The point we need to have foremost in mind when planning an Active Directory schema extension is the word "schema". As in a Relational Database Management System (RDBMS) schema [27], just in case the reader is familiar with database systems, every change we make to the predefined data types or the relationships between tables can lead to unwanted results. So, before going forward, it's important to understand what the changes are and whether or not we really need to make them; as in the case of the Active Directory schema extensions, once created they are not reversible [28].

In the Active Directory world, maybe the schema does not have much of the complexity of an RDBMS schema, but it is a crucial, very important definition all the same, as any error can lead to the unavailability of the service. The Active Directory schema maintains definitions for all objects in the directory; thus, the creation of any new object is validated using the object...