Wide-Area Networfth • .Data communications networks differ in so many respects that each specific network may be unique. Nevertheless, they can be classified in terms of service areas and basic hardware/software architectures. With respect to service ar-
eas, networks may be classified as wide-area and local-area. A wide-area network (WAN) is formed among computers and interconnected devices that are geographi-
cally distant from one another. Two wide-area network architectures are centralized networks and distributed networks.
A centralized WAN concentrates all application processing at one geographical
location. It consists essentially of one central mainframe computer (or a cluster of
centrally located computers), as well as one or more physically remote terminals and