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host

HOST(1)                                                                HOST(1)



NAME
       host - DNS lookup utility

SYNOPSIS
       host  [  -aCdlnrTwv  ]  [ -c class ]  [ -N ndots ]  [ -R number ]  [ -t
       type ]  [ -W wait ]  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 argu-
       ments 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 dot-
       ted-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  debug-
       ging traces and -v enabled verbose output.

       List  mode is selected by the -l option. This makes host perform a zone
       transfer for zone name. The argument is provided for compatibility with
       older implemementations. This option is equivalent to making a query of
       type AXFR.

       The -n option specifies that reverse lookups of IPv6  addresses  should
       use  the IP6.INT domain and "nibble" labels as defined in RFC1886.  The
       default is to use IP6.ARPA and binary labels as defined in RFC2874.

       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
       behaviour of a name server by making non-recursive queries and  expect-
       ing  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 auto-
       matically selected for queries that require it, such as  zone  transfer
       (AXFR) requests.

       The -t option is used to select the query type.  type can be any recog-
       nised 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.

       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.

FILES
       /etc/resolv.conf

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



BIND9                            Jun 30, 2000                          HOST(1)