What does a MAC address signify in networking?

A MAC address signifies a unique identifier for devices on a network. It stands for Media Access Control address and is used to distinguish each device connected to a network. This unique identifier is essential for network communication, as it allows devices to identify each other at the data link layer of the OSI model. MAC addresses are typically assigned by the hardware manufacturer and are embedded into the device's network interface card (NIC), ensuring that no two devices on the same local network have the same MAC address, facilitating accurate data delivery.

The other choices describe characteristics or metrics that relate to networking but do not accurately represent what a MAC address does. For instance, the maximum allowed bandwidth pertains to a device's data transmission capabilities rather than identification. Similarly, the number of devices connected to a router is a count of active connections, and a protocol for data transmission describes rules for transmitting data without focusing on individual device identifiers.