host(1)

NAME

       host - DNS lookup utility

SYNOPSIS

       host [-aCdlnrsTwv] [-c class] [-N ndots] [-R number] [-t type]
            [-W wait] [-m flag] [-4] [-6] [-v] [-V] {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.

OPTIONS

       -4
           Use IPv4 only for query transport. See also the -6 option.

       -6
           Use IPv6 only for query transport. See also the -4 option.

       -a
           "All". The -a option is normally equivalent to -v -t ANY. It also
           affects the behaviour of the -l list zone option.

       -c class
           Query class: This can be used to lookup HS (Hesiod) or CH
           (Chaosnet) class resource records. The default class is IN
           (Internet).

       -C
           Check consistency: host will query 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.

       -d
           Print debugging traces. Equivalent to the -v verbose option.

       -i
           Obsolete. Use the IP6.INT domain for reverse lookups of IPv6
           addresses as defined in RFC1886 and deprecated in RFC4159. The
           default is to use IP6.ARPA as specified in RFC3596.

       -l
           List zone: The host command performs a zone transfer of zone name
           and prints out the NS, PTR and address records (A/AAAA).

           Together, the -l -a options print all records in the zone.

       -N ndots
           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.

       -r
           Non-recursive query: Setting this option clears the RD (recursion
           desired) bit in the query. 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 can be referrals to other name servers.

       -R number
           Number of retries for UDP queries: If number is negative or zero,
           the number of retries will default to 1. The default value is 1.

       -s
           Do not send the query to the next nameserver if any server responds
           with a SERVFAIL response, which is the reverse of normal stub
           resolver behavior.

       -t type
           Query type: The type argument can be any recognized query type:
           CNAME, NS, SOA, TXT, DNSKEY, 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. If the -C option is given, queries will be made for SOA
           records. 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 (like -t IXFR=12345678).

       -T
           TCP: 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.

       -m flag
           Memory usage debugging: the flag can be record, usage, or trace.
           You can specify the -m option more than once to set multiple flags.

       -v
           Verbose output. Equivalent to the -d debug option.

       -V
           Print the version number and exit.

       -w
           Wait forever: The query timeout is set to the maximum possible. See
           also the -W option.

       -W wait
           Timeout: Wait for up to wait seconds for a reply. If wait is less
           than one, the wait interval is set to one second.

           By default, host will wait for 5 seconds for UDP responses and 10
           seconds for TCP connections.

           See also the -w option.

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).

AUTHOR

       Internet Systems Consortium, Inc.

COPYRIGHT

       Copyright (C) 2004, 2005, 2007-2009, 2014-2016 Internet Systems
       Consortium, Inc. ("ISC")
       Copyright (C) 2000-2002 Internet Software Consortium.

ISC                               2009-01-20                           HOST(1)