MSM DNS issue with 2 SSIDs

[tnorko]

We are a school and have had an MSM 760 in place for some time now.  We recently added a guest network with HTML authentication tied to AD.  This all works fine.  The issue is the guest network is 192.168.x.x while the secure network is 10.5.x.x.  The DNS servers exit on the 10.5.x.x side.  The problem is when a user on the guest network tries to connect to an internal resource.  IE the exchange server.  I want the 192.168.x.x network not to resolve with the internal IP of the exchange server because the two networks aren't connect by design.  But how do I setup DNS to resolve to the public ip of the exchanger server for the guest ssid?