Domains created prior to Server 2008 used FRS. FRS was replaced with DFS-R after Server 2008.
Note: All domain controllers that are functioning as domain controller need to be Server 2008 before migrating to DFS-R.
The Migration is broken down into 3 steps, each step can take up-to a day and should be done one step per days to ensure replication is working correctly.
A few commands:
dfsrmig /getglobalstate – if this comes back as eliminated then you’ve already been upgraded to DFS-R
Step 1: dfsrmig /setglobalstate 1 – this is a pre-staging step, can rollback if needed
Step 2: dfsrmig /setglobalstate 2 – this is a staging step, can rollback if needed
Step 3: dfsrmig /setglobalstate 3 – this is the final migration from FRS to DFS-R, once you press enter with this command you can’t rollback.