Each OSI layer contain a set of functions performed by programs to enable data to travel from a source to a destination on a network. In this article I will provide brief descriptions of each layer in the OSI reference model. Application Layer The application layer is the OSI layer that is closest to the user. This layer provides network services to the user's applications. It differs from the other layers in that it does not provide services to any other OSI layer, but only to applications outside the OSI reference model. Applications layer provide a platform to access the data of remote computer. The application layer protocols that you should know are as follows: SNMP (Simple Network Management Protocol)— Communicates status and allows control of networked devices. TFTP (Trivial File Transfer Protocol)— Simple, lightweight file transfer. DNS (Domain Naming System)— Translates a website name (easy for people) to an IP address (easy for computers)....