d6fa26d0adaec6c910115be34fe7a5a5f402c14fMark Andrews<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"

5347c0fcb04eaea19d9f39795646239f487c6207Tinderbox User [<!ENTITY mdash "&#8212;">]>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User<refentry id="man.host">

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <refentryinfo>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <date>Jun 30, 2000</date>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User </refentryinfo>

14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <refmeta>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <refentrytitle>host</refentrytitle>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <manvolnum>1</manvolnum>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <refmiscinfo>BIND9</refmiscinfo>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User </refmeta>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <refnamediv>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <refname>host</refname>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <refpurpose>DNS lookup utility</refpurpose>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </refnamediv>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <docinfo>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <copyright>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <year>2004</year>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <year>2005</year>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <year>2007</year>

7e71f05d8643aca84914437c900cb716444507e4Tinderbox User <year>2008</year>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <year>2009</year>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <holder>Internet Systems Consortium, Inc. ("ISC")</holder>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User </copyright>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <copyright>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <year>2000</year>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <year>2001</year>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <year>2002</year>

7e71f05d8643aca84914437c900cb716444507e4Tinderbox User <holder>Internet Software Consortium.</holder>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </copyright>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User </docinfo>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <refsynopsisdiv>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <cmdsynopsis>

6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User <command>host</command>

6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User <arg><option>-aCdlnrsTwv</option></arg>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <arg><option>-c <replaceable class="parameter">class</replaceable></option></arg>

6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User <arg><option>-N <replaceable class="parameter">ndots</replaceable></option></arg>

6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User <arg><option>-R <replaceable class="parameter">number</replaceable></option></arg>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <arg><option>-t <replaceable class="parameter">type</replaceable></option></arg>

6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User <arg><option>-W <replaceable class="parameter">wait</replaceable></option></arg>

6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User <arg><option>-m <replaceable class="parameter">flag</replaceable></option></arg>

6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User <arg><option>-4</option></arg>

6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User <arg><option>-6</option></arg>

6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User <arg choice="req">name</arg>

6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User <arg choice="opt">server</arg>

6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User </cmdsynopsis>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </refsynopsisdiv>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <refsect1>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <title>DESCRIPTION</title>

14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt

14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt <para><command>host</command>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User is a simple utility for performing DNS lookups.

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User It is normally used to convert names to IP addresses and vice versa.

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User When no arguments or options are given,

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <command>host</command>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User prints a short summary of its command line arguments and options.

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <para><parameter>name</parameter> is the domain name that is to be

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User looked

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User up. It can also be a dotted-decimal IPv4 address or a colon-delimited

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User IPv6 address, in which case <command>host</command> will by

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User default

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User perform a reverse lookup for that address.

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <parameter>server</parameter> is an optional argument which

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User is either

6f1205897504b8f50b1785975482c995888dd630Tinderbox User the name or IP address of the name server that <command>host</command>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User should query instead of the server or servers listed in

6f1205897504b8f50b1785975482c995888dd630Tinderbox User <filename>/etc/resolv.conf</filename>.

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User The <option>-a</option> (all) option is equivalent to setting the

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <option>-v</option> option and asking <command>host</command> to make

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User a query of type ANY.

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User </para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt <para>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User When the <option>-C</option> option is used, <command>host</command>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User will attempt to display the SOA records for zone

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <parameter>name</parameter> from all the listed

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User authoritative name

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User servers for that zone. The list of name servers is defined by the NS

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User records that are found for the zone.

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User </para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User The <option>-c</option> option instructs to make a DNS query of class

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <parameter>class</parameter>. This can be used to lookup

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User Hesiod or

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User Chaosnet class resource records. The default class is IN (Internet).

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User </para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User Verbose output is generated by <command>host</command> when

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User the

14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt <option>-d</option> or <option>-v</option> option is used. The two

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User options are equivalent. They have been provided for backwards

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User compatibility. In previous versions, the <option>-d</option> option

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User switched on debugging traces and <option>-v</option> enabled verbose

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User output.

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User </para>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <para>

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User List mode is selected by the <option>-l</option> option. This makes

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <command>host</command> perform a zone transfer for zone

7e71f05d8643aca84914437c900cb716444507e4Tinderbox User <parameter>name</parameter>. Transfer the zone printing out

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User the NS, PTR

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User and address records (A/AAAA). If combined with <option>-a</option>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User all records will be printed.

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User </para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User The <option>-i</option>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User option specifies that reverse lookups of IPv6 addresses should

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User use the IP6.INT domain as defined in RFC1886.

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User The default is to use IP6.ARPA.

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User </para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <para>

cd32f419a8a5432fbb139f56ee73cbf68b9350ccTinderbox User The <option>-N</option> option sets the number of dots that have to be

14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt in <parameter>name</parameter> for it to be considered

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User absolute. The

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User default value is that defined using the ndots statement in

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <filename>/etc/resolv.conf</filename>, or 1 if no ndots

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User statement is

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User present. Names with fewer dots are interpreted as relative names and

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User will be searched for in the domains listed in the <type>search</type>

14a656f94b1fd0ababd84a772228dfa52276ba15Evan Hunt or <type>domain</type> directive in

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <filename>/etc/resolv.conf</filename>.

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User </para>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <para>

c2258eedf2d9d0207b45b90014f8fde5413b41a3Tinderbox User The number of UDP retries for a lookup can be changed with the

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User <option>-R</option> option. <parameter>number</parameter>

6e6f5e3e1111680cff3ef4a4fa27923548c88f70Tinderbox User indicates

how many times <command>host</command> will repeat a query

that does

not get answered. The default number of retries is 1. If

<parameter>number</parameter> is negative or zero, the

number of

retries will default to 1.

</para>

<para>

Non-recursive queries can be made via the <option>-r</option> option.

Setting this option clears the <type>RD</type> &mdash; recursion

desired &mdash; bit in the query which <command>host</command> makes.

This should mean that the name server receiving the query will not

attempt to resolve <parameter>name</parameter>. The

<option>-r</option> option enables <command>host</command>

to mimic

the behavior of a name server by making non-recursive queries and

expecting to receive answers to those queries that are usually

referrals to other name servers.

</para>

<para>

By default, <command>host</command> uses UDP when making

queries. The

<option>-T</option> option makes it use a TCP connection when querying

the name server. TCP will be automatically selected for queries that

require it, such as zone transfer (AXFR) requests.

</para>

<para>

The <option>-4</option> option forces <command>host</command> to only

use IPv4 query transport. The <option>-6</option> option forces

<command>host</command> to only use IPv6 query transport.

</para>

<para>

The <option>-t</option> option is used to select the query type.

<parameter>type</parameter> can be any recognized query

type: CNAME,

NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,

<command>host</command> automatically selects an appropriate

query

type. By default, it looks for A, AAAA, and MX records, but if the

<option>-C</option> option was given, queries will be made for SOA

records, and if <parameter>name</parameter> is a

dotted-decimal IPv4

address or colon-delimited IPv6 address, <command>host</command> will

query for PTR records. If a query type of IXFR is chosen the starting

serial number can be specified by appending an equal followed by the

starting serial number (e.g. -t IXFR=12345678).

</para>

<para>

The time to wait for a reply can be controlled through the

<option>-W</option> and <option>-w</option> options. The

<option>-W</option> option makes <command>host</command>

wait for

<parameter>wait</parameter> seconds. If <parameter>wait</parameter>

is less than one, the wait interval is set to one second. When the

<option>-w</option> option is used, <command>host</command>

will

effectively wait forever for a reply. The time to wait for a response

will be set to the number of seconds given by the hardware's maximum

value for an integer quantity.

</para>

<para>

The <option>-s</option> option tells <command>host</command>

<emphasis>not</emphasis> to send the query to the next nameserver

if any server responds with a SERVFAIL response, which is the

reverse of normal stub resolver behavior.

</para>

<para>

The <option>-m</option> can be used to set the memory usage debugging

flags

<parameter>record</parameter>, <parameter>usage</parameter> and

<parameter>trace</parameter>.

</para>

</refsect1>

<refsect1>

<title>IDN SUPPORT</title>

<para>

If <command>host</command> has been built with IDN (internationalized

domain name) support, it can accept and display non-ASCII domain names.

<command>host</command> appropriately converts character encoding of

domain name before sending a request to DNS server or displaying a

reply from the server.

If you'd like to turn off the IDN support for some reason, defines

the <envar>IDN_DISABLE</envar> environment variable.

The IDN support is disabled if the variable is set when

<command>host</command> runs.

</para>

</refsect1>

<refsect1>

<title>FILES</title>

<para><filename>/etc/resolv.conf</filename>

</para>

</refsect1>

<refsect1>

<title>SEE ALSO</title>

<para><citerefentry>

<refentrytitle>dig</refentrytitle><manvolnum>1</manvolnum>

</citerefentry>,

<citerefentry>

<refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>

</citerefentry>.

</para>

</refsect1>

</refentry><!--