Media Access Control Address (MAC)

Computers have a unique ID called the MAC address just as people have different names which enable to differentiate and recognize them. This ID is hard-coded in a component called the Network Interface Card (NIC). The NIC is what provides the connection between the computer and the physical medium (cables, optical fibers) of the network. The entire MAC address is not a random creation of numbers and letters, but it is formed based on a conventional standard sequence which even shows the manufacturer of the NIC. A sample MAC address looks like 00-0C-F1-38-87-AD. However in most of the hardware today, MAC spoofing is possible where it is possible to change the MAC address.

Among Repeaters, Bridges, Switches, Routers and Gateways, the Bridges and Switches are internetworking devices which have the capability to examine the MAC address and forward packets to their destination. Switches, being hardware-based, can actually switch packets faster than a bridge and hence are more commonly used these days. Even routers which use a logical IP address for communication, finally uses a protocol (ARP) which enables to convert the destination IP address to the actual MAC address in order to deliver the packet to the correct place.

Any device that is connected to a network will have a MAC address. The printer that shoots out copies of your documents too has a MAC address! Even the routers and switches which are used for the purpose of network transmission have their own MAC address. The source and destination in a communication scenario, in raw terms are really unique MAC addresses in the networking world and not the boxes we see right in front of us!

On most Windows systems, the MAC address can be found using the following steps:
1. Click Start
2. Select Run
3. In the Run dialog, type cmd
4. Click OK.
5. At the DOS prompt, type ipconfig/all
6. Press Enter
The MAC address is represented in the line labelled “Physical Address”.