Here are some short and sweet items that i discovered yesterday;
Interestingly, ESXi does not allow you to change the timezone, it is permanently set to UTC.
Also, If you setup an NTP server on your ESXi hosts and that NTP server goes away for some reason, the ESXi host will not revert to using its’ own clock or even continuing to make a valient effort of keeping time, it instead reverts to January 1, 0001, to say this creates some issues is simplifying it. The ESX hosts complain about not being able to “synchronize”, which is the first clue you get about the issue. When you try and manually set the date through the VI-Client, you get a bunch of errors when you try and do anything and then the VI-Client froze. The only option i found was to get that NTP server online.
Note: It may have been possible to do it via powershell or cli commands, however i had needed to get the NTP servers online anyway, and once this occurred, the ESXi servers re-synced and was able to respond.