Wide Area Network

A wide area network (WAN) is a computer network that covers a board area.Less formally ,a WAN is a network that uses routers and public communications links.Contrast with personal area networks (PANs) ,local area networks (LANs) metropolitan area networks (MANs),which are usually limited to a room,building,campus or specific metropolitan area (e.g.,acity) respectively.The largest and most well-known example of a WAN is the internet.A WAN is a datacommunications network that coversa relatively broard geographic area(i.e.one city to another and one country to another country) and that often uses transmission facilities provided by common carries, such as telephone companies.WAN technologies generally function at the lower three layersof the lower three layers of the OSI reference model ,the physical layer, the data link layer and thenetwork layer.