port number for network time protocol
The Time Server will synchronize its time with the Internet Time Servers. Other systems on the network will then synchronize with the company Time Server over the LAN. NTP uses User Datagram Protocol (UDP) on Port 123 to synchronize time. UTC Clocks are referenced by Stratum. Basically, each stratum is a level of accuracy where the top level, or most accurate systems, is numbered as Stratum 0 (Reference Clocks).