Timeserver
Encyclopedia
A time server is a server
computer
that reads the actual time from a reference clock and distributes this information to its clients using a computer network
. 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 is the Network Time Protocol
(NTP), though other less-popular or outdated time protocols continue in use.
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
. The most common true time source is a GPS
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
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 0 to 14 where 0 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.
Server (computing)
In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...
computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
that reads the actual time from a reference clock and distributes this information to its clients using a computer network
Computer network
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
. 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 is the Network Time Protocol
Network Time Protocol
The Network Time Protocol is a protocol and software implementation for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. Originally designed by David L...
(NTP), though other less-popular or outdated time protocols continue in use.
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
Atomic clock
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...
. The most common true time source is a GPS
Global Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...
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
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
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 0 to 14 where 0 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 ProtocolNetwork Time ProtocolThe Network Time Protocol is a protocol and software implementation for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. Originally designed by David L...
- Inter-range instrumentation group time codesInter-range instrumentation group time codesInter-range instrumentation group time codes, commonly known as IRIG timecodes, were created by the TeleCommunications Working Group of the Inter-Range Instrumentation Group, the standards body of the Range Commanders Council...
(IRIG) - AFNOR-NFS 87-500
- NENA 911
- IEEE 1344IEEE 1344IEEE 1344 is a standard that defines parameters for synchrophasors for power systems. The standard added extension to the IRIG-B time code to cover year, time quality, daylight savings time, local time offset and leap second information...
- IEEE 1588