137 lines
5.8 KiB
Groff
137 lines
5.8 KiB
Groff
.\" Copyright (C) 2004 Internet Systems Consortium, Inc. ("ISC")
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.\" Copyright (C) 2000-2002 Internet Software Consortium.
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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.\" REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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.\" AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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.\" INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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.\" LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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.\" OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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.\" PERFORMANCE OF THIS SOFTWARE.
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.\"
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.\" $Id: host.1,v 1.11.2.1.4.4 2004/04/13 04:11:03 marka Exp $
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.\"
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.TH "HOST" "1" "Jun 30, 2000" "BIND9" ""
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.SH NAME
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host \- DNS lookup utility
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.SH SYNOPSIS
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.sp
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\fBhost\fR [ \fB-aCdlnrTwv\fR ] [ \fB-c \fIclass\fB\fR ] [ \fB-N \fIndots\fB\fR ] [ \fB-R \fInumber\fB\fR ] [ \fB-t \fItype\fB\fR ] [ \fB-W \fIwait\fB\fR ] [ \fB-4\fR ] [ \fB-6\fR ] \fBname\fR [ \fBserver\fR ]
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.SH "DESCRIPTION"
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.PP
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\fBhost\fR
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is a simple utility for performing DNS lookups.
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It is normally used to convert names to IP addresses and vice versa.
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When no arguments or options are given,
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\fBhost\fR
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prints a short summary of its command line arguments and options.
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.PP
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\fIname\fR is the domain name that is to be looked
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up. It can also be a dotted-decimal IPv4 address or a colon-delimited
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IPv6 address, in which case \fBhost\fR will by default
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perform a reverse lookup for that address.
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\fIserver\fR is an optional argument which is either
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the name or IP address of the name server that \fBhost\fR
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should query instead of the server or servers listed in
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\fI/etc/resolv.conf\fR.
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.PP
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The \fB-a\fR (all) option is equivalent to setting the
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\fB-v\fR option and asking \fBhost\fR to make
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a query of type ANY.
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.PP
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When the \fB-C\fR option is used, \fBhost\fR
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will attempt to display the SOA records for zone
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\fIname\fR from all the listed authoritative name
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servers for that zone. The list of name servers is defined by the NS
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records that are found for the zone.
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.PP
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The \fB-c\fR option instructs to make a DNS query of class
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\fIclass\fR. This can be used to lookup Hesiod or
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Chaosnet class resource records. The default class is IN (Internet).
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.PP
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Verbose output is generated by \fBhost\fR when the
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\fB-d\fR or \fB-v\fR option is used. The two
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options are equivalent. They have been provided for backwards
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compatibility. In previous versions, the \fB-d\fR option
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switched on debugging traces and \fB-v\fR enabled verbose
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output.
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.PP
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List mode is selected by the \fB-l\fR option. This makes
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\fBhost\fR perform a zone transfer for zone
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\fIname\fR. Transfer the zone printing out the NS, PTR
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and address records (A/AAAA). If combined with \fB-a\fR
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all records will be printed.
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.PP
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The \fB-i\fR
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option specifies that reverse lookups of IPv6 addresses should
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use the IP6.INT domain as defined in RFC1886.
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The default is to use IP6.ARPA.
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.PP
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The \fB-N\fR option sets the number of dots that have to be
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in \fIname\fR for it to be considered absolute. The
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default value is that defined using the ndots statement in
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\fI/etc/resolv.conf\fR, or 1 if no ndots statement is
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present. Names with fewer dots are interpreted as relative names and
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will be searched for in the domains listed in the \fBsearch\fR
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or \fBdomain\fR directive in
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\fI/etc/resolv.conf\fR.
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.PP
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The number of UDP retries for a lookup can be changed with the
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\fB-R\fR option. \fInumber\fR indicates
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how many times \fBhost\fR will repeat a query that does
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not get answered. The default number of retries is 1. If
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\fInumber\fR is negative or zero, the number of
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retries will default to 1.
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.PP
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Non-recursive queries can be made via the \fB-r\fR option.
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Setting this option clears the \fBRD\fR \(em recursion
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desired \(em bit in the query which \fBhost\fR makes.
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This should mean that the name server receiving the query will not
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attempt to resolve \fIname\fR. The
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\fB-r\fR option enables \fBhost\fR to mimic
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the behaviour of a name server by making non-recursive queries and
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expecting to receive answers to those queries that are usually
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referrals to other name servers.
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.PP
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By default \fBhost\fR uses UDP when making queries. The
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\fB-T\fR option makes it use a TCP connection when querying
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the name server. TCP will be automatically selected for queries that
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require it, such as zone transfer (AXFR) requests.
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.PP
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The \fB-4\fR option forces \fBhost\fR to only
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use IPv4 query transport. The \fB-6\fR option forces
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\fBhost\fR to only use IPv6 query transport.
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.PP
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The \fB-t\fR option is used to select the query type.
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\fItype\fR can be any recognised query type: CNAME,
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NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
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\fBhost\fR automatically selects an appropriate query
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type. By default it looks for A records, but if the
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\fB-C\fR option was given, queries will be made for SOA
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records, and if \fIname\fR is a dotted-decimal IPv4
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address or colon-delimited IPv6 address, \fBhost\fR will
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query for PTR records. If a query type of IXFR is chosen the starting
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serial number can be specified by appending an equal followed by the
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starting serial number (e.g. -t IXFR=12345678).
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.PP
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The time to wait for a reply can be controlled through the
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\fB-W\fR and \fB-w\fR options. The
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\fB-W\fR option makes \fBhost\fR wait for
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\fIwait\fR seconds. If \fIwait\fR
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is less than one, the wait interval is set to one second. When the
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\fB-w\fR option is used, \fBhost\fR will
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effectively wait forever for a reply. The time to wait for a response
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will be set to the number of seconds given by the hardware's maximum
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value for an integer quantity.
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.SH "FILES"
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.PP
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\fI/etc/resolv.conf\fR
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.SH "SEE ALSO"
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.PP
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\fBdig\fR(1),
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\fBnamed\fR(8).
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