The DNS Client Service Does Not Revert to Using the First Server in the List in Windows XP (320760)


The information in this article applies to:

  • Microsoft Windows XP Professional
This article was previously published under Q320760
IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

If you are using Windows XP, the DNS Client service may not revert to using the first server in the DNS server list.

CAUSE

This behavior occurs because the Windows XP DNS Client service (Dnscache) follows a certain algorithm when it decides the order that it uses the DNS servers configured in the TCP/IP properties. If the DNS server list is reprioritized, the Windows XP DNS Client service resets the server priority at periodic intervals. By default, the server priorities are reset every 15 minutes.

WORKAROUND

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 work around this behavior, modify the registry so that the DNS server that is configured first is tried first on each query. Follow these steps, and then quit Registry Editor:
  1. Click Start, click Run, type regedit, and then click OK.
  2. Locate and then click the following key in the registry:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters

  3. On the Edit menu, point to New, and then click REG_DWORD.
  4. Type ServerPriorityTimeLimit, and then press ENTER.
  5. On the Edit menu, click Modify.
  6. Type 0, and then click OK.
The default value for the ServerPriorityTimeLimit registry setting is 900, and it has a range 0x0 to 0xFFFFFFFF seconds. When you set ServerPriorityTimeLimit to 0 (zero), the server priorities are reset before the DNS Client service decides which DNS server to use. You must restart Windows XP for these changes to take affect.

STATUS

This behavior is by design.

MORE INFORMATION

This behavior also occurs in Windows 2000 DNS Client. This behavior is described in the Windows 2000 DNS white paper. To view this white paper, visit the following Microsoft Web site:

http://www.microsoft.com/technet/prodtechnol/windows2000serv/plan/w2kdns2.mspx

Modification Type:MinorLast Reviewed:12/9/2005
Keywords:kbnetwork kbprb KB320760
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