Network connectivity may be lost when you use DHCP to configure IP settings on a computer that is running Windows XP with Service Pack 1

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You configure a computer that is running Microsoft Windows XP with Service Pack 1 (SP1) in the following way:
  • You use Dynamic Host Configuration Protocol (DHCP) to configure IP settings.
  • You configure fallback options in case the client computer cannot connect to a DHCP server.
This configuration works even when the DHCP server is unavailable. However, the configuration may not work if you configure a user class on the computer by typing the following command:
ipconfig /setclassid * myuserclass
If you configure a class ID, the fallback IP configuration of the client computer cannot be used. Therefore, the IP addresses of the default gateway, of the DNS servers, and of the WINS servers are unavailable. Network connectivity may be lost.
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.


To apply this hotfix, you must have Windows XP Service Pack 1 (SP1) installed.

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.
File nameFile versionFile sizeDateTimePlatform
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
More information
When this problem occurs, the ipconfig /all command displays information that resembles the following:
Windows IP Configuration        Host Name . . . . . . . . . . . . : xp1        Primary Dns Suffix  . . . . . . . :        Node Type . . . . . . . . . . . . : Hybrid        IP Routing Enabled. . . . . . . . : No        WINS Proxy Enabled. . . . . . . . : No        DNS Suffix Search List. . . . . . : contoso.comEthernet adapter Local Area Connection:        Connection-specific DNS Suffix  . :         Description . . . . . . . . . . . : 3Com 3C920 Integrated Fast Ethernet Controller        Physical Address. . . . . . . . . : 00-01-02-03-04-05        Dhcp Enabled. . . . . . . . . . . : Yes        Autoconfiguration Enabled . . . . : Yes        Autoconfiguration IP Address. . . :        Subnet Mask . . . . . . . . . . . :        Default Gateway . . . . . . . . . :        DHCP Class ID . . . . . . . . . . : myclassid
Additionally, registry entries are removed from the following registry subkey:
These registry entries may include the DhcpDefaultGateway entry.

For more information about a similar problem in Windows XP with Service Pack 2, click the following article number to view the article in the Microsoft Knowledge Base:
915357 Network connectivity may be lost when you use DHCP to configure IP settings on a Windows XP Service Pack 2-based computer
For more information about the terms that are used in this article, 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

Article ID: 922861 - Last Review: 01/16/2015 15:41:30 - Revision: 4.0

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