[Gabrys1]

Having clocks synchronized between your servers is extremely useful. For example, having a guarantee that the timestamp of arrival of a packet (measured by the clock on the destination) is ALWAYS bigger than the timestamp recorded by the sender is a huge win, especially for things like database scaling.

For this though you need to go beyond NTP into PTP which is still usually based on GPS time and atomic clocks

[riedel]

Actually interesting to think about what UTC actually means and there is seems to be no absolute source of truth [0]. I guess the worry is not that much about the NTP servers (for which people anyways should configure fail overs) but the clocks themselves.

[0] https://www.septentrio.com/en/learn-more/insights/how-gps-br...

[pbhjpbhj]

Could you define an absolute source of truth based on extrinsic features. Something like taking an intrinsic time from atomic sources, pegged to an astronomic or celestial event; then a predicted astronomic event that would allow us to reconcile time in the future.

It might be difficult to generate enough resolution in measurable events that we can predict accurately enough? Like, I'm guessing the start of a transit or alignment event? Maybe something like predicting the time at which a laser pulse will be returnable from a lunar reflector -- if we can do the prediction accurately enough then we can re-establish time back to the current fixed scale.

I think I'm addressing an event that won't ever happen (all precise and accurate time sources are lost/perturbed), and if it does it won't be important to re-sync in this way. But you know...