4.21. host - DNS lookup utility

4.21.1. Synopsis

host [-a] [-C] [-d] [-l] [-n] [-r] [-s] [-T] [-w] [-v] [-c <class>] [-N <num-dots>] [-R <number>] [-t <type>] [-W <num-seconds>] [-m <flag>] [[-4] | [-6]] [-v] [-V] <name> [<server>]

4.21.2. 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 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 nameserver that host should query instead of the server or servers listed in /etc/resolv.conf.


This program may be removed from the Loop distribution in the future. Please use dig(1) instead.

4.21.3. Options


Use IPv4 only for query transport. See also the -6 option.


Use IPv6 only for query transport. See also the -4 option.


Stands for "all". The -a option is normally equivalent to -v -tANY. It also affects the behaviour of the -l list zone option.

-c <class>

Set the query class. The default class is IN (Internet). Other usable classes are HS (Hesiod) or CH (Chaosnet).


Check consistency. host will query the SOA records for zone <name> from all the listed authoritative nameservers for that zone. The list of nameservers is defined by the NS records that are found for the zone.


Print debugging traces. Equivalent to the -v option.


TODOMUKS: Combine -d and -v.


Do reverse IPv6 lookups using the obsolete RFC 1886 IP6.INT domain, which is no longer in use. Obsolete bit string label queries (RFC 2874) are not attempted.


TODOMUKS: Remove this option.


List zone. 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 <num-ndots>

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.


Non-recursive query. Setting this option clears the RD DNS message header flag in the query. This should mean that the nameserver receiving the query will not attempt to resolve <name>. The -r option enables host to mimic the behavior of a nameserver by making non-recursive queries and expecting to receive answers to those queries that can be referrals to other nameservers.

-R <count>

Number of retries for UDP queries. If <count> is less than 1, it will be set to 1. The default value is 1.


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.

-t <type>

Specifies the record type. The <type> argument can be any recognized RR 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).


Use TCP. By default, host uses UDP when making queries. The -T option makes it use a TCP connection when querying the nameserver. TCP will be automatically selected for queries that require it, such as zone transfer (AXFR) requests.


Print debugging traces. Equivalent to the -d option.


TODOMUKS: Combine -d and -v.


Print the program's version and exit.


Wait forever: The query timeout is set to the maximum possible. See also the -W option.

-W <num-seconds>

Timeout: Wait for up to <num-seconds> seconds for a reply. If <num-seconds> is less than 1, the wait interval is set to 1 second.

By default, host will wait for 5 seconds for UDP responses and 10 seconds for TCP connections.

Also see the -w option.

4.21.4. Files


4.21.5. See also

dig(1), named(8)