Raising Domain and Forest levels from 2003 to 2008R2 or 2016
We have one location.
It has a physical 2008R2 and a VM 2008R2 PDC and BDC
They are set as Domain and Forest functional levels 2003
There are no trust relationships I can see or know about (small possibility of one in past but unlikely and certainly not required)
I have two Hyper V instances of 2016 not joined to the Domain or with any roles
I have run DCdiag /c / e /v and Repadmin /showrpl on both servers along with AD PBA these show no issues. We have no issues with the servers or AD and I have latest updates and they are freshly rebooted last night.
My Plan was to upgrade the 2008R2 servers from 2003 functional levels to 2008R2, reboot recheck overnight. As long as this is OK I would then add the 2016 servers and look to decomission the 2008R2's once the 2016's had been promoted.
Does this all sound simple and relatively low risk? Any other checks or gotchas? This is quite a small simple environment, the only other servers have no DC functions and are 2008R2 terminal services and 2012 running SQL. DNS also looks good and is on PDC.