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ABOUT US
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Naval Oceanography One Pager
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Network Time Protocol (NTP)
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Search
Home
Our Commands
United States Naval Observatory
Precise Time Department
Network Time Protocol (NTP)
ABOUT US
Mission & Vision
History
Naval Oceanography One Pager
End of Year Graphic 2022
LEADERSHIP
Commander
Technical Director
Command Master Chief
All Leadership
OUR COMMANDS
Naval Oceanographic Office
Fleet Numerical Meteorology & Oceanography Center
United States Naval Observatory
News from the Naval Observatory
Earth Orientation Department
Precise Time Department
The USNO Master Clock
The USNO Master Clock
Time Dissemination at the USNO
USNO Alternate Master Clock (AMC)
Cesium Atomic Clocks
Hydrogen Masers at the USNO
Rubidium Fountain Clocks
USNO Time Scales
International Time Scales and the BIPM
Definitions of Systems of Time
Global Positioning System
Global Positioning System Overview
USNO GPS Data Categories Explanation
CGGTTS Data Format
USNO GPS Time Transfer
Leap Seconds
GPS Information: SA, DGPS, Leap Seconds, etc.
GPS Week Number Rollover
GPS Timing Data and Information
USNO Format Explanation
USNO Computer Display Clocks
Two-Way Satellite Time Transfer (TWSTT)
Telephone Time
Network Time Protocol (NTP)
US Eastern Time Zone NTP Servers
US Mountain Time Zone Servers
DoD Customer Servers
Astronomical Applications Department
Celestial Reference Frame Department
Optical/IR Products
Senior Enlisted Advisor
Naval Oceanography Operations Command
Fleet Weather Center - Norfolk
National Ice Center
Fleet Weather Center - San Diego
Joint Typhoon Warning Center
Naval Oceanography Anti-Submarine Warfare Center
Navy DoD Supercomputing Resource Center
PRESS ROOM
News Stories
Photo Gallery
Video Gallery
Public Use of Limitations
CONTACT US
Network Time Protocol
Network Time Protocol (NTP)
is an Internet standard protocol which enables client computers to maintain system time synchronization to the US Naval Observatory Master Clocks in Washington, DC and Colorado Springs, CO.
NTP runs as a client program on a computer. It sends periodic time requests to one or more servers, obtaining server time stamps and using them to adjust the client's clock.
Typical accuracy achieved is in the range 1 - 30 ms continuous, and is highly dependent on the symmetry and speed of the Internet path between client and server. Best results are achieved using a combination of servers which are closest to the client in a network sense.
To obtain precise time from USNO NTP servers, follow these procedures:
1. Download NTP client software from
WWW.NTP.ORG
.
2. Select one or more NTP servers and add to your client configuration.
3. Run the NTP client on your machine. We request that you allow no more than three of your clients to poll our servers directly. Organizations with many clients should obtain time from local stratum 2 servers. ISPs should configure routers or firewalls to serve as stratum 2 servers to the ISP network. Dial-in clients should contact your ISP for information about NTP services.
NTP Servers
All of the following stratum 1 NTP servers are open to
stratum 2 servers within the same time zone and to others by arrangement.
Individual users should consult the
public list of stratum 2 servers
.
US Eastern Time Zone Servers
US Mountain Time Zone Servers
DoD Customer Servers
Please note that these servers support the Network Time Protocol (Internet RFC-1305a, RFC-5905) and Simple Network Time Protocol (SNTP), as provided by NTP and Chrony software.
WE STRONGLY RECOMMEND THAT YOU CHOOSE ONE OR MORE SERVERS CLOSE TO YOU, AND IN ADDITION SELECT OTHER SERVERS FOR REDUNDANCY.
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