host

 

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 HOST(1)                 System General Commands Manual                 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 arguments or
      options are given, host prints a short summary of its command line argu­
      ments 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 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.  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 pre­
      sent.  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 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 automati­
      cally 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), resolver(5) named(8).
 
 BIND9 9                          Jun 30, 2000                          BIND9 9

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