Reliable data transfer mechanisms in Computer Networks - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main goal of reliable data transfer mechanisms in networking?

The main goal is to ensure data is delivered accurately and in order, without loss or duplication, despite errors or network issues.

beginner

What does the 'stop-and-wait' protocol do in reliable data transfer?

It sends one data packet and waits for an acknowledgment before sending the next, ensuring each packet is received correctly before proceeding.

intermediate

How does the 'sliding window' protocol improve data transfer efficiency?

It allows multiple packets to be sent before needing an acknowledgment, increasing throughput by using a window of packets that can be sent and acknowledged in sequence.

beginner

What role do acknowledgments (ACKs) play in reliable data transfer?

ACKs confirm receipt of data packets, helping the sender know which packets arrived successfully and which need retransmission.

beginner

Why is retransmission important in reliable data transfer mechanisms?

Retransmission ensures lost or corrupted packets are sent again, so the receiver eventually gets all data correctly.

Which protocol waits for an acknowledgment after sending each packet before sending the next?

A Sliding window

B Stop-and-wait

C UDP

D Broadcast

Stop-and-wait sends one packet and waits for an ACK before sending the next, ensuring reliability.

What does an acknowledgment (ACK) signal in reliable data transfer?

A Sender should stop sending

B Packet was lost

C Packet was received correctly

D Network is down

An ACK tells the sender that the packet arrived correctly and no retransmission is needed.

How does the sliding window protocol increase data transfer speed?

A By sending multiple packets before waiting for ACKs

B By ignoring lost packets

C By sending packets one at a time

D By using smaller packets

Sliding window allows multiple packets to be sent before waiting for acknowledgments, improving throughput.

What happens if a packet is lost during transmission in a reliable data transfer system?

A It is ignored

B The receiver sends a negative acknowledgment

C The connection closes

D It is retransmitted

Lost packets are retransmitted to ensure all data is received correctly.

Which of the following is NOT a feature of reliable data transfer?

A Data encryption

B Error detection

C Acknowledgments

D Retransmission

Data encryption is about security, not reliability; reliable data transfer focuses on error detection, acknowledgments, and retransmission.

Explain how the stop-and-wait protocol ensures reliable data transfer.

Think about how the sender waits before sending more data.

Describe the advantages of the sliding window protocol over stop-and-wait.

Consider how sending more than one packet at once helps speed.