In OSI networking model Data Link Layer consists of two sublayers: Logic Link Control (LLC) sublayer and Medium Access Control (MAC) sublayer.

One of the responsibilities of the MAC sublayer is to uniquely identify devices connected to the network. The identifiers assigned to machines in the network are known as MAC addresses.

For networks that use Ethernet technology MAC address is the 48 bit number that is burnt into the hardware (NIC or LAN card) of the machine. MAC addresses can be represented in various formats as follows:

• In Linux systems: 94:65:9C:3B:8A:E5
• In Windows: 94-65-9C-3B-8A-E5
• In Cisco: 9465.9C3B.8AE5