I have (2) Exchange 2013 servers that both have the CAS and Mailbox roles installed, with plans to build out CAS redundancy using a load balancing appliance (e.g., Kemp or Barracuda) and a mailbox DAG. 1 server will reside at our primary site and the other will live in our co-lo facility. The material I've read so far about load balancing only takes Exchange server failure into consideration.
One scenario that's unclear to me is if the hardware load balancer itself lives at the primary site and either an extended power outage at the primary site or loss of the WAN router were to happen, effectively taking out both the active Exchange server and the hardware load balancer, does that mean that I'd have to have a hardware load balancer at both our primary site and the co-lo facility? We have 10 physical sites that have Outlook clients and they would need direction for which Exchange server they need to be talking to.