Apple Mac OS X Server (Administrator’s Guide) - Manual (Page 79)

Directory Services 79
Two-Level Hierarchies
The simplest hierarchy is a two-level hierarchy:
Here’s a scenario in which a two-level hierarchy might be used:
Each department (English, Math, Science) has its own computer. The students in each
department are defined as users in the local domain of that department’s computer. All three
of these local domains have the same shared domain, in which all the instructors are defined.
Instructors, as members of the shared domain, can use services on all the departmental
computers. The members of each local domain can only use services on the server where
their local domain resides.
Shared
directory domain
Local directory
domain
Local domain on
English department’s
computer
Local domain on
Math department’s
computer
Local domain on
Science department’s
computer
Shared domain