DOCUMENT:Q271374  08-MAY-2002  [winnt]
TITLE   :Windows NT 4.0 SP6 Clients Contact the PDC Every 21 Minutes
PRODUCT :Microsoft Windows NT
PROD/VER::4.0 SP6,4.0 SP6a
OPER/SYS:
KEYWORDS:kbenv kbdomain kbWinNT400PreSP7Fix

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The information in this article applies to:

 - Microsoft Windows NT Server versions 4.0 SP6, 4.0 SP6a 
 - Microsoft Windows NT Workstation versions 4.0 SP6, 4.0 SP6a 
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SYMPTOMS
========

Microsoft Windows NT 4.0 may contact the primary domain controller (PDC) when
you start your computer and every 21 minutes to get a Distributed File System
(DFS) referral. When this occurs, there may be unwanted network traffic and
unwanted load on the server service in larger domains.

CAUSE
=====

This problem can occur because there are changes to the Mup.sys file from
Q242001. It is necessary to periodically check with a Microsoft Windows
2000-based domain controller for a DFS referral. Because Windows NT 4.0 Service
Pack 6 (SP6) cannot locate a Windows 2000-based domain controller if one exists,
it must contact the PDC. Note that the PDC is the only system in a domain that
is guaranteed to be a Windows 2000 domain controller if any Windows 2000-based
domain controllers exist.


RESOLUTION
==========

A supported fix is now available from Microsoft, but it is only intended to
correct the problem described in this article and should be applied only to
systems experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the
fix. For a complete list of Microsoft Product Support Services phone numbers and
information on support costs, please go to the following address on the World
Wide Web:

   http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are normally incurred for support calls may
be canceled, if a Microsoft Support Professional determines that a specific
update will resolve your problem. Normal support costs will apply to additional
support questions and issues that do not qualify for the specific update in
question.

The English-language version of this fix should have the following file
attributes or later:

   Date        Time     Version        Size     File name  Platform
   ----------------------------------------------------------------
   09/08/2000  01:33pm  4.0.1381.7086  80,848   Mup.sys    Intel
   09/08/2000  01:32pm  4.0.1381.7086  142,800  Mup.sys    Alpha 



The Mup.sys file enables a new registry entry to be specified that can enable a
delay. The delay is specified in minutes, starting at 21 minutes. When you
enable this registry entry, the initial traffic when you start the computer is
not prevented, however, the subsequent traffic is prevented.

1. Start Registry Editor (Regedt32.exe).

2. Locate and click the following registry key:

   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanWorkstation\

3. On the Edit menu, click Add Value, and then add the following registry value:

   Value Name: DfsDcNameDelay
   Data Type: REG_DWORD
   Radix: select Decimal
   Value: Delay in minutes

4. Quit Registry Editor.


STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft products that are
listed at the beginning of this article.



Additional query words: mup

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Keywords          : kbenv kbdomain kbWinNT400PreSP7Fix 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400sp6 kbWinNTS400search kbWinNTW400sp6 kbWinNTW400SP6a
Version           : :4.0 SP6,4.0 SP6a
Hardware          : ALPHA x86
Issue type        : kbprb
Solution Type     : kbfix

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