The question of administrative subdivisions deals with matters of size and control. The more hosts and servers you have in a network, the more complex your management task. You may wish to handle such situations by setting up additional administrative divisions in the form of more additional networks of a particular class or by dividing existing networks into subnets. The decision as to whether to set up administrative subdivisions for your network hinges on the following factors:
How large is the network?
A single network of several hundred hosts, all in the same physical location and requiring the same administrative services, can be handled by a single administrative division. On the other hand, a network of fewer machines, divided into a number of subnets and physically scattered over an extensive geographic area, would be likely to benefit from the establishment of several administrative subdivisions.
Do users on the network have similar needs?
For example, you may have a network that is confined to a single building and supports a relatively small number of machines. These machines are divided among a number of subnetworks, each supporting groups of users with different needs. Such a case could call for an administrative subdivision for each subnet.
Solaris Naming Administration Guide discusses administrative subdivisions in detail.