What is a MAC address used for?

A MAC (Media Access Control) address is used to permanently identify a network device on a local network. Every network interface card (NIC) is assigned a unique MAC address that serves as a hardware identifier. This address allows devices to communicate with each other within a network at the data link layer of the OSI model. The permanence of the MAC address is important because it ensures that the device can consistently be recognized by the network, enabling reliable communication.

In a local area network (LAN), switches use MAC addresses to forward data to the correct destination devices. Unlike IP addresses, which can change depending on the network configuration, MAC addresses remain static and are hardcoded into the hardware of the network device. This unique identification is crucial for managing network traffic and ensuring that data packets reach the correct devices without confusion.

The other options describe functions not performed by MAC addresses. For instance, while some identifiers may be temporary, MAC addresses serve a constant purpose in network identification. Additionally, MAC addresses do not handle data encryption or the establishment of security protocols; these functions are managed by higher-level protocols and mechanisms in networking.