Really, if you are going to migrate off 2003 to a newer Microsoft platform , bypass 2008 , 2008 R2 , 2012 and go straight for 2012 R2. The Time you are going to invest in the migration, you may as well go directly to the stable product that is 2012 R2
Virtualisation Support in Hyper-V and WMware 5.1 for Domain Controllers
With Server 2012 came the ability for the domain controller to understand it was virtualised. (AKA VM-Generation ID support ) This means with things like snapshotting a DC and rolling back the snapshot, the Domain Controller will know it has been rolled back and not try and continue servicing AD requests, or talk to the other Domain Controllers
Hyper-V
Active Directory Domain Services (AD DS) Virtualization
VMWare
Three important document’s to read and understand:
Windows Server 2012 VM-Generation ID Support in vSphere
https://blogs.vmware.com/apps/2014/01/which-vsphere-operation-impacts-windows-vm-generation-id.html
Virtualizing Active Directory Domain Services PDF
DHCP
With 2012 cam a new version of DHCP. Gone is the need to do split scopes. DHCP HA can be setup in two ways
- Load sharing mode, where two DHCP servers are clustered together and serve the clients
- Hot standby mode, where you can setup one DHCP server to be the active node and fail back to a standby DHCP server. This can be a many to one relations ship, e.g. 4 remote sites can have the active node and they all fall back to one Standby DHCP server at Head Office.
What’s New in DHCP in Windows Server
Step-by-Step: Configure DHCP for Failover
How to initiate replication between DHCP Servers
PowerShell
2012 was just the start of it, there are 24 more DHCP cmdlets with 2012 R2 for example. PowerShell just makes an admins life easier