Before we get to what an NTP server is and what its uses are, we need to dive into the importance of accurate time synchronization.
Time synchronization is essential for all computer networks - especially for those that perform time-sensitive transactions. Time, in the form of timestamps, is used, for example, to determine when a transaction has occurred or needs to be made. If the time varies within the network, data may be lost or the transaction may not take place at all.
What is an NTP?
NTP (Network Time Protocol) is a protocol for synchronizing computers' internal clocks, which ensures that all computers in the network have the same and accurate time. Developed by David L. Mills of the University of Delaware, NTP was commissioned in 1985. It uses a single time source that allows time to be synchronized between all devices in the network and has been designed to withstand packet delivery delays. NTP is one of the oldest IP protocols among those still in use.
Exact time thanks to GPS
One of the safest and most accurate ways to obtain accurate time is to use time codes transmitted by GPS networks. Atomic clocks onboard satellites generate these time codes, which are then very accurate. In addition, the GPS system is available anywhere on the planet where's a view of the sky.
GPS time codes are received by the NTP GPS server, which also processes and distributes them over the network.
NTP servers in everyday life
NTP time servers work all around us. Security cameras, ATMs, speed cameras, and all other systems that deal with time-sensitive data are dependent on time synchronization. NTP is also essential in the case of exchange rates, where prices change every second. Satellite navigation systems, such as GPS, also rely on accurate timekeeping for error-free position calculations.
Atomic clocks
NTP servers take the exact time from the atomic clock. These are one of the most accurate timing devices in history. There are currently about 400 atomic clocks worldwide, which contribute to the calculation of the International Atomic Time (TAI). Their error rate is only one second in 100 million years.
Leap second
Time is also measured by the rotation of the earth, which lasts a fraction of a second longer per year than the measurement of the atomic clocks. To equalize the time, a so-called leap second is added to the atomic time once every few years. Since 1972, 27 leap seconds have been added. In practice, the time on the atomic clock looks like on midnight, when the second is added, as follows:
23:59:59
23:59:60
00:00:00
00:00:01
Accurate time is essential for servers to run
Time is a connection between the virtual world and the real world. An example is shopping on an e-shop. The creation of an order for goods in the e-shop must be recorded with the exact date and time due to the connection to other transactions in the real world (payment on time, delivery within the agreed delivery time, settlement of complaints, etc.).
Exact time is also required to run basic applications such as calendars, alarms, and running tasks on servers. Most operations within server groups (clusters, cloud, distributed storage systems) must take place at the same time or have a specific time sequence, and therefore time synchronization is necessary.
NTP at vshosting~
vshosting~ operates two physical time servers:ntp1.vshosting.cz and ntp2.vshosting.cz. Both servers are reserved for this purpose and the RTC HW in these servers is modified for higher accuracy. Both servers are synchronized from the atomic clock (stratum 1) of the Institute of Photonics and Electronics of the Academy of Sciences of the Czech Republic and the Federal Institute of Physics and Technology (PTB.de).