Microsoft KB Archive/837928

= DNS suppresses responses to EDNS packets in Windows 2000 Server =

Article ID: 837928

Article Last Modified on 10/26/2006

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server

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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
A Microsoft Windows 2000 DNS server may suppress responses to DNS queries in cases where the extension mechanisms for DNS (EDNS) queries come from other servers that use Secure Network Address Translation (SecureNAT). In this scenario, all queries appear to come from the same DNS server.



CAUSE
This problem occurs because a DNS server suppresses responses when the server detects a format error in a DNS request. Because DNS does not support EDNS, the EDNS query is detected as a bad format DNS query. After a Windows 2000 DNS server detects a bad format query, the server does not respond to the computer that sent the query for 60 seconds.



Hotfix information
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;[LN;CNTACTMS]

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites
No prerequisites are required.

Restart requirement
You must restart the DNS service after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

File information
The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.   Date         Time   Version        Size     File name 02-Mar-2004 11:32  5.0.2195.6903  327,440  Dns.exe

Hotfix activation
This hotfix is activated automatically when you install this hotfix. (By default, Bad Sender Suppression is turned on.) To deactivate this hotfix, see the &quot;More Information&quot; section of this article.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section of this article.



MORE INFORMATION
Warning If you deactivate this hotfix, you will turn off all Bad Sender Suppression and your DNS server will try to respond to all malformed queries. Deactivate this hotfix only in a controlled environment.

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.

To deactivate this hotfix, follow these steps:  Click Start, and then click Run. In the Open box, type regedit, and then click OK. Locate and then click the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\Parameters

 Point to New on the Edit menu, and then click DWORD Value. Type EnableSendErrorSuppression, and then press ENTER.</li> Right-click EnableSendErrorSuppression, and then click Modify.</li> In the Value data box, type 0, and then click OK.</li> On the File menu, click Exit to quit Registry Editor.</li> Restart the DNS service.</li></ol>

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