/contrib/bind9/bin/dig/host.docbook
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1<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" 2 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" 3 [<!ENTITY mdash "—">]> 4<!-- 5 - Copyright (C) 2004, 2005, 2007-2009 Internet Systems Consortium, Inc. ("ISC") 6 - Copyright (C) 2000-2002 Internet Software Consortium. 7 - 8 - Permission to use, copy, modify, and/or 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. 11 - 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 17 - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 18 - PERFORMANCE OF THIS SOFTWARE. 19--> 20 21<!-- $Id: host.docbook,v 1.20 2009/01/20 23:47:56 tbox Exp $ --> 22<refentry id="man.host"> 23 24 <refentryinfo> 25 <date>Jun 30, 2000</date> 26 </refentryinfo> 27 28 <refmeta> 29 <refentrytitle>host</refentrytitle> 30 <manvolnum>1</manvolnum> 31 <refmiscinfo>BIND9</refmiscinfo> 32 </refmeta> 33 34 <refnamediv> 35 <refname>host</refname> 36 <refpurpose>DNS lookup utility</refpurpose> 37 </refnamediv> 38 39 <docinfo> 40 <copyright> 41 <year>2004</year> 42 <year>2005</year> 43 <year>2007</year> 44 <year>2008</year> 45 <year>2009</year> 46 <holder>Internet Systems Consortium, Inc. ("ISC")</holder> 47 </copyright> 48 <copyright> 49 <year>2000</year> 50 <year>2001</year> 51 <year>2002</year> 52 <holder>Internet Software Consortium.</holder> 53 </copyright> 54 </docinfo> 55 56 <refsynopsisdiv> 57 <cmdsynopsis> 58 <command>host</command> 59 <arg><option>-aCdlnrsTwv</option></arg> 60 <arg><option>-c <replaceable class="parameter">class</replaceable></option></arg> 61 <arg><option>-N <replaceable class="parameter">ndots</replaceable></option></arg> 62 <arg><option>-R <replaceable class="parameter">number</replaceable></option></arg> 63 <arg><option>-t <replaceable class="parameter">type</replaceable></option></arg> 64 <arg><option>-W <replaceable class="parameter">wait</replaceable></option></arg> 65 <arg><option>-m <replaceable class="parameter">flag</replaceable></option></arg> 66 <arg><option>-4</option></arg> 67 <arg><option>-6</option></arg> 68 <arg choice="req">name</arg> 69 <arg choice="opt">server</arg> 70 </cmdsynopsis> 71 </refsynopsisdiv> 72 73 <refsect1> 74 <title>DESCRIPTION</title> 75 76 <para><command>host</command> 77 is a simple utility for performing DNS lookups. 78 It is normally used to convert names to IP addresses and vice versa. 79 When no arguments or options are given, 80 <command>host</command> 81 prints a short summary of its command line arguments and options. 82 </para> 83 84 <para><parameter>name</parameter> is the domain name that is to be 85 looked 86 up. It can also be a dotted-decimal IPv4 address or a colon-delimited 87 IPv6 address, in which case <command>host</command> will by 88 default 89 perform a reverse lookup for that address. 90 <parameter>server</parameter> is an optional argument which 91 is either 92 the name or IP address of the name server that <command>host</command> 93 should query instead of the server or servers listed in 94 <filename>/etc/resolv.conf</filename>. 95 </para> 96 97 <para> 98 The <option>-a</option> (all) option is equivalent to setting the 99 <option>-v</option> option and asking <command>host</command> to make 100 a query of type ANY. 101 </para> 102 103 <para> 104 When the <option>-C</option> option is used, <command>host</command> 105 will attempt to display the SOA records for zone 106 <parameter>name</parameter> from all the listed 107 authoritative name 108 servers for that zone. The list of name servers is defined by the NS 109 records that are found for the zone. 110 </para> 111 112 <para> 113 The <option>-c</option> option instructs to make a DNS query of class 114 <parameter>class</parameter>. This can be used to lookup 115 Hesiod or 116 Chaosnet class resource records. The default class is IN (Internet). 117 </para> 118 119 <para> 120 Verbose output is generated by <command>host</command> when 121 the 122 <option>-d</option> or <option>-v</option> option is used. The two 123 options are equivalent. They have been provided for backwards 124 compatibility. In previous versions, the <option>-d</option> option 125 switched on debugging traces and <option>-v</option> enabled verbose 126 output. 127 </para> 128 129 <para> 130 List mode is selected by the <option>-l</option> option. This makes 131 <command>host</command> perform a zone transfer for zone 132 <parameter>name</parameter>. Transfer the zone printing out 133 the NS, PTR 134 and address records (A/AAAA). If combined with <option>-a</option> 135 all records will be printed. 136 </para> 137 138 <para> 139 The <option>-i</option> 140 option specifies that reverse lookups of IPv6 addresses should 141 use the IP6.INT domain as defined in RFC1886. 142 The default is to use IP6.ARPA. 143 </para> 144 145 <para> 146 The <option>-N</option> option sets the number of dots that have to be 147 in <parameter>name</parameter> for it to be considered 148 absolute. The 149 default value is that defined using the ndots statement in 150 <filename>/etc/resolv.conf</filename>, or 1 if no ndots 151 statement is 152 present. Names with fewer dots are interpreted as relative names and 153 will be searched for in the domains listed in the <type>search</type> 154 or <type>domain</type> directive in 155 <filename>/etc/resolv.conf</filename>. 156 </para> 157 158 <para> 159 The number of UDP retries for a lookup can be changed with the 160 <option>-R</option> option. <parameter>number</parameter> 161 indicates 162 how many times <command>host</command> will repeat a query 163 that does 164 not get answered. The default number of retries is 1. If 165 <parameter>number</parameter> is negative or zero, the 166 number of 167 retries will default to 1. 168 </para> 169 170 <para> 171 Non-recursive queries can be made via the <option>-r</option> option. 172 Setting this option clears the <type>RD</type> — recursion 173 desired — bit in the query which <command>host</command> makes. 174 This should mean that the name server receiving the query will not 175 attempt to resolve <parameter>name</parameter>. The 176 <option>-r</option> option enables <command>host</command> 177 to mimic 178 the behavior of a name server by making non-recursive queries and 179 expecting to receive answers to those queries that are usually 180 referrals to other name servers. 181 </para> 182 183 <para> 184 By default, <command>host</command> uses UDP when making 185 queries. The 186 <option>-T</option> option makes it use a TCP connection when querying 187 the name server. TCP will be automatically selected for queries that 188 require it, such as zone transfer (AXFR) requests. 189 </para> 190 191 <para> 192 The <option>-4</option> option forces <command>host</command> to only 193 use IPv4 query transport. The <option>-6</option> option forces 194 <command>host</command> to only use IPv6 query transport. 195 </para> 196 197 <para> 198 The <option>-t</option> option is used to select the query type. 199 <parameter>type</parameter> can be any recognized query 200 type: CNAME, 201 NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified, 202 <command>host</command> automatically selects an appropriate 203 query 204 type. By default, it looks for A, AAAA, and MX records, but if the 205 <option>-C</option> option was given, queries will be made for SOA 206 records, and if <parameter>name</parameter> is a 207 dotted-decimal IPv4 208 address or colon-delimited IPv6 address, <command>host</command> will 209 query for PTR records. If a query type of IXFR is chosen the starting 210 serial number can be specified by appending an equal followed by the 211 starting serial number (e.g. -t IXFR=12345678). 212 </para> 213 214 <para> 215 The time to wait for a reply can be controlled through the 216 <option>-W</option> and <option>-w</option> options. The 217 <option>-W</option> option makes <command>host</command> 218 wait for 219 <parameter>wait</parameter> seconds. If <parameter>wait</parameter> 220 is less than one, the wait interval is set to one second. When the 221 <option>-w</option> option is used, <command>host</command> 222 will 223 effectively wait forever for a reply. The time to wait for a response 224 will be set to the number of seconds given by the hardware's maximum 225 value for an integer quantity. 226 </para> 227 228 <para> 229 The <option>-s</option> option tells <command>host</command> 230 <emphasis>not</emphasis> to send the query to the next nameserver 231 if any server responds with a SERVFAIL response, which is the 232 reverse of normal stub resolver behavior. 233 </para> 234 235 <para> 236 The <option>-m</option> can be used to set the memory usage debugging 237 flags 238 <parameter>record</parameter>, <parameter>usage</parameter> and 239 <parameter>trace</parameter>. 240 </para> 241 </refsect1> 242 243 <refsect1> 244 <title>IDN SUPPORT</title> 245 <para> 246 If <command>host</command> has been built with IDN (internationalized 247 domain name) support, it can accept and display non-ASCII domain names. 248 <command>host</command> appropriately converts character encoding of 249 domain name before sending a request to DNS server or displaying a 250 reply from the server. 251 If you'd like to turn off the IDN support for some reason, defines 252 the <envar>IDN_DISABLE</envar> environment variable. 253 The IDN support is disabled if the variable is set when 254 <command>host</command> runs. 255 </para> 256 </refsect1> 257 258 <refsect1> 259 <title>FILES</title> 260 <para><filename>/etc/resolv.conf</filename> 261 </para> 262 </refsect1> 263 264 <refsect1> 265 <title>SEE ALSO</title> 266 <para><citerefentry> 267 <refentrytitle>dig</refentrytitle><manvolnum>1</manvolnum> 268 </citerefentry>, 269 <citerefentry> 270 <refentrytitle>named</refentrytitle><manvolnum>8</manvolnum> 271 </citerefentry>. 272 </para> 273 274 </refsect1> 275</refentry><!-- 276 - Local variables: 277 - mode: sgml 278 - End: 279-->