Exchange Server 2016 support domain controllers in the forest need to be running one of the following:
Windows Server 2016 Standard or Datacenter
Windows Server 2012 R2 Standard or Datacenter
Windows Server 2012 Standard or Datacenter
Windows Server 2008 R2 Standard or Enterprise
Windows Server 2008 R2 Datacenter RTM or later
Windows Server 2008 Standard, Enterprise, or Datacenter
Supported operating systems for Exchange 2016
Windows Server 2016 Standard or Datacenter*
Windows Server 2012 R2 Standard or Datacenter
Windows Server 2012 Standard or Datacenter
#Supported clients
Outlook 2016
Outlook 2013
Outlook 2010 SP2 and updates KB2956191 and KB2965295
Outlook for Mac for Office 365
Outlook for Mac 2011