Query NTP server
NTP is an abbreviation for "network time protocol". It is a method of synchronizing the internal clock of multiple computers. If one (or, preferably at least 4) has an atomic clock (or a receiver of the DCF77 time broadcast (or any other time signal radio stations)), precisions of milli- and even microseconds can be achieved.
On this page you can check if your own NTP server is reachable over the internet. This can be usefull when your NTP-server is part of the public NTP pool (which serves as a public pool of NTP servers available to all users on the internet).
Note: the special options (query peer list, etc) usually don't work because most sysadmins disable them to mitigate DDOS-abuse. Of course it will still poll the NTP server and return its time.
Questions? Feedback? Send them to: firstname.lastname@example.org