etwork) A communications network that is confined to a building or building complex. A LAN is a local network, whereas a WAN is a wide area network that spans long distances (see WAN
). A wireless router generally has four or more LAN ports that create a small local network in the home or office (see wireless router
The "clients" in a LAN are the user's computers running Windows, Mac or Linux, while the "servers" hold programs and data shared by the clients. Servers come in a wide range of sizes from PCs to mainframes (see server
). The Internet hosts millions of them.
Data transfer over a LAN is managed by the TCP/IP transport protocol, and the physical transmission by cable is Ethernet. Mobile devices are connected by Wi-Fi, Ethernet's wireless counterpart. See twisted pair
, optical fiber
Thick and Thin Clients
In a company LAN, the client machines are typically Windows or Mac, possibly some Linux, and each platform has many installed applications. These "thick" clients are the norm; however, some organizations use "thin" clients, whereby their PCs function like terminals to a server (see Remote Desktop Services
). See thin client
The Network OS
The software that enables sharing between machines is the network operating system, typically Linux, Windows or Unix. The network OS is in the servers with a component in each client, allowing each to access files from each other. Folders must be made "sharable" for file transfers to work.
Clients and Servers in a LAN
This shows the private employee-facing side and the public-facing site. In large companies, multiple servers are used for each type of service. Today, it is uncommon to see a remote access server for dial-up connections.
Software in a Network Client
Software in a Network Server
These are examples of common applications found in a user's machine. Printers may be connected to clients or servers wired or wireless (see print server
These are the common services in a network server.