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Q230744: Windows NT 4.0 SP4 DNR Does Not Send Unqualified DNS Queries

Article: Q230744
Product(s): Microsoft Windows NT
Version(s): winnt:4.0 SP4
Operating System(s): 
Keyword(s): kbenv kbnetwork
Last Modified: 06-AUG-2002

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The information in this article applies to:

- Microsoft Windows NT Server version 4.0 SP4 
- Microsoft Windows NT Server, Enterprise Edition version 4.0 SP4 
- Microsoft Windows NT Server version 4.0 SP4, Terminal Server Edition 
- Microsoft Windows NT Workstation version 4.0 SP4 
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IMPORTANT: This article contains information about modifying the registry. Before you 
modify the registry, make sure to back it up and make sure that you understand how to restore 
the registry if a problem occurs. For information about how to back up, restore, and edit the 
registry, click the following article number to view the article in the Microsoft Knowledge Base:

  Q256986 Description of the Microsoft Windows Registry

SYMPTOMS
========

The Domain Name Resolver (DNR) client implemented in Windows NT 4.0 Service Pack
4 (SP4) does not send unqualified queries to the Domain Name System (DNS)
server.

CAUSE
=====

An unqualified query is a DNS short name query for the host name sent after
stripping the domain name portion of the Fully Qualified Domain Name (FQDN).
This is not a valid DNS query. Eliminating this last short name query from the
DNS lookup phase in SP4 enhances DNR performance.

RESOLUTION
==========

WARNING: If you use Registry Editor incorrectly, you may cause serious problems
that may require you to reinstall your operating system. Microsoft cannot
guarantee that you can solve problems that result from using Registry Editor
incorrectly. Use Registry Editor at your own risk.

If you want to re-enable last short name query using DNS, set the data value of
the AllowUnqualifiedQuery value to 1 in the following registry key:

  HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters\

  Value Name: AllowUnqualifiedQuery
  Data Type: REG_DWORD
  Valid Range: 0-1
  Default: 0

MORE INFORMATION
================

"Devolution" may be appropriate in normal DNR usage. If a DNS query for
<client>.<domainname>.com is unresolved, it is devolved to
<client>.com and eventually to <client>. This last unqualified query
is eliminated from the name query process.

REFERENCES
==========

For additional information about DNR optimization and name devolution
enhancements in SP4, please see the following articles in the Microsoft
Knowledge Base:

  Q198550 SP4 Changes DNS Name Resolution

  Q195611 DNS Client Does Not Try All Servers in DNS Service List

  Q214467 Windows NT 4.0 DNR Only "Devolves" Two Domain Suffixes

Additional query words:

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Keywords          : kbenv kbnetwork 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400search kbWinNT400search kbWinNTW400sp4 kbWinNTSsearch kbWinNTSEntSearch kbWinNTSEnt400sp4 kbWinNTS400sp4 kbWinNTS400search kbNTTermServ400sp4 kbNTTermServSearch
Version           : winnt:4.0 SP4
Hardware          : ALPHA x86
Issue type        : kbprb
Solution Type     : kbfix

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