Which field is created by a source node to ensure the integrity of a transmitted data signal?

The Frame Check Sequence (FCS) field is crucial for ensuring the integrity of a transmitted data signal. It is a sequence of bits added to the end of a frame that enables the receiving node to check for errors that may have occurred during transmission. This checking is typically done using a cyclic redundancy check (CRC), which is a mathematical algorithm that generates a unique value based on the frame's contents.

When a data frame is sent, the source node computes the FCS value based on the data within the frame and appends it to the frame before transmission. Upon receiving the frame, the destination node performs the same calculation using the received data and compares its computed value to the FCS. If the values match, it indicates that the data has likely been transmitted without errors. Conversely, if there is a mismatch, it suggests that the frame may have been corrupted during transmission, prompting the receiving device to discard the frame and possibly request retransmission.

Understanding the role of the FCS field is essential for networking, as it underpins error detection mechanisms that help maintain data integrity across a network. Other fields mentioned, like the address, control, and data fields, perform different functions and do not specifically focus on ensuring integrity during transmission.