What is the function of the CRC value in the FCS field of a frame?

• A. to verify the integrity of the received frame
• B. to verify the physical address in the frame
• C. to verify the logical address in the frame
• D. to compute the checksum header for the data field in the frame

Answer: (A)

The function of the CRC value in the FCS field is to detect errors that may have occurred during transmission, ensuring the frame’s data integrity. The sender computes a CRC over most of the frame (header and payload) and places the resulting value in the FCS. The receiver then recomputes the CRC on the received frame and compares it to the FCS. If they match, the frame is considered intact; if they don’t, the frame is discarded or flagged for error handling. This mechanism can catch common error patterns, including many burst errors, and is not used to verify a specific address.