312-50V11 · Question #74
Identify the UDP port that Network Time Protocol (NTP) uses as its primary means of communication?
The correct answer is A. 123. NTP communicates exclusively over UDP port 123 as standardized in RFC 5905.
Question
Identify the UDP port that Network Time Protocol (NTP) uses as its primary means of communication?
Options
- A123
- B161
- C69
- D113
How the community answered
(24 responses)- A92% (22)
- B4% (1)
- D4% (1)
Why each option
NTP communicates exclusively over UDP port 123 as standardized in RFC 5905.
Network Time Protocol (NTP) is standardized to use UDP port 123 for all time synchronization communications, as defined in RFC 5905. UDP is used because NTP requires low-latency, lightweight message exchange and does not need the connection overhead of TCP. This port is formally registered with IANA specifically for NTP.
UDP port 161 is assigned to SNMP (Simple Network Management Protocol), not NTP.
UDP port 69 is assigned to TFTP (Trivial File Transfer Protocol), not NTP.
Port 113 is associated with the Ident/Authentication Service as defined in RFC 1413, not NTP.
Concept tested: NTP protocol UDP port assignment
Source: https://www.rfc-editor.org/rfc/rfc5905
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