Why does the system time change after reboot, even when it has been set with the 'date' command?

Issue

• Why was the system time changed after reboot even though date/time has been set with 'date' command?
• The ESX host that my VM was on experienced an HA event. When the server rebooted on another host the time was one hour ahead of where it should be. However the other VMs that were also involved came up with the correct time. Can Red Hat help with this issue?