2 Replies Latest reply on Dec 2, 2019 12:37 PM by andrewpilachowski

    ESXi NTP Servers?

    BSiegfried Lurker

      Curious to know how everyone sets up NTP on their ESXi hosts and if my setup is acceptable.

       

      I have the NTP service running on all hosts and pointing to NTP server 1.pool.ntp.org.

       

      For my DC's only, in the VM settings I have checked Synchronize guest time with host.

        • 1. Re: ESXi NTP Servers?
          msripada Expert
          vExpert

          are the hosts joined to domain? if yes then it should be set to sync with AD

           

          thanks,

          MS

          • 2. Re: ESXi NTP Servers?
            andrewpilachowski Novice

            This was way back around 5.0/5.5 before I fixed it, but I had bad issues with clock drift when I tried to use synchronize with host for DC/domain joined VMs

             

            Synchronize guest time with host I would reserve for non-domain joined machines or ones that may not have network/domain/Internet access.

             

            I am not sure I would want to have the host synchronize off the VM DCs running on the host either.

             

            Best bet would be to set both the DCs and the host to sync off the same hardware NTP source. If no hardware source is available on the network, a good fallback would be NTP pool or if you are running Cisco switches I believe you can use the default gateway as an NTP source, as long as it is running off an external NTP source itself.

             

            Because the host synchronizes its BIOS off the clock time and the VMs are running off the host timing, it can get you into a weird situation where the clocks will be off if one is trying to sync back off the other, or performing non-stop clock corrections as it drifts or ping-pongs from one source timing to another.