This article discusses how to configure an ESXi 6.7 host to synchronize time with an upstream NTP server and how to verify that it's actually working.

NTP Configuration

The first step is to configure time synchronization on the ESXi host(s).  This can be done using the VMware Host Client, the vSphere Web Client or the vSphere Client.  Let's look at using the VMware Host Client or the vSphere Client.

VMware Host Client Configuration

vSphere Client Configuration

Verify NTP Operation

To verify that the ESXi host is receiving NTP updates from the NTP server:

This will return the following information:

Reach Value

The reach value represents the success and failure of the last eight polls to the NTP server.  It is a bit-shift register, which means the values are added to the right.  A value of 0 means the NTP server was not contacted, while a value of 1 means a successful synchronization.  The reach value will be displayed as an octal (base 8) value.  Here are some possible reach values:

BINARY VALUE OCTAL VALUE RESULT
00000000 0 No successful synchronizations
00000001 1 One successful synchronization
00100101 45 Three successful synchronizations, but not in a row
11111111 377 Eight successful synchronizations

 
To learn more about binary to octal conversion, click here.

Once the NTP client has been running for several hours on the ESXi host, the desired result would be a reach value of 377.  This would be a 100% successful synchronization rate.  If the reach value remains 0 after several hours, it’s time to troubleshoot NTP.  I would look at things like:

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