1 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.1//EN">
3 - Copyright (C) 2004 Internet Systems Consortium, Inc. ("ISC")
4 - Copyright (C) 2000-2002 Internet Software Consortium.
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19 <!-- $Id: host.docbook,v 1.2.2.2.4.5 2004/04/13 01:26:26 marka Exp $ -->
24 <date>Jun 30, 2000</date>
28 <refentrytitle>host</refentrytitle>
29 <manvolnum>1</manvolnum>
30 <refmiscinfo>BIND9</refmiscinfo>
34 <refname>host</refname>
35 <refpurpose>DNS lookup utility</refpurpose>
40 <command>host</command>
41 <arg><option>-aCdlnrTwv</option></arg>
42 <arg><option>-c <replaceable class="parameter">class</replaceable></option></arg>
43 <arg><option>-N <replaceable class="parameter">ndots</replaceable></option></arg>
44 <arg><option>-R <replaceable class="parameter">number</replaceable></option></arg>
45 <arg><option>-t <replaceable class="parameter">type</replaceable></option></arg>
46 <arg><option>-W <replaceable class="parameter">wait</replaceable></option></arg>
47 <arg><option>-4</option></arg>
48 <arg><option>-6</option></arg>
49 <arg choice=req>name</arg>
50 <arg choice=opt>server</arg>
55 <title>DESCRIPTION</title>
57 <command>host</command>
58 is a simple utility for performing DNS lookups.
59 It is normally used to convert names to IP addresses and vice versa.
60 When no arguments or options are given,
61 <command>host</command>
62 prints a short summary of its command line arguments and options.
66 <parameter>name</parameter> is the domain name that is to be looked
67 up. It can also be a dotted-decimal IPv4 address or a colon-delimited
68 IPv6 address, in which case <command>host</command> will by default
69 perform a reverse lookup for that address.
70 <parameter>server</parameter> is an optional argument which is either
71 the name or IP address of the name server that <command>host</command>
72 should query instead of the server or servers listed in
73 <filename>/etc/resolv.conf</filename>.
77 The <option>-a</option> (all) option is equivalent to setting the
78 <option>-v</option> option and asking <command>host</command> to make
83 When the <option>-C</option> option is used, <command>host</command>
84 will attempt to display the SOA records for zone
85 <parameter>name</parameter> from all the listed authoritative name
86 servers for that zone. The list of name servers is defined by the NS
87 records that are found for the zone.
91 The <option>-c</option> option instructs to make a DNS query of class
92 <parameter>class</parameter>. This can be used to lookup Hesiod or
93 Chaosnet class resource records. The default class is IN (Internet).
97 Verbose output is generated by <command>host</command> when the
98 <option>-d</option> or <option>-v</option> option is used. The two
99 options are equivalent. They have been provided for backwards
100 compatibility. In previous versions, the <option>-d</option> option
101 switched on debugging traces and <option>-v</option> enabled verbose
106 List mode is selected by the <option>-l</option> option. This makes
107 <command>host</command> perform a zone transfer for zone
108 <parameter>name</parameter>. Transfer the zone printing out the NS, PTR
109 and address records (A/AAAA). If combined with <option>-a</option>
110 all records will be printed.
114 The <option>-i</option>
115 option specifies that reverse lookups of IPv6 addresses should
116 use the IP6.INT domain as defined in RFC1886.
117 The default is to use IP6.ARPA.
121 The <option>-N</option> option sets the number of dots that have to be
122 in <parameter>name</parameter> for it to be considered absolute. The
123 default value is that defined using the ndots statement in
124 <filename>/etc/resolv.conf</filename>, or 1 if no ndots statement is
125 present. Names with fewer dots are interpreted as relative names and
126 will be searched for in the domains listed in the <type>search</type>
127 or <type>domain</type> directive in
128 <filename>/etc/resolv.conf</filename>.
132 The number of UDP retries for a lookup can be changed with the
133 <option>-R</option> option. <parameter>number</parameter> indicates
134 how many times <command>host</command> will repeat a query that does
135 not get answered. The default number of retries is 1. If
136 <parameter>number</parameter> is negative or zero, the number of
137 retries will default to 1.
141 Non-recursive queries can be made via the <option>-r</option> option.
142 Setting this option clears the <type>RD</type> — recursion
143 desired — bit in the query which <command>host</command> makes.
144 This should mean that the name server receiving the query will not
145 attempt to resolve <parameter>name</parameter>. The
146 <option>-r</option> option enables <command>host</command> to mimic
147 the behaviour of a name server by making non-recursive queries and
148 expecting to receive answers to those queries that are usually
149 referrals to other name servers.
153 By default <command>host</command> uses UDP when making queries. The
154 <option>-T</option> option makes it use a TCP connection when querying
155 the name server. TCP will be automatically selected for queries that
156 require it, such as zone transfer (AXFR) requests.
160 The <option>-4</option> option forces <command>host</command> to only
161 use IPv4 query transport. The <option>-6</option> option forces
162 <command>host</command> to only use IPv6 query transport.
166 The <option>-t</option> option is used to select the query type.
167 <parameter>type</parameter> can be any recognised query type: CNAME,
168 NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
169 <command>host</command> automatically selects an appropriate query
170 type. By default it looks for A records, but if the
171 <option>-C</option> option was given, queries will be made for SOA
172 records, and if <parameter>name</parameter> is a dotted-decimal IPv4
173 address or colon-delimited IPv6 address, <command>host</command> will
174 query for PTR records. If a query type of IXFR is chosen the starting
175 serial number can be specified by appending an equal followed by the
176 starting serial number (e.g. -t IXFR=12345678).
180 The time to wait for a reply can be controlled through the
181 <option>-W</option> and <option>-w</option> options. The
182 <option>-W</option> option makes <command>host</command> wait for
183 <parameter>wait</parameter> seconds. If <parameter>wait</parameter>
184 is less than one, the wait interval is set to one second. When the
185 <option>-w</option> option is used, <command>host</command> will
186 effectively wait forever for a reply. The time to wait for a response
187 will be set to the number of seconds given by the hardware's maximum
188 value for an integer quantity.
196 <filename>/etc/resolv.conf</filename>
201 <title>SEE ALSO</title>
204 <refentrytitle>dig</refentrytitle><manvolnum>1</manvolnum>
207 <refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>