On Wed, 2003-12-31 at 09:31, Greg A. Woods wrote:
> If you're going to use multiple hostnames for a single address for some
> bizzare (and likely unnecessary) reason, and if you're going to publish
> any reverse DNS for that address at all, then you really, Really, REALLY
> _should_ do your damndest to publish complete, correct, and of course
> valid, PTRs giving each and every one of those hostnames. Not doing so
> can only result, at best, in confusing everyone not familiar with your
> internal insanity.
[RFC 1912]:
| Make sure your PTR and A records match. For every IP address, there
| should be a matching PTR record in the in-addr.arpa domain. If a
| host is multi-homed, (more than one IP address) make sure that all IP
| addresses have a corresponding PTR record (not just the first one).
| Failure to have matching PTR and A records can cause loss of Internet
| services similar to not being registered in the DNS at all. Also,
| PTR records must point back to a valid A record, not a alias defined
| by a CNAME.
note it says "for every IP address", not "for every A record". it also
explicitly disallows a PTR pointing to a CNAME.
[RFC 1034]:
| A type PTR query is used to get the RR with the primary name of
| the host. For example, a request for the host name corresponding
| to IP address 1.2.3.4 looks for PTR RRs for domain name
| "4.3.2.1.IN-ADDR.ARPA".
note "primary name of the host", indicating that there is only one. the
standard does allow more than one PTR RR, however.
so traditionally, you will find only one PTR RR, even if the host has
more than one A RR pointing to its IP address. trying to get that
changed will be almost impossible.
--
Kjetil T.
