*Question G8C05:
In an ARQ mode, what is meant by a NAK response to a transmitted packet?*  

*Correct Answer is  A: Request retransmission of the packet*  

### AI Response: (may contain errors)  

In an ARQ (Automatic Repeat reQuest) mode, communication involves error detection and correction by requesting retransmission of data packets when errors are detected.

1. **Correct Answer: A - Request retransmission of the packet**

   - A NAK (Negative Acknowledgment) response indicates that the receiving station has detected an error in the transmitted packet. The NAK is a request for the sender to retransmit the packet to ensure accurate data transfer. This is a fundamental part of ARQ protocols, which aim to ensure data integrity by allowing the receiver to request retransmission of corrupted packets.

2. **Why the other choices are incorrect:**

   - **B: Packet was received without error**  
     This would be indicated by an ACK (Acknowledgment) response, not a NAK. An ACK means the packet was received correctly and no retransmission is needed.

   - **C: Receiving station connected and ready for transmissions**  
     This is not related to the NAK response. A NAK specifically deals with error detection in received packets, not the connection status or readiness for transmission.

   - **D: Entire file received correctly**  
     This would typically be indicated by a final ACK or a similar positive acknowledgment, not a NAK. A NAK is used when there is an error in a specific packet, not when the entire file is received correctly.

3. **Useful Concepts:**

   - **ARQ Protocols:**  
     These protocols use both ACK and NAK responses to manage data transmission. ACKs confirm correct receipt, while NAKs request retransmission of erroneous packets.

Understanding the role of NAK in ARQ protocols is crucial for ensuring reliable data communication by allowing error correction through retransmission requests.