purpose of PTR record ?

Joseph S D Yao jsdy at center.osis.gov
Thu Dec 4 00:15:10 UTC 2003


On Wed, Dec 03, 2003 at 10:14:32AM +1100, Mark_Andrews at isc.org wrote:
...
> > The RFC for mail servers requires a reverse record.
> 
> 	I suggest that you actually quote it if you can find it:-)
> 
> 	There is *no* RFC that mandates that a PTR record MUST exist
> 	for anything or if they exist that the HELO/EHLO MUST match.

RFC 2821, the current SMTP RFC, actually describes a case where
"... no reverse mapping record is available", thus seemingly
legitimizing anonymous mail servers.  The particular case was a mail
server that had received a random DHCP-style IP address with no reverse
DNS name.  In this case, however, it has to use the literal IP address,
e.g., "[198.182.196.60]" or IPv6 version of same, to respond to HELO or
EHLO.

-- 
Joe Yao				jsdy at center.osis.gov - Joseph S. D. Yao
OSIS Center Systems Support					EMT-B
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