Which of the following are examples of NIC communication protocols at the data link layer?

• A. TCP
• B. IP
• C. Ethernet protocol
• D. UDP

Answer: (C)

At the data link layer, NICs communicate by exchanging frames on the local link, using a protocol that defines how those frames are formatted, addressed, and placed onto the media. Ethernet (IEEE 802.3) is the standard data-link protocol used by NICs on most LANs. It specifies the frame structure, MAC addresses for local delivery, and how frames are transmitted and checked for errors.

The other options operate at higher layers: TCP and UDP are transport-layer protocols that provide end-to-end communication between processes, relying on the network layer (IP) to route packets between hosts. IP is a network-layer protocol that handles logical addressing and routing between networks, not the local framing on a single link. So Ethernet is the NIC data-link layer protocol.