Which show command indicates frames that failed their error check in the Ethernet FCS trailer?

The chosen answer is correct because the CRC (Cyclic Redundancy Check) is a method used to detect errors in data frames transmitted over a network. In Ethernet frames, the FCS (Frame Check Sequence) trailer contains the CRC value, which is a checksum used to verify the integrity of the data.

When a frame is received, the receiving device calculates its own CRC based on the data it has received and compares it to the CRC value contained in the FCS trailer. If the two values do not match, it indicates that there was an error during transmission, and thus, the frame has failed its error check. This is often referred to as a "CRC error."

The other options, while related to frame characteristics, do not specifically address failure checks based on the FCS trailer. Giants refer to frames that exceed the maximum size allowed for Ethernet frames, while runts are frames that are smaller than the minimum frame size. The term "frame," as an option, does not pinpoint a specific measurement or type of error detection related to the error-checking process.