On Wed, Apr 27, 2022 at 10:45:09PM -0400, Stefan Monnier wrote: > Another option might be that your system's time was "reset". > This shouldn't happen, but it can happen if your NTP was down, the > machine got out-of-sync over time and you restart the NTP server at > which point it may(!) decide to jump the clock if the difference is > large enough (i.e. too large to catch up gradually). > Can't remember how large is "large enough".
It would depend on which NTP implementation is in use. The traditonal "ntp" package should not do a large jump like that, except at boot. It should just make the clock drift toward the correct time. Other implementations may be more aggressive about it. Debian 11 uses systemd-timesyncd by default, but I don't know how it behaves. I've not used chrony either. I did experiment with openntpd for a while, but it was many years ago when it was pretty new, so it might have changed a lot. In any case, that's a clever theory. The OP could look for evidence of an NTP time jump in whatever logs survive from the offending time period.