NTP server tester
Check any public time server live. Our reference clock in Frankfurt, synchronised with Germany’s atomic time, queries it four times and checks whether it supports NTS, the secure version of NTP.
Try:
Reading the result
- Stratum
- 1 means the server is connected directly to a reference clock such as an atomic clock or GPS; 2 means it synchronises from a stratum 1 server, and so on. 16 means it is not synchronised at all.
- Offset
- How far the server’s time is from our reference clock. Good servers are within a few milliseconds; part of that is usually network path asymmetry, not the server’s clock.
- Round trip
- Time for a query to reach the server and come back, from Frankfurt. Your own figures depend on where you are.
- Jitter
- How much the offset varies between the four queries. Low jitter means a stable path and server.
- NTS
- Network Time Security (RFC 8915) proves that answers come from the real server and were not altered. We check whether the NTS key exchange answers on port 4460 with a valid certificate.
Limits: 10 tests per 10 minutes per visitor, and the same server at most a few times a minute, to respect the operators. Only public internet addresses can be tested. Looking for good servers? See the European NTP server list.