bind9/bin/dig/host.1

.\" Copyright (C) 2004, 2005, 2007-2009, 2014, 2015 Internet Systems Consortium, Inc. ("ISC")
.\" Copyright (C) 2000-2002 Internet Software Consortium.
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.\"     Title: host
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: 2009-01-20
.\"    Manual: BIND9
.\"    Source: ISC
.\"  Language: English
.\"
.TH "HOST" "1" "2009\-01\-20" "ISC" "BIND9"
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.SH "NAME"
host \- DNS lookup utility
.SH "SYNOPSIS"
.HP \w'\fBhost\fR\ 'u
\fBhost\fR [\fB\-aCdlnrsTwv\fR] [\fB\-c\ \fR\fB\fIclass\fR\fR] [\fB\-N\ \fR\fB\fIndots\fR\fR] [\fB\-R\ \fR\fB\fInumber\fR\fR] [\fB\-t\ \fR\fB\fItype\fR\fR] [\fB\-W\ \fR\fB\fIwait\fR\fR] [\fB\-m\ \fR\fB\fIflag\fR\fR] [\fB\-4\fR] [\fB\-6\fR] [\fB\-v\fR] [\fB\-V\fR] {name} [server]
.SH "DESCRIPTION"
.PP
\fBhost\fR
is a simple utility for performing DNS lookups\&. It is normally used to convert names to IP addresses and vice versa\&. When no arguments or options are given,
\fBhost\fR
prints a short summary of its command line arguments and options\&.
.PP
\fIname\fR
is the domain name that is to be looked up\&. It can also be a dotted\-decimal IPv4 address or a colon\-delimited IPv6 address, in which case
\fBhost\fR
will by default perform a reverse lookup for that address\&.
\fIserver\fR
is an optional argument which is either the name or IP address of the name server that
\fBhost\fR
should query instead of the server or servers listed in
/etc/resolv\&.conf\&.
.PP
The
\fB\-a\fR
(all) option is equivalent to setting the
\fB\-v\fR
option and asking
\fBhost\fR
to make a query of type ANY\&.
.PP
When the
\fB\-C\fR
option is used,
\fBhost\fR
will attempt to display the SOA records for zone
\fIname\fR
from all the listed authoritative name servers for that zone\&. The list of name servers is defined by the NS records that are found for the zone\&.
.PP
The
\fB\-c\fR
option instructs to make a DNS query of class
\fIclass\fR\&. This can be used to lookup Hesiod or Chaosnet class resource records\&. The default class is IN (Internet)\&.
.PP
Verbose output is generated by
\fBhost\fR
when the
\fB\-d\fR
or
\fB\-v\fR
option is used\&. The two options are equivalent\&. They have been provided for backwards compatibility\&. In previous versions, the
\fB\-d\fR
option switched on debugging traces and
\fB\-v\fR
enabled verbose output\&.
.PP
List mode is selected by the
\fB\-l\fR
option\&. This makes
\fBhost\fR
perform a zone transfer for zone
\fIname\fR\&. Transfer the zone printing out the NS, PTR and address records (A/AAAA)\&. If combined with
\fB\-a\fR
all records will be printed\&.
.PP
The
\fB\-i\fR
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\&.
.PP
The
\fB\-N\fR
option sets the number of dots that have to be in
\fIname\fR
for it to be considered absolute\&. The default value is that defined using the ndots statement in
/etc/resolv\&.conf, 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
\fBsearch\fR
or
\fBdomain\fR
directive in
/etc/resolv\&.conf\&.
.PP
The number of UDP retries for a lookup can be changed with the
\fB\-R\fR
option\&.
\fInumber\fR
indicates how many times
\fBhost\fR
will repeat a query that does not get answered\&. The default number of retries is 1\&. If
\fInumber\fR
is negative or zero, the number of retries will default to 1\&.
.PP
Non\-recursive queries can be made via the
\fB\-r\fR
option\&. Setting this option clears the
\fBRD\fR
\(em recursion desired \(em bit in the query which
\fBhost\fR
makes\&. This should mean that the name server receiving the query will not attempt to resolve
\fIname\fR\&. The
\fB\-r\fR
option enables
\fBhost\fR
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\&.
.PP
By default,
\fBhost\fR
uses UDP when making queries\&. The
\fB\-T\fR
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\&.
.PP
The
\fB\-4\fR
option forces
\fBhost\fR
to only use IPv4 query transport\&. The
\fB\-6\fR
option forces
\fBhost\fR
to only use IPv6 query transport\&.
.PP
The
\fB\-t\fR
option is used to select the query type\&.
\fItype\fR
can be any recognized query type: CNAME, NS, SOA, SIG, KEY, AXFR, etc\&. When no query type is specified,
\fBhost\fR
automatically selects an appropriate query type\&. By default, it looks for A, AAAA, and MX records, but if the
\fB\-C\fR
option was given, queries will be made for SOA records, and if
\fIname\fR
is a dotted\-decimal IPv4 address or colon\-delimited IPv6 address,
\fBhost\fR
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)\&.
.PP
The time to wait for a reply can be controlled through the
\fB\-W\fR
and
\fB\-w\fR
options\&. The
\fB\-W\fR
option makes
\fBhost\fR
wait for
\fIwait\fR
seconds\&. If
\fIwait\fR
is less than one, the wait interval is set to one second\&. When the
\fB\-w\fR
option is used,
\fBhost\fR
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\*(Aqs maximum value for an integer quantity\&.
.PP
The
\fB\-s\fR
option tells
\fBhost\fR\fInot\fR
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\&.
.PP
The
\fB\-m\fR
can be used to set the memory usage debugging flags
\fIrecord\fR,
\fIusage\fR
and
\fItrace\fR\&.
.PP
The
\fB\-V\fR
option causes
\fBhost\fR
to print the version number and exit\&.
.SH "IDN SUPPORT"
.PP
If
\fBhost\fR
has been built with IDN (internationalized domain name) support, it can accept and display non\-ASCII domain names\&.
\fBhost\fR
appropriately converts character encoding of domain name before sending a request to DNS server or displaying a reply from the server\&. If you\*(Aqd like to turn off the IDN support for some reason, defines the
\fBIDN_DISABLE\fR
environment variable\&. The IDN support is disabled if the variable is set when
\fBhost\fR
runs\&.
.SH "FILES"
.PP
/etc/resolv\&.conf
.SH "SEE ALSO"
.PP
\fBdig\fR(1),
\fBnamed\fR(8)\&.
.SH "AUTHOR"
.PP
\fBInternet Systems Consortium, Inc\&.\fR
.SH "COPYRIGHT"
.br
Copyright \(co 2004, 2005, 2007-2009, 2014, 2015 Internet Systems Consortium, Inc. ("ISC")
.br
Copyright \(co 2000-2002 Internet Software Consortium.
.br