Most Widely Used Sources of UTC

UTC as the coordinated universal time is called as, is at present the recognized universal timescale system used globally. Since the late seventies it has substituted the Greenwich Meantime (GMT), which was developed based on the movement of Earth's sun. UTC on the other hand relies on the time of atomic clocks and this time is coordinated with the GMT by the inclusion of leap seconds, which are used to balance the changes like the slowing down of Earth's rotation during certain time periods in a year.

UTC is widely used by many computer networks to set the ideal time ensuring proper transactions across the world in an efficient and dependable manner. A committed network time server also called as NTP is used by several computer networks for an accurate UTC reading throughout the network eliminating any discrepancies within the system regarding the exact time.

Though NTP server is considered by many computer professionals to be the most efficient one for almost all computer networks for an UTC reading, there is some discord as to the source of the time. There are three categories that are in regular use, regarding the time source.

Internet is one reliable source of UTC with sites like time.nist.gov and time.windows.com eliminating the need of NTP. But if security is the main criteria then, even Microsoft does not advice the use of internet as the UTC source, and security is the major concern arguably for most systems. It is quite difficult to validate an internet UTC source and the entire system may be in jeopardy if any program is allowed to function outside a firewall.

Another source of UTC in use is the NTP servers employing GPS. This is similar to the GPS navigational technique followed by most of the cars at present. GPS is just a simple coding of time produced by an atomic clock present in the satellite. The main advantage of this UTC source is that the signal can be received throughout the world but needs a clear view of sky for the antenna to receive the signal.

The long range radio transmissions provide an alternative source of UTC to GPS. These signals are sent out by several national physics laboratories. But the main drawback of this method is the weak signals which are easily interfered by the local weather patterns or signals. Even tall structures and the difference in the local topography may interfere with the proper transmission of these signals.