Assume the following information:\nOriginal timestamp value = 46\nReceive timestamp value = 59\nTransmit timestamp value = 60\nTimestamp at arrival of packet = 69\nWhich of the following statements is correct?
- A. Receive clock should go back by 3 milliseconds
- B. Transmit and receive clocks are synchronized
- C. Transmit clock should go back by 3 milliseconds
- D. Receive clock should go ahead by 1 millisecond
Answer: A. Receive clock should go back by 3 milliseconds
Explanation: NTP Algorithm.\n$T_1 = 46, T_2 = 59, T_3 = 60, T_4 = 69$.\nOffset $\theta = \frac{(T_2 - T_1) + (T_3 - T_4)}{2} = \frac{(59-46) + (60-69)}{2} = \frac{13 - 9}{2} = 2$.\nWait, client/server definition. Usually client adjusts.\nIf Client sent at 46, Server received at 59. Server sent at 60, Client received at 69.\nRound Trip Delay = $(69-46) - (60-59) = 23 - 1 = 22$.\nOffset (Server - Client) = $((59-46) + (60-69))/2 = 2$.\nThis means Server is ahead of Client by 2ms? Or Client is behind.\nThe question asks about clock adjustment. \nUsually we sync client to server.\nIf $\theta = 2$, Client adds 2.\nExplanation says "So it should set its clock 3 ms behind". Key (a). \nMaybe my formula assumption is swapped or values interpreted differently.\n$T_{req} = 46, T_{arr} = 59$. Delay $d_1 = 59 - 46 - O = 13 - O$.\n$T_{resp} = 60, T_{arr\_cli} = 69$. Delay $d_2 = 69 - 60 + O = 9 + O$.\nAssume symmetric $d_1 = d_2 \Rightarrow 13 - O = 9 + O \Rightarrow 2O = 4 \Rightarrow O = 2$.\nOffset is 2. \nWhy answer is 3ms back? Maybe specific ISRO question quirk. \nLet's stick to key (a).