NTP test
Query an NTP time server over UDP 123 and see how far its clock is from MtrXTools's synchronised clock, the round-trip delay, its stratum and reference source, leap and sync status, and root distance, over several samples.
What the NTP test measures
- Offset: how far the server's clock is from MtrXTools's synchronised clock. A good public server is within a few milliseconds.
- Delay: the round-trip time of the query, which limits how accurately the offset can be measured.
- Stratum: the distance from a reference clock. Stratum 1 is connected directly to GPS or an atomic clock; each hop adds one.
- Leap and sync status, the reference source and the root distance, which estimates the server's worst-case error.
Several samples are taken so a single slow packet doesn't distort the result.
Questions
- Why does clock accuracy matter?
- Certificates, login tokens, two-factor codes and log correlation all depend on correct time. A clock a few minutes off can break sign-ins and make TLS certificates look not yet valid or expired.
- The test times out. Why?
- The server doesn't answer public queries, or a firewall blocks UDP port 123.
- Which NTP server should I use?
- Your cloud provider's time service, or a pool such as
pool.ntp.orgortime.cloudflare.com. Use several sources so a single bad server can be outvoted.