Three-way handshake in Computer Networks - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of the Three-way Handshake

What is the main purpose of the three-way handshake in TCP connections?

A To encrypt data before transmission to ensure security

B To establish a reliable connection by synchronizing sequence numbers between client and server

C To check the bandwidth availability between two hosts

D To immediately transfer data without any delay

💡 Hint

Think about what needs to happen before data can be sent reliably.

The three-way handshake is used to establish a reliable connection by synchronizing sequence numbers and confirming both sides are ready to communicate.

📋 Factual

intermediate

Sequence of Messages in Three-way Handshake

Which sequence correctly represents the three messages exchanged during the TCP three-way handshake?

A ACK, ACK, SYN

B ACK, SYN, SYN-ACK

C SYN-ACK, SYN, ACK

D SYN, SYN-ACK, ACK

💡 Hint

The first message initiates the connection.

The client sends SYN to start, server replies with SYN-ACK, and client responds with ACK to complete the handshake.

🔍 Analysis

advanced

Impact of Missing Final ACK in Three-way Handshake

What happens if the final ACK message from the client is lost during the three-way handshake?

A The client will close the connection immediately

B The connection is immediately established without any issues

C The server will retransmit SYN-ACK and wait until it receives the ACK to establish the connection

D The server will send data without waiting for the ACK

💡 Hint

Consider how TCP ensures reliability in message delivery.

If the final ACK is lost, the server retransmits SYN-ACK and waits for the ACK to confirm the connection before proceeding.

❓ Comparison

advanced

Difference Between Three-way Handshake and Four-way Handshake

Which statement correctly distinguishes the TCP three-way handshake from the four-way handshake used in connection termination?

A The three-way handshake establishes a connection, while the four-way handshake gracefully closes it

B The four-way handshake is faster and replaces the three-way handshake in modern TCP

C Both handshakes are used to establish connections but differ in encryption methods

D The three-way handshake is used only for UDP connections

💡 Hint

Think about connection setup versus connection teardown.

The three-way handshake is for starting a TCP connection; the four-way handshake is for closing it properly.

❓ Reasoning

expert

Why is the Three-way Handshake Considered Reliable?

Why does the TCP three-way handshake provide a reliable way to establish a connection over an unreliable network?

A Because it uses acknowledgments and sequence numbers to confirm both sides are ready and synchronized

B Because it encrypts all messages to prevent data loss

C Because it sends data multiple times regardless of acknowledgments

D Because it uses UDP packets which are faster and more reliable

💡 Hint

Consider how TCP handles message loss and ordering.

The handshake uses sequence numbers and acknowledgments to ensure both sides agree on connection parameters, making the connection reliable despite network issues.