Todays post, we see how to raise the domain/forest functional level from an older Windows 2008 server to allow a new Windows 2019 server to join the domain and become a DC ?
The issue:
There are very few reasons why you would upgrade your functional level, after all if its not broke? But in this particular case I wanted to join a new Windows server 2019 DC to the domain, and even though I could of left it, I thought id promote it to share with you all.
Another reason for this would be if you want to activate AD recycle bin which is only available on 2008 R2 and above, a must if you dont want to get into tombstone recovery etc which can get quite messy (trust me its not good trying to restore a whole companies AD because some numpty deleted the entire AD by accident when decommissioning an Exchange server, we’ve all been there ?)
In this example, I have both a domain and forest at the functional level of 2008 R2 going to 2012 R2.
The resolution:
We must raise the functional level of all domains within the forest and then the forest itself, in this example we only have one domain and one forest to worry about.
First open up “Active directory users and computers” and right click the domain and choose to “Raise domain functional level”
The higest level we can go to is 2012 R2 as this is the lowest DC on the domain, click “raise” to raise:
This will now give you a warning:
and click ok to confirm its been done:
Your domain functional level is at the new level in this case is “Windows server 2012 R2”, you will need to allow time for replication.
Now, after we allow some time for replication (again this depends on the size of your estate) we can open up “Active directory Domains and Trusts” and right click the top level and choose to “Raise Forest functional level”
The higest level we can go to is 2012 R2 as this is the lowest DC on the domain, click “raise” to raise:
This will now give you a warning:
and click ok to confirm its been done:
This will now show your forest functional level is at the new level in this case is “Windows server 2012 R2”:
Please note if your domain is quite old it may be using FSR for replication which will mean even after this the server will fail to add, please see here how to migrate FSR to DFSR.
You have successsfully completed raise the domain/forest functional level! You can read more via the official Microsoft page here.
For more tips on anything to do with Migration services, or anything else, please feel free to get in touch ?
