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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  by  default  performs  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     This option specifies that only IPv4 should be  used  for  query
              transport. See also the -6 option.

       -6     This  option  specifies  that only IPv6 should be used for query
              transport. See also the -4 option.

       -a     The -a ("all") option is normally equivalent to -v  -t  ANY.  It
              also affects the behavior of the -l list zone option.

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

       -c class
              This option specifies the query class,  which  can  be  used  to
              lookup  HS (Hesiod) or CH (Chaosnet) class resource records. The
              default class is IN (Internet).

       -C     This option indicates that named should check consistency, mean-
              ing that host queries 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     This option prints debugging traces, and is equivalent to the -v
              verbose option.

       -l     This  option  tells  named` to list the zone, meaning 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
              This option specifies the number of dots (ndots) 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  are  searched for in the
              domains  listed  in  the   search   or   domain   directive   in
              /etc/resolv.conf.

       -p port
              This  option  specifies  the  port  to  query on the server. The
              default is 53.

       -r     This option specifies a non-recursive query; setting this option
              clears  the  RD (recursion desired) bit in the query. This means
              that the name server receiving the query  does  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
              This option specifies the number of retries for UDP queries.  If
              number  is  negative  or zero, the number of retries is silently
              set to 1. The default value is 1, or the value of  the  attempts
              option in /etc/resolv.conf, if set.

       -s     This  option tells named not to send the query to the next name-
              server if any server responds with a SERVFAIL response, which is
              the reverse of normal stub resolver behavior.

       -t type
              This  option  specifies the 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 are made for SOA
              records.  If  name  is  a   dotted-decimal   IPv4   address   or
              colon-delimited IPv6 address, host queries for PTR records.

              If  a  query  type of IXFR is chosen, the starting serial number
              can be specified by appending an equals sign  (=),  followed  by
              the starting serial number, e.g., -t IXFR=12345678.

       -T; -U This option specifies TCP or UDP. By default, host uses UDP when
              making queries; the -T option makes it use a TCP connection when
              querying  the  name  server.  TCP  is automatically selected for
              queries that require it, such as zone transfer (AXFR)  requests.
              Type  ANY  queries  default to TCP, but can be forced to use UDP
              initially via -U.

       -m flag
              This option sets memory usage debugging: the flag can be record,
              usage,  or  trace. The -m option can be specified more than once
              to set multiple flags.

       -v     This option sets verbose output, and is  equivalent  to  the  -d
              debug  option. Verbose output can also be enabled by setting the
              debug option in /etc/resolv.conf.

       -V     This option prints the version number and exits.

       -w     This option sets "wait forever": the query timeout is set to the
              maximum possible. See also the -W option.

       -W wait
              This  options  sets  the  length of the wait timeout, indicating
              that named should wait for up to wait seconds for  a  reply.  If
              wait is less than 1, the wait interval is set to 1 second.

              By  default,  host  waits 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 a domain name before sending a
       request to a DNS server or displaying a reply from the server.  To turn
       off  IDN support, define the IDN_DISABLE environment variable. IDN sup-
       port 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

       2021, Internet Systems Consortium



9.16.12                           2021-02-04                           host(1)

bind 9.16.12 - Generated Sat Feb 20 09:12:49 CST 2021
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