Extending the schema
Some applications require additional object types and/or attributes to store their information in Active Directory. Some good examples of these types of applications are Microsoft Exchange Server and Microsoft's free Local Administration Password Solution (LAPS).
These applications and their schema changes are thoroughly tested, but there's also the option to create your own custom Active Directory schema extension. For instance, you can introduce your own employee or customer ID type attribute to the user object class.
Getting ready
The domain controller holding the Schema Master FSMO role is authoritative for the Active Directory schema throughout an Active Directory forest. Microsoft recommends that you perform the following actions on the domain controller that is holding the Schema Master FSMO role.
To find this domain controller, run the following command on any domain-joined device, member server, or domain controller:
netdom.exe...