d to a physical layer but performs functions of both the physical and data link layer. Some of the physical can be of different types like open-wire circuits, twisted pair cables, coaxial cables, or fiber optic cables Physical layer is the lowest layer in the OSI model concerned with data encoding, signaling, transmission, and reception over network devices. Some of the functions of the physical layer are: Encoding: This would involve transformation of data in the form of bits with the device into signals for sending over a physical medium. Hardware specifications: Both the physical and data link layer together detail the operation of network interface cards and cables. Seven-Layer Communication Model Data transport between devices: The physical layer is responsible for trans- mission and reception of data. Network topology design: The topology and physical network design is han- dled by the physical layer. Some of the hardware related issues are caused due to missed configurations in the physical layer. The encoding can result in conversion of data bits to signals of various schemas. Some of the signaling schemas that the physical layer can encode to are: Pulse signaling: Where the zero level represents "logic zero" and any other level can represent "logic one." This signaling schema is also called "return to zero." Level signaling: A predefined level of voltage or current can represent logic one and zero. There is no restriction that zero should be used to represent the logic zero. This schema is also called "non return to zero" Manchester encoding: In this schema "logic one" is represented by a transi- tion in a particular direction in the center of each bit, where an example of transition can be a rising edge. Transition in the opposite direction is used to represent logic 0. Physical layer also determines the utilization of media during data transmission based on signaling. When using "base band signaling" all available frequencies (the entire bandwidth) is used for data transmission. Ethernet mostly uses ba