span> statement. Once a message
+ has successfully matched a rule, the operation is immediately
+ granted or denied, and no further rules are examined. There
+ are 13 types of rules; the rule type is specified by the
+ <span class="command"><strong>ruletype</strong></span> 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
+ <span class="command"><strong>identity</strong></span> field, the name of the record
+ to be updated matches the <span class="command"><strong>name</strong></span> field
+ (in the manner specified by the <span class="command"><strong>ruletype</strong></span>
+ field), and the type of the record to be updated matches the
+ <span class="command"><strong>types</strong></span> field. Details for each rule type
+ are described below.
+ </p>
+ <p>
+ The <span class="command"><strong>identity</strong></span> field must be set to
+ a fully-qualified domain name. In most cases, this
+ represensts the name of the TSIG or SIG(0) 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 will be
+ used as the identity of the shared secret. Some rule types
+ use identities matching the client's Kerberos principal
+ (e.g, <strong class="userinput"><code>"host/machine@REALM"</code></strong>) or
+ Windows realm (<strong class="userinput"><code>machine$@REALM</code></strong>).
+ </p>
+ <p>
+ The <em class="replaceable"><code>name</code></em> 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 <span class="command"><strong>types</strong></span> are explicitly specified,
+ then a rule matches all types except RRSIG, NS, SOA, NSEC
+ and NSEC3. Types may be specified by name, including
+ "ANY" (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>
+ The <em class="replaceable"><code>ruletype</code></em> field has 16
+ values:
+ <code class="varname">name</code>, <code class="varname">subdomain</code>,
+ <code class="varname">wildcard</code>, <code class="varname">self</code>,
+ <code class="varname">selfsub</code>, <code class="varname">selfwild</code>,
+ <code class="varname">krb5-self</code>, <code class="varname">ms-self</code>,
+ <code class="varname">krb5-selfsub</code>, <code class="varname">ms-selfsub</code>,
+ <code class="varname">krb5-subdomain</code>,
+ <code class="varname">ms-subdomain</code>,
+ <code class="varname">tcp-self</code>, <code class="varname">6to4-self</code>,
+ <code class="varname">zonesub</code>, and <code class="varname">external</code>.
+ </p>
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="0.819in" class="1">
+<col width="3.681in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ <code class="varname">name</code>
+ </p>
+ </td>
+<td>
+ <p>
+ Exact-match semantics. This rule matches
+ when the name being updated is identical
+ to the contents of the
+ <em class="replaceable"><code>name</code></em> field.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">subdomain</code>
+ </p>
+ </td>
+<td>
+ <p>
+ This rule matches when the name being updated
+ is a subdomain of, or identical to, the
+ contents of the <em class="replaceable"><code>name</code></em>
+ field.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">zonesub</code>
+ </p>
+ </td>
+<td>
+ <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
+ <span class="command"><strong>update-policy</strong></span> statement
+ appears. This obviates the need to type the zone
+ name twice, and enables the use of a standard
+ <span class="command"><strong>update-policy</strong></span> statement in
+ multiple zones without modification.
+ </p>
+ <p>
+ When this rule is used, the
+ <em class="replaceable"><code>name</code></em> field is omitted.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">wildcard</code>
+ </p>
+ </td>
+<td>
+ <p>
+ The <em class="replaceable"><code>name</code></em> field
+ is subject to DNS wildcard expansion, and
+ this rule matches when the name being updated
+ is a valid expansion of the wildcard.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">self</code>
+ </p>
+ </td>
+<td>
+ <p>
+ This rule matches when the name of the record
+ being updated matches the contents of the
+ <em class="replaceable"><code>identity</code></em> field.
+ The <em class="replaceable"><code>name</code></em> field
+ is ignored. To avoid confusion, it is recommended
+ that this field be set to the same value as the
+ <em class="replaceable"><code>identity</code></em> field or to
+ "."
+ </p>
+ <p>
+ The <code class="varname">self</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 <em class="replaceable"><code>identity</code></em> field
+ can be specified as <code class="constant">*</code>
+ (an asterisk).
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">selfsub</code>
+ </p>
+ </td>
+<td>
+ <p>
+ This rule is similar to <code class="varname">self</code>
+ except that subdomains of <code class="varname">self</code>
+ can also be updated.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">selfwild</code>
+ </p>
+ </td>
+<td>
+ <p>
+ This rule is similar to <code class="varname">self</code>
+ except that only subdomains of
+ <code class="varname">self</code> can be updated.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">ms-self</code>
+ </p>
+ </td>
+<td>
+ <p>
+ When a client sends an UPDATE using a Windows
+ machine principal (for example, 'machine$@REALM'),
+ this rule allows records with the absolute name
+ of 'machine.REALM' to be updated.
+ </p>
+ <p>
+ The realm to be matched is specified in the
+ <em class="replaceable"><code>identity</code></em> field.
+ </p>
+ <p>
+ The <em class="replaceable"><code>name</code></em> field has
+ no effect on this rule; it should be set to "."
+ as a placeholder.
+ </p>
+ <p>
+ For example,
+ <strong class="userinput"><code>grant EXAMPLE.COM ms-self . A AAAA</code></strong>
+ allows any machine with a valid principal in
+ the realm <strong class="userinput"><code>EXAMPLE.COM</code></strong> to update
+ its own address records.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">ms-selfsub</code>
+ </p>
+ </td>
+<td>
+ <p>
+ This is similar to <span class="command"><strong>ms-self</strong></span>
+ except it also allows updates to any subdomain of
+ the name specified in the Windows machine
+ principal, not just to the name itself.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">ms-subdomain</code>
+ </p>
+ </td>
+<td>
+ <p>
+ When a client sends an UPDATE using a Windows
+ machine principal (for example, 'machine$@REALM'),
+ 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
+ <em class="replaceable"><code>identity</code></em> field.
+ </p>
+ <p>
+ The <em class="replaceable"><code>name</code></em> 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 <span class="command"><strong>update-policy</strong></span>
+ for the zone "example.com" includes
+ <strong class="userinput"><code>grant EXAMPLE.COM ms-subdomain hosts.example.com. A AAAA</code></strong>,
+ any machine with a valid principal in
+ the realm <strong class="userinput"><code>EXAMPLE.COM</code></strong> will
+ be able to update address records at or below
+ "hosts.example.com".
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">krb5-self</code>
+ </p>
+ </td>
+<td>
+ <p>
+ When a client sends an UPDATE using a
+ Kerberos machine principal (for example,
+ 'host/machine@REALM'), this rule allows
+ records with the absolute name of 'machine'
+ to be updated provided it has been authenticated
+ by REALM. This is similar but not identical
+ to <span class="command"><strong>ms-self</strong></span> due to the
+ 'machine' part of the Kerberos principal
+ being an absolute name instead of a unqualified
+ name.
+ </p>
+ <p>
+ The realm to be matched is specified in the
+ <em class="replaceable"><code>identity</code></em> field.
+ </p>
+ <p>
+ The <em class="replaceable"><code>name</code></em> field has
+ no effect on this rule; it should be set to "."
+ as a placeholder.
+ </p>
+ <p>
+ For example,
+ <strong class="userinput"><code>grant EXAMPLE.COM krb5-self . A AAAA</code></strong>
+ allows any machine with a valid principal in
+ the realm <strong class="userinput"><code>EXAMPLE.COM</code></strong> to update
+ its own address records.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">krb5-selfsub</code>
+ </p>
+ </td>
+<td>
+ <p>
+ This is similar to <span class="command"><strong>krb5-self</strong></span>
+ except it also allows updates to any subdomain of
+ the name specified in the 'machine' part of the
+ Kerberos principal, not just to the name itself.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">krb5-subdomain</code>
+ </p>
+ </td>
+<td>
+ <p>
+ This rule is identical to
+ <span class="command"><strong>ms-subdomain</strong></span>, except that it works
+ with Kerberos machine principals (i.e.,
+ 'host/machine@REALM') rather than Windows machine
+ principals.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">tcp-self</code>
+ </p>
+ </td>
+<td>
+ <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="literal">in-addr.arpa</code> and
+ <code class="literal">ip6.arpa</code>
+ namespaces match the name to be updated.
+ The <span class="command"><strong>identity</strong></span> field must match
+ that name. The <span class="command"><strong>name</strong></span> 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="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ It is theoretically possible to spoof these TCP
+ sessions.
+ </div>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">6to4-self</code>
+ </p>
+ </td>
+<td>
+ <p>
+ This allows the name matching a 6to4 IPv6 prefix,
+ as specified in RFC 3056, 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="literal">ip6.arpa</code> reverse tree.
+ </p>
+ <p>
+ The <span class="command"><strong>identity</strong></span> field must match
+ the 6to4 prefix in <code class="literal">ip6.arpa</code>.
+ The <span class="command"><strong>name</strong></span> 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="literal">ip6.arpa</code> name outside of the
+ <code class="literal">2.0.0.2.ip6.arpa</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="literal">C.0.D.E.8.B.D.0.1.0.0.2.ip6.arpa</code>.
+ </p>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ It is theoretically possible to spoof these TCP
+ sessions.
+ </div>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="varname">external</code>
+ </p>
+ </td>
+<td>
+ <p>
+ This rule allows <span class="command"><strong>named</strong></span>
+ 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 <em class="replaceable"><code>identity</code></em>
+ field, the format of which is
+ "<code class="constant">local:</code><em class="replaceable"><code>path</code></em>",
+ where <em class="replaceable"><code>path</code></em> 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>
+ <pre class="programlisting">
+ Protocol version number (4 bytes, network byte order, currently 1)
+ Request length (4 bytes, network byte order)
+ Signer (null-terminated string)
+ Name (null-terminated string)
+ TCP source address (null-terminated string)
+ Rdata type (null-terminated string)
+ Key (null-terminated string)
+ TKEY token length (4 bytes, network byte order)
+ TKEY token (remainder of packet)</pre>
+ <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>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="multiple_views"></a>Multiple views</h4></div></div></div>
+
+ <p>
+ When multiple views are in use, a zone may be
+ referenced by more than one of them. Often, the views
+ will 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
+ <span class="command"><strong>in-view</strong></span> 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. Example:
+ </p>
+ <pre class="programlisting">
+view internal {
+ match-clients { 10/8; };
+
+ zone example.com {
+ type master;
+ file "example-external.db";
+ };
+};
+
+view external {
+ match-clients { any; };
+
+ zone example.com {
+ in-view internal;
+ };
+};
+ </pre>
+ <p>
+ An <span class="command"><strong>in-view</strong></span> option cannot refer to a view
+ that is configured later in the configuration file.
+ </p>
+ <p>
+ A <span class="command"><strong>zone</strong></span> statement which uses the
+ <span class="command"><strong>in-view</strong></span> option may not use any other
+ options with the exception of <span class="command"><strong>forward</strong></span>
+ and <span class="command"><strong>forwarders</strong></span>. (These options control
+ the behavior of the containing view, rather than changing
+ 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. Care
+ need to be taken to ensure that acls are wide enough
+ for all views referencing the zone.
+ </p>
+ <p>
+ An <span class="command"><strong>in-view</strong></span> zone cannot be used as a
+ response policy zone.
+ </p>
+ <p>
+ An <span class="command"><strong>in-view</strong></span> zone is not intended to reference
+ a <span class="command"><strong>forward</strong></span> zone.
+ </p>
+ </div>
+
+ </div>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h2 class="title" style="clear: both">
+<a name="zone_file"></a>Zone File</h2></div></div></div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="types_of_resource_records_and_when_to_use_them"></a>Types of Resource Records and When to Use Them</h3></div></div></div>
+
+ <p>
+ This section, largely borrowed from RFC 1034, describes the
+ concept of a Resource Record (RR) and explains when each is used.
+ Since the publication of RFC 1034, several new RRs have been
+ identified
+ and implemented in the DNS. These are also included.
+ </p>
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="id-1.7.6.2.3"></a>Resource Records</h4></div></div></div>
+
+ <p>
+ A domain name identifies a node. Each node has a set of
+ resource information, which may be empty. The set of resource
+ information associated with a particular name is composed of
+ separate RRs. The order of RRs in a set is not significant and
+ need not be preserved by name servers, resolvers, or other
+ parts of the DNS. However, sorting of multiple RRs is
+ permitted for optimization purposes, for example, to specify
+ that a particular nearby server be tried first. See <a class="xref" href="Bv9ARM.ch06.html#the_sortlist_statement" title="The sortlist Statement">the section called &#8220;The <span class="command"><strong>sortlist</strong></span> Statement&#8221;</a> and <a class="xref" href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">the section called &#8220;RRset Ordering&#8221;</a>.
+ </p>
+
+ <p>
+ The components of a Resource Record are:
+ </p>
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.000in" class="1">
+<col width="3.500in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ owner name
+ </p>
+ </td>
+<td>
+ <p>
+ The domain name where the RR is found.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ type
+ </p>
+ </td>
+<td>
+ <p>
+ An encoded 16-bit value that specifies
+ the type of the resource record.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ TTL
+ </p>
+ </td>
+<td>
+ <p>
+ The time-to-live of the RR. This field
+ is a 32-bit integer in units of seconds, and is
+ primarily used by
+ resolvers when they cache RRs. The TTL describes how
+ long a RR can
+ be cached before it should be discarded.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ class
+ </p>
+ </td>
+<td>
+ <p>
+ An encoded 16-bit value that identifies
+ a protocol family or instance of a protocol.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ RDATA
+ </p>
+ </td>
+<td>
+ <p>
+ The resource data. The format of the
+ data is type (and sometimes class) specific.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ <p>
+ The following are <span class="emphasis"><em>types</em></span> of valid RRs:
+ </p>
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="0.875in" class="1">
+<col width="3.625in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ A
+ </p>
+ </td>
+<td>
+ <p>
+ A host address. In the IN class, this is a
+ 32-bit IP address. Described in RFC 1035.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ AAAA
+ </p>
+ </td>
+<td>
+ <p>
+ IPv6 address. Described in RFC 1886.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ A6
+ </p>
+ </td>
+<td>
+ <p>
+ IPv6 address. This can be a partial
+ address (a suffix) and an indirection to the name
+ where the rest of the
+ address (the prefix) can be found. Experimental.
+ Described in RFC 2874.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ AFSDB
+ </p>
+ </td>
+<td>
+ <p>
+ Location of AFS database servers.
+ Experimental. Described in RFC 1183.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ APL
+ </p>
+ </td>
+<td>
+ <p>
+ Address prefix list. Experimental.
+ Described in RFC 3123.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ ATMA
+ </p>
+ </td>
+<td>
+ <p>
+ ATM Address.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ AVC
+ </p>
+ </td>
+<td>
+ <p>
+ Application Visibility and Control record.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ CAA
+ </p>
+ </td>
+<td>
+ <p>
+ Identifies which Certificate Authorities can issue
+ certificates for this domain and what rules they
+ need to follow when doing so. Defined in RFC 6844.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ CDNSKEY
+ </p>
+ </td>
+<td>
+ <p>
+ Identifies which DNSKEY records should be published
+ as DS records in the parent zone.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ CDS
+ </p>
+ </td>
+<td>
+ <p>
+ Contains the set of DS records that should be published
+ by the parent zone.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ CERT
+ </p>
+ </td>
+<td>
+ <p>
+ Holds a digital certificate.
+ Described in RFC 2538.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ CNAME
+ </p>
+ </td>
+<td>
+ <p>
+ Identifies the canonical name of an alias.
+ Described in RFC 1035.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ CSYNC
+ </p>
+ </td>
+<td>
+ <p>
+ Child-to-Parent Synchronization in DNS as described
+ in RFC 7477.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ DHCID
+ </p>
+ </td>
+<td>
+ <p>
+ Is used for identifying which DHCP client is
+ associated with this name. Described in RFC 4701.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ DLV
+ </p>
+ </td>
+<td>
+ <p>
+ A DNS Look-aside Validation record which contains
+ the records that are used as trust anchors for
+ zones in a DLV namespace. Described in RFC 4431.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ DNAME
+ </p>
+ </td>
+<td>
+ <p>
+ Replaces the domain name specified with
+ another name to be looked up, effectively aliasing an
+ entire
+ subtree of the domain name space rather than a single
+ record
+ as in the case of the CNAME RR.
+ Described in RFC 2672.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ DNSKEY
+ </p>
+ </td>
+<td>
+ <p>
+ Stores a public key associated with a signed
+ DNS zone. Described in RFC 4034.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ DOA
+ </p>
+ </td>
+<td>
+ <p>
+ Implements the Digital Object Architecture over
+ DNS. Experimental.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ DS
+ </p>
+ </td>
+<td>
+ <p>
+ Stores the hash of a public key associated with a
+ signed DNS zone. Described in RFC 4034.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ EID
+ </p>
+ </td>
+<td>
+ <p>
+ End Point Identifier.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ EUI48
+ </p>
+ </td>
+<td>
+ <p>
+ A 48-bit EUI address. Described in RFC 7043.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ EUI64
+ </p>
+ </td>
+<td>
+ <p>
+ A 64-bit EUI address. Described in RFC 7043.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ GID
+ </p>
+ </td>
+<td>
+ <p>
+ Reserved.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ GPOS
+ </p>
+ </td>
+<td>
+ <p>
+ Specifies the global position. Superseded by LOC.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ HINFO
+ </p>
+ </td>
+<td>
+ <p>
+ Identifies the CPU and OS used by a host.
+ Described in RFC 1035.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ HIP
+ </p>
+ </td>
+<td>
+ <p>
+ Host Identity Protocol Address.
+ Described in RFC 5205.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ IPSECKEY
+ </p>
+ </td>
+<td>
+ <p>
+ Provides a method for storing IPsec keying material in
+ DNS. Described in RFC 4025.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ ISDN
+ </p>
+ </td>
+<td>
+ <p>
+ Representation of ISDN addresses.
+ Experimental. Described in RFC 1183.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ KEY
+ </p>
+ </td>
+<td>
+ <p>
+ Stores a public key associated with a
+ DNS name. Used in original DNSSEC; replaced
+ by DNSKEY in DNSSECbis, but still used with
+ SIG(0). Described in RFCs 2535 and 2931.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ KX
+ </p>
+ </td>
+<td>
+ <p>
+ Identifies a key exchanger for this
+ DNS name. Described in RFC 2230.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ L32
+ </p>
+ </td>
+<td>
+ <p>
+ Holds 32-bit Locator values for
+ Identifier-Locator Network Protocol. Described
+ in RFC 6742.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ L64
+ </p>
+ </td>
+<td>
+ <p>
+ Holds 64-bit Locator values for
+ Identifier-Locator Network Protocol. Described
+ in RFC 6742.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ LOC
+ </p>
+ </td>
+<td>
+ <p>
+ For storing GPS info. Described in RFC 1876.
+ Experimental.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ LP
+ </p>
+ </td>
+<td>
+ <p>
+ Identifier-Locator Network Protocol.
+ Described in RFC 6742.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ MB
+ </p>
+ </td>
+<td>
+ <p>
+ Mail Box. Historical.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ MD
+ </p>
+ </td>
+<td>
+ <p>
+ Mail Destination. Historical.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ MF
+ </p>
+ </td>
+<td>
+ <p>
+ Mail Forwarder. Historical.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ MG
+ </p>
+ </td>
+<td>
+ <p>
+ Mail Group. Historical.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ MINFO
+ </p>
+ </td>
+<td>
+ <p>
+ Mail Information.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ MR
+ </p>
+ </td>
+<td>
+ <p>
+ Mail Rename. Historical.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ MX
+ </p>
+ </td>
+<td>
+ <p>
+ Identifies a mail exchange for the domain with
+ a 16-bit preference value (lower is better)
+ followed by the host name of the mail exchange.
+ Described in RFC 974, RFC 1035.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NAPTR
+ </p>
+ </td>
+<td>
+ <p>
+ Name authority pointer. Described in RFC 2915.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NID
+ </p>
+ </td>
+<td>
+ <p>
+ Holds values for Node Identifiers in
+ Identifier-Locator Network Protocol. Described
+ in RFC 6742.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NINFO
+ </p>
+ </td>
+<td>
+ <p>
+ Contains zone status information.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NIMLOC
+ </p>
+ </td>
+<td>
+ <p>
+ Nimrod Locator.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NSAP
+ </p>
+ </td>
+<td>
+ <p>
+ A network service access point.
+ Described in RFC 1706.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NSAP-PTR
+ </p>
+ </td>
+<td>
+ <p>
+ Historical.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NS
+ </p>
+ </td>
+<td>
+ <p>
+ The authoritative name server for the
+ domain. Described in RFC 1035.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NSEC
+ </p>
+ </td>
+<td>
+ <p>
+ Used in DNSSECbis to securely indicate that
+ RRs with an owner name in a certain name interval do
+ not exist in
+ a zone and indicate what RR types are present for an
+ existing name.
+ Described in RFC 4034.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NSEC3
+ </p>
+ </td>
+<td>
+ <p>
+ Used in DNSSECbis to securely indicate that
+ RRs with an owner name in a certain name
+ interval do not exist in a zone and indicate
+ what RR types are present for an existing
+ name. NSEC3 differs from NSEC in that it
+ prevents zone enumeration but is more
+ computationally expensive on both the server
+ and the client than NSEC. Described in RFC
+ 5155.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NSEC3PARAM
+ </p>
+ </td>
+<td>
+ <p>
+ Used in DNSSECbis to tell the authoritative
+ server which NSEC3 chains are available to use.
+ Described in RFC 5155.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NULL
+ </p>
+ </td>
+<td>
+ <p>
+ This is an opaque container.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ NXT
+ </p>
+ </td>
+<td>
+ <p>
+ Used in DNSSEC to securely indicate that
+ RRs with an owner name in a certain name interval do
+ not exist in
+ a zone and indicate what RR types are present for an
+ existing name.
+ Used in original DNSSEC; replaced by NSEC in
+ DNSSECbis.
+ Described in RFC 2535.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ OPENPGPKEY
+ </p>
+ </td>
+<td>
+ <p>
+ Used to hold an OPENPGPKEY.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ PTR
+ </p>
+ </td>
+<td>
+ <p>
+ A pointer to another part of the domain
+ name space. Described in RFC 1035.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ PX
+ </p>
+ </td>
+<td>
+ <p>
+ Provides mappings between RFC 822 and X.400
+ addresses. Described in RFC 2163.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ RKEY
+ </p>
+ </td>
+<td>
+ <p>
+ Resource key.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ RP
+ </p>
+ </td>
+<td>
+ <p>
+ Information on persons responsible
+ for the domain. Experimental. Described in RFC 1183.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ RRSIG
+ </p>
+ </td>
+<td>
+ <p>
+ Contains DNSSECbis signature data. Described
+ in RFC 4034.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ RT
+ </p>
+ </td>
+<td>
+ <p>
+ Route-through binding for hosts that
+ do not have their own direct wide area network
+ addresses.
+ Experimental. Described in RFC 1183.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ SIG
+ </p>
+ </td>
+<td>
+ <p>
+ Contains DNSSEC signature data. Used in
+ original DNSSEC; replaced by RRSIG in
+ DNSSECbis, but still used for SIG(0).
+ Described in RFCs 2535 and 2931.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ SINK
+ </p>
+ </td>
+<td>
+ <p>
+ The kitchen sink record.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ SMIMEA
+ </p>
+ </td>
+<td>
+ <p>
+ The S/MIME Security Certificate Association.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ SOA
+ </p>
+ </td>
+<td>
+ <p>
+ Identifies the start of a zone of authority.
+ Described in RFC 1035.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ SPF
+ </p>
+ </td>
+<td>
+ <p>
+ Contains the Sender Policy Framework information
+ for a given email domain. Described in RFC 4408.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ SRV
+ </p>
+ </td>
+<td>
+ <p>
+ Information about well known network
+ services (replaces WKS). Described in RFC 2782.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ SSHFP
+ </p>
+ </td>
+<td>
+ <p>
+ Provides a way to securely publish a secure shell key's
+ fingerprint. Described in RFC 4255.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ TA
+ </p>
+ </td>
+<td>
+ <p>
+ Trust Anchor. Experimental.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ TALINK
+ </p>
+ </td>
+<td>
+ <p>
+ Trust Anchor Link. Experimental.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ TLSA
+ </p>
+ </td>
+<td>
+ <p>
+ Transport Layer Security Certificate Association.
+ Described in RFC 6698.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ TXT
+ </p>
+ </td>
+<td>
+ <p>
+ Text records. Described in RFC 1035.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ UID
+ </p>
+ </td>
+<td>
+ <p>
+ Reserved.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ UINFO
+ </p>
+ </td>
+<td>
+ <p>
+ Reserved.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ UNSPEC
+ </p>
+ </td>
+<td>
+ <p>
+ Reserved. Historical.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ URI
+ </p>
+ </td>
+<td>
+ <p>
+ Holds a URI. Described in RFC 7553.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ WKS
+ </p>
+ </td>
+<td>
+ <p>
+ Information about which well known
+ network services, such as SMTP, that a domain
+ supports. Historical.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ X25
+ </p>
+ </td>
+<td>
+ <p>
+ Representation of X.25 network addresses.
+ Experimental. Described in RFC 1183.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ <p>
+ The following <span class="emphasis"><em>classes</em></span> of resource records
+ are currently valid in the DNS:
+ </p>
+ <div class="informaltable">
+<table border="1">
+<colgroup>
+<col width="0.875in" class="1">
+<col width="3.625in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ IN
+ </p>
+ </td>
+<td>
+ <p>
+ The Internet.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ CH
+ </p>
+ </td>
+<td>
+ <p>
+ Chaosnet, a LAN protocol created at MIT in the
+ mid-1970s.
+ Rarely used for its historical purpose, but reused for
+ BIND's
+ built-in server information zones, e.g.,
+ <code class="literal">version.bind</code>.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ HS
+ </p>
+ </td>
+<td>
+ <p>
+ Hesiod, an information service
+ developed by MIT's Project Athena. It is used to share
+ information
+ about various systems databases, such as users,
+ groups, printers
+ and so on.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+
+ <p>
+ The owner name is often implicit, rather than forming an
+ integral
+ part of the RR. For example, many name servers internally form
+ tree
+ or hash structures for the name space, and chain RRs off nodes.
+ The remaining RR parts are the fixed header (type, class, TTL)
+ which is consistent for all RRs, and a variable part (RDATA)
+ that
+ fits the needs of the resource being described.
+ </p>
+ <p>
+ The meaning of the TTL field is a time limit on how long an
+ RR can be kept in a cache. This limit does not apply to
+ authoritative
+ data in zones; it is also timed out, but by the refreshing
+ policies
+ for the zone. The TTL is assigned by the administrator for the
+ zone where the data originates. While short TTLs can be used to
+ minimize caching, and a zero TTL prohibits caching, the
+ realities
+ of Internet performance suggest that these times should be on
+ the
+ order of days for the typical host. If a change can be
+ anticipated,
+ the TTL can be reduced prior to the change to minimize
+ inconsistency
+ during the change, and then increased back to its former value
+ following
+ the change.
+ </p>
+ <p>
+ The data in the RDATA section of RRs is carried as a combination
+ of binary strings and domain names. The domain names are
+ frequently
+ used as "pointers" to other data in the DNS.
+ </p>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="rr_text"></a>Textual expression of RRs</h4></div></div></div>
+
+ <p>
+ RRs are represented in binary form in the packets of the DNS
+ protocol, and are usually represented in highly encoded form
+ when
+ stored in a name server or resolver. In the examples provided
+ in
+ RFC 1034, a style similar to that used in master files was
+ employed
+ in order to show the contents of RRs. In this format, most RRs
+ are shown on a single line, although continuation lines are
+ possible
+ using parentheses.
+ </p>
+ <p>
+ The start of the line gives the owner of the RR. If a line
+ begins with a blank, then the owner is assumed to be the same as
+ that of the previous RR. Blank lines are often included for
+ readability.
+ </p>
+ <p>
+ Following the owner, we list the TTL, type, and class of the
+ RR. Class and type use the mnemonics defined above, and TTL is
+ an integer before the type field. In order to avoid ambiguity
+ in
+ parsing, type and class mnemonics are disjoint, TTLs are
+ integers,
+ and the type mnemonic is always last. The IN class and TTL
+ values
+ are often omitted from examples in the interests of clarity.
+ </p>
+ <p>
+ The resource data or RDATA section of the RR are given using
+ knowledge of the typical representation for the data.
+ </p>
+ <p>
+ For example, we might show the RRs carried in a message as:
+ </p>
+ <div class="informaltable">
+<table border="1">
+<colgroup>
+<col width="1.381in" class="1">
+<col width="1.020in" class="2">
+<col width="2.099in" class="3">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ <code class="literal">ISI.EDU.</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">MX</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">10 VENERA.ISI.EDU.</code>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p></p>
+ </td>
+<td>
+ <p>
+ <code class="literal">MX</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">10 VAXA.ISI.EDU</code>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="literal">VENERA.ISI.EDU</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">A</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">128.9.0.32</code>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p></p>
+ </td>
+<td>
+ <p>
+ <code class="literal">A</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">10.1.0.52</code>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="literal">VAXA.ISI.EDU</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">A</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">10.2.0.27</code>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p></p>
+ </td>
+<td>
+ <p>
+ <code class="literal">A</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">128.9.0.33</code>
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ <p>
+ The MX RRs have an RDATA section which consists of a 16-bit
+ number followed by a domain name. The address RRs use a
+ standard
+ IP address format to contain a 32-bit internet address.
+ </p>
+ <p>
+ The above example shows six RRs, with two RRs at each of three
+ domain names.
+ </p>
+ <p>
+ Similarly we might see:
+ </p>
+ <div class="informaltable">
+<table border="1">
+<colgroup>
+<col width="1.491in" class="1">
+<col width="1.067in" class="2">
+<col width="2.067in" class="3">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ <code class="literal">XX.LCS.MIT.EDU.</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">IN A</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">10.0.0.44</code>
+ </p>
+ </td>
+</tr>
+<tr>
+<td> </td>
+<td>
+ <p>
+ <code class="literal">CH A</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">MIT.EDU. 2420</code>
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ <p>
+ This example shows two addresses for
+ <code class="literal">XX.LCS.MIT.EDU</code>, each of a different class.
+ </p>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="mx_records"></a>Discussion of MX Records</h3></div></div></div>
+
+ <p>
+ As described above, domain servers store information as a
+ series of resource records, each of which contains a particular
+ piece of information about a given domain name (which is usually,
+ but not always, a host). The simplest way to think of a RR is as
+ a typed pair of data, a domain name matched with a relevant datum,
+ and stored with some additional type information to help systems
+ determine when the RR is relevant.
+ </p>
+
+ <p>
+ MX records are used to control delivery of email. The data
+ specified in the record is a priority and a domain name. The
+ priority
+ controls the order in which email delivery is attempted, with the
+ lowest number first. If two priorities are the same, a server is
+ chosen randomly. If no servers at a given priority are responding,
+ the mail transport agent will fall back to the next largest
+ priority.
+ Priority numbers do not have any absolute meaning &#8212; they are
+ relevant
+ only respective to other MX records for that domain name. The
+ domain
+ name given is the machine to which the mail will be delivered.
+ It <span class="emphasis"><em>must</em></span> have an associated address record
+ (A or AAAA) &#8212; CNAME is not sufficient.
+ </p>
+ <p>
+ For a given domain, if there is both a CNAME record and an
+ MX record, the MX record is in error, and will be ignored.
+ Instead,
+ the mail will be delivered to the server specified in the MX
+ record
+ pointed to by the CNAME.
+ For example:
+ </p>
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.708in" class="1">
+<col width="0.444in" class="2">
+<col width="0.444in" class="3">
+<col width="0.976in" class="4">
+<col width="1.553in" class="5">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ <code class="literal">example.com.</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">IN</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">MX</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">10</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">mail.example.com.</code>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p></p>
+ </td>
+<td>
+ <p>
+ <code class="literal">IN</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">MX</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">10</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">mail2.example.com.</code>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p></p>
+ </td>
+<td>
+ <p>
+ <code class="literal">IN</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">MX</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">20</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">mail.backup.org.</code>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="literal">mail.example.com.</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">IN</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">A</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">10.0.0.1</code>
+ </p>
+ </td>
+<td>
+ <p></p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="literal">mail2.example.com.</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">IN</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">A</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">10.0.0.2</code>
+ </p>
+ </td>
+<td>
+ <p></p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+<p>
+ Mail delivery will be attempted to <code class="literal">mail.example.com</code> and
+ <code class="literal">mail2.example.com</code> (in
+ any order), and if neither of those succeed, delivery to <code class="literal">mail.backup.org</code> will
+ be attempted.
+ </p>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="Setting_TTLs"></a>Setting TTLs</h3></div></div></div>
+
+ <p>
+ The time-to-live of the RR field is a 32-bit integer represented
+ in units of seconds, and is primarily used by resolvers when they
+ cache RRs. The TTL describes how long a RR can be cached before it
+ should be discarded. The following three types of TTL are
+ currently
+ used in a zone file.
+ </p>
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="0.750in" class="1">
+<col width="4.375in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ SOA
+ </p>
+ </td>
+<td>
+ <p>
+ The last field in the SOA is the negative
+ caching TTL. This controls how long other servers will
+ cache no-such-domain
+ (NXDOMAIN) responses from you.
+ </p>
+ <p>
+ The maximum time for
+ negative caching is 3 hours (3h).
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ $TTL
+ </p>
+ </td>
+<td>
+ <p>
+ The $TTL directive at the top of the
+ zone file (before the SOA) gives a default TTL for every
+ RR without
+ a specific TTL set.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ RR TTLs
+ </p>
+ </td>
+<td>
+ <p>
+ Each RR can have a TTL as the second
+ field in the RR, which will control how long other
+ servers can cache it.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ <p>
+ All of these TTLs default to units of seconds, though units
+ can be explicitly specified, for example, <code class="literal">1h30m</code>.
+ </p>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="ipv4_reverse"></a>Inverse Mapping in IPv4</h3></div></div></div>
+
+ <p>
+ Reverse name resolution (that is, translation from IP address
+ to name) is achieved by means of the <span class="emphasis"><em>in-addr.arpa</em></span> domain
+ and PTR records. Entries in the in-addr.arpa domain are made in
+ least-to-most significant order, read left to right. This is the
+ opposite order to the way IP addresses are usually written. Thus,
+ a machine with an IP address of 10.1.2.3 would have a
+ corresponding
+ in-addr.arpa name of
+ 3.2.1.10.in-addr.arpa. This name should have a PTR resource record
+ whose data field is the name of the machine or, optionally,
+ multiple
+ PTR records if the machine has more than one name. For example,
+ in the [<span class="optional">example.com</span>] domain:
+ </p>
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.125in" class="1">
+<col width="4.000in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ <code class="literal">$ORIGIN</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">2.1.10.in-addr.arpa</code>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>
+ <code class="literal">3</code>
+ </p>
+ </td>
+<td>
+ <p>
+ <code class="literal">IN PTR foo.example.com.</code>
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ The <span class="command"><strong>$ORIGIN</strong></span> lines in the examples
+ are for providing context to the examples only &#8212; they do not
+ necessarily
+ appear in the actual usage. They are only used here to indicate
+ that the example is relative to the listed origin.
+ </p>
+ </div>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="zone_directives"></a>Other Zone File Directives</h3></div></div></div>
+
+ <p>
+ The Master File Format was initially defined in RFC 1035 and
+ has subsequently been extended. While the Master File Format
+ itself
+ is class independent all records in a Master File must be of the
+ same
+ class.
+ </p>
+ <p>
+ Master File Directives include <span class="command"><strong>$ORIGIN</strong></span>, <span class="command"><strong>$INCLUDE</strong></span>,
+ and <span class="command"><strong>$TTL.</strong></span>
+ </p>
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="atsign"></a>The <span class="command"><strong>@</strong></span> (at-sign)</h4></div></div></div>
+
+ <p>
+ When used in the label (or name) field, the asperand or
+ at-sign (@) symbol represents the current origin.
+ At the start of the zone file, it is the
+ &lt;<code class="varname">zone_name</code>&gt; (followed by
+ trailing dot).
+ </p>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="origin_directive"></a>The <span class="command"><strong>$ORIGIN</strong></span> Directive</h4></div></div></div>
+
+ <p>
+ Syntax: <span class="command"><strong>$ORIGIN</strong></span>
+ <em class="replaceable"><code>domain-name</code></em>
+ [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
+ </p>
+ <p><span class="command"><strong>$ORIGIN</strong></span>
+ sets the domain name that will be appended to any
+ unqualified records. When a zone is first read in there
+ is an implicit <span class="command"><strong>$ORIGIN</strong></span>
+ &lt;<code class="varname">zone_name</code>&gt;<span class="command"><strong>.</strong></span>
+ (followed by trailing dot).
+ The current <span class="command"><strong>$ORIGIN</strong></span> is appended to
+ the domain specified in the <span class="command"><strong>$ORIGIN</strong></span>
+ argument if it is not absolute.
+ </p>
+
+<pre class="programlisting">
+$ORIGIN example.com.
+WWW CNAME MAIN-SERVER
+</pre>
+
+ <p>
+ is equivalent to
+ </p>
+
+<pre class="programlisting">
+WWW.EXAMPLE.COM. CNAME MAIN-SERVER.EXAMPLE.COM.
+</pre>
+
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="include_directive"></a>The <span class="command"><strong>$INCLUDE</strong></span> Directive</h4></div></div></div>
+
+ <p>
+ Syntax: <span class="command"><strong>$INCLUDE</strong></span>
+ <em class="replaceable"><code>filename</code></em>
+ [<span class="optional">
+<em class="replaceable"><code>origin</code></em> </span>]
+ [<span class="optional"> <em class="replaceable"><code>comment</code></em> </span>]
+ </p>
+ <p>
+ Read and process the file <code class="filename">filename</code> as
+ if it were included into the file at this point. If <span class="command"><strong>origin</strong></span> is
+ specified the file is processed with <span class="command"><strong>$ORIGIN</strong></span> set
+ to that value, otherwise the current <span class="command"><strong>$ORIGIN</strong></span> is
+ used.
+ </p>
+ <p>
+ The origin and the current domain name
+ revert to the values they had prior to the <span class="command"><strong>$INCLUDE</strong></span> once
+ the file has been read.
+ </p>
+ <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
+<h3 class="title">Note</h3>
+ <p>
+ RFC 1035 specifies that the current origin should be restored
+ after
+ an <span class="command"><strong>$INCLUDE</strong></span>, but it is silent
+ on whether the current
+ domain name should also be restored. BIND 9 restores both of
+ them.
+ This could be construed as a deviation from RFC 1035, a
+ feature, or both.
+ </p>
+ </div>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="ttl_directive"></a>The <span class="command"><strong>$TTL</strong></span> Directive</h4></div></div></div>
+
+ <p>
+ Syntax: <span class="command"><strong>$TTL</strong></span>
+ <em class="replaceable"><code>default-ttl</code></em>
+ [<span class="optional">
+<em class="replaceable"><code>comment</code></em> </span>]
+ </p>
+ <p>
+ Set the default Time To Live (TTL) for subsequent records
+ with undefined TTLs. Valid TTLs are of the range 0-2147483647
+ seconds.
+ </p>
+ <p><span class="command"><strong>$TTL</strong></span>
+ is defined in RFC 2308.
+ </p>
+ </div>
+ </div>
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="generate_directive"></a><acronym class="acronym">BIND</acronym> Master File Extension: the <span class="command"><strong>$GENERATE</strong></span> Directive</h3></div></div></div>
+
+ <p>
+ Syntax: <span class="command"><strong>$GENERATE</strong></span>
+ <em class="replaceable"><code>range</code></em>
+ <em class="replaceable"><code>lhs</code></em>
+ [<span class="optional"><em class="replaceable"><code>ttl</code></em></span>]
+ [<span class="optional"><em class="replaceable"><code>class</code></em></span>]
+ <em class="replaceable"><code>type</code></em>
+ <em class="replaceable"><code>rhs</code></em>
+ [<span class="optional"><em class="replaceable"><code>comment</code></em></span>]
+ </p>
+ <p><span class="command"><strong>$GENERATE</strong></span>
+ is used to create a series of resource records that only
+ differ from each other by an
+ iterator. <span class="command"><strong>$GENERATE</strong></span> can be used to
+ easily generate the sets of records required to support
+ sub /24 reverse delegations described in RFC 2317:
+ Classless IN-ADDR.ARPA delegation.
+ </p>
+
+<pre class="programlisting">$ORIGIN 0.0.192.IN-ADDR.ARPA.
+$GENERATE 1-2 @ NS SERVER$.EXAMPLE.
+$GENERATE 1-127 $ CNAME $.0</pre>
+
+ <p>
+ is equivalent to
+ </p>
+
+<pre class="programlisting">0.0.0.192.IN-ADDR.ARPA. NS SERVER1.EXAMPLE.
+0.0.0.192.IN-ADDR.ARPA. NS SERVER2.EXAMPLE.
+1.0.0.192.IN-ADDR.ARPA. CNAME 1.0.0.0.192.IN-ADDR.ARPA.
+2.0.0.192.IN-ADDR.ARPA. CNAME 2.0.0.0.192.IN-ADDR.ARPA.
+...
+127.0.0.192.IN-ADDR.ARPA. CNAME 127.0.0.0.192.IN-ADDR.ARPA.
+</pre>
+
+ <p>
+ Generate a set of A and MX records. Note the MX's right hand
+ side is a quoted string. The quotes will be stripped when the
+ right hand side is processed.
+ </p>
+
+<pre class="programlisting">
+$ORIGIN EXAMPLE.
+$GENERATE 1-127 HOST-$ A 1.2.3.$
+$GENERATE 1-127 HOST-$ MX "0 ."</pre>
+
+ <p>
+ is equivalent to
+ </p>
+
+<pre class="programlisting">HOST-1.EXAMPLE. A 1.2.3.1
+HOST-1.EXAMPLE. MX 0 .
+HOST-2.EXAMPLE. A 1.2.3.2
+HOST-2.EXAMPLE. MX 0 .
+HOST-3.EXAMPLE. A 1.2.3.3
+HOST-3.EXAMPLE. MX 0 .
+...
+HOST-127.EXAMPLE. A 1.2.3.127
+HOST-127.EXAMPLE. MX 0 .
+</pre>
+
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="0.875in" class="1">
+<col width="4.250in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p><span class="command"><strong>range</strong></span></p>
+ </td>
+<td>
+ <p>
+ This can be one of two forms: start-stop
+ or start-stop/step. If the first form is used, then step
+ is set to 1. start, stop and step must be positive
+ integers between 0 and (2^31)-1. start must not be
+ larger than stop.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>lhs</strong></span></p>
+ </td>
+<td>
+ <p>This
+ describes the owner name of the resource records
+ to be created. Any single <span class="command"><strong>$</strong></span>
+ (dollar sign)
+ symbols within the <span class="command"><strong>lhs</strong></span> string
+ are replaced by the iterator value.
+
+ To get a $ in the output, you need to escape the
+ <span class="command"><strong>$</strong></span> using a backslash
+ <span class="command"><strong>\</strong></span>,
+ e.g. <span class="command"><strong>\$</strong></span>. The
+ <span class="command"><strong>$</strong></span> may optionally be followed
+ by modifiers which change the offset from the
+ iterator, field width and base.
+
+ Modifiers are introduced by a
+ <span class="command"><strong>{</strong></span> (left brace) immediately following the
+ <span class="command"><strong>$</strong></span> as
+ <span class="command"><strong>${offset[,width[,base]]}</strong></span>.
+ For example, <span class="command"><strong>${-20,3,d}</strong></span>
+ subtracts 20 from the current value, prints the
+ result as a decimal in a zero-padded field of
+ width 3.
+
+ Available output forms are decimal
+ (<span class="command"><strong>d</strong></span>), octal
+ (<span class="command"><strong>o</strong></span>), hexadecimal
+ (<span class="command"><strong>x</strong></span> or <span class="command"><strong>X</strong></span>
+ for uppercase) and nibble
+ (<span class="command"><strong>n</strong></span> or <span class="command"><strong>N</strong></span>\
+ for uppercase). The default modifier is
+ <span class="command"><strong>${0,0,d}</strong></span>. If the
+ <span class="command"><strong>lhs</strong></span> is not absolute, the
+ current <span class="command"><strong>$ORIGIN</strong></span> is appended
+ to the name.
+ </p>
+ <p>
+ In nibble mode the value will be treated as
+ if it was a reversed hexadecimal string
+ with each hexadecimal digit as a separate
+ label. The width field includes the label
+ separator.
+ </p>
+ <p>
+ For compatibility with earlier versions,
+ <span class="command"><strong>$$</strong></span> is still recognized as
+ indicating a literal $ in the output.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>ttl</strong></span></p>
+ </td>
+<td>
+ <p>
+ Specifies the time-to-live of the generated records. If
+ not specified this will be inherited using the
+ normal TTL inheritance rules.
+ </p>
+ <p><span class="command"><strong>class</strong></span>
+ and <span class="command"><strong>ttl</strong></span> can be
+ entered in either order.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>class</strong></span></p>
+ </td>
+<td>
+ <p>
+ Specifies the class of the generated records.
+ This must match the zone class if it is
+ specified.
+ </p>
+ <p><span class="command"><strong>class</strong></span>
+ and <span class="command"><strong>ttl</strong></span> can be
+ entered in either order.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>type</strong></span></p>
+ </td>
+<td>
+ <p>
+ Any valid type.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>rhs</strong></span></p>
+ </td>
+<td>
+ <p>
+ <span class="command"><strong>rhs</strong></span>, optionally, quoted string.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ <p>
+ The <span class="command"><strong>$GENERATE</strong></span> directive is a <acronym class="acronym">BIND</acronym> extension
+ and not part of the standard zone file format.
+ </p>
+ <p>
+ BIND 8 did not support the optional TTL and CLASS fields.
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="zonefile_format"></a>Additional File Formats</h3></div></div></div>
+
+ <p>
+ In addition to the standard textual format, BIND 9
+ supports the ability to read or dump to zone files in
+ other formats.
+ </p>
+ <p>
+ The <code class="constant">raw</code> format is
+ a binary representation of zone data in a manner similar
+ to that used in zone transfers. Since it does not require
+ parsing text, load time is significantly reduced.
+ </p>
+ <p>
+ An even faster alternative is the <code class="constant">map</code>
+ format, which is an image of a <acronym class="acronym">BIND</acronym> 9
+ in-memory zone database; it is capable of being loaded
+ directly into memory via the <span class="command"><strong>mmap()</strong></span>
+ function; the zone can begin serving queries almost
+ immediately.
+ </p>
+ <p>
+ For a primary server, a zone file in
+ <code class="constant">raw</code> or <code class="constant">map</code>
+ format is expected to be generated from a textual zone
+ file by the <span class="command"><strong>named-compilezone</strong></span> command.
+ For a secondary server or for a dynamic zone, it is automatically
+ generated (if this format is specified by the
+ <span class="command"><strong>masterfile-format</strong></span> option) when
+ <span class="command"><strong>named</strong></span> dumps the zone contents after
+ zone transfer or when applying prior updates.
+ </p>
+ <p>
+ If a zone file in a binary format needs manual modification,
+ it first must be converted to a textual form by the
+ <span class="command"><strong>named-compilezone</strong></span> command. All
+ necessary modification should go to the text file, which
+ should then be converted to the binary form by the
+ <span class="command"><strong>named-compilezone</strong></span> command again.
+ </p>
+ <p>
+ Note that <span class="command"><strong>map</strong></span> format is extremely
+ architecture-specific. A <code class="constant">map</code>
+ file <span class="emphasis"><em>cannot</em></span> be used on a system
+ with different pointer size, endianness or data alignment
+ than the system on which it was generated, and should in
+ general be used only inside a single system.
+ While <code class="constant">raw</code> format uses
+ network byte order and avoids architecture-dependent
+ data alignment so that it is as portable as
+ possible, it is also primarily expected to be used
+ inside the same single system. To export a
+ zone file in either <code class="constant">raw</code> or
+ <code class="constant">map</code> format, or make a
+ portable backup of such a file, conversion to
+ <code class="constant">text</code> format is recommended.
+ </p>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h2 class="title" style="clear: both">
+<a name="statistics"></a>BIND9 Statistics</h2></div></div></div>
+
+ <p>
+ <acronym class="acronym">BIND</acronym> 9 maintains lots of statistics
+ information and provides several interfaces for users to
+ get access to the statistics.
+ The available statistics include all statistics counters
+ that were available in <acronym class="acronym">BIND</acronym> 8 and
+ are meaningful in <acronym class="acronym">BIND</acronym> 9,
+ and other information that is considered useful.
+ </p>
+
+ <p>
+ The statistics information is categorized into the following
+ sections.
+ </p>
+
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="3.300in" class="1">
+<col width="2.625in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>Incoming Requests</p>
+ </td>
+<td>
+ <p>
+ The number of incoming DNS requests for each OPCODE.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>Incoming Queries</p>
+ </td>
+<td>
+ <p>
+ The number of incoming queries for each RR type.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>Outgoing Queries</p>
+ </td>
+<td>
+ <p>
+ The number of outgoing queries for each RR
+ type sent from the internal resolver.
+ Maintained per view.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>Name Server Statistics</p>
+ </td>
+<td>
+ <p>
+ Statistics counters about incoming request processing.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>Zone Maintenance Statistics</p>
+ </td>
+<td>
+ <p>
+ Statistics counters regarding zone maintenance
+ operations such as zone transfers.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>Resolver Statistics</p>
+ </td>
+<td>
+ <p>
+ Statistics counters about name resolution
+ performed in the internal resolver.
+ Maintained per view.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>Cache DB RRsets</p>
+ </td>
+<td>
+ <p>
+ The number of RRsets per RR type and nonexistent
+ names stored in the cache database.
+ If the exclamation mark (!) is printed for a RR
+ type, it means that particular type of RRset is
+ known to be nonexistent (this is also known as
+ "NXRRSET"). If a hash mark (#) is present then
+ the RRset is marked for garbage collection.
+ Maintained per view.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p>Socket I/O Statistics</p>
+ </td>
+<td>
+ <p>
+ Statistics counters about network related events.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+
+ <p>
+ A subset of Name Server Statistics is collected and shown
+ per zone for which the server has the authority when
+ <span class="command"><strong>zone-statistics</strong></span> is set to
+ <strong class="userinput"><code>full</code></strong> (or <strong class="userinput"><code>yes</code></strong>
+ for backward compatibility. See the description of
+ <span class="command"><strong>zone-statistics</strong></span> in <a class="xref" href="Bv9ARM.ch06.html#options" title="options Statement Definition and Usage">the section called &#8220;<span class="command"><strong>options</strong></span> Statement Definition and
+ Usage&#8221;</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 the plain text format dumped to the file specified
+ by the <span class="command"><strong>statistics-file</strong></span> configuration option.
+ The other is remotely accessible via a statistics channel
+ when the <span class="command"><strong>statistics-channels</strong></span> statement
+ is specified in the configuration file
+ (see <a class="xref" href="Bv9ARM.ch06.html#statschannels" title="statistics-channels Statement Grammar">the section called &#8220;<span class="command"><strong>statistics-channels</strong></span> Statement Grammar&#8221;</a>.)
+ </p>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="statsfile"></a>The Statistics File</h3></div></div></div>
+
+ <p>
+ The text format statistics dump begins with a line, like:
+ </p>
+ <p>
+ <span class="command"><strong>+++ Statistics Dump +++ (973798949)</strong></span>
+ </p>
+ <p>
+ The number in parentheses is a standard
+ Unix-style timestamp, measured as 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>
+ <span class="command"><strong>++ Name Server Statistics ++</strong></span>
+ </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>
+ <span class="command"><strong>--- Statistics Dump --- (973798949)</strong></span>
+ </p>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h3 class="title">
+<a name="statistics_counters"></a>Statistics Counters</h3></div></div></div>
+
+ <p>
+ The following tables summarize statistics counters that
+ <acronym class="acronym">BIND</acronym> 9 provides.
+ For each row of the tables, the leftmost column is the
+ abbreviated symbol name of that counter.
+ These symbols are shown in the statistics information
+ accessed via an HTTP statistics channel.
+ The rightmost column gives the description of the counter,
+ which is also shown in the statistics file
+ (but, in this document, possibly with slight modification
+ for better readability).
+ Additional notes may also be provided in this column.
+ When a middle column exists between these two columns,
+ it gives the corresponding counter name of the
+ <acronym class="acronym">BIND</acronym> 8 statistics, if applicable.
+ </p>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="stats_counters"></a>Name Server Statistics Counters</h4></div></div></div>
+
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.150in" class="1">
+<col width="1.150in" class="2">
+<col width="3.350in" class="3">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ <span class="emphasis"><em>Symbol</em></span>
+ </p>
+ </td>
+<td>
+ <p>
+ <span class="emphasis"><em>BIND8 Symbol</em></span>
+ </p>
+ </td>
+<td>
+ <p>
+ <span class="emphasis"><em>Description</em></span>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>Requestv4</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RQ</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv4 requests received.
+ Note: this also counts non query requests.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>Requestv6</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RQ</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv6 requests received.
+ Note: this also counts non query requests.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>ReqEdns0</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Requests with EDNS(0) received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>ReqBadEDNSVer</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Requests with unsupported EDNS version received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>ReqTSIG</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Requests with TSIG received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>ReqSIG0</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Requests with SIG(0) received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>ReqBadSIG</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Requests with invalid (TSIG or SIG(0)) signature.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>ReqTCP</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RTCP</strong></span></p>
+ </td>
+<td>
+ <p>
+ TCP requests received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>AuthQryRej</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RUQ</strong></span></p>
+ </td>
+<td>
+ <p>
+ Authoritative (non recursive) queries rejected.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>RecQryRej</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RURQ</strong></span></p>
+ </td>
+<td>
+ <p>
+ Recursive queries rejected.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>XfrRej</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RUXFR</strong></span></p>
+ </td>
+<td>
+ <p>
+ Zone transfer requests rejected.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>UpdateRej</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RUUpd</strong></span></p>
+ </td>
+<td>
+ <p>
+ Dynamic update requests rejected.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>Response</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>SAns</strong></span></p>
+ </td>
+<td>
+ <p>
+ Responses sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>RespTruncated</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Truncated responses sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>RespEDNS0</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Responses with EDNS(0) sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>RespTSIG</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Responses with TSIG sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>RespSIG0</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Responses with SIG(0) sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QrySuccess</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries resulted in a successful answer.
+ This means the query which returns a NOERROR response
+ with at least one answer RR.
+ This corresponds to the
+ <span class="command"><strong>success</strong></span> counter
+ of previous versions of
+ <acronym class="acronym">BIND</acronym> 9.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryAuthAns</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries resulted in authoritative answer.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryNoauthAns</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>SNaAns</strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries resulted in non authoritative answer.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryReferral</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries resulted in referral answer.
+ This corresponds to the
+ <span class="command"><strong>referral</strong></span> counter
+ of previous versions of
+ <acronym class="acronym">BIND</acronym> 9.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryNxrrset</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries resulted in NOERROR responses with no data.
+ This corresponds to the
+ <span class="command"><strong>nxrrset</strong></span> counter
+ of previous versions of
+ <acronym class="acronym">BIND</acronym> 9.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QrySERVFAIL</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>SFail</strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries resulted in SERVFAIL.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryFORMERR</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>SFErr</strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries resulted in FORMERR.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryNXDOMAIN</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>SNXD</strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries resulted in NXDOMAIN.
+ This corresponds to the
+ <span class="command"><strong>nxdomain</strong></span> counter
+ of previous versions of
+ <acronym class="acronym">BIND</acronym> 9.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryRecursion</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RFwdQ</strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries which caused the server
+ to perform recursion in order to find the final answer.
+ This corresponds to the
+ <span class="command"><strong>recursion</strong></span> counter
+ of previous versions of
+ <acronym class="acronym">BIND</acronym> 9.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryDuplicate</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RDupQ</strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries which the server attempted to
+ recurse but discovered an existing query with the same
+ IP address, port, query ID, name, type and class
+ already being processed.
+ This corresponds to the
+ <span class="command"><strong>duplicate</strong></span> counter
+ of previous versions of
+ <acronym class="acronym">BIND</acronym> 9.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryDropped</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Recursive queries for which the server
+ discovered an excessive number of existing
+ recursive queries for the same name, type and
+ class and were subsequently dropped.
+ This is the number of dropped queries due to
+ the reason explained with the
+ <span class="command"><strong>clients-per-query</strong></span>
+ and
+ <span class="command"><strong>max-clients-per-query</strong></span>
+ options
+ (see the description about
+ <a class="xref" href="Bv9ARM.ch06.html#clients-per-query"><span class="command"><strong>clients-per-query</strong></span></a>.)
+ This corresponds to the
+ <span class="command"><strong>dropped</strong></span> counter
+ of previous versions of
+ <acronym class="acronym">BIND</acronym> 9.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryFailure</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Other query failures.
+ This corresponds to the
+ <span class="command"><strong>failure</strong></span> counter
+ of previous versions of
+ <acronym class="acronym">BIND</acronym> 9.
+ Note: this counter is provided mainly for
+ backward compatibility with the previous versions.
+ Normally a more fine-grained counters such as
+ <span class="command"><strong>AuthQryRej</strong></span> and
+ <span class="command"><strong>RecQryRej</strong></span>
+ that would also fall into this counter are provided,
+ and so this counter would not be of much
+ interest in practice.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryNXRedir</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries resulted in NXDOMAIN that were redirected.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryNXRedirRLookup</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries resulted in NXDOMAIN that were redirected
+ and resulted in a successful remote lookup.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>XfrReqDone</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Requested zone transfers completed.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>UpdateReqFwd</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Update requests forwarded.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>UpdateRespFwd</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Update responses forwarded.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>UpdateFwdFail</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Dynamic update forward failed.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>UpdateDone</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Dynamic updates completed.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>UpdateFail</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Dynamic updates failed.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>UpdateBadPrereq</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Dynamic updates rejected due to prerequisite failure.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>RateDropped</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Responses dropped by rate limits.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>RateSlipped</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Responses truncated by rate limits.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>RPZRewrites</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Response policy zone rewrites.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="zone_stats"></a>Zone Maintenance Statistics Counters</h4></div></div></div>
+
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.150in" class="1">
+<col width="3.350in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ <span class="emphasis"><em>Symbol</em></span>
+ </p>
+ </td>
+<td>
+ <p>
+ <span class="emphasis"><em>Description</em></span>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>NotifyOutv4</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv4 notifies sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>NotifyOutv6</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv6 notifies sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>NotifyInv4</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv4 notifies received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>NotifyInv6</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv6 notifies received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>NotifyRej</strong></span></p>
+ </td>
+<td>
+ <p>
+ Incoming notifies rejected.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>SOAOutv4</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv4 SOA queries sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>SOAOutv6</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv6 SOA queries sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>AXFRReqv4</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv4 AXFR requested.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>AXFRReqv6</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv6 AXFR requested.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>IXFRReqv4</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv4 IXFR requested.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>IXFRReqv6</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv6 IXFR requested.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>XfrSuccess</strong></span></p>
+ </td>
+<td>
+ <p>
+ Zone transfer requests succeeded.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>XfrFail</strong></span></p>
+ </td>
+<td>
+ <p>
+ Zone transfer requests failed.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="resolver_stats"></a>Resolver Statistics Counters</h4></div></div></div>
+
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.150in" class="1">
+<col width="1.150in" class="2">
+<col width="3.350in" class="3">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ <span class="emphasis"><em>Symbol</em></span>
+ </p>
+ </td>
+<td>
+ <p>
+ <span class="emphasis"><em>BIND8 Symbol</em></span>
+ </p>
+ </td>
+<td>
+ <p>
+ <span class="emphasis"><em>Description</em></span>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>Queryv4</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>SFwdQ</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv4 queries sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>Queryv6</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>SFwdQ</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv6 queries sent.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>Responsev4</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RR</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv4 responses received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>Responsev6</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RR</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv6 responses received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>NXDOMAIN</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RNXD</strong></span></p>
+ </td>
+<td>
+ <p>
+ NXDOMAIN received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>SERVFAIL</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RFail</strong></span></p>
+ </td>
+<td>
+ <p>
+ SERVFAIL received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>FORMERR</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RFErr</strong></span></p>
+ </td>
+<td>
+ <p>
+ FORMERR received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>OtherError</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RErr</strong></span></p>
+ </td>
+<td>
+ <p>
+ Other errors received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>EDNS0Fail</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ EDNS(0) query failures.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>Mismatch</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RDupR</strong></span></p>
+ </td>
+<td>
+ <p>
+ Mismatch responses received.
+ 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 <span class="command"><strong>port</strong></span> option.)
+ This may be an indication of a cache
+ poisoning attempt.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>Truncated</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Truncated responses received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>Lame</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>RLame</strong></span></p>
+ </td>
+<td>
+ <p>
+ Lame delegations received.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>Retry</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>SDupQ</strong></span></p>
+ </td>
+<td>
+ <p>
+ Query retries performed.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QueryAbort</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Queries aborted due to quota control.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QuerySockFail</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Failures in opening query sockets.
+ One common reason for such failures is a
+ failure of opening a new socket due to a
+ limitation on file descriptors.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QueryTimeout</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Query timeouts.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>GlueFetchv4</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>SSysQ</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv4 NS address fetches invoked.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>GlueFetchv6</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong>SSysQ</strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv6 NS address fetches invoked.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>GlueFetchv4Fail</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv4 NS address fetch failed.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>GlueFetchv6Fail</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ IPv6 NS address fetch failed.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>ValAttempt</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ DNSSEC validation attempted.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>ValOk</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ DNSSEC validation succeeded.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>ValNegOk</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ DNSSEC validation on negative information succeeded.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>ValFail</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ DNSSEC validation failed.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>QryRTTnn</strong></span></p>
+ </td>
+<td>
+ <p><span class="command"><strong></strong></span></p>
+ </td>
+<td>
+ <p>
+ Frequency table on round trip times (RTTs) of
+ queries.
+ Each <span class="command"><strong>nn</strong></span> specifies the corresponding
+ frequency.
+ In the sequence of
+ <span class="command"><strong>nn_1</strong></span>,
+ <span class="command"><strong>nn_2</strong></span>,
+ ...,
+ <span class="command"><strong>nn_m</strong></span>,
+ the value of <span class="command"><strong>nn_i</strong></span> is the
+ number of queries whose RTTs are between
+ <span class="command"><strong>nn_(i-1)</strong></span> (inclusive) and
+ <span class="command"><strong>nn_i</strong></span> (exclusive) milliseconds.
+ For the sake of convenience we define
+ <span class="command"><strong>nn_0</strong></span> to be 0.
+ The last entry should be represented as
+ <span class="command"><strong>nn_m+</strong></span>, which means the
+ number of queries whose RTTs are equal to or over
+ <span class="command"><strong>nn_m</strong></span> milliseconds.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="socket_stats"></a>Socket I/O Statistics Counters</h4></div></div></div>
+
+ <p>
+ Socket I/O statistics counters are defined per socket
+ types, which are
+ <span class="command"><strong>UDP4</strong></span> (UDP/IPv4),
+ <span class="command"><strong>UDP6</strong></span> (UDP/IPv6),
+ <span class="command"><strong>TCP4</strong></span> (TCP/IPv4),
+ <span class="command"><strong>TCP6</strong></span> (TCP/IPv6),
+ <span class="command"><strong>Unix</strong></span> (Unix Domain), and
+ <span class="command"><strong>FDwatch</strong></span> (sockets opened outside the
+ socket module).
+ In the following table <span class="command"><strong>&lt;TYPE&gt;</strong></span>
+ represents a socket type.
+ Not all counters are available for all socket types;
+ exceptions are noted in the description field.
+ </p>
+
+ <div class="informaltable">
+ <table border="1">
+<colgroup>
+<col width="1.150in" class="1">
+<col width="3.350in" class="2">
+</colgroup>
+<tbody>
+<tr>
+<td>
+ <p>
+ <span class="emphasis"><em>Symbol</em></span>
+ </p>
+ </td>
+<td>
+ <p>
+ <span class="emphasis"><em>Description</em></span>
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>&lt;TYPE&gt;Open</strong></span></p>
+ </td>
+<td>
+ <p>
+ Sockets opened successfully.
+ This counter is not applicable to the
+ <span class="command"><strong>FDwatch</strong></span> type.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>&lt;TYPE&gt;OpenFail</strong></span></p>
+ </td>
+<td>
+ <p>
+ Failures of opening sockets.
+ This counter is not applicable to the
+ <span class="command"><strong>FDwatch</strong></span> type.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>&lt;TYPE&gt;Close</strong></span></p>
+ </td>
+<td>
+ <p>
+ Sockets closed.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>&lt;TYPE&gt;BindFail</strong></span></p>
+ </td>
+<td>
+ <p>
+ Failures of binding sockets.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>&lt;TYPE&gt;ConnFail</strong></span></p>
+ </td>
+<td>
+ <p>
+ Failures of connecting sockets.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>&lt;TYPE&gt;Conn</strong></span></p>
+ </td>
+<td>
+ <p>
+ Connections established successfully.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>&lt;TYPE&gt;AcceptFail</strong></span></p>
+ </td>
+<td>
+ <p>
+ Failures of accepting incoming connection requests.
+ This counter is not applicable to the
+ <span class="command"><strong>UDP</strong></span> and
+ <span class="command"><strong>FDwatch</strong></span> types.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>&lt;TYPE&gt;Accept</strong></span></p>
+ </td>
+<td>
+ <p>
+ Incoming connections successfully accepted.
+ This counter is not applicable to the
+ <span class="command"><strong>UDP</strong></span> and
+ <span class="command"><strong>FDwatch</strong></span> types.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>&lt;TYPE&gt;SendErr</strong></span></p>
+ </td>
+<td>
+ <p>
+ Errors in socket send operations.
+ This counter corresponds
+ to <span class="command"><strong>SErr</strong></span> counter of
+ <span class="command"><strong>BIND</strong></span> 8.
+ </p>
+ </td>
+</tr>
+<tr>
+<td>
+ <p><span class="command"><strong>&lt;TYPE&gt;RecvErr</strong></span></p>
+ </td>
+<td>
+ <p>
+ Errors in socket receive operations.
+ This includes errors of send operations on a
+ connected UDP socket notified by an ICMP error
+ message.
+ </p>
+ </td>
+</tr>
+</tbody>
+</table>
+ </div>
+ </div>
+
+ <div class="section">
+<div class="titlepage"><div><div><h4 class="title">
+<a name="bind8_compatibility"></a>Compatibility with <span class="emphasis"><em>BIND</em></span> 8 Counters</h4></div></div></div>
+
+ <p>
+ Most statistics counters that were available
+ in <span class="command"><strong>BIND</strong></span> 8 are also supported in
+ <span class="command"><strong>BIND</strong></span> 9 as shown in the above tables.
+ Here are notes about other counters that do not appear
+ in these tables.
+ </p>
+
+ <div class="variablelist"><dl class="variablelist">
+<dt><span class="term"><span class="command"><strong>RFwdR,SFwdR</strong></span></span></dt>
+<dd>
+ <p>
+ These counters are not supported
+ because <span class="command"><strong>BIND</strong></span> 9 does not adopt
+ the notion of <span class="emphasis"><em>forwarding</em></span>
+ as <span class="command"><strong>BIND</strong></span> 8 did.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>RAXFR</strong></span></span></dt>
+<dd>
+ <p>
+ This counter is accessible in the Incoming Queries section.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>RIQ</strong></span></span></dt>
+<dd>
+ <p>
+ This counter is accessible in the Incoming Requests section.
+ </p>
+ </dd>
+<dt><span class="term"><span class="command"><strong>ROpts</strong></span></span></dt>
+<dd>
+ <p>
+ This counter is not supported
+ because <span class="command"><strong>BIND</strong></span> 9 does not care
+ about IP options in the first place.
+ </p>
+ </dd>
+</dl></div>
+ </div>
+ </div>
+ </div>
+
+ </div>
+<div class="navfooter">
+<hr>
+<table width="100%" summary="Navigation footer">
+<tr>
+<td width="40%" align="left">
+<a accesskey="p" href="Bv9ARM.ch05.html">Prev</a> </td>
+<td width="20%" align="center"> </td>
+<td width="40%" align="right"> <a accesskey="n" href="Bv9ARM.ch07.html">Next</a>
+</td>
+</tr>
+<tr>
+<td width="40%" align="left" valign="top">Chapter 5. The <acronym class="acronym">BIND</acronym> 9 Lightweight Resolver </td>
+<td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td>
+<td width="40%" align="right" valign="top"> Chapter 7. <acronym class="acronym">BIND</acronym> 9 Security Considerations</td>
+</tr>
+</table>
+</div>
+<p xmlns:db="http://docbook.org/ns/docbook" style="text-align: center;">BIND 9.11.5-P4 (Extended Support Version)</p>
+</body>
+</html>
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