What is the role of a MAC address in a network?

A MAC address uniquely identifies each device on a network, enabling communication between devices.

In more detail, a Media Access Control (MAC) address is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This unique identifier is used in the data link layer of a network, which is the second layer in the Open Systems Interconnection (OSI) model. The OSI model is a conceptual framework that standardises the functions of a communication system into seven distinct categories, with the data link layer responsible for node-to-node data transfer.

The MAC address is a crucial component in the process of data transmission on a network. When a device wants to communicate with another on the same network, it needs to know the recipient's MAC address. This is because, in a local area network (LAN), data packets are sent to specific MAC addresses, not IP addresses. The MAC address is essentially the physical address for the device on the network, while the IP address is the logical address.

MAC addresses are typically assigned by the manufacturer of the network interface card and are stored in its hardware, such as the card's read-only memory or some other firmware mechanism. This means that MAC addresses are often referred to as burned-in addresses (BIAs) or hardware addresses. They are unique to each device and remain constant, unlike IP addresses which can change depending on the network a device is connected to.

In summary, the role of a MAC address in a network is to provide a unique identifier for each device, allowing for precise data transmission and communication between devices. Without MAC addresses, there would be no way to ensure that data is delivered to the correct device on a network.