Here is a example of one case I worked few days ago about how to raise the Domain and Forest Level
The example and how to do is pretty simple, but there're 5 questions that many people also can thing about.
>>Q1: Step-by-Step to Raise the Forest and Domain Level
>>Q2: What's the time needed to wait between Domain Raise to do the next action "Forest raise"? (Replication topic).
>>Q3: Should I make all actions on Schema Master?
>>Q4: Where can I find logs that show me the progress and the successful for this Raise Action.
>>Q5: What should be the action to be done on Exchange Servers? What impact will have on Exchange 2007?
>> A1: First check if all DCs are Windows Server 2003.
Review if all DCs are replicate fine.
You can used the option to review the following command to check "Repadmin/Showrepl * /CSV>showrepl.csv" or Replmon
All these tools are under Resource Kit 2003 and Support Tools
If all DCs are replicating fine you can go to next steps
To raise the domain functional level
a. Open Active Directory Domains and Trusts.
b. In the console tree, right-click the domain for which you want to raise functionality, and then click Raise Domain Functional Level.
c. In Select an available domain functional level, do one of the following:
§ To raise domain functional level to Windows Server 2003, click Windows Server 2003, and then click Raise.
To raise the forest functional level
1. Open Active Directory Domains and Trusts.
2. In the console tree, right-click the Active Directory Domains and Trusts node, and then click Raise Forest Functional Level.
3. In Select an available forest functional level, click Windows Server 2003, and then click Raise.
>>A2: You can use the command "repadmin" to check if the replication between DCs were completed successfully.
>>A3: For Raise Domain and Forest Level it can be done on any DC.
For use the adprep for extend Schema for Exchange 2010 will MUST be done Schema Master.
>>A4: You can use Event Viewer Log -> Directory Service - Event ID 2039 and 2040
>>A5: There are no impact and nothing should be done at the exchange server when the functional level is raised, if he is only concerned with the functional level raise and not at the Exchange migration.
Raise the domain functional level
How to raise Active Directory domain and forest functional levels
What Are Active Directory Functional Levels?