Can't resolve mx records

[Ray]

I have three Win2003 DNS servers, AD integrated. I have
set up forwards to our isp on the primary dns server. All
are behind a firewall. Here is the problem. I can perform
lookups on internet domains and they return records. I set
type to mx and several domains fail this lookup. For
instance earthlink.net and aol.com both fail mx lookups.
Mail in the Exchange 2003 queue backsup for these domains.
After a day or so the domains will eventually be resolved
and mail will be sent. So far these are the only two
domains that I have had problems with. Everything else
resolves immediately. Earlier today I was able to resolve
Earthlink but 30 minutes later it wouldn't resolve. The
only records that are not being resolved are the mx
records. Host records are being resolved so web sites are
available to these two domains. I can change the server in
nslookup to our isp's dns server and these mx records are
being resolved so it appears to me that our dns server is
not looking to our isp's server to resolve these mx
records. Any help in this matter is appreciated.

Ray

 

[Lanwench [MVP - Exchange]]

What if you try different public DNS servers in your forwards? Sounds like
there may be a problem there.

You can always try nslookup using a different DNS server to check ...

 

[Ray]

Thanks for the reply. If I do a nslookup using my isp's
dns servers the mx records resolves. When I do the
nslookup against my dns server the mx record lookup times
out.

I tried different servers as you suggested. Setting these
servers in a nslookup works. Using my dns server for a
lookup of the mx record still fails.

Ray

 

[Shane Brasher]

Hello All,

You may want to look at the below articles in relation to your failed MX
queries from your W23K DNS server.

828731 An External DNS Query May Cause an Error Message in Windows Server
2003
http://support.microsoft.com/?id=828731

828263 DNS query responses do not travel through a firewall in Windows
Server
http://support.microsoft.com/?id=828263

832223 Some DNS Name Queries Are Unsuccessful After You Upgrade Your DNS
Server
http://support.microsoft.com/?id=832223

http://www.microsoft.com/technet/treeview/default.asp?url=/technet/prodtechn
ol/windowsserver2003/proddocs/standard/sag_DNS_imp_EDNSsupport.asp

It sounds like you are struggling with the EDNS0 problem, which can be
resolved via a simple command line syntax typed on the DNS servers. I
suggest that you look at the above articles.

Question
***********
What type of firewall and/or router separates the DNS servers from the
internet?

Shane Brasher
MCSE (2003,2000,NT),MCSA, A+
Microsoft Platforms Support
Windows NT/2000 Networking

 

[Ray]

We have a Cisco PIX 515 Firewall. Port 53 is open on TCP
and UDP. the router is a Cisco also. It is supplied by our
ISP...Bellsouth. Thanks for the response. I guess I need
to work on my search technique because I couldn't locate
any articles on it. I will look at the articles you
suggest. This DNS server was an upgrade so this may be the
solution I am looking for. Thanks for your response. I
will let you know if this solves the problem.

Ray

 

[Ray]

Shane,

Thanks for the help. Using the info in KB832223 solved the
problem.

Ray

 

[Shane Brasher]

Anytime Ray.

Shane Brasher
MCSE (2003,2000,NT),MCSA, A+
Microsoft Platforms Support
Windows NT/2000 Networking