I have a client with an AD environment. His internal domain is a a.local but since he is hosting his own exchange I had to create an internal zone lookup for a.com so things work correctly for internal clients to find the exchange server exchange.a.com. As the a.com zone exists in the environment I had to add the a recs for other resources hosted outside ie. www.a.com
. no big deal just pointed them out. external users are using an outside third party DNS provider who is also managing the web site. the issue is that sometimes for testing purposes the third party will switch the normal traffic to a different IP address. They make the switch on the external dns servers but obviously internal users are not seeing this because internal ad servers are not updated.
is there a way to point an internal ad dns server to uses an external dns server for certain a records while leaving it as internally authoritative for others like the exchange box?