In data communications, what is the control information appended to the end of a packet by the Data Link layer called?

• A. header
• B. payload
• C. checksum
• D. trailer

Answer: (D)

In the Data Link layer, the information added to the end of a frame to help with error detection and frame integrity is called the trailer. The trailer sits after the payload and typically contains an error-detection code, such as a Frame Check Sequence (CRC). This distinguishes it from the header, which is at the front and carries addressing and control fields, and from the payload, which is the actual data being transmitted. While an error-detection value is a form of checksum, the established term for the end-of-frame information is trailer, since it completes the frame structure at the tail end.