Derek J. Balling wrote:
On Feb 21, 2008, at 11:16 AM, Tony Hansen wrote:
The result of an MX lookup MUST NOT be a
CNAME.
I still say that verbiage, wherever it is, will be unnecessarily
confusing. If a lookup for "the MX of a domain" yields a CNAME RR, then
it could be said that the MX lookup was a CNAME, and that's *not* what
is being proscribed against.
That above sentence needs to be reworded to actually be syntactically
correct, IMHO.
Cheers,
D
+1, especially since the DNS client performing a MX lookup will resolve
the CNAME and that that overall request would not result in a CNAME for
SMTP MX expansions. It essence, the semantics seem to be more
appropriately applied as a reminder to DNS clients doing a MX request in
general.
I actually recall seeing this before but decided it wasn't worth the
aggravation. After all, it isn't the current SMTP vendors problem. They
are doing it right and future SMTP vendors/clients who decide to roll
their own DNS Client will find out the hard way that a CNAME is part of
the MX expansion process. But if they use a DNS client API, these
library already figured it out. It will be transparent to the SMTP
client using a DNS client API.
--
Sincerely
Hector Santos, CTO
http://www.santronics.com
http://santronics.blogspot.com