host



HOST(1)                                                                HOST(1)




NAME

       host - DNS lookup utility


SYNOPSIS

       host  [  -aCdlnrTwv  ]  [ -c class ]  [ -N ndots ]  [ -R number ]  [ -t
       type ]  [ -W wait ]  [ -4 ]  [ -6 ] [ -s ] 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. 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
       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  -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 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. 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 behaviour.


FILES

       /etc/resolv.conf


SEE ALSO

       dig(1), named(8).



BIND9                            Jun 30, 2000                          HOST(1)

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