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1 .\" $NetBSD: host.1,v 1.5 2014/12/10 04:37:51 christos Exp $
2 .\"
3 .\" Copyright (C) 2004, 2005, 2007-2009, 2014 Internet Systems Consortium, Inc. ("ISC")
4 .\" Copyright (C) 2000-2002 Internet Software Consortium.
5 .\"
6 .\" Permission to use, copy, modify, and/or distribute this software for any
7 .\" purpose with or without fee is hereby granted, provided that the above
8 .\" copyright notice and this permission notice appear in all copies.
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10 .\" THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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13 .\" INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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18 .\" Id
19 .\"
20 .hy 0
21 .ad l
22 .\" Title: host
23 .\" Author:
24 .\" Generator: DocBook XSL Stylesheets v1.71.1 <http://docbook.sf.net/>
25 .\" Date: January 20, 2009
26 .\" Manual: BIND9
27 .\" Source: BIND9
28 .\"
29 .TH "HOST" "1" "January 20, 2009" "BIND9" "BIND9"
30 .\" disable hyphenation
31 .nh
32 .\" disable justification (adjust text to left margin only)
33 .ad l
34 .SH "NAME"
35 host \- DNS lookup utility
36 .SH "SYNOPSIS"
37 .HP 5
38 \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]
39 .SH "DESCRIPTION"
40 .PP
41 \fBhost\fR
42 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,
43 \fBhost\fR
44 prints a short summary of its command line arguments and options.
45 .PP
46 \fIname\fR
47 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
48 \fBhost\fR
49 will by default perform a reverse lookup for that address.
50 \fIserver\fR
51 is an optional argument which is either the name or IP address of the name server that
52 \fBhost\fR
53 should query instead of the server or servers listed in
54 \fI/etc/resolv.conf\fR.
55 .PP
56 The
57 \fB\-a\fR
58 (all) option is equivalent to setting the
59 \fB\-v\fR
60 option and asking
61 \fBhost\fR
62 to make a query of type ANY.
63 .PP
64 When the
65 \fB\-C\fR
66 option is used,
67 \fBhost\fR
68 will attempt to display the SOA records for zone
69 \fIname\fR
70 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.
71 .PP
72 The
73 \fB\-c\fR
74 option instructs to make a DNS query of class
75 \fIclass\fR. This can be used to lookup Hesiod or Chaosnet class resource records. The default class is IN (Internet).
76 .PP
77 Verbose output is generated by
78 \fBhost\fR
79 when the
80 \fB\-d\fR
81 or
82 \fB\-v\fR
83 option is used. The two options are equivalent. They have been provided for backwards compatibility. In previous versions, the
84 \fB\-d\fR
85 option switched on debugging traces and
86 \fB\-v\fR
87 enabled verbose output.
88 .PP
89 List mode is selected by the
90 \fB\-l\fR
91 option. This makes
92 \fBhost\fR
93 perform a zone transfer for zone
94 \fIname\fR. Transfer the zone printing out the NS, PTR and address records (A/AAAA). If combined with
95 \fB\-a\fR
96 all records will be printed.
97 .PP
98 The
99 \fB\-i\fR
100 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.
101 .PP
102 The
103 \fB\-N\fR
104 option sets the number of dots that have to be in
105 \fIname\fR
106 for it to be considered absolute. The default value is that defined using the ndots statement in
107 \fI/etc/resolv.conf\fR, 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
108 \fBsearch\fR
109 or
110 \fBdomain\fR
111 directive in
112 \fI/etc/resolv.conf\fR.
113 .PP
114 The number of UDP retries for a lookup can be changed with the
115 \fB\-R\fR
116 option.
117 \fInumber\fR
118 indicates how many times
119 \fBhost\fR
120 will repeat a query that does not get answered. The default number of retries is 1. If
121 \fInumber\fR
122 is negative or zero, the number of retries will default to 1.
123 .PP
124 Non\-recursive queries can be made via the
125 \fB\-r\fR
126 option. Setting this option clears the
127 \fBRD\fR
128 \(em recursion desired \(em bit in the query which
129 \fBhost\fR
130 makes. This should mean that the name server receiving the query will not attempt to resolve
131 \fIname\fR. The
132 \fB\-r\fR
133 option enables
134 \fBhost\fR
135 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.
136 .PP
137 By default,
138 \fBhost\fR
139 uses UDP when making queries. The
140 \fB\-T\fR
141 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.
142 .PP
143 The
144 \fB\-4\fR
145 option forces
146 \fBhost\fR
147 to only use IPv4 query transport. The
148 \fB\-6\fR
149 option forces
150 \fBhost\fR
151 to only use IPv6 query transport.
152 .PP
153 The
154 \fB\-t\fR
155 option is used to select the query type.
156 \fItype\fR
157 can be any recognized query type: CNAME, NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
158 \fBhost\fR
159 automatically selects an appropriate query type. By default, it looks for A, AAAA, and MX records, but if the
160 \fB\-C\fR
161 option was given, queries will be made for SOA records, and if
162 \fIname\fR
163 is a dotted\-decimal IPv4 address or colon\-delimited IPv6 address,
164 \fBhost\fR
165 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).
166 .PP
167 The time to wait for a reply can be controlled through the
168 \fB\-W\fR
169 and
170 \fB\-w\fR
171 options. The
172 \fB\-W\fR
173 option makes
174 \fBhost\fR
175 wait for
176 \fIwait\fR
177 seconds. If
178 \fIwait\fR
179 is less than one, the wait interval is set to one second. When the
180 \fB\-w\fR
181 option is used,
182 \fBhost\fR
183 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.
184 .PP
185 The
186 \fB\-s\fR
187 option tells
188 \fBhost\fR
189 \fInot\fR
190 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.
191 .PP
192 The
193 \fB\-m\fR
194 can be used to set the memory usage debugging flags
195 \fIrecord\fR,
196 \fIusage\fR
197 and
198 \fItrace\fR.
199 .PP
200 The
201 \fB\-V\fR
202 option causes
203 \fBhost\fR
204 to print the version number and exit.
205 .SH "IDN SUPPORT"
206 .PP
207 If
208 \fBhost\fR
209 has been built with IDN (internationalized domain name) support, it can accept and display non\-ASCII domain names.
210 \fBhost\fR
211 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
212 \fBIDN_DISABLE\fR
213 environment variable. The IDN support is disabled if the variable is set when
214 \fBhost\fR
215 runs.
216 .SH "FILES"
217 .PP
218 \fI/etc/resolv.conf\fR
219 .SH "SEE ALSO"
220 .PP
221 \fBdig\fR(1),
222 \fBnamed\fR(8).
223 .SH "COPYRIGHT"
224 Copyright \(co 2004, 2005, 2007\-2009, 2014 Internet Systems Consortium, Inc. ("ISC")
225 .br
226 Copyright \(co 2000\-2002 Internet Software Consortium.
227 .br