At 7:18 PM -0500 12/23/1996, Chip Rosenthal wrote:
>Milam, Charles R. 1LT CAP writes:
>> Just this last week, my named reports a whole screen full of:
>>
>> ==> /var/log/messages <==
>> Dec 23 14:31:01 mitchell named[16444]: "aol.com IN MX" points to a CNAME
>> (b.mr.aol.com)
>> Dec 23 14:31:01 mitchell named[16444]: "aol.com IN MX" points to a CNAME
>> (a.mx.aol.com)
>
>Looks like AOL broke their DNS. The MX records used to point to round
>robins of A RRs. Now they are pointing to CNAMEs. That's illegal.
>They should fix it.
I used to think it was illegal, too. However, after
conversations with Paul Vixie and other DNS gurus, it is now my
understanding that this is not the greatest solution, but is not
technically illegal, and does help us solve a much more severe
problem -- that of DNS truncation, and many SMTP MTAs not properly
understanding how to deal with truncation (misreading RFC 1123, they
interpret any kind of truncation as meaning that all the data has to
be thrown away, when in fact you only throw it away if the truncation
occurred in the Authority section, while we were only truncating in
the Additional section).
Even IBM's VM SMTP V2R2 got this one wrong, and many of the
world's largest listserv sites had problems getting mail to AOL until
we were able to figure out which patches actually fixed the problem.
This was made even more difficult by the fact that we didn't have
anyone over at IBM we could talk directly to, so we had to work
through affected third parties, who would tell us which patches they
applied and we'd work with them to figure out if they actually worked.
We're aware of the problem, and are working on a better solution
for it. However, in the meanwhile, people who do query logging will
run into these error messages, even though they're not technically
correct.
--
Brad Knowles, MIME/PGP: brad@his.com
comp.mail.sendmail FAQ Maintainer <http://www.his.com/~brad/>
finger brad@his.com for my PGP Public Keys and Geek Code
The comp.mail.sendmail FAQ is at <http://www.his.com/~brad/sendmail/>
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