Configure NTP Time Sync Using Group Policy

The Windows Time service is the basis for the normal functioning of Active Directory domain. Kerberos, the AD primary authentication protocol, uses the W32Time (Windows Time) time service to work properly. In AD environment, the time synchronization is performed according a strict hierarchy: domain joined computers and servers get the time from the nearest domain controller which they are logged on, all domain controllers synchronize their time with a single DC that owns the PDC Emulator FSMO role.

PDC Emulator (Primary Domain Controller) synchronize time with an external time source. The external time source is usually one or more public NTP (Network Time Protocol) servers, like time.windows.com or NTP-server of your provider. Please note that by the default time is provided to clients using the Windows Time service (instead of native NTP).

How the Windows Time Service Works in Domain?

All versions of Windows have a W32Time service. This service is used to synchronize the time in the AD organization. A computer can be both a client and an NTP server. By default, clients in the domain synchronize time using the Windows Time service rather than using NTP.

By default, the Windows Time Service is configured as follows:

  • After performing a clean Windows installation, an NTP client is launched on the computer, which is synchronized with an external time source;
  • If you joined a computer to a domain, the sync type changes. All client computers and member servers in the domain use a domain controller for time synchronization;
  • When a member server is promoted to a domain controller, an NTP server is launched on it, which uses a DC with the PDC emulator role as a time source;
  • The PDC emulator is the main time server for the entire organization. At the same time, it also synchronizes itself with an external time source or with the server’s hardware clock in CMOS (this method of time synchronization is not recommended);
  • This scheme works in most cases and does not require admin intervention. However, the structure of the time service in Windows may not follow the domain hierarchy.
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If you are facing a problem when time on clients and domain controllers is different, most likely your domain has a problem with time synchronization and then this article can be very useful for you.

First of all, it is necessary to select an NTP server that you want to use. The list of public NTP atomic clock servers is available at http://ntp.org. In our example, we will use: 0.us.pool.ntp.org, 1.us.pool.ntp.org, 2.us.pool.ntp.org and 3.us.pool.ntp.org.

Configuring domain time synchronization using Group Policy consists of 2 steps:

  1. Create a GPO for the domain controller with PDC role;
  2. Create a GPO for Windows client computers in the AD Domain.

Configuring NTP Server on PDC

First of all, you need to configure the PDC and enable the NTP service on it. Open a command prompt and run:

w32tm /query /source

If you see in the output:

  • Local CMOS Clock — the time source on this server is its own local hardware clock.
  • VM IC Time Synchronization Provider — then your domain controller with the PDC role is a virtual machine that synchronizes the time with the host.

Disable time synchronization with the host via the registry:

  • Set the Enabled parameter to 0 in the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\VMICTimeProvider

or in the settings of the virtual machine (the screenshot below shows how to disable the time synchronization of the VM with the Hyper-V host using the Time Synchronization option in the Integration Services section).

ntp gpo

Note. The virtual PDC emulator must always synchronize the time with an external source, and the time synchronization with the host must be disabled. This also applies to any other VMs joined to the domain.

Make sure NTP service is enabled on the domain controller. To do this, open the registry editor, go to the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer and check that the value of the Enabled parameter is 1.

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ntp group policy

Configure NTP Setting on PDC DC Using GPO

At this step, you need to configure your domain controller with the PDC Emulator role to synchronize time with an external source. PDC Emulator role can be transferred between domain controllers, so we need to make sure that GPO applied only to the current holder of the Primary Domain Controller role. To do this, run the Group Policy Management Console (GPMC.msc). Select the WMI Filters section and create a new WMI filter with name Filter PDC Emulator and the following WMI query in the root\CIMv2 namespace Select * from Win32_ComputerSystem where DomainRole = 5.

gpo ntp

Create a new GPO and link it to the OU named Domain Controllers.

group policy time server

Select this GPO and switch to the Edit mode. Go to the following section of Group Policy Editor Console:  Computer Configuration > Administrative Templates > System > Windows Time Service > Time Providers.

Enable the following policy settings:

  • Configure Windows NTP Client: Enabled (policy settings are described below);
  • Enable Windows NTP Client: Enabled;
  • Enable Windows NTP Server: Enabled.

gpo time sync

Specify following settings in Configure Windows NTP Client policy:

  • NtpServer: us.pool.ntp.org,0x1 1.us.pool.ntp.org,0x1 2.us.pool.ntp.org,0x1 3.us.pool.ntp.org,0x1;
  • Type: NTP;
  • CrossSiteSyncFlags: 2;
  • ResolvePeerBackoffMinutes: 15;
  • Resolve Peer BAckoffMaxTimes: 7;
  • SpecilalPoolInterval: 3600;
  • EventLogFlags: 0.

Note. Do not forget to configure your firewall properly and allow your PDC access the external NTP servers over NTP protocol (UDP port 123).

gpo ntp server

Assign a WMI filter Filter PDC Emulator that you created earlier to the GPO.

group policy ntp

Tip. You can locate the current PDC server using the command: netdom query fsmo

It remains to update the Group Policy settings on PDC:

gpupdate /force

Perform a manual time synchronization with your NTP source:

w32tm /resync

And check the current NTP settings:

w32tm /query /status

Tip. If something does not work, try to restart the Windows Time service and reset its configuration:

net stop w32time

w32tm.exe /unregister

w32tm.exe /register

net stop w32tim

Configure Client Time Sync Settings Using GPO

By default in Active Directory, domain clients synchronize their time with domain controllers (option Nt5DS — synchronize time to domain hierarchy). Typically, this behavior does not need to be reconfigured. However, if there are problems with time sync on your domain clients, you can try to specify the time server directly on clients using GPO.

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To do this, create a new GPO and assign it to the OU with computers. In the GPO Editor go to the following section Computer Configuration > Administrative Templates > System > Windows Time Service > Time Providers and enable the policy Configure Windows NTP Client.

sync time with domain controller group policy

As an NTP server specify the name or IP address of the PDC:  lon-dc1.adatum.com,0x9

Set Type: NT5DS

Note. Possible values for the Type parameter:

  • NoSync — the NTP server is not synchronized with any external time source. The system clock built into the server’s CMOS chip is used;
  • NTP — the NTP server is synchronized with external time servers, which are specified in the NtpServer registry parameter (this is default behavior on a stand-alone computer);
  • NT5DS — the NTP server performs synchronization according to the domain hierarchy (used by default on domain-joined computers;
  • AllSync — the NTP server uses all available sources for time synchronization.

Update Group Policy settings on the clients and check received time sync settings as described above.

Cyril Kardashevsky
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15 comments

  1. One or more Network Time Protocol (NTP) servers have been incorrectly defined on the PDC emulator. Do you have any suggestions?

    The PDC (DC1) is showing the “state” in Pending. This is not the case for DC2 (which is active).

    Peer: 1.us.pool.ntp.org.0x1,
    State: Pending
    Time Remaining: 42611.2161762s
    Mode: 0 (reserved)
    Stratum: 0 (unspecified)
    PeerPoll Interval: 0 (unspecified)
    HostPoll Interval: 0 (unspecified)

    The event log error is “NtpClient was unable to set a manual peer to use as a time source because of DNS resolution error on ‘us.pool.ntp.org.0x1.”

    1. C:\Windows\system32>w32tm /stripchart /computer:1.us.pool.ntp.org
      Tracking 1.us.pool.ntp.org [129.6.15.30:123].
      The current time is 4/6/2018 10:52:38 AM.
      10:52:38 error: 0x800705B4
      10:52:41 error: 0x800705B4
      10:52:44 d:-00.0000006s o:+27.2452328s [ |
      @]
      10:52:46 d:-00.0000008s o:+27.2451255s [ |
      @]
      10:52:49 error: 0x800705B4
      10:52:52 error: 0x800705B4
      10:52:55 error: 0x800705B4
      10:52:58 error: 0x800705B4
      10:53:01 error: 0x800705B4
      10:53:04 error: 0x800705B4
      10:53:07 error: 0x800705B4
      10:53:10 d:-00.0000008s o:+27.2458764s [ |

    2. This may be a typo fromwhen this was put on the web, but:
      Peer: 1.us.pool.ntp.org.0x1,

      It’s a comma, not a period between ORG and the ox1
      The ‘0x1’ is a flag value, and not part of the DNS name. The way it is entered here however, the server is going to think the DNS name is 1.us.pool.ntp.org.0x1 without a flag value.

  2. Thanks. This helped me figure out why and how to get my time sync corrected. I did end up using “pool.ntp.org” for my source but everything else was just what the doctor ordered.

  3. Good article but I was getting this error: “The computer did not resync because no time data was available.”

    Found that the NTP Server list is not the right format. The NTP server list should be: us.pool.ntp.org,0x1 1.us.pool.ntp.org,0x1 2.us.pool.ntp.org,0x1 3.us.pool.ntp.org,0x1

    It now works perfectly :D

  4. This is an excellent article but you should correct the typos in the NtpServer: us.pool.ntp.org.0x1
    You entered “.0x1” folllwing “.org” but it should be “,0x1” otherwise this will result in unresponsive DNS queries

  5. So I have been reading a lot of instructions for this setup for the PDC configuration part. This article references 0x1 as a flag but the example in the GPO uses 0x9 as the flag (time.windows.com,0x9) and I see other articles with similar configuration that also reference using the 0x9 flag. Which is the correct flag to use for the PDC that gets its time from NTP internet servers such as the pool.ntp.org servers?

    (Also, this article still needs to correct the comma before the 0x1 flag instead of a period in the NTP server listings).

  6. I am finding this info very helpful in understanding the basic approach to creating Domain time syncing. I have not be able to resolve the issues I have though. Does NT5DS reside in a GPO for clients to have it added for membership? My networking staff expect the Forest to be configured to use NT5DS by default with no modifications and everything suggested to fix the issue revolves around Windows Time at the client. A bit of explanation of my issue, I have some PCs that are specialized in our network that we do not join to the normal set of GPOs and they are the PCs that don’t time sync. I have found Windows Time service disabled but even after enabling it the PCs do not sync. W32TM /query /status returns results that time sync has never occurred. W32TM /query /configuration reveals that the PCs have no DC server designated for time sync. I can’t find a GPO in my forest that has a time sync function. Another wierd thing I found is that the problemed PCs will not run NETDOM either.

  7. Is it possible to correct the original information so the comments below the article are incorporated back into the original article.

    i.e.:

    NtpServer: us.pool.ntp.org,0x9 1.us.pool.ntp.org,0x9 2.us.pool.ntp.org,0x9 3.us.pool.ntp.org,0x9;
    Type: NTP;
    CrossSiteSyncFlags: 2;
    ResolvePeerBackoffMinutes: 15;
    Resolve Peer BAckoffMaxTimes: 7;
    SpecilalPoolInterval: 3600;
    EventLogFlags: 0.

  8. Does anyone have a method to allow AD clients to sync to an Internet time source when they aren’t connected to the corporate network?

    1. Chris,

      In my experience, it works to apply the policy The IT Bros suggest above for PDC DC, to AD clients. I have a private/internal time server (let’s call it pvtntpserver.mydomain) configured much as this post suggests for PDC DC (but the server isn’t a DC). For AD clients, my NtpServer setting/list looks like: pvtntpserver.mydomain,0x1 0.something.pool.ntp.org,0x1 1.something.pool.ntp.org,0x1 2.something.pool.ntp.org,0x1 3.something.pool.ntp.org,0x1
      Otherwise, my AD client Windows NTP Client Group Policy config is as this post recommends for PDC DC. Of course, make sure the policy is linked to an OU where the policy will apply to your AD clients. This seems to work fine for me.

  9. Can someone please help me on how to sync to NTP server that we recently setup? We setup NTP server on CentOS7 but have not joined in our domain. Just want to use the server IP to sync.

  10. Hi team,
    in my company, i configured group policy for ntp. all servers and desktops are taking time from my active directory server thats good. But my ad server taking the time from its cmos clock,its not good. actually ad server should take time from my fortigate firewall.can you please help on this issue.Is there anything to do in ad server group policy or in the firewall it self. we are using firewall as ntp server.

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