Windows NT 4.0 SP4 DNR Client Does Not Send Unqualified DNS Queries (230744)


The information in this article applies to:

  • Microsoft Windows NT Server 4.0 Terminal Server Edition SP4
  • Microsoft Windows NT Server 4.0 SP4
  • Microsoft Windows NT Server, Enterprise Edition 4.0 SP4
  • Microsoft Windows NT Workstation 4.0 SP4
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 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:

198550 SP4 Changes DNS Name Resolution

195611 DNS Client Does Not Try All Servers in DNS Service List

214467 Windows NT 4.0 DNR Only "Devolves" Two Domain Suffixes

Modification Type:MajorLast Reviewed:5/14/2003
Keywords:kbenv kbfix kbnetwork kbprb kbQFE KB230744
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