


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.



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HOST(1)                       BIND9                       HOST(1)


       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 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.




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HOST(1)                       BIND9                       HOST(1)


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

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 Internet Systems
       Consortium, Inc. ("ISC")
       Copyright (C) 2000-2002 Internet Software Consortium.


































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