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HOST(1)                                             BIND9                                            HOST(1)



NAME
       host - DNS lookup utility

SYNOPSIS
       host [-aCdlnrsTwv] [-c class] [-N ndots] [-R number] [-t type] [-W wait] [-m flag] [-4] [-6] {name}
            [server]

DESCRIPTION
       host 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, host prints a short summary of its
       command line arguments and options.

       name 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 host will by default perform a reverse lookup for that
       address.  server is an optional argument which is either the name or IP address of the name server
       that host should query instead of the server or servers listed in /etc/resolv.conf.

       The -a (all) option is equivalent to setting the -v option and asking host to make a query of type
       ANY.

       When the -C option is used, host will attempt to display the SOA records for zone name 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.

       The -c option instructs to make a DNS query of class class. This can be used to lookup Hesiod or
       Chaosnet class resource records. The default class is IN (Internet).

       Verbose output is generated by host when the -d or -v option is used. The two options are equivalent.
       They have been provided for backwards compatibility. In previous versions, the -d option switched on
       debugging traces and -v enabled verbose output.

       List mode is selected by the -l option. This makes host perform a zone transfer for zone name.
       Transfer the zone printing out the NS, PTR and address records (A/AAAA). If combined with -a all
       records will be printed.

       The -i 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.

       The -N option sets the number of dots that have to be in name 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 search or domain directive in /etc/resolv.conf.

       The number of UDP retries for a lookup can be changed with the -R option.  number indicates how many
       times host will repeat a query that does not get answered. The default number of retries is 1. If
       number is negative or zero, the number of retries will default to 1.

       Non-recursive queries can be made via the -r option. Setting this option clears the RD -- recursion
       desired -- bit in the query which host makes. This should mean that the name server receiving the
       query will not attempt to resolve name. The -r option enables host 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.

       By default, host uses UDP when making queries. The -T 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.

       The -4 option forces host to only use IPv4 query transport. The -6 option forces host to only use
       IPv6 query transport.

       The -t option is used to select the query type.  type can be any recognized query type: CNAME, NS,
       SOA, SIG, KEY, AXFR, etc. When no query type is specified, host automatically selects an appropriate
       query type. By default, it looks for A, AAAA, and MX records, but if the -C option was given, queries
       will be made for SOA records, and if name is a dotted-decimal IPv4 address or colon-delimited IPv6
       address, host 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).

       The time to wait for a reply can be controlled through the -W and -w options. The -W option makes
       host wait for wait seconds. If wait is less than one, the wait interval is set to one second. When
       the -w option is used, host 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.

       The -s option tells host not 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.

       The -m can be used to set the memory usage debugging flags record, usage and trace.


Mac OS X NOTICE
       The host command does not use the host name and address resolution or the DNS query routing
       mechanisms used by other processes running on Mac OS X.  The results of name or address queries
       printed by host may differ from those found by other processes that use the Mac OS X native name and
       address resolution mechanisms.  The results of DNS queries may also differ from queries that use the
       Mac OS X DNS routing library.

IDN SUPPORT
       If host has been built with IDN (internationalized domain name) support, it can accept and display
       non-ASCII domain names.  host 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 IDN_DISABLE environment variable. The IDN support is disabled if
       the variable is set when host runs.

FILES
       /etc/resolv.conf

SEE ALSO
       dig(1), named(8).

COPYRIGHT
       Copyright (C) 2004, 2005, 2007-2009 Internet Systems Consortium, Inc. ("ISC")
       Copyright (C) 2000-2002 Internet Software Consortium.



BIND9                                           Jun 30, 2000                                         HOST(1)