Raising Domain and Forest functional levels


Just a few questions on raising Domain and Forest Functional Levels.

1. Once you have upgraded the Domain functional level, how long should you wait before upgrading the forest functional level?

2. By raising the root domain functional level, will this automatically raise any child domains or do we need to raise the level on the PDC of the root domain then raise the level on the PDC in the child domain? Or do we do the child first then the root domain?

3. What is the best way to recover if things don't go to plan? For e.g With a root domain with 2 DCs and a child domain with 5 DCs?

4. If we are running at Windows 2000 native domain level with all Windows 2008 R2 servers, can we raise the domain functional level straight to Windows Server 2008 R2?
rhiancohenVMware Senior ConsultantAsked:
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Tony GiangrecoCommented:
the change should be in effect immediately as soon as the operation completes on the server. if you have multiple DC's or domain, it may take longer. If you have plenty of time and want to play it safe, wait 24 hours but normally 15 minutes is fine. if you have multiple DC's, you can log into each DC and verify the functional level.

Hope this helps!
1.  See above. Note: Forest Functional Levels can only be raised on the Schema Operations Master.  As such, if the PDCe and Schema Operations Master FSMO roles are on the same server, raising the domain functional level allows for you to raise the forest functional level immediately.

2.  No, each individual domain PDCe is responsible for maintaining it's domain functional level.  Because of this, where you raise the domain functional level first, does not matter (parent domain or child domain).  Each domain's DC's will operate at the domain functional level of it's PDCe (so long as it is supported).  The Forest Functional Level affects all domains.  As such all domains must be operating at or above the proposed Forest Functional Level.

3.  Before Windows Server 2008 R2, the only ways to recover are rebuild or restore from backup.

4.  If all of your DC's are running Windows Server 2008 R2 then yes.

What Are Active Directory Functional Levels?
Understanding Active Directory Domain Services (AD DS) Functional Levels


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rhiancohenVMware Senior ConsultantAuthor Commented:
That's great, thankyou both very much.

Just one more question.

If we had to do a restore, what would be the first steps... Is there a specific FSMO role holder which would need restoring first like the schema or domain naming master and would you start on a child domain DC first or restore on a forest root DC

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As the PDCe is responsible for the Domain Functional Level and the Schema Operations Master is responsible for the Forest Functional Level.

First, you would have to restore the server that holds the Schema Operations Master in the Parent domain (if you will be reverting to a Domain Functional Level less than allowed by the Forest Functional Level).

Then you would restore the server that holds the PDCe FSMO role for each child domain.

rhiancohenVMware Senior ConsultantAuthor Commented:
OK and then would it replicate to the other DCs with the old forest functional level in that particular domain without any intervention/restore to the other DCs?

rhiancohenVMware Senior ConsultantAuthor Commented:
Great, Really useful information thanks

Lets hope I don't have to do a forest recovery ;-)
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