Which OSI layer is primarily responsible for end-to-end communication and error recovery?

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

Answer: (C)

End-to-end communication and error recovery are handled by the Transport layer. This layer provides reliable data transfer between processes on different hosts, handling segmentation and reassembly, flow control, and mechanisms for detecting and correcting errors such as acknowledgments and retransmissions. It enables end-to-end delivery across multiple networks and paths, abstracting those details away from the applications.

The network layer is focused on routing data between hosts across networks and does not guarantee end-to-end reliability. The data link layer manages error detection and control on a single link between two nodes, not across an entire path. The physical layer deals with the actual signaling and transmission medium, with no concept of end-to-end reliability. Therefore, the transport layer is the one primarily responsible for end-to-end communication and error recovery.