Consider the three-way hand shaking process followed during TCP connection establishment between two hosts A and B. Let S and R be two random 32-bit starting sequence numbers chosen by A and B, respectively. Suppose A sends a TCP segment having SYN bit =1, SEQ number = S and ACK bit = 0 and B accepts the connection request.
Which one of the following choices represents the information present in the TCP segment header that is sent by B to A?

Correct option is C

In the TCP three-way handshake, two hosts (A and B) establish a connection by following these steps:
1. Step 1 (SYN): Host A initiates the connection by sending a segment with the SYN flag set to 1, a randomly chosen sequence number SSS, and an ACK flag set to 0.
2. Step 2 (SYN-ACK): Host B, upon receiving the SYN request from A, responds by sending a segment with:
· SYN = 1 to acknowledge the SYN from A.
· SEQ = R, where R is a randomly chosen sequence number by B.
· ACK = 1 to confirm receipt of A's SYN segment.
· ACK Number = S + 1 to acknowledge the sequence number from A.
· FIN = 0 since this is a connection establishment, not a termination.
3. Step 3 (ACK): Host A responds by sending an ACK to confirm the connection.
Information Booster:
· SYN Flag: Used to initiate a TCP connection.
· SEQ Number: This is a unique identifier to synchronize the sequence.
· ACK Number: Increments the received SEQ number by 1 to confirm successful receipt.
· FIN Flag: Used to indicate the termination of the connection.
Additional Knowledge:
· Option (a) is incorrect because ACK = 0 is set incorrectly; ACK should be 1 for B to confirm receipt.
· Option (b) sets SYN = 0, which would not establish a connection.
· Option (d) has ACK Number = S, which does not acknowledge A's sequence correctly.