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Server Systems, Data Management and IP-Based Dissemination of Time

Working Group Q.42

Time Synchronization of Computers using the "Network Time Protocol" (NTP)

For the time synchronization of computers via the Internet, PTB offers three time servers. To disseminate the time information, these servers use the Network Time Protocol" (NTP) which was developed for the synchronization of computers in local networks and on the internet. The protocol is based on the IP protocol used on the internet and it is available for all relevant operating systems.

To be able to use time servers of PTB for synchronizing a computer, you will need a program which supports this protocol. Such programs are available for the operating systems Windows, UNIX, Macintosh and etc. You can find a list of suitable programs at "Time Synchronization Software" . After installing such a program, you will have to add the address of the NTP servers to be used for synchronization. To use PTB's time servers for synchronization, one or several of the following addresses must be entered:


Please note the following aspects:


Within the limits of the data processing center of PTB in Braunschweig, we do our best to make one of these three time servers accessible at any time. However, we cannot guarantee permanent and disturbance free operation without interruption.


PTB cannot be held liable for damage caused to the users due to failure of PTB`s time service, due to defective transmission by PTB's time servers or due to deviations caused by delays on the internet.

If you use this service, we ask you to please send a message to ntp-admin(at)ptb.de.

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