VIRTUAL PRIVATE NETWORK

                                                           A virtual private network  is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network, such as the Internet, as opposed to running across a single private network.One common application is to secure communications through the public Internet, but a VPN does not need to have explicit security features such as authentication or content encryption.It is used by the strong security so that no hackers can interpret the data or the information.VPN service providers may offer best-effort performance.Wide Area Network  links from a telecommunications service provider interconnected network nodes within a single enterprise. WAN are network is mainly used for the one organisation to other organisation so the data transfer must be good so that they used wide area network.When an enterprise interconnects a set of nodes  all under its administrative control through a LAN network  that is termed an intranet.A Layer 2 technique that allows for the coexistence of multiple LAN broadcast domains, interconnected via trunks using the IEEE 802.1Q trunking protocol.So that we are using the VPN for security purpose mainly used for the protecting the data from the unauthorised users.