Being Active directory Administrator, you should know what is you Forest Functional level(FFL) and Domain Functional Level(DFL). It is very much required for the applications and add-on features of active directory.
Use below command to get Forest Functional Level(FFL)
Get-ADForest | fl Name,ForestMode
Use below command to get Domain Functional Level(DFL)
Get-ADForest | fl Name,DomainMode