.\" Copyright (C) 2000-2002, 2004, 2005, 2007-2009, 2014-2019 Internet Systems Consortium, Inc. ("ISC") .\" .\" This Source Code Form is subject to the terms of the Mozilla Public .\" License, v. 2.0. If a copy of the MPL was not distributed with this .\" file, You can obtain one at http://mozilla.org/MPL/2.0/. .\" .hy 0 .ad l '\" t .\" Title: host .\" Author: .\" Generator: DocBook XSL Stylesheets v1.78.1 .\" Date: 2009-01-20 .\" Manual: BIND9 .\" Source: ISC .\" Language: English .\" .TH "HOST" "1" "2009\-01\-20" "ISC" "BIND9" .\" ----------------------------------------------------------------- .\" * Define some portability stuff .\" ----------------------------------------------------------------- .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .\" http://bugs.debian.org/507673 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" ----------------------------------------------------------------- .\" * set default formatting .\" ----------------------------------------------------------------- .\" disable hyphenation .nh .\" disable justification (adjust text to left margin only) .ad l .\" ----------------------------------------------------------------- .\" * MAIN CONTENT STARTS HERE * .\" ----------------------------------------------------------------- .SH "NAME" host \- DNS lookup utility .SH "SYNOPSIS" .HP \w'\fBhost\fR\ 'u \fBhost\fR [\fB\-aCdlnrsTUwv\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\&. .SH "OPTIONS" .PP \-4 .RS 4 Use IPv4 only for query transport\&. See also the \fB\-6\fR option\&. .RE .PP \-6 .RS 4 Use IPv6 only for query transport\&. See also the \fB\-4\fR option\&. .RE .PP \-a .RS 4 "All"\&. The \fB\-a\fR option is normally equivalent to \fB\-v \-t \fR\fBANY\fR\&. It also affects the behaviour of the \fB\-l\fR list zone option\&. .RE .PP \-c \fIclass\fR .RS 4 Query class: This can be used to lookup HS (Hesiod) or CH (Chaosnet) class resource records\&. The default class is IN (Internet)\&. .RE .PP \-C .RS 4 Check consistency: \fBhost\fR will query 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\&. .RE .PP \-d .RS 4 Print debugging traces\&. Equivalent to the \fB\-v\fR verbose option\&. .RE .PP \-i .RS 4 Obsolete\&. Use the IP6\&.INT domain for reverse lookups of IPv6 addresses as defined in RFC1886 and deprecated in RFC4159\&. The default is to use IP6\&.ARPA as specified in RFC3596\&. .RE .PP \-l .RS 4 List zone: The \fBhost\fR command performs a zone transfer of zone \fIname\fR and prints out the NS, PTR and address records (A/AAAA)\&. .sp Together, the \fB\-l \-a\fR options print all records in the zone\&. .RE .PP \-N \fIndots\fR .RS 4 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\&. .RE .PP \-r .RS 4 Non\-recursive query: Setting this option clears the RD (recursion desired) bit in the query\&. 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 can be referrals to other name servers\&. .RE .PP \-R \fInumber\fR .RS 4 Number of retries for UDP queries: If \fInumber\fR is negative or zero, the number of retries will default to 1\&. The default value is 1, or the value of the \fIattempts\fR option in /etc/resolv\&.conf, if set\&. .RE .PP \-s .RS 4 Do \fInot\fR send the query to the next nameserver if any server responds with a SERVFAIL response, which is the reverse of normal stub resolver behavior\&. .RE .PP \-t \fItype\fR .RS 4 Query type: The \fItype\fR argument can be any recognized query type: CNAME, NS, SOA, TXT, DNSKEY, AXFR, etc\&. .sp When no query type is specified, \fBhost\fR automatically selects an appropriate query type\&. By default, it looks for A, AAAA, and MX records\&. If the \fB\-C\fR option is given, queries will be made for SOA records\&. If \fIname\fR is a dotted\-decimal IPv4 address or colon\-delimited IPv6 address, \fBhost\fR will query for PTR records\&. .sp 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 (like \fB\-t \fR\fBIXFR=12345678\fR)\&. .RE .PP \-T, \-U .RS 4 TCP/UDP: 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\&. Type ANY queries default to TCP but can be forced to UDP initially using \fB\-U\fR\&. .RE .PP \-m \fIflag\fR .RS 4 Memory usage debugging: the flag can be \fIrecord\fR, \fIusage\fR, or \fItrace\fR\&. You can specify the \fB\-m\fR option more than once to set multiple flags\&. .RE .PP \-v .RS 4 Verbose output\&. Equivalent to the \fB\-d\fR debug option\&. Verbose output can also be enabled by setting the \fIdebug\fR option in /etc/resolv\&.conf\&. .RE .PP \-V .RS 4 Print the version number and exit\&. .RE .PP \-w .RS 4 Wait forever: The query timeout is set to the maximum possible\&. See also the \fB\-W\fR option\&. .RE .PP \-W \fIwait\fR .RS 4 Timeout: Wait for up to \fIwait\fR seconds for a reply\&. If \fIwait\fR is less than one, the wait interval is set to one second\&. .sp By default, \fBhost\fR will wait for 5 seconds for UDP responses and 10 seconds for TCP connections\&. These defaults can be overridden by the \fItimeout\fR option in /etc/resolv\&.conf\&. .sp See also the \fB\-w\fR option\&. .RE .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 2000-2002, 2004, 2005, 2007-2009, 2014-2019 Internet Systems Consortium, Inc. ("ISC") .br