Six GPS-based, fast, high-accuracy [10-nanosecond] Stratum-1 NTP Internet time servers that you can use for any timing needs, such as keeping your computer's clock synchronized to UTC, are available free for public use. All six are equally accurate and are accessible via the three domain names given in the table below.

Server Information
Domain Name Time Source Oscillator NTP Line Notes GPS Rubidium V2 V3 V4 Cable A
C GPS Rubidium V2 V3 V4 Cable A
C GPS Rubidium V2 V3 V4 Cable A
Which Domain Name should you use? Any one of them. The times returned on the three lines have identical accuracy.
Current Server Status:MINormal Operation
Server locations: Valencia, California [near Los Angeles]

For your computer, decide on a particular server line and then:

For the PC (Windows 7):
1. Navigate to the menu item Start > Control Panel > Date and Time.
2. Click the Internet Time tab at the top of the window.
3. Click Change Settings...
4. Check the box next to Synchronize with an Internet time server.
5. Enter either or or as the server name.
6. Click Update Now.
7. When you get the 'successfully' message, click OK in the two open windows.

For the Macintosh (OS X):
1. Open System Preferences. . . in the Apple menu.
2. In the 'System' bar, click Date & Time.
3. In the window that opens, click the Date & Time tab.
4. Check the box next to Set date & time automatically.
5. Enter either or or as the servername.
6. Press the Return key.
7. Close the window.

Be sure that the IP address of your client host computer is valid. The Internet has seven ranges of contiguous IP addresses that are not recognized by Internet routers or are not available for assignment:

Ranges of Invalid IP Addresses
Lowest Address in Range Highest Address in Range Remarks; Address Type
0. 0.0.0 0. 255.255.255 No Network Number
10. 0.0.0 10. 255.255.255 Local - Class A
127. 0.0.0 127. 255.255.255 Reserved for Testing
169.254. 0.0 169.254. 255.255 Local - DHCP Default
172.16. 0.0 172.31. 255.255 Local - Class B
192.168. 0.0 192.168. 255.255 Local - Class C
240. 0.0.0 255. 255.255.255 Internet IP Development

Do not use an address in any of the above ranges to identify your computer to the outside world. A received IP address belonging to one of these ranges will be discarded by the servers. [If you connect to the Internet through a gateway in an organization's network, that is usually OK; in most cases local addresses will be temporarily converted to a valid number before being transmitted.]

Please note: The time derived from GPS by the servers is within a few nanoseconds of UTC; however, because of unpredictable transmission delays within the Internet, the time received from the servers will be accurate typically to a few milliseconds of UTC.

For questions or comments, e-mail

This page was last updated on March 31, 2016. You are visitor number _

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