I don't know how to title this question as it's a very odd situation.
I have a corp domain with it's PDC/BDC and DNS on corp.thisdomain.com in a datacenter. It also has a cloud hosted email server at mail.thisdomain.com.
The issue is that internally all clients need to resolve to the actual internal IP address of mail.thisdomain.com server, but instead via the PDC/DNS are going outside the network first, then resolving to mail.thisdomain.com external address. This is creating a loop back of all traffic and affecting performance.
Is there a way in windows DNS to create an exception for a higher level request? Considering that in the domain hierarchy ., com, thisdomain, would be above the corp.thisdomain.com domain used on the PDC for the internal network. Very curious problem and I can't seem to find a working solution.
Thus far I've tried a manual root hint entry, and an alias of "mail.thisdomain.com.corp.thisdomain.com" which works for nslookup, but ping tests still show the external address.