One of the most important aspects of networking is keeping all devices synchronised to the correct time. Incorrect network time and lack of synchronisation can play havoc with system processes and can lead to untold errors and problems debugging.
And failing to ensure devices are continually checked to prevent drift can also lead to a synchronised network slowly becoming unsynchronised and leading to the kinds of problems aforementioned.
However, ensuring a network not only has the correct time but that that time is not drifting is achieved using the time protocol NTP.
Network Time Protocol (NTP) is not the only time synchronisation protocol but it is by far the most widely used. It is an open source protocol but is continually updated by a large community of Internet time keepers.
NTP is based around an algorithm that can work out the correct and most accurate time from a range of sources. NTP allows a single time source to be used by a network of hundreds and thousands of machines and it can keep each one accurate to that time source to within a few milliseconds.
These time signals are generated by atomic clocks which are many times more accurate than the clocks on computers and servers. NTP will distribute this atomic clock time to all devices on a network it will then keep checking each device to ensure there is no drift and correcting the device if there is.