Exchange Server 2013, Database Availability Groups, NAT, and High Availability

Question

Dilemma here

I want a high availability/failover solution for people accessing outlook anywhere or exchange from outside the network.

I have 2 exchange servers (EXCH1 and EXCH2) that have Exchange 2013 on them. They are both on Windows Server 2012 R2 (Standard) machines. They are also a part of a DAG (Database Availability Group) (DAG1). Both servers are CAS (Client Access Server) and MAILBOX roles.

Currently, my router NAT settings are forwarding ports 25, 110, 80, and 443 to EXCH1. Would it be possible to port forward to DAG1 for these ports and let the Failover Cluster Manager decide which machine to use?

I tried Network Load Balancer, but it cannot co-exist with Failover Cluster Manager. So because of that I believe the solution should be to point router to the DAG instead of one of the exchange servers, but not sure.

Answer 1

No, the DAG IP address is not a client access endpoint. You're on the right track by looking into load balancing, but NLB is also not a good choice (you've already discovered it's unsupported to use it on DAGs anyway).

So the solution for your scenario is to implement a load balancer. If Exchange is the only application you need to load balance, then I would look closely at a Kemp VLM.