How does the FCS detect errors in the Ethernet frame?

The correct answer highlights that the receiver compares results using a complex math formula, often involving a cyclic redundancy check (CRC). When an Ethernet frame is created, a Frame Check Sequence (FCS) is generated based on the content of the frame using this formula. This FCS value is then appended to the end of the frame. Upon receiving the frame, the receiving device calculates its own FCS value from the received data and compares it with the FCS value included in the frame.

If the two values match, it indicates that the frame was likely received without errors. However, if there is a mismatch, it suggests that the frame has suffered errors during transmission, prompting the receiver to discard the frame or request a retransmission if necessary. This error-detection mechanism is critical for maintaining the integrity and reliability of data communication in Ethernet networks.