Hi,
We have 4 2012 R2 DCs and 1 2003 server. Our domain and forest functional level is 2003. I want to upgrade to 2012 and want to check what could be impacted, here's what I'm planning to do:
- Lower compatible encryption and GPO settings to accommodate older clients (i.e. NT).
- Highlight to the business that the 100 Windows NT and Windows 2000 servers we have may no longer work as normal.
- Ask the business to identify all of their critical services which are dependent on AD and then ask vendors of each app whether a domain or forest upgrade to 2012 could cause any issues (from past experience I found an issue with a telephony provider not supporting 2012 domain and forest functional levels).
- Come up with a roll back plan, so far, I have:
1. Restore DCs using NetBackup as a standard restore - not officially supported, but should work fine.
2. Run through the AD DS restore mode process which will take AD offline and take a few hours.
Advice is appreciated...