Which directory partition contains the definition of Active Directory objects and their attributes for all domains in a forest?

The schema directory partition holds the definitions of Active Directory objects and their attributes for all domains within a forest. This partition is crucial because it defines the types of objects that can be created within Active Directory, such as users, groups, and computers, as well as the attributes associated with those object types.

In more detail, the schema defines the classes of objects and their properties by using a set of rules and guidelines for what can be added or modified within Active Directory. Changes to the schema affect all domains within the forest, making it a central component for managing the data structure of the entire directory service.

The other choices do serve important functions in Active Directory: the domain partition contains the actual data for a specific domain, while the configuration partition includes data necessary for the operation and replication of Active Directory itself. The global catalog, on the other hand, is a distributed data store that enables the quick search of objects in the entire forest but does not store the full definition of the objects. Thus, the schema directory partition is the correct answer, as it specifically contains the definitions for all objects and attributes found in all domains in a forest.