Devices for communicating the time over an Ethernet connection using Network Time Protocol. Client devices query these servers to keep in sync. There are many free client timekeeping applications available for all Operating Systems. Applications include keeping broadcast automation systems to time, laboratories and financial/industrial applications - where an accurate time stamp is required by industry regulators or to provide traceable proof of when a transaction occurred. The sever can obtain its time from several possible sources - commonly GPS (directly or indirectly via CDMA phone towers), public atomic clock based time servers, low frequency time transmission via WWVB etc, IRIG timecode input or serial time code input. Check that the unit you are interested in has the right time source option for your application.