Which ICMP method queries the target for a timestamp to obtain time information?

Which ICMP method queries the target for a timestamp to obtain time information?

• A. ICMP timestamp ping
• B. ICMP address mask ping
• C. TCP SYN ping
• D. TCP Connect / Full Open Scan

Answer: (A)

The function being tested is using ICMP to fetch the remote clock. An ICMP timestamp request asks the target to provide its current time, and the reply returns the original timestamp along with the receive and transmit times, letting you obtain time information from the host. This is exactly what an ICMP timestamp ping does. The ICMP address mask ping would request the target’s network mask, which isn’t about time. The TCP-based methods operate at the TCP layer and don’t query time information at all. In practice, many systems may not respond to ICMP timestamp requests, but when they do, this is the mechanism used to learn the target’s clock.

The function being tested is using ICMP to fetch the remote clock. An ICMP timestamp request asks the target to provide its current time, and the reply returns the original timestamp along with the receive and transmit times, letting you obtain time information from the host. This is exactly what an ICMP timestamp ping does. The ICMP address mask ping would request the target’s network mask, which isn’t about time. The TCP-based methods operate at the TCP layer and don’t query time information at all. In practice, many systems may not respond to ICMP timestamp requests, but when they do, this is the mechanism used to learn the target’s clock.