As I understand it, the CAS handles all new traffic for web access during install (OWA, ActiveSync, Outlook Anywhere, etc.). That being said, I have a network that essentially has a VIP that load balances 2 Exchange 2003 OWA servers that then enter our SPAM filter then onto the Exchange 2003 MBXs.
So if I change the VIP to redirect to the new CAS after install, the old 2003 environment is still active since no mailboxes have been moved, correct? Essentially the CAS takes the traffic from the VIP, and if the mailbox exists on the 03 servers, it does a URL redirect to "legacy.example.com", right? We have a very large environment and I really need to understand exactly how the routing works before we attempt approval. I need to be the subject matter expert in a matter of a few weeks.
I hope I explained how it works currently. I appreciate the assist in advance.