Exchange 2010 – Send Connector – 451.4.4.0 DNS query Failed:

[shawn.pederson]

Running into issues with Exchange 2010. Have done some initial trouble shooting but wanted to gain some insight from the community.

Looks like we have 2 internet send connectors:

 

 

Both with verify similar settings, except the Internet Outbound one has no source server and looks to be the remains of a migration before my time.

 

Now when I attempt to add a source server (in trouble shooting) it throws me “Source server “X” isn’t in the connector’s source routing group”.

 

 

Now several TechNet articles and Google searches later have lead me to digging around in ADSI edit under the Configuration Naming context. Which seems to include many signs of an old server in the Configuration > Services > Microsoft Exchange > Exchange Admin. Groups > Routing Group > Connections:

 

First off I would like to know if there is a way to verify that this is the cause of the error. Is there anyone to explicitly track what send connector a message is trying to send out with?

 

What’s weird is this only seems to be happening when trying to send out to one domain… at least that we have run into? Anyone have any guidance?

[shawn.pederson]

I figured out how to use the Log Tracker (EMC > Tool box > Log Tracker) and it doesn't appear to be trying to use any connector...

 

[shawn.pederson]

I was able to "band aid" the issue by adding an external DNS server to the Exchange servers IPv4 adapter settings. It is now able to resolve the external domain MX records. I figured it out by testing inside and outside out network with the commands below from the cmd prompt:

• NSLOOKUP
• SET TYPE=MX
• "External domain" (i.e. gmail.com)

Note: If you want to test a different DNS server (then the default one in your domain) you can do this with a SERVER 8.8.8.8 (Google's public DNS server) after entering NSLOOKUP.

When I ran this outside (i.e. different DNS server) I get the domains mail servers. Within our internal network (i.e. domain DNS servers) I get a server error instantly.

Watching the mail queue shows the actions connect and send the emails no problem.

Thanks for the responses everyone