Network connectivity may be lost when you use DHCP to configure IP settings on a Windows XP Service Pack 2-based computer (915357)

SYMPTOMS

You configure a Microsoft Windows XP Service Pack 2 (SP2)-based client computer as follows:

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. IP addresses, such as those of the default gateway, of the DNS servers, and of the WINS servers are unavailable. Network connectivity may be lost.

RESOLUTION

Hotfix information

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Windows XP service pack that contains this hotfix.

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

http://support.microsoft.com/contactus/?ws=support

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

There are no prerequisites to install this hotfix.

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 name	File version	File size	Date	Time	Platform
Dhcpcsvc.dll	5.1.2600.2855	111,104	23-Feb-2006	04:40	x86

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  . . . . . . . : contoso.com
        Node Type . . . . . . . . . . . . : Hybrid
        IP Routing Enabled. . . . . . . . : No
        WINS Proxy Enabled. . . . . . . . : No
        DNS Suffix Search List. . . . . . : contoso.com

Ethernet 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. . . : 10.10.99.99
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . :
        DHCP Class ID . . . . . . . . . . : myclassid

Additionally, registry entries, such as the DhcpDefaultGateway entry, are removed from the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\TCPIP\Parameters\Interfaces\<GUID>

For more information about this problem in Windows XP with Service Pack 1, click the following article number to view the article in the Microsoft Knowledge Base:

922861 Network connectivity may be lost when you use DHCP to configure IP settings on a Windows XP Service Pack 1-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