TCP client P successfully establishes a connection to TCP server Q. Let NP denote the sequence number in the SYN sent from P to Q. Let NQ denote the acknowledgement number in the SYN ACK from Q to P. Which of the following statements is/are CORRECT? A) The sequence number NP is chosen randomly by P B) The sequence number NP is always 0 for a new connection C) The acknowledgement number NQ is equal to NP D) The acknowledgement number NQ is equal to NP + 1

Official answer: A) The sequence number NP is chosen randomly by P; D) The acknowledgement number NQ is equal to NP + 1. Explanation: During the TCP 3-way handshake: 1. Initial Sequence Number (ISN): The initial sequence number NP is chosen dynamically/randomly (often using a clock-based or pseudo-random algorithm) by client P to prevent sequence number prediction attacks and avoid confusion with old duplicate packets from previous connections. Hence, NP is not always 0. Thus, (A) is correct and (B) is incorrect. 2. SYN Packet Consumption: A TCP segment with the `SYN` flag set consumes one logical sequence number (even though it carries no user data). 3. Acknowledgement Number: The server acknowledges the receipt of the SYN by sending a `SYN+ACK` segment with an acknowledgement field containing the next expected sequence number from client P, which is NP + 1. Thus, NQ = NP + 1. Hence, (D) is correct and (C) is incorrect. Therefore, statements (A) and (D) are correct.

A) The sequence number NP is chosen randomly by P

B) The sequence number NP is always 0 for a new connection

C) The acknowledgement number NQ is equal to NP

D) The acknowledgement number NQ is equal to NP + 1

Computer Networks · TCP Flow and Congestion Control

Official IIT answer key · IISc Bangalore · Audited Aug 2026

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GATE CSE 2024 Set 1 Q29 · MSQ · 1 mark

TCP client P successfully establishes a connection to TCP server Q. Let $N_P$ denote the sequence number in the SYN sent from P to Q. Let $N_Q$ denote the acknowledgement number in the SYN ACK from Q to P. Which of the following statements is/are CORRECT?

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TCP Flow and Congestion Control

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How GATE tests TCP Flow and Congestion Control

GATE CS tests TCP across three primary areas: congestion control dynamics (window growth phases, timeout recovery, and round-by-round segment tracking), sequence number wrap-around time and bit-budget calculations against MSL, and connection lifecycle mechanics (3-way handshake flags, state transitions during active/passive close, and crash recovery with RST segments). Questions are balanced between computational NATs involving RTTs and discrete bit math, and conceptual MSQ/MCQs focusing on byte-stream mechanics, piggybacking, and RFC 793 protocol invariants.

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Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.

Computer Networks · TCP Flow and Congestion Control

Official IIT answer key · IISc Bangalore · Audited Aug 2026

Take topic test

GATE CSE 2024 Set 1 Q29 · MSQ · 1 mark

TCP client P successfully establishes a connection to TCP server Q. Let $N_P$ denote the sequence number in the SYN sent from P to Q. Let $N_Q$ denote the acknowledgement number in the SYN ACK from Q to P. Which of the following statements is/are CORRECT?

Select one or more options

Key concept

TCP Flow and Congestion Control

Step-by-step verified solution

Examiner trap & misconception

Topic notes

How GATE tests TCP Flow and Congestion Control

Full TCP Flow and Congestion Control guide →

More on TCP Flow and Congestion Control

All 23 questions on TCP Flow and Congestion Control →

Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.

TCP client P successfully establishes a connection to TCP server Q. Let $N_P$ denote the sequence number in the SYN sent from P to Q. Let $N_Q$ denote the acknowledgement number in the SYN ACK from Q to P. Which of the following statements is/are CORRECT?

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TCP client P successfully establishes a connection to TCP server Q. Let $N_P$ denote the sequence number in the SYN sent from P to Q. Let $N_Q$ denote the acknowledgement number in the SYN ACK from Q to P. Which of the following statements is/are CORRECT?

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TCP client P successfully establishes a connection to TCP server Q. Let NPN_PNP​ denote the sequence number in the SYN sent from P to Q. Let NQN_QNQ​ denote the acknowledgement number in the SYN ACK from Q to P. Which of the following statements is/are CORRECT?

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TCP client P successfully establishes a connection to TCP server Q. Let NPN_PNP​ denote the sequence number in the SYN sent from P to Q. Let NQN_QNQ​ denote the acknowledgement number in the SYN ACK from Q to P. Which of the following statements is/are CORRECT?

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TCP client P successfully establishes a connection to TCP server Q. Let $N_P$ denote the sequence number in the SYN sent from P to Q. Let $N_Q$ denote the acknowledgement number in the SYN ACK from Q to P. Which of the following statements is/are CORRECT?

TCP client P successfully establishes a connection to TCP server Q. Let $N_P$ denote the sequence number in the SYN sent from P to Q. Let $N_Q$ denote the acknowledgement number in the SYN ACK from Q to P. Which of the following statements is/are CORRECT?