I have inherited a customer that is currently on 3 workgroups with a file server in each workgroup. Workgroup 1 is accounting & office PCs on 192.168.0.X, workgroup 2 is Production Machines on 192.168.1.X & workgroup 3 is Shipping & Receiving on 192.168.100.X.; all set up that way from previous tech. They purchased a new Windows 2012 std. server several months ago before their "IT Guy" died & have asked me to research installing & configuring this new server as a the Primary DC with AD DS, DNS & DHCP for the entire physical network. They would like to keep the subnets as they are now due to the number of devices attached to those networks.
I'm researching to see what best practices would be in this scenario or to place everything into 1 network & use GP to define the separation between areas/groups. I would have to change a lot of IPs locally because of off-site tech support for production machines, etc.
Any & all suggestions would be greatly appreciated.