Microsoft KB Archive/196500

= New Registry Value to Disable DNR Local Network Priority Sorting =

Article ID: 196500

Article Last Modified on 2/25/2007

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Professional Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 4.0 Standard Edition

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This article was previously published under Q196500



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
When connecting from a Windows NT 4.0 Service Pack 4 client to a multihomed server by using the DNS namespace, if the client and server have a common subnet, the DNS "round-robin" randomizing of server IP addresses is ignored. This means that the client always connects to the "near side" IP address of the server. Also, if there are a number of servers sharing the same name, and one of the servers is on the same subnet as the client, all connections go to that one server.

For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

182644 DNR Now Sorts IP Addresses for a Multihomed Host Before Returning the List to Winsock Applications



CAUSE
In Windows NT 4.0 SP4, the Domain Name Resolver (DNR) was modified to sort the list of IP addresses returned by the gethostbyname call into "best to worst" order, based on the client computer route table. This behavior was implemented to optimize client/server connections, and should be useful in most environments.



RESOLUTION
A new version of Rnr20.dll is available. It supports the following new registry parameter:

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.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters \PrioritizeRecordData

NOTE: The above registry key is one path; it has been wrapped for readability.

Value Type: REG_DWORD

Valid Range: 0,1 (False,True)

Default: 1

Setting this parameter to 0 disables the sorting behavior described above.

A supported fix that corrects this problem is now available from Microsoft, but has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Windows NT service pack that contains this fix.

To resolve this problem immediately, 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

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

  Date      Time                  Size    File Name     Platform --  11/20/98  12:40p                42,768  Rnr20.dll     (x86) 11/20/98 12:39p                71,440  Rnr20.dll     (Alpha)

More Information
In Windows 2000, the registry value:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters \PrioritizeRecordData

NOTE: The above registry key is one path; it has been wrapped for readability.

is defaulted to 1.



STATUS
Microsoft has confirmed this to be a problem in Windows NT version 4.0.

Additional query words: 4.00

Keywords: kbhotfixserver kbqfe kbbug kbfix kbqfe KB196500

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