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.. |date| date::

.. meta::
  :description: Managing NTP on Windows clients
  :keywords: Documentation, Samba-AD, Network Time Protocol, NTP

.. _managing_ntp_clients:

###############################
Managing NTP on Windows clients
###############################

****************************************************
Forcing a resynchronization on a windows workstation
****************************************************

Run the command :command:`w32tm /resync /nowait` **in a shell with admins rights** to force the local :abbr:`NTP (Network Time Protocol)` service of the Windows client to synchronize its clock with the NTP server.
If all goes well, the command returns **The command ended correctly**).

.. note::

  an NTP server must be given some time before asking for its time, otherwise it declares itself to be an unreliable source.

In the event of a problem
=========================

The service is called :program:`w32time` while the management tool is called :program:`w32tm`. You may also need the commands :command:`net` and :command:`time`.

******************************************************************************************
Reconfiguring the domain’s Windows clients to synchronize their clocks with Samba-AD’s NTP
******************************************************************************************

On the Windows client, run the following instructions:

.. code-block:: bash

  w32tm /config /syncfromflags:domhier
  w32tm /config /update
  w32tm /resync /nowait

*********************************************
Debugging the NTP service on a Windows client
*********************************************

To define a log file to debug the operation of the NTP service on a Windows client, the following registry keys can be defined:

.. code-block:: bash

  Windows Registry Editor Version 5.00

  [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config]
  "FileLogSize"=dword:01000000
  "FileLogName"="c:\\w32time_debug.txt"
  "FileLogEntries"="0-300"

For more information, visit this `article from Microsoft <http://support.microsoft.com/kb/816043/en-us>`_.

*****************************************************
Choosing the operating mode of the Windows NTP client
*****************************************************

There are two operating modes of the Windows NTP client, *Nt5DS* and *named*.

The standard operating mode of a Windows client registered in the domain is *Nt5DS*.

.. code-block:: bash

  Windows Registry Editor Version 5.00

  [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters]
  ...
  "Type"="Nt5DS"

If for some reason you prefer to switch to the *named* operating mode, do :command:`net time /setsntp:ad.mydomain.lan`, which should return:

.. code-block:: bash

  [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters]
  ...
  "Type"="NTP"
  "ntpserver"="ad.mydomain.lan"

If you have chosen this mode, make sure the client is pointing to the correct NTP server.
If the :abbr:`DHCP (Dynamic Host Configuration Protocol)` gave an NTP server that is not the domain controller, this may be a problem.
To check, use the command :command:`w32tm /monitor`.