Which OSI layer is described as controlling when computers transmit, detecting and correcting transmission errors, identifying the start and end of a message, and managing physical transmission?

Which OSI layer is described as controlling when computers transmit, detecting and correcting transmission errors, identifying the start and end of a message, and managing physical transmission?

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

Answer: (A)

Data Link layer is responsible for how data moves across a single link between two devices. It governs when a device can transmit on a shared medium (media access control), it frames the data so there are clear start and end boundaries for each message, and it provides error detection (and, in some protocols, basic error correction) for frames as they travel across the link. All of these together ensure reliable communication on the local link without getting into the raw signaling details. The Physical layer handles the actual electrical or optical signaling and the physical transmission itself, not framing or error detection. The Network layer deals with routing and addressing across networks, and the Transport layer handles end-to-end reliability and flow control.

Data Link layer is responsible for how data moves across a single link between two devices. It governs when a device can transmit on a shared medium (media access control), it frames the data so there are clear start and end boundaries for each message, and it provides error detection (and, in some protocols, basic error correction) for frames as they travel across the link. All of these together ensure reliable communication on the local link without getting into the raw signaling details.

The Physical layer handles the actual electrical or optical signaling and the physical transmission itself, not framing or error detection. The Network layer deals with routing and addressing across networks, and the Transport layer handles end-to-end reliability and flow control.