Microsoft KB Archive/230744

= Windows NT 4.0 SP4 DNR Client Does Not Send Unqualified DNS Queries =

Article ID: 230744

Article Last Modified on 2/27/2007

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APPLIES TO


 * Microsoft Windows NT Server 4.0, Terminal Server Edition Service Pack 4
 * Microsoft Windows NT 4.0 Service Pack 4
 * Microsoft Windows NT 4.0 Service Pack 4
 * Microsoft Windows NT Workstation 4.0 Developer Edition

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This article was previously published under Q230744



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:

256986 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. .com is unresolved, it is devolved to .com and eventually to. This last unqualified query is eliminated from the name query process.

