Linux Network Administrators Guide

This record associates an alias with a host's canonical hostname . It provides an alternate name by which users can refer to the host whose canonical name is supplied as a parameter. The canonical hostname is the one the master file provides an A record for; aliases are simply linked to that name by a CNAME record, but don't have any other records of their own.

This type of record is used to associate names in the in-addr.arpa domain with hostnames. It is used for reverse mapping of IP addresses to hostnames. The hostname given must be the canonical hostname.

This RR announces a mail exchanger for a domain. Mail exchangers are discussed in Section 17.4.1 ." The syntax of an MX record is:

 [domain] [ttl] [class] MX preference host 

host names the mail exchanger for domain . Every mail exchanger has an integer preference associated with it. A mail transport agent that wants to deliver mail to domain tries all hosts who have an MX record for this domain until it succeeds. The one with the lowest preference value is tried first, then the others, in order of increasing preference value.

This record provides information on the system's hardware and software. Its syntax is:

 [domain] [ttl] [class] HINFO hardware software 

The hardware field identifies the hardware used by this host. Special conventions are used to specify this. A list of valid "machine names" is given in the Assigned Numbers RFC (RFC-1700). If the field contains any blanks, it must be enclosed in double quotes. The software field names the operating system software used by the system. Again, a valid name from the Assigned Numbers RFC should be chosen.

An HINFO record to describe an Intel-based Linux machine should look something like:

 tao 36500 IN HINFO IBM-PC LINUX2.2 

and HINFO records for Linux running on Motorola 68000-based machines might look like:

 cevad 36500 IN HINFO ATARI-104ST LINUX2.0
 jedd 36500 IN HINFO AMIGA-3000 LINUX2.0