Knowledge Base / What port does NTP use?

What port does NTP use?

NTP uses UDP port 123 for time synchronization between clients and servers.

Applies to: GMR, NTDS, NTP100, PCIe, RC

NTDS/TCDS displays, including LUX: NTP and network instructions apply to NTP or dual controllers. TC controllers have no NTP or network options.

Answer

NTP (Network Time Protocol) uses UDP port 123. Clients send requests to UDP/123 and servers reply from UDP/123.

Network filtering

This is most relevant when NTP works on one network but not another, or when network filtering is suspected. Allowing UDP/123 between clients and the time source is required for NTP to function.

Clients cannot sync to the NTP server

Article ID: KB-NET-003
KB Version:

Answer

Network filtering

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