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Overview

NTP (Network Time Protocol), in Hungarian network time protocol, a network protocol for synchronizing computer clocks. NTP is one of the oldest Internet protocols developed by David L. Mills (University of Delaware), an American computer engineer at 1981.

NTP aims to synchronize all computers that use the protocol Coordinated Universal Timein a fraction of a second. It uses a modified version of Marzullo’s algorithm to select accurate time servers and aims to mitigate the effects of changing network latency. The protocol is usually able to maintain synchronization over the Internet for a few hundredths of a second, and on local area networks (ideally) the synchronization time can reach a millisecond. However, asymmetric paths and network congestion can cause 100 ms or more errors.

The protocol is typically characterized by a server-client model, but is just as easy to use in point-to-point connections when both participants see the other as a potential time source. Computers use timestamps in UDP number 123 (User Datagram Protocol) is sent and received. They may also use broadcasting or multicastingalso, where clients receive time updates in passive mode after the first calibration data exchange. NTP alerts you of all upcoming hopping seconds, but does not provide information about local time zones and daylight saving time.