The Partition ID of the External Reference Partition is always 2.
To avoid having to repeat the process, NDS builds an NDS External References, essentially a pointer, to that object and stores it in the External Reference Partition on the server from which the User object is making the request. The next time this user authenticates to the network, the NDS External References is used to quickly locate the object within NDS. The NDS External References are deleted if not used for an extended period of time.
NOTE In addition to providing tree connectivity (that is, tree-walking ) and speeding up object authentication, exrefs are also used to keep track of nonlocal objects when an object is added as a file system or local object trustee, or when an object is added as a member of a group .
NOTE Objects stored in the ExRef partition are called NDS External References objects.