A large network is usually made up of hundreds of entities that are physically or logically
connected to one another. These entities have an initial configuration when the network
is set up, but can change with time. Desktop computers may be replaced by others;
application software may be updated to a newer version; and users may move from one
group to another. The configuration management system must know, at any time, the
status of each entity and its relation to other entities. Configuration management can
be divided into two subsystems: reconfiguration and documentation.