GATE | Gate IT 2008 | Question 67

The three way handshake for TCP connection establishment is shown below.

Which of the following statements are TRUE?
(S1) Loss of SYN + ACK from the server will not establish a connection
(S2) Loss of ACK from the client cannot establish the connection
(S3) The server moves LISTEN → SYN_RCVD → SYN_SENT → ESTABLISHED in the state machine on no packet loss

(S4) The server moves LISTEN → SYN_RCVD → ESTABLISHED in the state machine on no packet loss.

(A) S2 and S3 only
(B) S1 and S4
(C) S1 and S3
(D) S2 and S4

Answer: (B)

Explanation: Before Three Way Hand Shake both client and server are in closed state for start sending or receiving both client and server comes in Listen state.


1) Client sent SYN packet which will be received by the server.
2) Server will SYN + ACK packet so as to establish the connection of client. Now Client is ready to send the data.
3) Then Client will send ACK packet to server when this packet is received by server the server will also be in established state.

Loss of SYN + ACK will not result in connection establishment of Client and thus it will not be able to send data to server.

While ACK from client is not necessary because if client will send data packet immediately, it will considered as acknowledgement for the server .

This explanation has been contributed by Abhishek Kumar.

Quiz of this Question

My Personal Notes arrow_drop_up
Article Tags :


Please write to us at to report any issue with the above content.