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Re: MX to CNAME and (mis)interpretation of 2821 (was: rfc2821bis-07)

2008-02-22 18:13:33

--On Friday, 22 February, 2008 20:25 +0100 Frank Ellermann
<nobody(_at_)xyzzy(_dot_)claranet(_dot_)de> wrote:

John C Klensin wrote:

if we stick with Option 1 and the language isn't clear enough,
the relevant sentence can be supplemented with an explicit 
statement to the effect that any values that point to CNAMEs
that appear are nonconformant and out of the scope of the

That would be good and hopefully address Trevor's concerns in

Paul Smith proposed 2007-12-14 (getting two ACKs):
| 2821bis should state that "putting CNAMES as the target of
| MX records is not allowed, as stated in RFC 2181"

After an exchange of notes with John Leslie, we have arrived at
a way to handle this that is consistent with the above, but that
really spells out the restriction and points to RFC 2181 for
additional explanation.

Incidentally, 2181 says "address records" and then does a little
handwaving about "other record types giving addressing
information".  The proposed 2821bis text now says "
address record (e.g., A or AAAA RR)..." which should eliminate
any possible doubt.