What is an Active/Active datacenter?
An Active/Active datacenter is Microsoft’s Preferred Architecture (PA) for both Exchange 2016 and 2013.
So what does Active Active really mean?
An Active/Active datacenter within Exchange is when you have Exchange servers deployed to multiple sites with an equal number of servers in each site. The Exchange servers from both sites are added as members of a Database Availability Group (DAG), each holding active databases. (see Figure 1).