Data networks are two or more computers that are connected to share information, hardware, programs and so forth. In order to communicate on the network, every computer is required to have a network interface card (NIC), a transmission medium, a Network Operating System (NOS), and a network connectivity device. Data networks can be categorized and labeled according to the geographical area that the network covers.
The four geographically defined networks: a Local Area Network (LAN), a Campus Area Network (CAN), a Metropolitan Area Network (MAN), and a Wide Area Network (WAN). According to the network’s infrastructure, there are three additional network descriptions: the Internet, an Intranet and an Extranet. The most common network definitions are LAN, WAN and the Internet.
Wide Area Networks (WAN)
A Wide Area Network (WAN) is an admixture of physically or logically interconnected subnetwork that incorporates a larger geographic area than LANs and extends across metropolitan, regional, and national boundaries. The differences between WAN and LANs are that WANs cover long distances, have slower speeds, have both on-demand and permanent connectivity. LANs have permanent connections between stations. WANs can use public or private network transports.
Internet, Intranet and Extranet
Internet: The Internet is a TCP/IP-based WAN that was originally planned for the U.S. Department of Defense (DoD). Internet Service Providers (ISPs) connect the global network, both public and private, that comprises the Internet.
Intranet: An intranet is a logical network that utilizes an organization’s internal, physical network infrastructure that extends over large areas. Intranets employ TCP/IP and HTTP standards which are used to activate corporate web sites accessed by all employees on the intranet. This method is more secure and controlled than publishing corporate web sites on the World Wide Web.
Extranet: This shares similarities with the intranet — it’s a private network that uses Internet protocols and can be used to publish corporate web sites. The main difference is users outside of the organization have access to the system, such as business associates.