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DC with Sync time in Hyper-V

Takami Chiro 291 Reputation points
2026-01-28T00:15:48.6966667+00:00

Hello everyone,

I hope you all are doing well! I have two DCs in this network and both are running in HyperV. Now we just found out the domain PCs could not sync the time with the DC. Instead they sync with external source time.windows.com. And the time source on the DC displayed as using the VM host...

After some research (https://wmatthyssen.com/2020/02/28/hyper-v-configure-time-synchronization-for-a-virtual-domain-controller/),

I know that the "Time Synchronization" box is NOT UNCHECKED on the HyperV settings. So my plan is to uncheck that box for the both DC (the PDCEmulator) first. However, I have some questions in the sequence on what to do:

1.) Should I complete the whole process, including running this command " w32tm /config /manualpeerlist:time.windows.com /syncfromflags:manual /reliable:yes /update" first on the DC with PD Emulator before doing the same on the second DC (uncheck box, run command). Which order should I do first?

2.) What else do I need to pay attention in order not to mess up the time on the DC?

3.) Some people put down 0x1, 0x8 or 0x9 after the time source. Do I need to put this on? If so, which one should I use in this case (I plan to use 0x1).

4.) Do I need to set the time zone (now I am on pacific time zone on the dc, which is correct).

Hope you can help! Thank you again for your help!

Takami Chiro

Windows for business | Windows Server | Directory services | Active Directory
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Answer accepted by question author

Harry Phan 20,615 Reputation points Independent Advisor
2026-01-28T06:35:18.1133333+00:00

Hello Takami Chiro

You should start by unchecking the “Time Synchronization” integration service on the Hyper‑V settings for both domain controllers. The PDC Emulator is the authoritative time source in the forest, so configure it first. Run w32tm /config /manualpeerlist:"time.windows.com" /syncfromflags:manual /reliable:yes /update on the PDC Emulator only. Do not run this command on the second DC; it should remain configured to sync from the PDC Emulator automatically once the host sync setting is disabled. Afterward, restart the Windows Time service with net stop w32time && net start w32time and confirm with w32tm /query /status that the source is set correctly.

The sequence is important: disable host sync on both DCs, then configure the PDC Emulator as reliable and pointing to an external NTP source. The other DC will follow the PDC Emulator. Regarding the flags like 0x1, 0x8, or 0x9, those are registry values under HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Parameters when defining multiple peers. For a single external source, 0x1 (special poll) is correct. You don’t need to add others unless you are mixing multiple NTP servers. The time zone setting on the DC should remain Pacific Time if that matches your environment; NTP deals only with UTC, so the local time zone doesn’t affect synchronization.

Finally, verify replication health with dcdiag /test:systemlog and check event logs under System for W32Time (Event ID 37, 47, 49) to ensure synchronization is stable. I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer. Should you have more questions, feel free to leave a message. Have a nice day!

Harry.

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  1. AI answer

    2026-01-28T00:15:59.11+00:00

    To address your questions regarding time synchronization for your domain controllers (DCs) running in Hyper-V:

    1. Order of Operations: It is generally recommended to configure the primary domain controller (PDC) emulator first. You should run the command w32tm /config /manualpeerlist:time.windows.com /syncfromflags:manual /reliable:yes /update on the PDC emulator before unchecking the time synchronization box in Hyper-V settings. After ensuring the PDC is correctly configured and synchronized, you can then proceed to the second DC.
    2. Pay Attention To: When making changes to time synchronization, ensure that the PDC emulator is configured to use a reliable time source. It is crucial that the guest DCs are not left without a time source, as this can lead to time skew issues. Also, make sure that the time zone is correctly set on all DCs to avoid discrepancies.
    3. Using 0x1, 0x8, or 0x9: The values you mention (0x1, 0x8, or 0x9) are used to specify the type of time source. In your case, using 0x1 (which indicates a reliable time source) is appropriate when configuring the PDC emulator. Ensure that you use the correct value based on your environment and requirements.
    4. Setting the Time Zone: Yes, it is important to ensure that the time zone is set correctly on the DCs. Since you mentioned that you are currently on Pacific Time and it is correct, you should maintain this setting to avoid any time-related issues.

    Following these guidelines should help you manage time synchronization effectively in your Hyper-V environment.

    References:

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