NAKs

NAKs, or Negative Acknowledgments, are a type of control character used in data communication protocols to indicate that a received data frame or packet has errors or is otherwise unacceptable. They are typically used in synchronous data link control (SDLC) and High-level Data Link Control (HDLC) protocols. When a receiving device detects an error in a data frame, it sends a NAK to the transmitting device, prompting it to retransmit the frame. This mechanism is crucial for ensuring data integrity and reliability in communication systems. NAKs are distinct from ACKs (Acknowledgments), which indicate successful receipt of data. The use of NAKs helps in error recovery and maintains the accuracy of transmitted data.