New Registry Value to Disable DNR Local Network Priority Sorting

ID: Q196500

The information in this article applies to:

Microsoft Windows NT Workstation version 4.0
Microsoft Windows NT Server version 4.0

IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information on how to do this, view the "Restoring the Registry" online Help topic in Regedit.exe or the "Restoring a Registry Key" online Help topic in Regedt32.exe.

SYMPTOMS

When connecting from a Windows NT 4.0 Service Pack 4 client to a multihomed server 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 will always connect 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 will go to that one server.

For additional information on this behavior, please see the following article in the Microsoft Knowledge Base:

Q182644 DNR Sorts IP Address for Multihomed Hosts Before Returning List

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: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).

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

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/support/supportnet/default.asp

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)

NOTE: If you contact Microsoft to obtain this fix, a fee may be charged. This fee is refundable if it is determined that you only require the fix you requested. However, this fee is non-refundable if you request additional technical support.

For more information about eligibility for no-charge technical support, see the following article in the Microsoft Knowledge Base:

Q154871 Determining If Your Product Is Eligible for No-Charge Technical Support

STATUS

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

Additional query words: 4.00

Keywords : kbbug4.00 kbfix4.00
Version : WinNT:4.0
Platform : winnt
Issue type : kbbug