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Responses are incorrectly marked as invalid on a DNS server in Windows Server 2008 R2

When you query for a name on a Domain Name System (DNS) server that is running Windows Server 2008 R2, the DNS service may parse the OPT record in a DNS response packet incorrectly. Therefore, a DNS response packet is marked as invalid, and a "Server Failure" error is returned to the client. This name resolution failure can cause connectivity failures.

When this issue occurs, DNS Event ID 5501 is logged in the event log, together with the following message: 

The DNS Server encountered a bad packet from <ip of remote DNS serve>.  Packet processing leads beyond packet length. The event data contains the DNS packet.

Additionally, when you run the following nslookup command to diagnose the issues in the DNS infrastructure, the command operation fails togethet with a "Server Failure" error:
set type=MX
set timeout=120
<An external domain name>

This issue occurs because the DNS service parses the OPT record in a DNS response packet incorrectly.

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 the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

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, contact 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 website: 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.


To apply this hotfix, you must be running Windows Server 2008 R2 or Windows Server 2008 R2 Service Pack 1 (SP1).
For more information about how to obtain a Windows Server 2008 R2 service pack, click the following article number to view the article in the Microsoft Knowledge Base:
976932 Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2

Registry information

To apply this hotfix, you do not have to change the registry.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The global version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.
Windows Server 2008 R2 file information notes
Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.
  • The files that apply to a specific product, milestone (RTM,SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    VersionProductMilestoneService branch
    6.1.760 0.21xxxWindows Server 2008 R2RTMLDR
    6.1.760 1.22xxxWindows Server 2008 R2SP1LDR
  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.
  • The MANIFEST files (.manifest) that are installed for each environment are listed separately in the "Additional file information for Windows Server 2008 R2" section. MANIFEST files and the associated security catalog (.cat) files, are extremely important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.
For all supported x64-based versions of Windows Server 2008 R2
File nameFile versionFile sizeDateTime
Cache.dnsNot applicable3,19810-Jun-200920:31
Dns.exe6.1.7600.21320697,85606-Sep-201218:03 applicable60910-Jun-200920:31
Cache.dnsNot applicable3,19805-Nov-201001:52
Dns.exe6.1.7601.22108699,90406-Sep-201217:59 applicable60905-Nov-201001:52
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
More information
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates

Additional file information

Additional file information for Windows Server 2008 R2

Additional files for all supported x64-based versions of Windows Server 2008 R2
File nameAmd64_593889b567fb049cf7da7d773db92da7_31bf3856ad364e35_6.1.7600.21320_none_a96cd62d07236390.manifest
File versionNot applicable
File size710
Date (UTC)07-Sep-2012
Time (UTC)15:51
File nameAmd64_a70a4d7d927d593ec8da3d3e5dae4fb7_31bf3856ad364e35_6.1.7601.22108_none_a25234e1e01a20f2.manifest
File versionNot applicable
File size710
Date (UTC)07-Sep-2012
Time (UTC)15:51
File nameAmd64_microsoft-windows-dns-server-service_31bf3856ad364e35_6.1.7600.21320_none_aac039500937359d.manifest
File versionNot applicable
File size158,131
Date (UTC)06-Sep-2012
Time (UTC)20:35
File nameAmd64_microsoft-windows-dns-server-service_31bf3856ad364e35_6.1.7601.22108_none_acc4387e0646345f.manifest
File versionNot applicable
File size158,131
Date (UTC)06-Sep-2012
Time (UTC)18:30

Article ID: 2739005 - Last Review: 11/02/2012 03:36:00 - Revision: 5.0

Windows Server 2008 R2 Enterprise, Windows Server 2008 R2 Datacenter, Windows Server 2008 R2 for Itanium-Based Systems, Windows Server 2008 R2 Foundation, Windows Server 2008 R2 Standard, Windows Web Server 2008 R2

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