Which layer in the OSI reference model is the only layer that adds a trailer to the data it transmits?

The Data Link Layer is responsible for adding a trailer to the data it transmits because it is tasked with preparing packets for transmission over a physical medium. This layer encapsulates the data received from the Network Layer into frames that can be sent over the various physical transport media.

The trailer typically includes a Frame Check Sequence (FCS), which is used for error detection. This helps ensure data integrity by allowing the receiving end to check whether the data was transmitted correctly. By placing a trailer at the end of the frame, the Data Link Layer enables the detection of transmission errors that may occur during the physical transfer of data.

Other layers of the OSI model do not add a trailer to their data. The Session Layer, for instance, is concerned with establishing, managing, and terminating sessions between applications, but it does not involve data framing or manage physical transmission. The Network Layer primarily handles routing and addressing packets but focuses on sending data packets rather than encapsulating them with trailers. The Transport Layer is responsible for end-to-end communication and reliability, managing segmentation and reassembly of data but does not add a trailer either.

Thus, it is the Data Link Layer that uniquely adds a trailer to the data, which is essential for maintaining data integrity at the