Internetwork
Work is an Internet connection between two or more different networks or network segments via a common technology for routing. The result is called Internetwork (often shortened to internet). Two or more networks or network segments connected using devices that operate at layer 3 (layer “network”) of the Open Society Institute, the basic model, such as a router. Any connection between or among public, private, commercial, industrial or governmental networks may be defined as an Internetwork.
In current practice, interconnected networks using Internet Protocol. There are at least three versions of the Internet works, depending on who administers and who participates in them:
* Intranet
* Extranet
* Internet
Intranets and extranets may or may not have an Internet connection. When connected to the Internet, intranet or extranet is normally protected against access from the Internet without proper authorization. The Internet is not considered part of an intranet or extranet, although it may serve as a portal for access to parts of the extranet.
Intranet
Intranet is a collection of networks using Internet protocol and IP-based tools such as Web browsers and applications files, which are under the control of an administrative organ transfer. This unit closes the intranet to all but specific, authorized users. Usually, an intranet is the internal network of the organization. Large intranet usually has at least one Web server for users of organizational information.
Extranet
Extranet is a network or internetwork, is limited to a single organization or entity, but also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities (eg customers of the company may be provides access to a portion of its intranet creating in this way an extranet, while customers can not be regarded as “trust” in terms of security). Technically, an extranet can be categorized as a box, MAN, WAN, or other type of network, although by definition an extranet existence of a local network, it at least one network connection to the outside world.
Computer-network 