1HOST(1)                              BIND9                             HOST(1)
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NAME

6       host - DNS lookup utility
7

SYNOPSIS

9       host [-aCdlnrsTUwv] [-c class] [-N ndots] [-p port] [-R number]
10            [-t type] [-W wait] [-m flag] [[-4] | [-6]] [-v] [-V] {name}
11            [server]
12

DESCRIPTION

14       host is a simple utility for performing DNS lookups. It is normally
15       used to convert names to IP addresses and vice versa. When no arguments
16       or options are given, host prints a short summary of its command line
17       arguments and options.
18
19       name is the domain name that is to be looked up. It can also be a
20       dotted-decimal IPv4 address or a colon-delimited IPv6 address, in which
21       case host will by default perform a reverse lookup for that address.
22       server is an optional argument which is either the name or IP address
23       of the name server that host should query instead of the server or
24       servers listed in /etc/resolv.conf.
25

OPTIONS

27       -4
28           Use IPv4 only for query transport. See also the -6 option.
29
30       -6
31           Use IPv6 only for query transport. See also the -4 option.
32
33       -a
34           "All". The -a option is normally equivalent to -v -t ANY. It also
35           affects the behaviour of the -l list zone option.
36
37       -c class
38           Query class: This can be used to lookup HS (Hesiod) or CH
39           (Chaosnet) class resource records. The default class is IN
40           (Internet).
41
42       -C
43           Check consistency: host will query the SOA records for zone name
44           from all the listed authoritative name servers for that zone. The
45           list of name servers is defined by the NS records that are found
46           for the zone.
47
48       -d
49           Print debugging traces. Equivalent to the -v verbose option.
50
51       -i
52           Obsolete. Use the IP6.INT domain for reverse lookups of IPv6
53           addresses as defined in RFC1886 and deprecated in RFC4159. The
54           default is to use IP6.ARPA as specified in RFC3596.
55
56       -l
57           List zone: The host command performs a zone transfer of zone name
58           and prints out the NS, PTR and address records (A/AAAA).
59
60           Together, the -l -a options print all records in the zone.
61
62       -N ndots
63           The number of dots that have to be in name for it to be considered
64           absolute. The default value is that defined using the ndots
65           statement in /etc/resolv.conf, or 1 if no ndots statement is
66           present. Names with fewer dots are interpreted as relative names
67           and will be searched for in the domains listed in the search or
68           domain directive in /etc/resolv.conf.
69
70       -p port
71           Specify the port on the server to query. The default is 53.
72
73       -r
74           Non-recursive query: Setting this option clears the RD (recursion
75           desired) bit in the query. This should mean that the name server
76           receiving the query will not attempt to resolve name. The -r option
77           enables host to mimic the behavior of a name server by making
78           non-recursive queries and expecting to receive answers to those
79           queries that can be referrals to other name servers.
80
81       -R number
82           Number of retries for UDP queries: If number is negative or zero,
83           the number of retries will default to 1. The default value is 1, or
84           the value of the attempts option in /etc/resolv.conf, if set.
85
86       -s
87           Do not send the query to the next nameserver if any server responds
88           with a SERVFAIL response, which is the reverse of normal stub
89           resolver behavior.
90
91       -t type
92           Query type: The type argument can be any recognized query type:
93           CNAME, NS, SOA, TXT, DNSKEY, AXFR, etc.
94
95           When no query type is specified, host automatically selects an
96           appropriate query type. By default, it looks for A, AAAA, and MX
97           records. If the -C option is given, queries will be made for SOA
98           records. If name is a dotted-decimal IPv4 address or
99           colon-delimited IPv6 address, host will query for PTR records.
100
101           If a query type of IXFR is chosen the starting serial number can be
102           specified by appending an equal followed by the starting serial
103           number (like -t IXFR=12345678).
104
105       -T, -U
106           TCP/UDP: By default, host uses UDP when making queries. The -T
107           option makes it use a TCP connection when querying the name server.
108           TCP will be automatically selected for queries that require it,
109           such as zone transfer (AXFR) requests. Type ANY queries default to
110           TCP but can be forced to UDP initially using -U.
111
112       -m flag
113           Memory usage debugging: the flag can be record, usage, or trace.
114           You can specify the -m option more than once to set multiple flags.
115
116       -v
117           Verbose output. Equivalent to the -d debug option. Verbose output
118           can also be enabled by setting the debug option in
119           /etc/resolv.conf.
120
121       -V
122           Print the version number and exit.
123
124       -w
125           Wait forever: The query timeout is set to the maximum possible. See
126           also the -W option.
127
128       -W wait
129           Timeout: Wait for up to wait seconds for a reply. If wait is less
130           than one, the wait interval is set to one second.
131
132           By default, host will wait for 5 seconds for UDP responses and 10
133           seconds for TCP connections. These defaults can be overridden by
134           the timeout option in /etc/resolv.conf.
135
136           See also the -w option.
137

IDN SUPPORT

139       If host has been built with IDN (internationalized domain name)
140       support, it can accept and display non-ASCII domain names.  host
141       appropriately converts character encoding of domain name before sending
142       a request to DNS server or displaying a reply from the server. If you'd
143       like to turn off the IDN support for some reason, define the
144       IDN_DISABLE environment variable. The IDN support is disabled if the
145       variable is set when host runs.
146

FILES

148       /etc/resolv.conf
149

SEE ALSO

151       dig(1), named(8).
152

AUTHOR

154       Internet Systems Consortium, Inc.
155
157       Copyright © 2000-2002, 2004, 2005, 2007-2009, 2014-2020 Internet
158       Systems Consortium, Inc. ("ISC")
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162ISC                               2009-01-20                           HOST(1)
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