1HOST(1) BIND9 HOST(1)
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6 host - DNS lookup utility
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9 host [-aCdlnrsTwv] [-c class] [-N ndots] [-R number] [-t type]
10 [-W wait] [-m flag] [-4] [-6] {name} [server]
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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 The -a (all) option is equivalent to setting the -v option and asking
26 host to make a query of type ANY.
27 When the -C option is used, host will attempt to display the SOA
29 records for zone name from all the listed authoritative name servers
30 for that zone. The list of name servers is defined by the NS records
31 that are found for the zone.
32 The -c option instructs to make a DNS query of class class. This can be
34 used to lookup Hesiod or Chaosnet class resource records. The default
35 class is IN (Internet).
36 Verbose output is generated by host when the -d or -v option is used.
38 The two options are equivalent. They have been provided for backwards
39 compatibility. In previous versions, the -d option switched on
40 debugging traces and -v enabled verbose output.
41 List mode is selected by the -l option. This makes host perform a zone
43 transfer for zone name. Transfer the zone printing out the NS, PTR and
44 address records (A/AAAA). If combined with -a all records will be
45 printed.
46 The -i option specifies that reverse lookups of IPv6 addresses should
48 use the IP6.INT domain as defined in RFC1886. The default is to use
49 IP6.ARPA.
50 The -N option sets the number of dots that have to be in name for it to
52 be considered absolute. The default value is that defined using the
53 ndots statement in /etc/resolv.conf, or 1 if no ndots statement is
54 present. Names with fewer dots are interpreted as relative names and
55 will be searched for in the domains listed in the search or domain
56 directive in /etc/resolv.conf.
57 The number of UDP retries for a lookup can be changed with the -R
59 option. number indicates how many times host will repeat a query that
60 does not get answered. The default number of retries is 1. If number is
61 negative or zero, the number of retries will default to 1.
62 Non-recursive queries can be made via the -r option. Setting this
64 option clears the RD — recursion desired — bit in the query which host
65 makes. This should mean that the name server receiving the query will
66 not attempt to resolve name. The -r option enables host to mimic the
67 behavior of a name server by making non-recursive queries and expecting
68 to receive answers to those queries that are usually referrals to other
69 name servers.
70 By default, host uses UDP when making queries. The -T option makes it
72 use a TCP connection when querying the name server. TCP will be
73 automatically selected for queries that require it, such as zone
74 transfer (AXFR) requests.
75 The -4 option forces host to only use IPv4 query transport. The -6
77 option forces host to only use IPv6 query transport.
78 The -t option is used to select the query type. type can be any
80 recognized query type: CNAME, NS, SOA, SIG, KEY, AXFR, etc. When no
81 query type is specified, host automatically selects an appropriate
82 query type. By default, it looks for A, AAAA, and MX records, but if
83 the -C option was given, queries will be made for SOA records, and if
84 name is a dotted-decimal IPv4 address or colon-delimited IPv6 address,
85 host will query for PTR records. If a query type of IXFR is chosen the
86 starting serial number can be specified by appending an equal followed
87 by the starting serial number (e.g. -t IXFR=12345678).
88 The time to wait for a reply can be controlled through the -W and -w
90 options. The -W option makes host wait for wait seconds. If wait is
91 less than one, the wait interval is set to one second. When the -w
92 option is used, host will effectively wait forever for a reply. The
93 time to wait for a response will be set to the number of seconds given
94 by the hardware's maximum value for an integer quantity.
95 The -s option tells host not to send the query to the next nameserver
97 if any server responds with a SERVFAIL response, which is the reverse
98 of normal stub resolver behavior.
99 The -m can be used to set the memory usage debugging flags record,
101 usage and trace.
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104 If host has been built with IDN (internationalized domain name)
105 support, it can accept and display non-ASCII domain names. host
106 appropriately converts character encoding of domain name before sending
107 a request to DNS server or displaying a reply from the server. If you'd
108 like to turn off the IDN support for some reason, defines the
109 IDN_DISABLE environment variable. The IDN support is disabled if the
110 variable is set when host runs.
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113 /etc/resolv.conf
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116 dig(1), named(8).
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119 Copyright © 2004, 2005, 2007-2009 Internet Systems Consortium, Inc.
120 ("ISC")
121 Copyright © 2000-2002 Internet Software Consortium.
122BIND9 Jun 30, 2000 HOST(1)