Which layer controls the way messages are sent on the physical media and manages framing, error control, and media access?

• A. Physical Layer
• B. Data Link Layer
• C. Network Layer
• D. Transport Layer

Answer: (B)

The Data Link Layer is in charge of moving data across a single link between two directly connected nodes. It handles framing, which means it packages network-layer data into frames with addresses and control information. It provides error detection within those frames (using a frame check sequence) to notice if something went wrong on the link. It also governs how devices access the shared medium, using MAC protocols to decide who can transmit and when. This layer sits between the Physical Layer, which actually sends the raw bits, and the Network Layer, which handles routing across networks. While the Physical Layer focuses on signaling and hardware, and the Network and Transport Layers handle end-to-end delivery and routing, the Data Link Layer ties it together on a local link with framing, error detection, and access control.