{{Short description, Server that reads time information and distributes it
A time server is a
server
Server may refer to:
Computing
*Server (computing), a computer program or a device that provides requested information for other programs or devices, called clients.
Role
* Waiting staff, those who work at a restaurant or a bar attending custome ...
computer
A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...
that reads the actual time from a reference clock and distributes this information to its clients using a
computer network
A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...
. The time server may be a local network time server or an internet time server.
The most important and widely used protocol for distributing and synchronising time over the Internet is the
Network Time Protocol
The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-Network latency, latency data networks. In operation since before 1985, NTP is one of the oldest Intern ...
(NTP), though other less-popular or outdated time protocols continue in use. A variety of protocols are in common use for sending time signals over radio links and serial connections.
The time reference used by a time server could be another time server on the network or the Internet, a connected radio clock or an
atomic clock
An atomic clock is a clock that measures time by monitoring the resonant frequency of atoms. It is based on atoms having different energy levels. Electron states in an atom are associated with different energy levels, and in transitions betwee ...
. The most common true time source is a
GPS
The Global Positioning System (GPS) is a satellite-based hyperbolic navigation system owned by the United States Space Force and operated by Mission Delta 31. It is one of the global navigation satellite systems (GNSS) that provide geol ...
or GPS master clock. Time servers are sometimes multi-purpose network servers, dedicated network servers, or dedicated devices. All a dedicated time server does is provide accurate time.
An existing network server (e.g. a file server) can become a time server with additional software. The NTP homepage provides a free and widely used reference implementation of the NTP server and client for many popular
operating system
An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ...
s. The other choice is a dedicated time server device.
The term "stratum" is used to label the closeness to a central or high quality time server. The stratum indicates the place of a particular time server in a hierarchy of servers. The scale is 1 to 15 where 1 is the most accurate and likely a highly specialized physical hardware device. Some time clients will reject a time update from a server whose stratum is too high, and most will prefer low strata time sources to higher ones. This can be a pitfall for administrators setting up an in-house time server with no true time source.
See also
*
Network Time Protocol
The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-Network latency, latency data networks. In operation since before 1985, NTP is one of the oldest Intern ...
NMEA 0183
NMEA 0183 is a combined electrical and data specification for communication between marine electronics such as echo sounder, sonars, anemometer, gyrocompass, Self-steering gear, autopilot, GPS receivers and many other types of instruments. It has b ...
References
NTP FAQ for detailed descriptions of reference clocks used by a
computer
A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...