What is a MAC Address
MAC Address also known as Media Access Control Address is a hardware address or physical address which uniquely identifies each node of the network and is associated with a network adapter. MAC address is a 48 bit or 64 bit address. MAC address uniquely identifies an adapter on a LAN. The Data Link Layer of the OSI model is divided into two layers which are Logical link layer (LLC) and Media Access Control (MAC). MAC layer interfaces directly with network medium or each network medium requires a different MAC layer.
When a user is connected to the internet via his or her workstation, the IP address is related to the computer’s physical address (MAC address) on the LAN. This also helps the routers to send IP packets to the destined system. MAC address is also referred to as Ethernet Address because the MAC addresses originated in the Ethernet specification.
MAC address is stored on the computer’s network card and this address cannot be changed (unlike IP address). It can also be used for connecting several PCs using a Hub. Hub finds certain MAC address and sends information there and a router uses IP Addresses.
The IP Addresses are associated with software whereas the MAC Address is linked to the hardware of network adapters. This is the reason why MAC address is also sometimes called the Hardware address or physical address. These are expresses in hexadecimal notations. These addresses are written into the hardware at the time of manufacture and are therefore also called burned in address (BIA). The MAC address of a device, after manufacture, can be changed in software.
System that wants to communicate with other system within the local network needs to obtain network address of the system whereas if the system wants to communicate to the device which is beyond local address of system, then it needs MAC address.
The MAC address can be located easily. For example, on a PC or a laptop with an integrated network adapter, the user need to find MAC address using software or on a Windows 2000 or Windows XP machine, MAC address can be known by using “IPCONFIG” command on the DOS command prompt.
Thus MAC addresses are also useful for security purposes as they are rarely changed from the default and that too only by the users who have good knowledge about it. MAC addresses are often a more reliable way to identify senders and receivers of network traffic. MAC address filtering is quite popular for preventing unwanted network access on a wireless network.