What does the Data Link layer use to identify devices on the Physical layer?

The Data Link layer uses MAC (Media Access Control) addresses to identify devices on the Physical layer. This is essential for enabling communication between devices on the same local network segment. MAC addresses are unique identifiers assigned to network interfaces for communications at the Data Link layer, allowing devices to recognize each other and facilitate the transmission of frames containing data.

While IP addresses are used at the Network layer to route packets between different networks, they do not directly identify devices on a local physical network. TCP ports operate at the Transport layer to facilitate communication between applications on devices, and URLs serve as human-readable addresses that map to specific resources on the internet, not as identifiers for the hardware itself. Thus, the use of MAC addresses is crucial for addressing and controlling access to the network at the Data Link layer.