What is MAC address/Burned In Addressses(BIA)/Ethernet addresses?

A MAC (Medium Access Control) addresses refers to hardware addresses or physical addresses, which is a unique value assigned to network adapters on LAN at the time of manufacture. Hence, these addresses are sometimes known as 'Burned In Addresses' (BIA). Since these addresses are created in the Ethernet specification they are also known as 'Ethernet addresses'. If a MAC address is assigned by the manufacturer it helps in encoding the manufacturers registered identification number. MAC addresses are also used to identify each node distinctly in a network. They are available on the data link layer of the OSI mode. The data link layer comprises two sublayers i.e., MAC and LLC (Logical Link Control). The MAC layer communicates directly with the network medium. As a result a distinct MAC sublayer exists for every distinct type of network medium.

A remote access to the internet from a local computer results in the creation of a table on LAN that relates IP address and MAC address of local computer. The MAC sub layer has the capability of controlling the way with which a network node accesses and transmits the data. A MAC address is used by the following technologies like Ethernet, 802.11, Bluetooth, Token ring, FDDI, SCSI, ATM and Fiber channel.

MAC addresses are 48 bits long and are represented as 12 digit hexadecimal number separated by colons (:) or hyphens (-). The format of MAC address is follows,

AA:AA:AA:BB:BB:BB (or)

AA-AA-AA-BB-BB-BB

The first half i.e., AA:AA:AA/AA-AA-AX specifies the ID of the adapter's manufacturer and the second half i.e., BB:BB:BB/BB-BB-BB specifies the serial number associated with the adapter. This serial number is assigned by the manufacturer to the adapter.

To formulate a MAC address, three numbering systems such as MAC-48, EUI-48 and EUI-64 are commonly used. These numbering systems are managed by the IEEE (Institute of Electrical and Electronics Engineer) standard. Although, MAC address refers to a permanent and unique identification number, its value can be changed. This action of changing the MAC address is usually known as MAC spoofing. There is a difference between MAC spoofing and IP spoofing. In IP address spoofing, when a sender spoofs its address in a request the response is received by an unintended entity, whereas, in MAC address spoofing, the response is received by the spoofing party. Using MAC address, the location of a host cannot be determined.

The communication between subnet MAC address and IP address in TCP/IP suite can be made possible using IPv4 or IPv6 internet protocol versions. IPv4 uses Neighbour Discovery Protocol (NDP), whereas IPv6 uses Address Resolution Protocol (ARP) for enabling such communication. In broadcast networks like Ethernet, MAC address is used to identify each node in the network and to assign frames for some particular hosts. Thus, most of the link layer protocols, upon which upper layer protocols rely, use this address so as to produce complex functioning networks.

To check MAC adress:

• Open Start menu and open cmd
•  Then type ipconfig/all and press enter
• There you can find your MAC address.

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