Keeping accurate time is essential for many applications and dedicated NTP time servers make the job easy for network administrators. These devices receive an external time signal, often from GPS or sometimes from broadcast signals put out by organisations such as NIST, NPL and PTB (national physics labs from US, UK and Germany).
Synchronization with a NTP time server is made all the more easier thanks to NTP (network time protocol) this software protocol distributes the time source by constantly checking the time on all devices and adjusting any drift to match the time signal that is received.
Time synchronization is not just the concern of large networks. Even single machines and routers ought to be synchronised because at the very least it will help keep a system secure and make error detection a whole lot easier.
Fortunately, most versions of Windows contain a form of NTP. Often it is a simplified version but it is enough to allow a PC to be synchronized with the global time scale UTC (Coordinated Universal Time). On most Windows machines this is relatively easy to do and can be achieved by double clicking on the clock icon in the task bar then selecting a time provider in the internet time tab.
These time sources are internet based meaning that they are external to the firewall so a UDP port has to be left open to allow the time signal to enter. This can cause some security issues so for those wanting perfect synchronization without any security issues then the best solution is to invest in a dedicated time server. These need not be expensive and as they receive an atomic clock time signal externally then here is no breach in the firewall leaving your network secure.