vSphere/ESX host time is a critical element in a time synchronization strategy across the organization, particularly when you've configured VMware Tools to periodically sync a guest clock with that of the host. If you've misconfigured the time on one of your hosts, you can end up with time sync issues that will create problems for you or your users that could result in downtime.
Make sure that you always keep your vSphere host time synchronized with an authoritative time source. There are a number of such sources available out there; we happen to use the Network Time Protocol project's freely available service at pool.ntp.org. This service is a "big virtual cluster of timeservers providing reliable easy to use NTP service for millions of clients." In other words, it's a robust time sync source relied upon by a whole lot of people.
To set your NTP host:
- On your vSphere host via vCenter, go to the Configuration tab
- Choose Time Configuration; the will display to you the current time settings
- At the far right side of the window, click the Properties option to open the Time Configuration window
- In the Time Configuration window, click the Options button
- On the NTP Daemon (ntpd) Options page, choose the NTP Settings option
- Add as many NTP servers as you like
- Click OK until you're back at the main console
The figure below gives you a look at the screens that you will see in this process.