To viewing the forest and domain functional level in the active directory.
Step 1 :- Open the active directory users and computers mmc snap in console. By executing the command dsa.msc .
Step2 :- Right click on the root domain and click properties. now domain properties will open. From there we can view the domain and forest functional levels under in the general tab.
We can view the information from windows xp and windows server. In windows xp , windows 2003 support should be installed to view the information .For more information watch the below video.