Appendix C: Synchronizing Time with NTP Servers

When you deploy the DNS forwarding proxy OVA package on ESXi servers, ensure that you enable the Synchronize guest time with host option during the deployment and that your ESXi host is synchronized with the NTP server so DNS can function properly.

If you do not select the Synchronize guest time with host option (or if this option is disabled), the DNS forwarding proxy synchronizes with the Ubuntu NTP servers: ntp.ubuntu.com and pool.ntp.org. When you disable this option, ensure that you open the UDP 123 port for time synchronization with the Ubuntu NTP servers.

For information about how to deploy the OVA image on ESXi servers, see the following sections:

• OVA on ESXi Using vCenter
• vCenter OVA on ESXi Using ovfttool

Synchronizing Time with the ESXi Host

To synchronize time on the DNS forwarding proxy with the ESXi host, complete the following:

1. In vCenter, navigate to the VM instance for the DNS forwarding proxy.
2. Click Edit Settings, and then navigate to the Options tab.

3. In the Advanced section, select the Synchronize guest time with host checkbox. This checkbox is selected by default during the OVA deployment.

   Note

   Ensure that your ESXi server is synchronized with the NTP server.

Synchronizing Time with the Ubuntu NTP Servers

To synchronize time with the Ubuntu NTP servers, complete the following:

1. In vCenter, navigate to the VM instance for the DNS forwarding proxy.
2. Click Edit Settings, and then navigate to the Options tab.

3. In the Advanced section, deselect the Synchronize guest time with host checkbox. When you deselect this option, the DNS forwarding proxy does not synchronize time with the ESXi host any more. It will listen on and synchronize with the default Ubuntu NTP servers.  Note that it might take a few minutes for the change to take effect.

   Note

   Ensure that you open UDP port 123 for the NTP servers.