about difference the public time server , time.microsoft.com , and Microsoft time server

ryo shinba 30 Reputation points

I investigate a time server in azure service.

please confirm my understanding .

・in using Asure VM service, the host machine syncronize "Windows time server", and a virtual machine syncronze "time.windows.com" , the public time server of Windows .

・"Windows time server" and "time.windows.com" are differet, and when a system connects to internet, the virtual machine can syncronize "time.windows.com".

In private network, be not able to do that.

・Directly, we can't connect to "Windows time server" which the host machine syncronize , from a virtual machine.

Azure Virtual Machines
Azure Virtual Machines
An Azure service that is used to provision Windows and Linux virtual machines.
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Accepted answer
  1. kobulloc-MSFT 24,321 Reputation points Microsoft Employee

    Hello, @ryo shinba !

    My understanding is that on Azure virtual machines (VMs), the VM synchronizes with "Windows Time Server" and "time.windows.com". Is that correct?

    Azure hosts are synchronized to internal Microsoft time servers that take their time from Microsoft-owned Stratum 1 devices, with GPS antennas. Virtual machines in Azure can either depend on their host to pass the accurate time (host time) on to the VM or the VM can directly get time from a time server, or a combination of both.

    On a Windows VM, that leaves you with the following three configuration options:

    This means that the VM synchronizes with the host time, time.windows.com, and/or another, external time server.

    Read more:

    "Host time" and "time.windows.com" are different, and when a VM is connected to the internet it can synchronize with "time.windows.com". Is that correct?

    Host time and time.windows.com are different. Host time is based on internal Microsoft time servers and time.windows.com would need a network connection.

    Read more:

    What about private networks?

    You can rely on internal host time from Azure, or make exceptions for time.windows.com or another external time service.

    I hope this helps!

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