1633838b8255282d10af15c5c84cee5a51466712Bob Halley<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

5dee04703805e9453ff4d8d77884391e3a185977Bob Halley "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"

1633838b8255282d10af15c5c84cee5a51466712Bob Halley [<!ENTITY mdash "&#8212;">]>

c50fd34a4e0e6978f8ca5f6f3ad8545549c3cfeeBob Halley

904a5734375869ffb504ed8cde6b68cafadb6d64Bob Halley<refentry id="man.host">

e4e071ae12aee942fefc2c0a3280e402938669deBob Halley

e4e071ae12aee942fefc2c0a3280e402938669deBob Halley <refentryinfo>

904a5734375869ffb504ed8cde6b68cafadb6d64Bob Halley <date>January 20, 2009</date>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley </refentryinfo>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley

904a5734375869ffb504ed8cde6b68cafadb6d64Bob Halley <refmeta>

904a5734375869ffb504ed8cde6b68cafadb6d64Bob Halley <refentrytitle>host</refentrytitle>

e4e071ae12aee942fefc2c0a3280e402938669deBob Halley <manvolnum>1</manvolnum>

c50fd34a4e0e6978f8ca5f6f3ad8545549c3cfeeBob Halley <refmiscinfo>BIND9</refmiscinfo>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley </refmeta>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <refnamediv>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <refname>host</refname>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <refpurpose>DNS lookup utility</refpurpose>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington </refnamediv>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <docinfo>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <copyright>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <year>2004</year>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <year>2005</year>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <year>2007</year>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <year>2008</year>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <year>2009</year>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <year>2014</year>

c50fd34a4e0e6978f8ca5f6f3ad8545549c3cfeeBob Halley <holder>Internet Systems Consortium, Inc. ("ISC")</holder>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley </copyright>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <copyright>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <year>2000</year>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <year>2001</year>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <year>2002</year>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <holder>Internet Software Consortium.</holder>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington </copyright>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington </docinfo>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <refsynopsisdiv>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <cmdsynopsis>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <command>host</command>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <arg><option>-aCdlnrsTwv</option></arg>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <arg><option>-c <replaceable class="parameter">class</replaceable></option></arg>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <arg><option>-N <replaceable class="parameter">ndots</replaceable></option></arg>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <arg><option>-R <replaceable class="parameter">number</replaceable></option></arg>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <arg><option>-t <replaceable class="parameter">type</replaceable></option></arg>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <arg><option>-W <replaceable class="parameter">wait</replaceable></option></arg>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <arg><option>-m <replaceable class="parameter">flag</replaceable></option></arg>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <arg><option>-4</option></arg>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <arg><option>-6</option></arg>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <arg choice="req">name</arg>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <arg choice="opt">server</arg>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington </cmdsynopsis>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington </refsynopsisdiv>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <refsect1>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <title>DESCRIPTION</title>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <para><command>host</command>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington is a simple utility for performing DNS lookups.

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington It is normally used to convert names to IP addresses and vice versa.

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington When no arguments or options are given,

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington <command>host</command>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington prints a short summary of its command line arguments and options.

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington </para>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <para><parameter>name</parameter> is the domain name that is to be

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley looked

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley up. It can also be a dotted-decimal IPv4 address or a colon-delimited

308c7ad5f68301d19f023af616f62f3e7cbce632Andreas Gustafsson IPv6 address, in which case <command>host</command> will by

04b8111f2137a9cf9b0b71228f76b3e40ffa1173Brian Wellington default

04b8111f2137a9cf9b0b71228f76b3e40ffa1173Brian Wellington perform a reverse lookup for that address.

ccad3c9ecbe8a1060ff7b407a318ccd592de536eBrian Wellington <parameter>server</parameter> is an optional argument which

ccad3c9ecbe8a1060ff7b407a318ccd592de536eBrian Wellington is either

ccad3c9ecbe8a1060ff7b407a318ccd592de536eBrian Wellington the name or IP address of the name server that <command>host</command>

ccad3c9ecbe8a1060ff7b407a318ccd592de536eBrian Wellington should query instead of the server or servers listed in

ccad3c9ecbe8a1060ff7b407a318ccd592de536eBrian Wellington <filename>/etc/resolv.conf</filename>.

8224be5129daebea8f0f5e8be5f925679ec893f1Brian Wellington </para>

8224be5129daebea8f0f5e8be5f925679ec893f1Brian Wellington

a413f94248ceed48a6b7aaa2fa1d2401fb8b9f30Brian Wellington <para>

d14b749789121d9d502fa1348e9e73270e9b039fBob Halley The <option>-a</option> (all) option is equivalent to setting the

63d1ef9e771b748ca9bf241dfc1f07d3730203faBob Halley <option>-v</option> option and asking <command>host</command> to make

659175b7d430afe13b439e499442a964e2c9110fMark Andrews a query of type ANY.

cd02757774252fe5b92dbd59a24b34721fb49ff4Bob Halley </para>

cd02757774252fe5b92dbd59a24b34721fb49ff4Bob Halley

7b4dcbb89b71b17f5c16ca19a0e705e09509f063Bob Halley <para>

73af6575e00f8cf4942abce177f435797b9cfe41Brian Wellington When the <option>-C</option> option is used, <command>host</command>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley will attempt to display the SOA records for zone

73af6575e00f8cf4942abce177f435797b9cfe41Brian Wellington <parameter>name</parameter> from all the listed

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley authoritative name

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley servers for that zone. The list of name servers is defined by the NS

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley records that are found for the zone.

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley </para>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <para>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley The <option>-c</option> option instructs to make a DNS query of class

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <parameter>class</parameter>. This can be used to lookup

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley Hesiod or

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley Chaosnet class resource records. The default class is IN (Internet).

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley </para>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <para>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley Verbose output is generated by <command>host</command> when

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley the

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <option>-d</option> or <option>-v</option> option is used. The two

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley options are equivalent. They have been provided for backwards

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley compatibility. In previous versions, the <option>-d</option> option

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley switched on debugging traces and <option>-v</option> enabled verbose

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley output.

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley </para>

125d72976ab6b8fa6629a5ace276a86e9fef91acBrian Wellington

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <para>

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley List mode is selected by the <option>-l</option> option. This makes

c50fd34a4e0e6978f8ca5f6f3ad8545549c3cfeeBob Halley <command>host</command> perform a zone transfer for zone

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley <parameter>name</parameter>. Transfer the zone printing out

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley the NS, PTR

25e43e68b7431d5e4ff8b5427108cd7f5f9bcf3eBob Halley and address records (A/AAAA). If combined with <option>-a</option>

c50fd34a4e0e6978f8ca5f6f3ad8545549c3cfeeBob Halley all records will be printed.

904a5734375869ffb504ed8cde6b68cafadb6d64Bob Halley </para>

904a5734375869ffb504ed8cde6b68cafadb6d64Bob Halley

c50fd34a4e0e6978f8ca5f6f3ad8545549c3cfeeBob Halley <para>

The <option>-i</option>

option specifies that reverse lookups of IPv6 addresses should

use the IP6.INT domain as defined in RFC1886.

The default is to use IP6.ARPA.

</para>

<para>

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

in <parameter>name</parameter> for it to be considered

absolute. The

default value is that defined using the ndots statement in

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

statement is

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

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

or <type>domain</type> directive in

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

</para>

<para>

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

<option>-R</option> option. <parameter>number</parameter>

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><!--