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5 - Copyright (C) 2004, 2005 Internet Systems Consortium, Inc. ("ISC")
6 - Copyright (C) 2000-2002 Internet Software Consortium.
8 - Permission to use, copy, modify, and distribute this software for any
9 - purpose with or without fee is hereby granted, provided that the above
10 - copyright notice and this permission notice appear in all copies.
12 - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
13 - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
14 - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
15 - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
16 - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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21 <!-- $Id: host.docbook,v 1.2.2.2.4.7 2005/05/13 01:22:32 marka Exp $ -->
26 <date>Jun 30, 2000</date>
30 <refentrytitle>host</refentrytitle>
31 <manvolnum>1</manvolnum>
32 <refmiscinfo>BIND9</refmiscinfo>
39 <holder>Internet Systems Consortium, Inc. ("ISC")</holder>
45 <holder>Internet Software Consortium.</holder>
50 <refname>host</refname>
51 <refpurpose>DNS lookup utility</refpurpose>
56 <command>host</command>
57 <arg><option>-aCdlnrTwv</option></arg>
58 <arg><option>-c <replaceable class="parameter">class</replaceable></option></arg>
59 <arg><option>-N <replaceable class="parameter">ndots</replaceable></option></arg>
60 <arg><option>-R <replaceable class="parameter">number</replaceable></option></arg>
61 <arg><option>-t <replaceable class="parameter">type</replaceable></option></arg>
62 <arg><option>-W <replaceable class="parameter">wait</replaceable></option></arg>
63 <arg><option>-4</option></arg>
64 <arg><option>-6</option></arg>
65 <arg choice="req">name</arg>
66 <arg choice="opt">server</arg>
71 <title>DESCRIPTION</title>
73 <command>host</command>
74 is a simple utility for performing DNS lookups.
75 It is normally used to convert names to IP addresses and vice versa.
76 When no arguments or options are given,
77 <command>host</command>
78 prints a short summary of its command line arguments and options.
82 <parameter>name</parameter> is the domain name that is to be looked
83 up. It can also be a dotted-decimal IPv4 address or a colon-delimited
84 IPv6 address, in which case <command>host</command> will by default
85 perform a reverse lookup for that address.
86 <parameter>server</parameter> is an optional argument which is either
87 the name or IP address of the name server that <command>host</command>
88 should query instead of the server or servers listed in
89 <filename>/etc/resolv.conf</filename>.
93 The <option>-a</option> (all) option is equivalent to setting the
94 <option>-v</option> option and asking <command>host</command> to make
99 When the <option>-C</option> option is used, <command>host</command>
100 will attempt to display the SOA records for zone
101 <parameter>name</parameter> from all the listed authoritative name
102 servers for that zone. The list of name servers is defined by the NS
103 records that are found for the zone.
107 The <option>-c</option> option instructs to make a DNS query of class
108 <parameter>class</parameter>. This can be used to lookup Hesiod or
109 Chaosnet class resource records. The default class is IN (Internet).
113 Verbose output is generated by <command>host</command> when the
114 <option>-d</option> or <option>-v</option> option is used. The two
115 options are equivalent. They have been provided for backwards
116 compatibility. In previous versions, the <option>-d</option> option
117 switched on debugging traces and <option>-v</option> enabled verbose
122 List mode is selected by the <option>-l</option> option. This makes
123 <command>host</command> perform a zone transfer for zone
124 <parameter>name</parameter>. Transfer the zone printing out the NS, PTR
125 and address records (A/AAAA). If combined with <option>-a</option>
126 all records will be printed.
130 The <option>-i</option>
131 option specifies that reverse lookups of IPv6 addresses should
132 use the IP6.INT domain as defined in RFC1886.
133 The default is to use IP6.ARPA.
137 The <option>-N</option> option sets the number of dots that have to be
138 in <parameter>name</parameter> for it to be considered absolute. The
139 default value is that defined using the ndots statement in
140 <filename>/etc/resolv.conf</filename>, or 1 if no ndots statement is
141 present. Names with fewer dots are interpreted as relative names and
142 will be searched for in the domains listed in the <type>search</type>
143 or <type>domain</type> directive in
144 <filename>/etc/resolv.conf</filename>.
148 The number of UDP retries for a lookup can be changed with the
149 <option>-R</option> option. <parameter>number</parameter> indicates
150 how many times <command>host</command> will repeat a query that does
151 not get answered. The default number of retries is 1. If
152 <parameter>number</parameter> is negative or zero, the number of
153 retries will default to 1.
157 Non-recursive queries can be made via the <option>-r</option> option.
158 Setting this option clears the <type>RD</type> — recursion
159 desired — bit in the query which <command>host</command> makes.
160 This should mean that the name server receiving the query will not
161 attempt to resolve <parameter>name</parameter>. The
162 <option>-r</option> option enables <command>host</command> to mimic
163 the behaviour of a name server by making non-recursive queries and
164 expecting to receive answers to those queries that are usually
165 referrals to other name servers.
169 By default <command>host</command> uses UDP when making queries. The
170 <option>-T</option> option makes it use a TCP connection when querying
171 the name server. TCP will be automatically selected for queries that
172 require it, such as zone transfer (AXFR) requests.
176 The <option>-4</option> option forces <command>host</command> to only
177 use IPv4 query transport. The <option>-6</option> option forces
178 <command>host</command> to only use IPv6 query transport.
182 The <option>-t</option> option is used to select the query type.
183 <parameter>type</parameter> can be any recognised query type: CNAME,
184 NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
185 <command>host</command> automatically selects an appropriate query
186 type. By default it looks for A records, but if the
187 <option>-C</option> option was given, queries will be made for SOA
188 records, and if <parameter>name</parameter> is a dotted-decimal IPv4
189 address or colon-delimited IPv6 address, <command>host</command> will
190 query for PTR records. If a query type of IXFR is chosen the starting
191 serial number can be specified by appending an equal followed by the
192 starting serial number (e.g. -t IXFR=12345678).
196 The time to wait for a reply can be controlled through the
197 <option>-W</option> and <option>-w</option> options. The
198 <option>-W</option> option makes <command>host</command> wait for
199 <parameter>wait</parameter> seconds. If <parameter>wait</parameter>
200 is less than one, the wait interval is set to one second. When the
201 <option>-w</option> option is used, <command>host</command> will
202 effectively wait forever for a reply. The time to wait for a response
203 will be set to the number of seconds given by the hardware's maximum
204 value for an integer quantity.
212 <filename>/etc/resolv.conf</filename>
217 <title>SEE ALSO</title>
220 <refentrytitle>dig</refentrytitle><manvolnum>1</manvolnum>
223 <refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>