Study guides
Computer Networks
2 guides for this subject — how to prepare, what to practise, and how to know it has gone in.
A spoken answer, marked
An examiner's question, answered out loud and marked criterion by criterion. From Computer Networks Viva Questions: A Practical Practice Guide.
Examiner
Explain the TCP three-way handshake and how TCP provides reliable delivery after the connection is established.
You correctly described SYN, SYN-ACK and the final ACK, and you linked acknowledgements to sequence numbers.
ImproveState that the handshake synchronises each endpoint's initial sequence number and confirms bidirectional reachability.
The normal exchange was in order, but reliability mechanisms were introduced before the handshake had been closed.
ImproveUse a clear sequence: handshake, byte numbering, acknowledgements, retransmission and congestion control.
You used a lost-segment example, but did not show what the receiver acknowledges when a segment arrives out of order.
ImproveExplain that duplicate cumulative ACKs can signal a missing earlier segment, contributing to fast retransmit.
You mentioned retransmission delay but did not distinguish congestion control from reliability.
ImproveAdd that retransmission repairs loss, while congestion control limits sending to avoid worsening congestion; neither encrypts the payload.
A strong answerThe client sends a SYN containing its initial sequence number, and the server replies with a SYN-ACK containing its own initial sequence number and an acknowledgement of the client’s SYN. The client sends an ACK, so both sides have confirmed the initial sequence numbers and the connection is established. TCP then numbers bytes, acknowledges received data and retransmits data when an acknowledgement does not arrive within the retransmission timeout; duplicate cumulative ACKs can also support fast retransmit. Its congestion-control algorithms adjust the sending rate, but TCP itself does not provide encryption or peer authentication; TLS is used above it for those properties.
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Guides
- How to Study Computer Networks: A Practical GuideA practical method for learning computer networks, from subnetting and packet flow to active recall, troubleshooting and exam-style practice.
- Computer Networks Viva Questions: A Practical Practice GuidePractise computer networks viva questions with realistic stations on TCP, subnetting, DNS, routing and network troubleshooting.
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