Network Time Protocol (NTP) synchronizes clocks of hosts and routers in the Internet.
NIST estimates 10-20 million NTP servers and clients deployed in the Internet and its tributaries all over the world. Every Windows/XP has an NTP client.
NTP provides nominal accuracies of low tens of milliseconds on WANs, submilliseconds on LANs, and submicroseconds using a precision time source such as a cesium oscillator or GPS receiver.
NTP software has been ported to almost every workstation and server platform available today - from PCs to Crays - Unix, Windows, VMS and embedded systems, even home routers.
The NTP architecture, protocol and algorithms have been evolved over the last two decades to the latest NTP Version 4 described in this and related briefings.
NTP is argueably the longest running, continuously operating, ubiquitously available protocol in the Internet
– USNO and NIST, as well as equivalents in other countries, provide multiple NTP primary servers directly synchronized to national standard cesium clock ensembles and GPS
– Over 230 Internet primary serversare in Australia, Canada, Chile, France, Germany, Isreal, Italy, Holland, Japan, Norway, Sweden, Switzerland, UK, and US.
Well over a million Internet servers and clients all over the world – National and regional service providers BBN, MCI, Sprint, Alternet, etc.
– Agencies and organizations: US Weather Service, US Treasury Service, IRS, PBS, Merrill Lynch, Citicorp, GTE, Sun, DEC, HP, etc.
– Private networks are reported to have over 10,000 NTP servers and clients behind firewalls; one (GTE) reports in the order of 30,000 NTP workstations and PCs.
– NTP has been on the NASA Shuttle and in Antarctica and planned for the Mars Internet.
Full report Available at http://www.eecis.udel.edu/