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host(1)                             BIND 9                             host(1)




NAME

       host - DNS lookup utility


SYNOPSIS

       host  [-aACdlnrsTUwv]  [-c  class] [-N ndots] [-p port] [-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 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.


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.

       -A     "Almost  all".  The  -A option is equivalent to -a except RRSIG,
              NSEC, and NSEC3 records are omitted from the output.

       -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.

       -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  consid-
              ered 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.

       -p port
              Specify the port on the server to query. The default is 53.

       -r     Non-recursive  query:  Setting this option clears the RD (recur-
              sion 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, or the value of the attempts option  in  /etc/resolv.conf,
              if set.

       -s     Do  not  send  the  query  to  the next nameserver if any server
              responds with a SERVFAIL response, which is the reverse of  nor-
              mal 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; -U TCP/UDP: 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. Type ANY
              queries default to TCP but can be forced to UDP initially  using
              -U.

       -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. Verbose out-
              put  can  also  be  enabled  by  setting  the  debug  option  in
              /etc/resolv.conf.

       -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. These defaults can be overridden
              by the timeout option in /etc/resolv.conf.

              See also the -w option.


IDN SUPPORT

       If  host  has  been built with IDN (internationalized domain name) sup-
       port, it can accept and display non-ASCII domain names. host  appropri-
       ately  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, define the IDN_DIS-
       ABLE 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


COPYRIGHT

       2020, Internet Systems Consortium



9.16.4                            2020-06-10                           host(1)

bind 9.16.4 - Generated Thu Jun 18 15:28:06 CDT 2020
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