On Sun, 16 Nov 2003, Philipp Morger wrote:
RFC2181
10.2. PTR records
Confusion about canonical names has lead to a belief that a PTR
record should have exactly one RR in its RRSet. This is incorrect,
And it get's used....
--($:~)-- dig -x 212.25.28.4
;; ANSWER SECTION:
4.28.25.212.in-addr.arpa. 86400 IN PTR lexx.zh.as8758.net.
4.28.25.212.in-addr.arpa. 86400 IN PTR dns.as8758.net.
sometimes "lexx" comes first... sometimes "dns"....
If this were a perfect RFC-abiding world we wouldn't need SPF :-)
All I can add to this is that, correctly or not, I believe that the spam
checking rules at the large ISP I work at tests to make sure that your
forward and reverse DNS is correct and matching, and that PTR rotors often
confuse it. Having not seen the code directly I can't comment on how,
but I suspect it is expecting only 1 PTR record back.
I imagine we are not alone in making this assumption.
Tim
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