host linux command

host

host [options] host [server]

host [options] zone [server]

System administration command. Print information about specified hosts or zones in DNS. Hosts may be IP addresses or hostnames; host converts IP addresses to hostnames by default and appends the local domain to hosts without a trailing dot. Default servers are determined in /etc/resolv.conf. For more information about hosts and zones, try Chapters 1 and 2 of DNS and BIND by Paul Albitz and Cricket Liu, published by O'Reilly & Associates.

Options

-a

Same as -t ANY.

-c class

Search for specified resource record class (IN, INTERNET, CS, CSNET, CH, CHAOS, HS, HESIOD, ANY, or *). Default is IN.

-d

Debugging mode. -dd is a more verbose version.

-e

Do not print information about domains outside of specified zone. For hostname queries, do not print 'additional information' or 'authoritative nameserver.'

-f file

Output to file as well as standard out.

-i

Given an IP address, return the corresponding in-addr.arpa address, class (always PTR), and hostname.

-l zone

List all machines in zone.

-m

Print only MR, MG, and MB records; recursively expand MR (renamed mail box) and MG (mail group) records to MB (mail box) records.

-o

Do not print output to standard out.

-p [server]

For use with -l. Query only the zone's primary nameserver (or server) for zone transfers, instead of those authoritative servers that respond. Useful for testing unregistered zones.

-q

Quiet. Suppress warning, but not error, messages.

-r

Do not ask contacted server to query other servers, but require only the information that it has cached.

-t type

Look for type entries in the resource record. type may be A, NS, PTR, ANY, or * (all).

-u

Use TCP, not UDP.

-v

Verbose. Include all fields from resource record, even time-to-live and class, as well as 'additional information' and 'authoritative nameservers' (provided by the remote nameserver).

-vv

Very verbose. Include information about host's defaults.

-w

Never give up on queried server.

-x

Allow multiple hosts or zones to be specified. If a server is also specified, the argument must be preceded by -X.

-A

For hostnames, look up the associated IP address, and then reverse look up the hostname, to see if a match occurs. For IP addresses, look up the associated hostname, and determine whether the host recognizes that address as its own. For zones, check IP addresses for all hosts. Exit silently if no incongruities are discovered.

-C

Similar to -l, but also check to see if the zone's name servers are really authoritative. The zone's SOA (start of authority) records specify authoritative name servers (in NS fields). Those servers are queried; if they do not have SOA records, host reports a lame delegation. Other checks are made as well.

-D

Similar to -H but include the names of hosts with more than one address per defined name.

-E

Similar to -H but do not treat extra-zone hosts as errors. Extra-zone hosts are hosts in an undefined subdomain.

-F file

Redirect standard out to file, and print extra resource record output only on standard out.

-G zone

Similar to -H but include the names of gateway hosts.

-H zone

Print the number of unique hosts within zone. Do not include aliases. Also list all errors found (extra-zone names, duplicate hosts).

-I chars

Do not print warnings about domain names containing illegal characters chars, such as _.

-L level

For use with -l. List all delegated zones within this zone, up to level deep, recursively.

-P servers

For use with -l. servers should be a comma-separated list. Specify preferred hosts for secondary servers to use when copying over zone data. Highest priority is given to those servers that match the most domain components in a given part of servers.

-R

Treat non-fully-qualified hostnames as BIND does, searching each component of the local domain.

-S

For use with -l. Print all hosts within the zone to standard out. Do not print hosts within subzones. Include class and IP address. Print warning messages (illegal names, lame delegations, missing records, etc.) to standard error.

-T

Print time-to-live values (how long information about each host will remain cached before the nameserver refreshes it).

-X server

Specify a server to query, and allow multiple hosts or zones to be specified.

-Z

When printing recource records, include trailing dot in domain names, and print time-to-live value and class name.