Which port and protocol does NTP use for time synchronization?

Which port and protocol does NTP use for time synchronization?

• A. 53 UDP
• B. 161 UDP
• C. 123 UDP
• D. 80 TCP

Answer: (C)

NTP time synchronization relies on small, time-stamped messages exchanged between devices, and UDP is chosen because it’s lightweight and fast—no connection setup is needed for each exchange, which helps keep clocks in sync across many machines. The fixed port used for NTP is 123, assigned by IANA, so devices and network equipment know where to send and listen for time updates. Other options point to different services: DNS uses UDP on port 53, SNMP uses UDP on port 161, and HTTP runs over TCP on port 80. Those services have different purposes and transport behaviors, so they aren’t used for time synchronization.

NTP time synchronization relies on small, time-stamped messages exchanged between devices, and UDP is chosen because it’s lightweight and fast—no connection setup is needed for each exchange, which helps keep clocks in sync across many machines. The fixed port used for NTP is 123, assigned by IANA, so devices and network equipment know where to send and listen for time updates.

Other options point to different services: DNS uses UDP on port 53, SNMP uses UDP on port 161, and HTTP runs over TCP on port 80. Those services have different purposes and transport behaviors, so they aren’t used for time synchronization.