CertiGuide to Network+  9  Chapter 0000:  Network Basics

Virtual Private Networks 1 VIII  Network Topologies

In the networking world, people will sometimes describe the boundaries or scope of a network in terms of these concepts.

An internet (or internetwork) is a network of networks, which are connected together to facilitate sharing resources and information among users. The Internet is the most famous of all internetworks, but not the only one.

An intranet is a network that is specific to a single organization. This does not mean that the network resides physically only within the organization – it can include wide area network links that use public networks like the Internet (and VPN technology for security!), as well as the main office’s corporate LAN. The intranet is the network over which the company’s staff shares information and computing resources with each other.

An extranet is a network that allows a business to connect with suppliers, vendors, customers, stockholders or others related to its business. Typically an extranet is run over the Internet, using a VPN for security. A company’s extranet is usually situated around the borders of its intranet, allowing limited access to some corporate resources to those outside the corporation, on a need-to-know basis, and allowing corporate staff to access limited resources on other organizations’ networks.

Virtual Private Networks 1 VIII  Network Topologies