Which protocol is commonly used for Layer 2 Protocol Data Units in Ethernet?

The Ethernet II frame is the foundational protocol used for Layer 2 Protocol Data Units (PDUs) in Ethernet networks. Ethernet is a widely accepted standard for networking that operates primarily at the data link layer of the OSI model. An Ethernet II frame structures the encapsulation of data and includes various fields—such as source and destination MAC addresses, type/length field, and the Frame Check Sequence (FCS)—which facilitate effective and reliable communication across Ethernet networks.

The significance of the Ethernet II frame lies in its ability to handle the formatting and addressing of data packets moving through a local area network (LAN). It ensures that these packets are correctly recognized and routed to the intended devices within the network.

Other options such as TCP/IP, Wi-Fi, and Frame Relay serve different purposes. TCP/IP is a suite of protocols used primarily at higher layers for data transmission over the internet, Wi-Fi refers to wireless networking technologies, and Frame Relay is a wide area networking (WAN) technology that encapsulates data for transmission over a shared medium but is not based directly on Ethernet. Therefore, among the provided options, the Ethernet II frame stands out as the correct protocol for Layer 2 PDUs in Ethernet environments.