I have to Exchange sites and 4 Exchange servers. 3 Servers at in Site A and 1 server is in Site B. In Site A the roles are broken out so I have a CAS, HUB, and DB server. In site B all roles are running on one server. I setup the DAG recently and that appears to be working without issue. I'm able to fail the database over and the Outlook MAPI connections keep working. However OWA is not proxying requests to the CAS server in Site B. I set Windows Authentication on the OWA virtual directory in both sites and that did not resolve my issue.
Both CAS servers have access to the internet and they currently have the same External URL set. The idea is, in case of a serious fail-over all I need to do is change a single DNS entry and people will be going into Site B. Site B does not have sufficient bandwidth so I do not want to use that server as an Active CAS server.
Vincent Sprague