In doing the setup of Exchange 2013 we made sure that the internal and external URLs on all 4 servers were the external FQDN. What I am wondering is if internally we pointed the URLs to the internal server mailbox/cas server for that particular AD site if an outage occurred, such a down for an offline defrag, would the DAG route the traffic to the other mailbox/cas server without the load balancer?
The reason I ask, is I think the LB and/or firewalls are negatively impacting the flow of traffic between clients and servers internally. So if the DAG will failover without a LB, and internal clients will not be affected, I'd prefer to route the clients internally to the internal FQDN of the servers.