ntpd update interval?

Question

How often does the NTPD service update system clocktime by default?

Answer 1

On most systems, including Linux, unless the clock is very off, ntpd doesn't set the clock, it instead varies the length of a second, so that the clock slowly becomes into sync with the master.

This is calling clock skewing, and it's beneficial because it's usually better for a second to be slightly wrong than for seconds to be missed, or even worse, redone.

Answer 2

It's also worth noting that if a clock is really off, NTP will refuse to do anything.