A CNAME lookup failure isn't necessarily due to an MX pointing to a
CNAME record. Or is it? This would be easy for us to check if Chandran
had posted the domain name. Chandran, you really need to do a better job
of providing details such as this in order for us to help you effectively.
Dan's suggestions are certainly appropriate. When I've identified a
domain with misconfigured DNS (typically a problem with rDNS), I attempt
to notify the domain's administrator (technical contact info can be
obtained from whois). They are usually grateful.
On the other hand, if changing the resolver your QMT uses improves
reliability by dealing effectively with some anomaly, why wouldn't you
want to make the change, especially if the anomaly is something outside
of your control?
--
-Eric 'shubes'
On 09/06/2013 08:14 AM, cj yother wrote:
Dan,
I agree. I think this is much more appropriate than changing your
server configuration based on a failed CNAME lookup. That's like
changing the engine because you ran out of gas.
On 09/06/2013 08:04 AM, Dan McAllister wrote:
Just to throw my 2-cents worth in...
If the other (receiving) domain is using an MX record value that is a
CNAME, this error can show... in such a case, this is not a name
resolver error, but rather a DNS error.
It is a violation of the RFCs for the MX record value to resolve
to anything BUT an A record.
I have recommended these sites before, but as a mail admin, checking
out the settings of the OTHER domain when delivery problems are being
reported is just a smart idea.
*intodns.com* - checks a wide variety of DNS issues, including MX
records
*mxtoolbox.com* - has a wide variety of tests available, including
SMTP connection tests. Many of these tests will FAIL if the MX
record for the domain is a CNAME
Good luck to you!
Dan McAllister
IT4SOHO
QMT DNS/Mirror Admin
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