Explain the role of a checksum/CRC in the EPD Protocol Pilot.

• A. It ensures encryption of the payload.
• B. It compresses the data.
• C. It authenticates the sender.
• D. It detects data corruption in a frame and enables integrity verification and retransmission if needed.

Answer: (D)

A checksum/CRC is used to verify data integrity for each frame in the communication. The sender computes a CRC from the frame’s data and attaches it to the frame. When the frame arrives, the receiver recalculates the CRC from the received data and compares it to the attached value. If they match, the data is considered intact; if they don’t match, the frame is likely corrupted by noise or interference, and the protocol can request a retransmission or handle the error accordingly. This role is about detecting errors, not hiding content, reducing size, or proving who sent the data. CRCs are fast and good at catching common error patterns, especially burst errors, which makes them well-suited for ensuring reliable transmission in the EPD Protocol Pilot by enabling integrity verification and retransmission when needed.