vSphere 5.5 Synchronize ESX and ESXi Clocks with a Network Time Server

ESX and ESXi Clocks with a Network Time Server
1 From the vSphere Web Client, connect to the vCenter Server.
2 Select the host in the inventory.
3 Select the Manage tab.
4 Select Settings.
5 In the System section, select Time Configuration.
6 Click Edit and set up the NTP server.
a Select Use Network Time Protocol (Enable NTP client).
b Set the NTP Service Startup Policy.
c Enter the IP addresses of the NTP servers to synchronize with.
d Click Start or Restart in the NTP Service Status section.
7 Click OK.
The host synchronizes with the NTP server.

Synchronize the vCenter Server Appliance Clock with an NTP Server
Before you deploy thevCenter Server Appliance, make sure all machines on the network have their clocks
synchronized. Unsynchronized clocks can cause installation and authentication errors.
On systems that are joined to a Windows domain, the vCenter Server Appliance clock is synchronized
automatically with the domain controller. On other systems, you can enable synchronizing the clock
through VMware Tools. As an alternative, you can use this procedure.
Procedure
1 Open a Web browser and navigate to thevCenter Server Appliance Management Interface
(https://vCenter-Appliance-Address:5480/).
2 Log in as root.
3 From the vCenter Server tab, select the Time subtab.
4 Select one or more of the available options.
Option Description
No synchronization Does not perform synchronization.
NTP synchronization Select this option and specify one or more NTP servers to configure the
appliance to synchronize with an NTP server directly.
VMware Tools synchronization Select this option to synchronize all virtual machines.
Active Directory synchronization This option becomes available only if you add the appliance to an Active
Directory domain. If you select this option, none of the other options is
available.
5 Click Save Settings.
The vCenter Server Appliance clock is synchronized with the NTP server.