1-Describe the 7-layer OSI network reference model. List the 7 components. The 7-layer OSI network reference model delineates a hierarchy of abstract building blocks that provide core protocols and services in a logically separated manner for network standardization (Serpanos and Wolf, 2011; Cowley, 2012; Egyedi, 1997 ). ).The OSI network reference model was developed by the International Organization for Standardization (ISO) to facilitate communication between networks by keeping certain standards open rather than proprietary (Serpanos & Wolf, 2011). Each layer is stacked with the physical layer as the lowest layer and the application layer as the highest and one can think of each layer as containing stacks of protocols that make network communications work (Serpanos & Wolf, 2011). A protocol is a set of rules written in a common language that allows computers to communicate with each other. Each communication network is a node and the corresponding layer on each node communicates with each other. The seven layers, from lowest to highest, are physical, data link control, network, transport, session, presentation, and application. Data travels along the layers on the sending node from the application layer until it reaches the physical layer. At the physical layer, data is transmitted over the physical medium to the physical layer of the receiving node. At this point, the data moves up the layers until it reaches the application layer in a format that the end user can use (Cowley, 2012). Layer 2, the data link control layer, is actually divided into two sublayers, the media access layer. control (MAC) and logistics link control (LLC). This change occurred in the baseline model due to the medium of ......ferent paper platforms (Melendez & Peterson, 1999). The highest layer of the OSI model is the application layer. While all other layers provide a general service to the other layers, the application does not provide any general service to the other layers (Melendez & Peterson, 1999). The application layer handles items that are not covered in any of the lower levels and also handles details specific to distributed applications. Some examples of distributed applications are Hypertext Transfer Protocol (HTTP), Domain Name System (DNS), and Session Initiation Protocol (SIP) (Serpanos & Wolf. 2011). The OSI model refers to the seventh layer as the application layer, but does not specifically include any of the examples mentioned above since the OSI model is abstract. As end users, we use the application layer every time we enter an HTTP URL on our Internet server..