Subject: PTRs, PTRs everywhere (was: Should a nameserver know about itself?)

From: Sam Trenholme <[email-masked]>
Date: Wed, 9 May 2001 17:08:23 -0700 (PDT)

> What does it mean to have a PTR record in anything other than the
> in-addr.arpa tree?

A PTR is a pointer to the FQDN for a given host name.  So, for example, if
artemas.reachin.com is the fully-qualified domain name for the ip of
www.reachin.com, it can make sense to have something like:

www.reachin.com		IN PTR	artemas.reachin.com.

or, using MaraDNS' 'csv1' zone file format:

Pwww.reachin.com.|3600|artemas.reachin.com.

A valid, if pointless, use of the PTR record.

Of course, as Cricket correctly pointed out, a more practical use is
classless in-addr.arpa delegation.

- Sam