When using ESXi host to manage your virtual environment it is very important to make sure that your host are using an accurate time server.
The reason behind this is the fact that all Virtual machine are using their host to get the time and date.
To keep you host time and date accurate you can configure them to use an NTP server to sync this info.
To configure NTP settings on your host follow these steps.
Open vSphere Client and select your host go to Configuration and click on Time Configuration
In the time configuration select properties in the top right menu
In the Time Coniguration menu select NTP client Enable and click on Options
In General Tick Start and Stop with host and
In the NTP setting click Add to add your NTP server and Tick Restart NTP, Click OK