The MAC (Media Access Control) address is a unique address assigned to the network interface cards installed on computer systems.
IP addresses are used for communication globally, but MAC addresses are used for communication within a physically local network segment.
MAC addresses are embedded into the ROM (read-only memory) of the network card by the card’s manufacturer.
MAC addresses are also known as hardware addresses and are sometimes also referred to as the “physical address” of the system.
MAC address naming conventions follow the IEEE guidelines. A MAC address is a group of 6 hexadecimal numbers. These hexadecimal numbers can be separated by colons ( : ) or hyphens ( – ).
Some examples of MAC addresses are 04:43:AF:C4:3D:5F or 04-43-AF-C4-3D-5F. Systems that want to communicate to the systems within the local network need to obtain the network address of that system.
If the system wants to communicate to a device that is beyond the local address of the system, the system would ask for the MAC address of the upstream router to get the packet out of the local network and onto the public network.
The ARP (address resolution protocol) allows a system to find out the MAC address of the system based on a known IP address. All networking protocols and methodologies use MAC addresses. Some of the technologies that use MAC addresses are:
- Ethernet
- 802.11 (wireless networks)
- Bluetooth
- IEEE 802.5 Token ring
- FDDI
- ATM
- Firewire
- IPv6
If a MAC address is burned onto the network interface card, then it is also known as a burned-in address.