We have Active Directory 2008R2 environment, we have 3 Domain controller server in at PCI zone. 2 AD (1 Physical + 1 VM) Server at PDC site and 1 AD (Physical) server at DR, as we all know server 2008R2 support going to expire on Jan 2020. so we are planning to upgrade AD from 2008R2 to 2012R2.
Here I am seeking best recommendation about infrastructure like we should take a new physical server for server 2012R2 or we can use the virtual machine for Active Directory.