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.

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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.

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Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

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 "More Information" section of this article.

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Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section of this article.

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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:

1.	Click Start, and then click Run.
2.	In the Open box, type regedit, and then click OK.
3.	Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\Parameters
4.	Point to New on the Edit menu, and then click DWORD Value.
5.	Type EnableSendErrorSuppression, and then press ENTER.
6.	Right-click EnableSendErrorSuppression, and then click Modify.
7.	In the Value data box, type 0, and then click OK.
8.	On the File menu, click Exit to quit Registry Editor.
9.	Restart the DNS service.

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For additional information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

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