MAC ( Media Access Control) is also know as Physical Address or Hardware Address or Burnt-in-Address. In network device MAC address is present on NIC (Network Interface card). It is globally unique; it means two devices cannot have the same MAC address. It is represented in a hexadecimal format on each device, such as 00:0a:95:9d:67:16. It is 12-digit, and 48 bits long, out of which the first 24 bits are used for OUI(Organization Unique Identifier), and 24 bits are for NIC/vendor-specific. It works on the data link layer of the OSI model. It is provided by the device’s vendor at the time of manufacturing and embedded in its NIC, which is ideally cannot be changed. The ARP protocol is used to associate a logical address with a physical or MAC address.