Use IPv4 only for query transport. See also the -6
Use IPv6 only for query transport. See also the -4
"All". The -a option is normally
equivalent to -v -t ANY. It also affects the behaviour of the
-l list zone option.
"Almost all". The -A option is
equivalent to -a except RRSIG, NSEC, and NSEC3 records are omitted from
Query class: This can be used to lookup HS (Hesiod) or CH
(Chaosnet) class resource records. The default class is IN (Internet).
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
Print debugging traces. Equivalent to the -v
List zone: The host
command performs a zone
transfer of zone name
and prints out the NS, PTR and address records
Together, the -l -a options print all records in the
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
Non-recursive query: Setting this option clears the RD
(recursion 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.
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
Do not send the query to the next nameserver if
any server responds with a SERVFAIL response, which is the reverse of normal
stub resolver behavior.
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).
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.
Memory usage debugging: the flag can be record,
usage, or trace. You can specify the -m option more than
once to set multiple flags.
Verbose output. Equivalent to the -d debug option.
Verbose output can also be enabled by setting the debug option in
Print the version number and exit.
Wait forever: The query timeout is set to the maximum
possible. See also the -W option.
Timeout: Wait for up to wait
seconds for a reply.
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.