why sometimes I see  clock_step but sometimes I see  time resetlog1:27 Jul 11:11:08 ntpd[100258]: 0.0.0.0 c515 05 clock_sync27 Jul 11:13:41 ntpd[100258]: 0.0.0.0 0613 03 spike_detect +4.152511 s27 Jul 11:27:01 ntpd[100258]: 0.0.0.0 061c 0c clock_step +4.151101 s27 Jul 11:27:05 ntpd[100258]: 0.0.0.0 0614 04 freq_modelog2:Apr  6 16:39:01 AAA3 ntpd[2576]: synchronized to 172.16.100.81, stratum 3Apr  6 16:56:16 AAA3 ntpd[2576]: time reset +6.288863 sApr  6 16:59:49 AAA3 ntpd[2576]: synchronized to 172.16.100.81, stratum 3
what's the difference between clock_step && time reset?
ntp