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Brian Cryer's Glossary of IT Terms with Links

MAC Address

MAC address
Media Access Control address. Hardware serial number that uniquely identifies a device on a local area network (commonly a NIC). (Sometimes also referred to as a NIC's "physical address".)

A MAC address is 6 bytes in length (i.e. 48 bits) and is normally written as a 12 digit hexadecimal number, with dashes or colons between each pair of hexadecimal digits. The first three bytes identify the manufacturer and the second three bytes represent a unique serial number generated by that manufacturer. MAC addresses should therefore always be unique (although some cards and switches allow the MAC address to be cloned).

To lookup the MAC address of a device on a local network try:

ping device
arp -a ip-address

For more information see: