GPSClock.com runs two stratum one NTP servers that are open to the public for time synchronization. We have provided time synchronization services to [an error occurred while processing this directive] unique hosts in the past twenty minutes.

We do ask that those who wish to use our time servers follow a few rules. Your cooperation will help us to keep these servers available for as long as possible.

Both Tick.gpsclock.com and Tock.gpsclock.com are NTP4 servers with a timestamp accuracy better than 4 microseconds more than 99% of the time. You may not use burst without permission (we routinely grant such permission, but you must ask). Tock.gpsclock.com is a higher capacity server than Tick and we generally prefer that you use it if you are only going to use one server.

Tock runs on FreeBSD and Tick runs Linux. They perform nearly identically.

If you are using these time servers to evaluate the GPSClock 200, please let us know. We'd like to send you some information to help you distinguish clock accuracy from network jitter.

Please refer to these servers by their DNS names. Their IP addresses are subject to change. Please use the server command in your ntp.conf files, do not use peer or your packets may be refused.

Understand that we do occasionally run queries to the NTP servers that use us (for statistical and quality control purposes). Do not be surprised if you see an occasional ntpq -p from our network. If this is going to trigger a complaint or investigation, please do not use our servers.

Open access is available only to stratum two servers that provide synchronization to ten or more hosts and are located in the US/Pacific/PAIX, Globix/SanJose, or Abovenet/SanJose areas. You can test if you are in our service area by pinging www.gpsclock.com. If your ping times (ignore the first two pings) average under 90 milliseconds, and are fairly uniform, you are in our service area. If you meet these qualifications, you may peer with both Tick and Tock if you wish; however, this will not provide as much redundancy as a second stratum one server in a different location.

We are generally willing to allow access to others for experimental or research purposes (or even if you just want your clock to be really accurate) -- just please ask us. If you operate a stratum one server near us and would like to peer with our stratum ones for mutual backup and accuracy tracking, feel free to contact us.

Anyone may use Tick and Tock in their ntpdate command line that executes automatically during startup. Please do not use ntpdate on a schedule (such as hourly or daily) without permission. Please do not use any software other than xntpd, ntpd or ntpdate to talk to Tick or Tock without prior permission.

Our time servers refuse outside queries for status information. This is done for security reasons. If you wish to check on the health of our servers, you can check them from our NTP Server Checker or you can try using them. There is no good way to evaluate a remote stratum one NTP server other than using it.

We appreciate a courtesy email letting us know that you are going to be using us. We won't add you to a commercial mailing list. We won't spam you. Unless you ask otherwise, we will only contact you to notify you of a change in our time servers that we suspect might affect you.

If you don't email us, please don't complain if things change and you aren't warned. We have no idea who to contact if you don't tell us.

If you do decide to run your own stratum one time server, please consider our clock, the GPSClock 200.