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1. Executable programs or shell commands

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HOST(1)                             BIND 9                             HOST(1)

       host - DNS lookup utility

       host  [-aACdlnrsTUwv]  [-c  class] [-N ndots] [-p port] [-R number] [-t
       type] [-W wait] [-m flag] [ [-4] | [-6] ] [-v] [-V] {name} [server]

       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.

       -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

       -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 com-
              mand 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  in-
              terpreted 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  de-
              fault 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 re-
              solve 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,

              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-de-
              limited 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 de-
              bug 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.

       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 re-
       quest  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.


       dig(1), named(8).

       Internet Systems Consortium

       2022, Internet Systems Consortium

9.18.1-1ubuntu1.3-Ubuntu          2022-03-07                           HOST(1)
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