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 list
ed 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 de
fault 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.
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 op
tions. 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 hard
ware's maximum value for an integer quantity.
FILES
/etc/resolv.conf
SEE ALSO
dig(1), resolver(5) named(8).
BIND9 Jun 30, 2000 2
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