Hi,
our users were getting a few e-mail errors about other mail servers failing to send mail to our domain as there were no CNAME records / lookup failures etc. So I checked, no CNAME records in ns1.ev1servers.net, ns2.ev1servers.net (how I did i get onto The Planet forums? just wondering....) so I read up on the things and added in CNAME records for our domains
then i started having issues with nslookups ON our box (I fiddled with resolv.conf and stuff as CPanel was bitching about something AND apparently ns1.ev1servers.net does NOT respond to DNS lookups if you're a dedicated server - ev1 has other NS for that group -- important to remember)
and checked with ev1 tech support. they turned out to be unhelpful as they did not seem to know that ns1 / ns2 are not the right NS for ev1 dedicated servers (am I right here? i fixed things again and it works as expected)
and they thought the problem was the CNAME stuff I had added to ns1 / ns2. well.... I did some lookups on 3rd party boxes and the results I get from dig etc indicate the mail.mydomain.com lookups were fine when CNAMEs were involved. so....
1) should I add CNAME entries for our domains to cover these few 3rd party mail servers that seem to be having trouble? or are they just broken / obsolete / and should be able to utilize the mail.mydomain.com A records in their lookup?
2) would a mail.mydomain.com CNAME mydomain.com along with a A record for mail and a A record for mydomain.com (to the IP address) cause problems? Or is ev1 wanting a very specific DNS configuration and i was coloring outside the lines?
I am trying to understand in depth what is going on and it looks like my initial understanding (of CNAMEs and resolv.conf's failure) was entirely correct and whatever this tech guy was saying was wrong or he didn't quite understand the nature of the problem.
thanks
doug
Full Version: question about DNS, CNAME and ev1servers
QUOTE (dfraser @ Feb 6 2007, 04:45 PM) 
Hi,
our users were getting a few e-mail errors about other mail servers failing to send mail to our domain as there were no CNAME records / lookup failures etc. So I checked, no CNAME records in ns1.ev1servers.net, ns2.ev1servers.net (how I did i get onto The Planet forums? just wondering....) so I read up on the things and added in CNAME records for our domains
then i started having issues with nslookups ON our box (I fiddled with resolv.conf and stuff as CPanel was bitching about something AND apparently ns1.ev1servers.net does NOT respond to DNS lookups if you're a dedicated server - ev1 has other NS for that group -- important to remember)
and checked with ev1 tech support. they turned out to be unhelpful as they did not seem to know that ns1 / ns2 are not the right NS for ev1 dedicated servers (am I right here? i fixed things again and it works as expected)
and they thought the problem was the CNAME stuff I had added to ns1 / ns2. well.... I did some lookups on 3rd party boxes and the results I get from dig etc indicate the mail.mydomain.com lookups were fine when CNAMEs were involved. so....
1) should I add CNAME entries for our domains to cover these few 3rd party mail servers that seem to be having trouble? or are they just broken / obsolete / and should be able to utilize the mail.mydomain.com A records in their lookup?
2) would a mail.mydomain.com CNAME mydomain.com along with a A record for mail and a A record for mydomain.com (to the IP address) cause problems? Or is ev1 wanting a very specific DNS configuration and i was coloring outside the lines?
I am trying to understand in depth what is going on and it looks like my initial understanding (of CNAMEs and resolv.conf's failure) was entirely correct and whatever this tech guy was saying was wrong or he didn't quite understand the nature of the problem.
thanks
doug
our users were getting a few e-mail errors about other mail servers failing to send mail to our domain as there were no CNAME records / lookup failures etc. So I checked, no CNAME records in ns1.ev1servers.net, ns2.ev1servers.net (how I did i get onto The Planet forums? just wondering....) so I read up on the things and added in CNAME records for our domains
then i started having issues with nslookups ON our box (I fiddled with resolv.conf and stuff as CPanel was bitching about something AND apparently ns1.ev1servers.net does NOT respond to DNS lookups if you're a dedicated server - ev1 has other NS for that group -- important to remember)
and checked with ev1 tech support. they turned out to be unhelpful as they did not seem to know that ns1 / ns2 are not the right NS for ev1 dedicated servers (am I right here? i fixed things again and it works as expected)
and they thought the problem was the CNAME stuff I had added to ns1 / ns2. well.... I did some lookups on 3rd party boxes and the results I get from dig etc indicate the mail.mydomain.com lookups were fine when CNAMEs were involved. so....
1) should I add CNAME entries for our domains to cover these few 3rd party mail servers that seem to be having trouble? or are they just broken / obsolete / and should be able to utilize the mail.mydomain.com A records in their lookup?
2) would a mail.mydomain.com CNAME mydomain.com along with a A record for mail and a A record for mydomain.com (to the IP address) cause problems? Or is ev1 wanting a very specific DNS configuration and i was coloring outside the lines?
I am trying to understand in depth what is going on and it looks like my initial understanding (of CNAMEs and resolv.conf's failure) was entirely correct and whatever this tech guy was saying was wrong or he didn't quite understand the nature of the problem.
thanks
doug
Doug,
1) No you should not. CNAME RR's should only be used as an alias such as ``www IN CNAME domain.tld.'' and never for an MX RR(see #2.)
2) You can NOT have a MX RR pointing to a CNAME. This violates RFC and will cause your server to be ignored by remote MTA's and possibly added to dnsbl's.
http://www.rfc-ignorant.org/policy-bogusmx.php
http://www.dns.net/dnsrd/rfc/
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