host Command

Purpose

Resolves a host name into an Internet Protocol (IP) address or an IP address into a host name.

Syntax

host [-n [-a ] [-c Class] [-d ] [-r ] [-t Type] [-v ] [-w ] ] Hostname | Address [Server]

hostnew [-a ] [-c Class ] [-d ] [-r ] [-t Type ] [-v ] [-w ] Hostname | Address [Server]

Description

The /usr/bin/host command returns the IP address of a host machine when the HostName parameter is specified and the name of the host when the Address parameter is specified. Depending on the configuration of name resolution service, the host command might also display any aliases that are associated with the HostName parameter. Examples of name resolution services include local, nis, and bind.

If the local host is using the Domain Name Protocol, the local or remote name server database is queried before it searches the local /etc/hosts file.

Flags

Item	Description
-a	Equivalent to using "`-v -t *`"
-c `Class`	Specifies the class to look in when it searches non-Internet data. Valid classes follow: IN Internet class CHAOS Chaos class HESIOD MIT Althena Hesiod class ANY Wildcard (any of the above)
-d	Turns on debugging mode.
-n	Equivalent to issuing the /usr/bin/hostnew command. The hostnew command performs bind resolution service.
-r	Disables recursive processing.
-t `Type`	Specifies the type of record to query for. Valid types follow: A Host's IP address CNAME Canonical name for an alias HINFO Host processor and operating system type KEY Security Key Record MINFO Mailbox or mail list information MX Mail exchanger NS Nameserver for the named zone PTR Host name if the query is an IP address; otherwise, the pointer to other information SIG Signature Record SOA Domain's "start-of-authority" information TXT Text information UINFO User information WKS Supported well-known services
-v	Verbose mode.
-w	Waits forever for a reply from the DNS server.

Parameters

Item	Description
`Address`	Specifies the IP address of the host machine to use in resolving the host name. The `Address` parameter must be a valid IP address in dotted decimal format.
`HostName`	Specifies the name of the host machine to use in resolving the IP address. The `HostName` parameter can be either a unique host name or a well-known host name (such as `nameserver`, `printserver`, or `timeserver`, if these names exist).
`Server`	Specifies the nameserver to query.

Examples

To display the address of a host machine named mephisto, enter the following command:
```
host mephisto
```
The output is similar to the following information:
```
mephisto is 192.100.13.5, Aliases: engr, sarah
```
To display the host whose address is 192.100.13.1, enter the following command:
```
host 192.100.13.1
```
The output is similar to the following information:
```
mercutio is 192.100.13.1
```

To display the MX records for the domain named test.ibm.com, enter:

host -n -t mx test.ibm.com

hostnew -t mx test.ibm.com

The output is similar to the following information:

test.ibm.com mail is handled (pri=10) by test1.tt.ibm.com
test.ibm.com mail is handled (pri=10) by test2.aix.ibm.com

Files

Item	Description
/etc/hosts	Contains the Internet Protocol (IP) name and addresses of hosts on the local network.