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The virtual IP address of a Windows Server 2008 NLB cluster is bound to the NetBIOS host name of a particular server or of multiple servers

When you run a Windows Server 2008 network load-balancing (NLB) cluster that has a virtual IP address configured, you may experience the following symptoms:
  • When you use the nbtstat -n command to check the IP address of a server, the virtual IP address is bound to the NetBIOS host name of a particular server or of multiple servers.
  • When you try to access a certain server by using its host name, you are routed to an incorrect server in the NLB cluster.
  • When you try to use the virtual IP address to access the NLB cluster, you are always routed to the same server.
Note You expect that the virtual IP address will not be bound to any host names.

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. 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 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.


No prerequisites are required.

Restart requirement

You must restart the computer 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 file attributes) 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 item in Control Panel.
Windows Server 2008, 32-bit editions
File nameFile versionFile sizeDateTimePlatform
Windows Server 2008, Itanium-based editions
File nameFile versionFile sizeDateTimePlatformService branch
Netbt.sys6.0.6001.22119634,36821-Feb-200803:02IA-64Not Applicable
Netbtugc.exe6.0.6001.2211952,22421-Feb-200803:01IA-64Not Applicable
Windows Server 2008, 64-bit editions
File nameFile versionFile sizeDateTimePlatformService branch
Netbt.sys6.0.6001.22119251,39221-Feb-200803:07x64Not Applicable
Netbtugc.exe6.0.6001.2211924,06421-Feb-200803:07x64Not Applicable
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
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
NLB VIP Windows 2008

Article ID: 949429 - Last Review: 09/11/2010 10:11:00 - Revision: 1.2

Windows Server 2008 Standard, Windows Server 2008 Enterprise, Windows Server 2008 Datacenter, Windows Server 2008 Datacenter without Hyper-V, Windows Server 2008 Enterprise without Hyper-V, Windows Server 2008 for Itanium-Based Systems, Windows Server 2008 Standard without Hyper-V, Windows Web Server 2008

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