NTP (Network Time Protocol)

INRIM provides a synchronization service for informatics system connected to the Internet, based on two primary NTP (Network Time Protocol) servers installed at the Time Laboratory. They are synchronized, through a date code generator, by the commercial cesium beam hosted at that Laboratory.

The time offset between the NTP servers reference time and the Italian national time scale is continuously monitored and is kept below the level of some milliseconds.

The synchronization precision depends on the informatics network topology and on the distance between the NTP servers and the PC/server to be synchronized. Normally a synchronization at the level of hundreds of microseconds for devices belonging to the NTP servers network can be achieved, while for remote networks some hundreds of millisecond could be achieved.

The INRIM NTP servers can be reached by means of the following addresses:

ntp1.inrim.it (

ntp2.inrim.it (

Network Time Protocol Servers at INRIM Time and Frequency Laboratory
Network Time Protocol Servers at INRIM Time Laboratory