Which OSI layer is responsible for the error-free delivery of data and uses switches and bridges?

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

Answer: (A)

Data Link Layer handles the transfer of data from one device to another on the same network segment. It breaks data into frames, uses MAC addresses to identify devices, and includes error detection so a frame with a corrupted bit can be detected. Switches and bridges operate at this layer, forwarding frames based on MAC addresses and helping ensure the data is delivered to the correct adjacent device without errors on that link. The Physical Layer is about the actual signals on the medium, the Network Layer handles routing between networks, and the Application Layer deals with software and services. End-to-end reliability, if needed, is provided by the Transport Layer, which isn’t about these link-level operations.