I have a set of 3 Windows 2012 Server VMs running as my domain controllers. These VMs are in an air-gap environment, meaning no access to upstream NTP servers.

I haven't been able to configure my ESXi hosts (running version 6) to act as NTP clients syncing with the W32time service on the DCs.

Each time I try an NTP query on the ESXi host, all I get is a timeout.

I am using the command ntpq -p "IP address of DC".

tcpdump on the ESXi hosts shows the outbound query packet, but no reply packet.

Is the lack of an upstream NTP server causing the problem?

  • Guest VMs don't need to be time synced as VMware Tools already does this. Only the host needs an uplink NTP server. – paradroid Oct 29 '15 at 18:26
  • Perhaps I didn't explain clearly. I am trying to use the VM as the uplink NTP server. Vmware recommends not syncing VMs with the host via Tools. – shifflettd Oct 29 '15 at 18:33
  • Can you ping the VM from the ESXi host? Check your vSwitch and VLAN and firewall configuration. If you can't even get packets back and forth, then don't even bother thinking about the configuration at the application layer. – Ryan Ries Nov 2 '15 at 0:17

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