Final answer:
The FCS field in a data link layer frame enables error detection in data transmission.
Step-by-step explanation:
The last field in a data link layer frame is called the FCS (Frame Check Sequence) field. Its function is to enable error detection in the transmission of data.
The FCS field is used to detect errors that may occur during the transmission of the frame over the network. It contains a checksum value that is calculated based on the content of the frame.
When the frame is received, the FCS field is recalculated and compared to the checksum value. If they match, it indicates that the frame was transmitted without errors. If they do not match, it indicates that there was a transmission error, and the frame is discarded.