man.host.html revision 983df82baf1d7d0b668c98cf45928a19f175c6e7
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - Copyright (C) 2004-2015 Internet Systems Consortium, Inc. ("ISC")
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - Copyright (C) 2000-2003 Internet Software Consortium.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - Permission to use, copy, modify, and/or distribute this software for any
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - purpose with or without fee is hereby granted, provided that the above
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - copyright notice and this permission notice appear in all copies.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen - PERFORMANCE OF THIS SOFTWARE.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
49b225e1cfa7bbf7738d4df0a03f18e3283426ebGavin Maltby<meta name="generator" content="DocBook XSL Stylesheets V1.71.1">
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<link rel="start" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual">
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<link rel="up" href="Bv9ARM.ch13.html" title="Manual pages">
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<link rel="prev" href="man.dig.html" title="dig">
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<link rel="next" href="man.delv.html" title="delv">
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<table width="100%" summary="Navigation header">
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<tr><th colspan="3" align="center">host</th></tr>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<a accesskey="p" href="man.dig.html">Prev</a>�</td>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<th width="60%" align="center">Manual pages</th>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<td width="20%" align="right">�<a accesskey="n" href="man.delv.html">Next</a>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<a name="man.host"></a><div class="titlepage"></div>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<div class="cmdsynopsis"><p><code class="command">host</code> [<code class="option">-aCdlnrsTwv</code>] [<code class="option">-c <em class="replaceable"><code>class</code></em></code>] [<code class="option">-N <em class="replaceable"><code>ndots</code></em></code>] [<code class="option">-R <em class="replaceable"><code>number</code></em></code>] [<code class="option">-t <em class="replaceable"><code>type</code></em></code>] [<code class="option">-W <em class="replaceable"><code>wait</code></em></code>] [<code class="option">-m <em class="replaceable"><code>flag</code></em></code>] [<code class="option">-4</code>] [<code class="option">-6</code>] [<code class="option">-v</code>] [<code class="option">-V</code>] {name} [server]</p></div>
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen<a name="id2617067"></a><h2>DESCRIPTION</h2>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<p><span><strong class="command">host</strong></span>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen is a simple utility for performing DNS lookups.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen It is normally used to convert names to IP addresses and vice versa.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen When no arguments or options are given,
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <span><strong class="command">host</strong></span>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen prints a short summary of its command line arguments and options.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<p><em class="parameter"><code>name</code></em> is the domain name that is to be
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen up. It can also be a dotted-decimal IPv4 address or a colon-delimited
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen IPv6 address, in which case <span><strong class="command">host</strong></span> will by
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen perform a reverse lookup for that address.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <em class="parameter"><code>server</code></em> is an optional argument which
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen the name or IP address of the name server that <span><strong class="command">host</strong></span>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen should query instead of the server or servers listed in
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <code class="filename">/etc/resolv.conf</code>.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen The <code class="option">-a</code> (all) option is equivalent to setting the
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <code class="option">-v</code> option and asking <span><strong class="command">host</strong></span> to make
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen a query of type ANY.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen When the <code class="option">-C</code> option is used, <span><strong class="command">host</strong></span>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen will attempt to display the SOA records for zone
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <em class="parameter"><code>name</code></em> from all the listed
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen authoritative name
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen servers for that zone. The list of name servers is defined by the NS
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen records that are found for the zone.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen The <code class="option">-c</code> option instructs to make a DNS query of class
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <em class="parameter"><code>class</code></em>. This can be used to lookup
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen Chaosnet class resource records. The default class is IN (Internet).
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen Verbose output is generated by <span><strong class="command">host</strong></span> when
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <code class="option">-d</code> or <code class="option">-v</code> option is used. The two
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen options are equivalent. They have been provided for backwards
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen compatibility. In previous versions, the <code class="option">-d</code> option
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen switched on debugging traces and <code class="option">-v</code> enabled verbose
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen output. Verbose output can also be enabled by setting the
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <em class="parameter"><code>debug</code></em> option in
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <code class="filename">/etc/resolv.conf</code>.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen List mode is selected by the <code class="option">-l</code> option. This makes
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <span><strong class="command">host</strong></span> perform a zone transfer for zone
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <em class="parameter"><code>name</code></em>. Transfer the zone printing out
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen and address records (A/AAAA). If combined with <code class="option">-a</code>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen all records will be printed.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen option specifies that reverse lookups of IPv6 addresses should
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen use the IP6.INT domain as defined in RFC1886.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen The default is to use IP6.ARPA.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen The <code class="option">-N</code> option sets the number of dots that have to be
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen in <em class="parameter"><code>name</code></em> for it to be considered
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen absolute. The
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen default value is that defined using the ndots statement in
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen <code class="filename">/etc/resolv.conf</code>, or 1 if no ndots
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen present. Names with fewer dots are interpreted as relative names and
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen will be searched for in the domains listed in the <span class="type">search</span>
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen or <span class="type">domain</span> directive in
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen <code class="filename">/etc/resolv.conf</code>.
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen The number of UDP retries for a lookup can be changed with the
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen <code class="option">-R</code> option. <em class="parameter"><code>number</code></em>
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen how many times <span><strong class="command">host</strong></span> will repeat a query
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen not get answered. If
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen <em class="parameter"><code>number</code></em> is negative or zero, the
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen retries will default to 1. The default value is 1, or
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen the value of the <em class="parameter"><code>attempts</code></em> option in
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <code class="filename">/etc/resolv.conf</code>, if set.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen Non-recursive queries can be made via the <code class="option">-r</code> option.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen Setting this option clears the <span class="type">RD</span> — recursion
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen desired — bit in the query which <span><strong class="command">host</strong></span> makes.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen This should mean that the name server receiving the query will not
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen attempt to resolve <em class="parameter"><code>name</code></em>. The
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <code class="option">-r</code> option enables <span><strong class="command">host</strong></span>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen the behavior of a name server by making non-recursive queries and
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen expecting to receive answers to those queries that are usually
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen referrals to other name servers.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen By default, <span><strong class="command">host</strong></span> uses UDP when making
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <code class="option">-T</code> option makes it use a TCP connection when querying
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen the name server. TCP will be automatically selected for queries that
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen require it, such as zone transfer (AXFR) requests.
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen The <code class="option">-4</code> option forces <span><strong class="command">host</strong></span> to only
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen use IPv4 query transport. The <code class="option">-6</code> option forces
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <span><strong class="command">host</strong></span> to only use IPv6 query transport.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen The <code class="option">-t</code> option is used to select the query type.
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen <em class="parameter"><code>type</code></em> can be any recognized query
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen <span><strong class="command">host</strong></span> automatically selects an appropriate
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen type. By default, it looks for A, AAAA, and MX records, but if the
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <code class="option">-C</code> option was given, queries will be made for SOA
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen records, and if <em class="parameter"><code>name</code></em> is a
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen dotted-decimal IPv4
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen address or colon-delimited IPv6 address, <span><strong class="command">host</strong></span> will
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen query for PTR records. If a query type of IXFR is chosen the starting
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen serial number can be specified by appending an equal followed by the
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen starting serial number (e.g. -t IXFR=12345678).
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen The time to wait for a reply can be controlled through the
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <code class="option">-W</code> and <code class="option">-w</code> options. The
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <code class="option">-W</code> option makes <span><strong class="command">host</strong></span>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <em class="parameter"><code>wait</code></em> seconds. If <em class="parameter"><code>wait</code></em>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen is less than one, the wait interval is set to one second. When the
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <code class="option">-w</code> option is used, <span><strong class="command">host</strong></span>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen effectively wait forever for a reply. The time to wait for a response
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen will be set to the number of seconds given by the hardware's maximum
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen value for an integer quantity. By default, <span><strong class="command">host</strong></span>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen will wait for 5 seconds for UDP responses and 10 seconds for TCP
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen connections. These defaults can be overridden by the
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen <em class="parameter"><code>timeout</code></em> option in
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen <code class="filename">/etc/resolv.conf</code>.
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen The <code class="option">-s</code> option tells <span><strong class="command">host</strong></span>
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen <span class="emphasis"><em>not</em></span> to send the query to the next nameserver
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen if any server responds with a SERVFAIL response, which is the
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen reverse of normal stub resolver behavior.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen The <code class="option">-m</code> can be used to set the memory usage debugging
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <em class="parameter"><code>record</code></em>, <em class="parameter"><code>usage</code></em> and
ba9236fbcb49a99c7d71c0c25d1e45cb2a75ac78Mike Christensen <em class="parameter"><code>trace</code></em>.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen The <code class="option">-V</code> option causes <span><strong class="command">host</strong></span>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen to print the version number and exit.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<a name="id2619883"></a><h2>IDN SUPPORT</h2>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen If <span><strong class="command">host</strong></span> has been built with IDN (internationalized
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen domain name) support, it can accept and display non-ASCII domain names.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <span><strong class="command">host</strong></span> appropriately converts character encoding of
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen domain name before sending a request to DNS server or displaying a
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen reply from the server.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen If you'd like to turn off the IDN support for some reason, defines
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen the <code class="envar">IDN_DISABLE</code> environment variable.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen The IDN support is disabled if the variable is set when
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <span><strong class="command">host</strong></span> runs.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<p><code class="filename">/etc/resolv.conf</code>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<p><span class="citerefentry"><span class="refentrytitle">dig</span>(1)</span>,
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>.
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<table width="100%" summary="Navigation footer">
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<a accesskey="p" href="man.dig.html">Prev</a>�</td>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<td width="20%" align="center"><a accesskey="u" href="Bv9ARM.ch13.html">Up</a></td>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<td width="40%" align="right">�<a accesskey="n" href="man.delv.html">Next</a>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<td width="40%" align="left" valign="top">dig�</td>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<td width="40%" align="right" valign="top">�delv</td>
30588217a56ff2c9137248fb2e5065c4f0101459Mike Christensen<p style="text-align: center;">BIND 9.11.0pre-alpha</p>