Which OSI layer is responsible for physical addressing using MAC addresses?

• A. Network Layer (Layer 3)
• B. Data Link Layer (Layer 2)
• C. Physical Layer (Layer 1)
• D. Transport Layer (Layer 4)

Answer: (B)

In networking, identifying devices on the local network uses physical addresses assigned to network interface cards, and this is a function of the Data Link layer. This layer encapsulates data into frames and attaches source and destination MAC addresses, which allow switches to deliver the frame to the correct device on the same local segment. MAC addresses are hardware identifiers tied to NICs and operate within the local broadcast domain.

The other layers don’t handle this kind of addressing: the Physical layer deals with sending raw bits over the medium, not addresses; the Network layer uses logical addresses like IPs for routing across networks; the Transport layer focuses on end-to-end delivery and uses ports rather than hardware addresses.