NTP setting revert problem with ESXi 6.7

Last weekend we had encountered a big problem with ESXi host time settings after upgrading one of the test servers to version 6.7 (and also last build 8941472, but I'm not really sure about that it's the cause of the problem). After server starting up, NTP service stop working correctly and sadly there is no way to change it (manually or automatic by any NTP servers) and any changes will fail back to defaults.
So after trying the  GUI method, we edited /etc/ntpd.conf file and unfortunately nothing happened. As the last way of NTP troubleshooting, useful ESXCLI commands help us to fix it by setting these below command:
# esxcli system time set -d 11 -H 01 -m 55 -M 05 -y 2018

To prevent possible host revert to old-time setting, you must ensure that the hardware clock is the same as the system time:
# esxcli hardware clock set -d 11 -H 01 -m 55 -M 05 -y 2018

There are some commands by shell our SSH access for ESXi NTP settings that's useful to know:

Enable NTP service:
# chkconfig ntpd on
# chkconfig --list | grep ntpd

Restart NTP service:
# /etc/init.d/ntpd restart

Display NTP peers:
# ntpq -p

Check ESXi time:
# esxcli hardware clock get
# esxcli system time get

Monitor NTP transmits between host (as NTP client) and NTP Server:
# watch ntpq -p Host / NTP server
# tcpdump-uw -c 5 -n -i vmk0 host NTP_server and port 123

I hope this is gonna be useful for you ;) ... and never lose your host's time as I do :D

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