Which layer in the OSI model does Ethernet primarily operate?

Ethernet primarily operates at the Data Link Layer of the OSI model. This layer is responsible for node-to-node data transfer and error detection and correction. Specifically, Ethernet manages the framing of data packets, addressing through MAC (Media Access Control) addresses, and access control to the physical medium using protocols like CSMA/CD (Carrier Sense Multiple Access with Collision Detection).

Choosing the Physical Layer indicates a misunderstanding of where Ethernet's functionalities lie. While Ethernet does involve the physical transmission of data (which is handled in the Physical Layer), its key characteristics—like framing, addressing, and error management—are defined at the Data Link Layer. Additionally, the Data Link Layer encapsulates the requirements needed for layers above it (such as the Network Layer), while the Physical Layer deals with the actual transmission over physical media (like cables). Therefore, acknowledging Ethernet's operation at the Data Link Layer is essential for a foundational understanding of networking.