DOCUMENT:Q230744 06-AUG-2002 [winnt] TITLE :Windows NT 4.0 SP4 DNR Does Not Send Unqualified DNS Queries PRODUCT :Microsoft Windows NT PROD/VER:winnt:4.0 SP4 OPER/SYS: KEYWORDS:kbenv kbnetwork ====================================================================== ------------------------------------------------------------------------------- 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 ------------------------------------------------------------------------------- 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 ..com is unresolved, it is devolved to .com and eventually to . 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: ====================================================================== 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 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2002.