[ntp:questions] Issues trying to sync to NIST public servers

Jason Rabel jasonrabel99 at gmail.com
Sun Feb 3 14:11:15 UTC 2019

> Yes, the main reason behind the requirement is probably the traceability
> to UTC of the stratum 0 used by the server : NIST servers are traceable
> to UTC, which is (formally) not the case for a server with a GNSS
> as stratum 0.
> In case NIST servers are hard to reach, a metrologically defendable fallback
> could be to use ntp servers from another national metrology institute
> which would provide the same traceability to UTC.

NIST does have a lookup that displays the difference between NIST &
GPS time. *If* it only requires logging to prove the source you are
using is accurate enough:


As someone else mentioned, hitting NIST @ 16s intervals (or any NTP
server for that matter) can get you rate-limited or blocked. I would
recommend doing a test at different intervals. Unless you are syncing
to another source on your LAN, lower is not always better.
Instabilities in the network can quickly skew your time off at low
poll intervals.

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