Manual dla host


host - DNS lookup utility

host [-aCdlnrTwv] [-c class] [-N ndots] [-R number] [-t type] [-W wait]
[-4] [-6] {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
dotted-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. Transfer the zone printing out the NS, PTR and
address records (A/AAAA). If combined with -a all records will be

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

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
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
automatically 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
recognised 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.


dig(1), named(8).

BIND9 Jun 30, 2000 HOST(1)