1HOST(1) BIND9 HOST(1)
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6 host - DNS lookup utility
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9 host [-aCdlnrsTUwv] [-c class] [-N ndots] [-R number] [-t type]
10 [-W wait] [-m flag] [[-4] | [-6]] [-v] [-V] {name} [server]
11
13 host is a simple utility for performing DNS lookups. It is normally
14 used to convert names to IP addresses and vice versa. When no arguments
15 or options are given, host prints a short summary of its command line
16 arguments and options.
17 name is the domain name that is to be looked up. It can also be a
19 dotted-decimal IPv4 address or a colon-delimited IPv6 address, in which
20 case host will by default perform a reverse lookup for that address.
21 server is an optional argument which is either the name or IP address
22 of the name server that host should query instead of the server or
23 servers listed in /etc/resolv.conf.
24
26 -4
27 Use IPv4 only for query transport. See also the -6 option.
28 -6
30 Use IPv6 only for query transport. See also the -4 option.
31 -a
33 "All". The -a option is normally equivalent to -v -t ANY. It also
34 affects the behaviour of the -l list zone option.
35 -c class
37 Query class: This can be used to lookup HS (Hesiod) or CH
38 (Chaosnet) class resource records. The default class is IN
39 (Internet).
40 -C
42 Check consistency: host will query the SOA records for zone name
43 from all the listed authoritative name servers for that zone. The
44 list of name servers is defined by the NS records that are found
45 for the zone.
46 -d
48 Print debugging traces. Equivalent to the -v verbose option.
49 -i
51 Obsolete. Use the IP6.INT domain for reverse lookups of IPv6
52 addresses as defined in RFC1886 and deprecated in RFC4159. The
53 default is to use IP6.ARPA as specified in RFC3596.
54 -l
56 List zone: The host command performs a zone transfer of zone name
57 and prints out the NS, PTR and address records (A/AAAA).
58 Together, the -l -a options print all records in the zone.
60 -N ndots
62 The number of dots that have to be in name for it to be considered
63 absolute. The default value is that defined using the ndots
64 statement in /etc/resolv.conf, or 1 if no ndots statement is
65 present. Names with fewer dots are interpreted as relative names
66 and will be searched for in the domains listed in the search or
67 domain directive in /etc/resolv.conf.
68 -r
70 Non-recursive query: Setting this option clears the RD (recursion
71 desired) bit in the query. This should mean that the name server
72 receiving the query will not attempt to resolve name. The -r option
73 enables host to mimic the behavior of a name server by making
74 non-recursive queries and expecting to receive answers to those
75 queries that can be referrals to other name servers.
76 -R number
78 Number of retries for UDP queries: If number is negative or zero,
79 the number of retries will default to 1. The default value is 1, or
80 the value of the attempts option in /etc/resolv.conf, if set.
81 -s
83 Do not send the query to the next nameserver if any server responds
84 with a SERVFAIL response, which is the reverse of normal stub
85 resolver behavior.
86 -t type
88 Query type: The type argument can be any recognized query type:
89 CNAME, NS, SOA, TXT, DNSKEY, AXFR, etc.
90 When no query type is specified, host automatically selects an
92 appropriate query type. By default, it looks for A, AAAA, and MX
93 records. If the -C option is given, queries will be made for SOA
94 records. If name is a dotted-decimal IPv4 address or
95 colon-delimited IPv6 address, host will query for PTR records.
96 If a query type of IXFR is chosen the starting serial number can be
98 specified by appending an equal followed by the starting serial
99 number (like -t IXFR=12345678).
100 -T, -U
102 TCP/UDP: By default, host uses UDP when making queries. The -T
103 option makes it use a TCP connection when querying the name server.
104 TCP will be automatically selected for queries that require it,
105 such as zone transfer (AXFR) requests. Type ANY queries default to
106 TCP but can be forced to UDP initially using -U.
107 -m flag
109 Memory usage debugging: the flag can be record, usage, or trace.
110 You can specify the -m option more than once to set multiple flags.
111 -v
113 Verbose output. Equivalent to the -d debug option. Verbose output
114 can also be enabled by setting the debug option in
115 /etc/resolv.conf.
116 -V
118 Print the version number and exit.
119 -w
121 Wait forever: The query timeout is set to the maximum possible. See
122 also the -W option.
123 -W wait
125 Timeout: Wait for up to wait seconds for a reply. If wait is less
126 than one, the wait interval is set to one second.
127 By default, host will wait for 5 seconds for UDP responses and 10
129 seconds for TCP connections. These defaults can be overridden by
130 the timeout option in /etc/resolv.conf.
131 See also the -w option.
133
135 If host has been built with IDN (internationalized domain name)
136 support, it can accept and display non-ASCII domain names. host
137 appropriately converts character encoding of domain name before sending
138 a request to DNS server or displaying a reply from the server. If you'd
139 like to turn off the IDN support for some reason, define the
140 IDN_DISABLE environment variable. The IDN support is disabled if the
141 variable is set when host runs.
142
144 /etc/resolv.conf
145
147 dig(1), named(8).
148
150 Internet Systems Consortium, Inc.
151
153 Copyright © 2000-2002, 2004, 2005, 2007-2009, 2014-2018 Internet
154 Systems Consortium, Inc. ("ISC")
155ISC 2009-01-20 HOST(1)