In computing, a file system or filesystem is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. File systems may use a data storage device such as a hard disk or CD-ROM and involve maintaining the physical location of the files, they might provide access to data on a file server by acting as clients for a network protocol, or they may be virtual and exist only as an access method for virtual data. The most familiar file systems make use of an underlying data storage device that offers access to an array of fixed-size blocks, sometimes called sectors, generally a power of 2 in size. The file system software is responsible for organizing these sectors into files and directories, and keeping track of which sectors belong to which file and which are not being used.

Distance-vector routing protocol is one of the two major classes of routing protocols used in packet-switched networks for computer communications, the other major class being the link-state protocol. A routing protocol is a protocol that specifies how routers communicate with each other to disseminate information that allows them to select routes between any two nodes on a network. In telecommunication, a store-and-forward switching center is a message switching center in which a message is accepted from the originating user, i.e., sender, when it is offered, held in a physical storage, and forwarded to the destination user, i.e., receiver, in accordance with the priority placed upon the message by the originating user and the availability of an outgoing channel. A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires.