What is the size of the Frame Check Sequence (FCS) in an Ethernet trailer?

The Frame Check Sequence (FCS) provides error detection for Ethernet frames by allowing the receiving device to verify the integrity of the transmitted data. In Ethernet frames, the FCS is included in the trailer of the frame and is always 4 bytes in size. This is a standard size used to perform the cyclic redundancy check (CRC) calculation, which helps ensure that any errors introduced during transmission can be detected by the receiving device.

When an Ethernet frame is transmitted, the sender computes the FCS based on the content of the frame and appends it to the end. Upon receiving the frame, the recipient calculates the FCS again to see if it matches the value in the trailer. If the values do not match, it indicates that the frame may have been corrupted during transmission, allowing for this error detection functionality to maintain data integrity in the network.