Microsoft KB Archive/195811

= DNS Server May Write Back Incorrect Root Hints =

Article ID: 195811

Article Last Modified on 10/31/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT Server 4.0 Enterprise Edition

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This article was previously published under Q195811



IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.



SYMPTOMS
Your DNS server may stop resolving domain names for which it is not authoritative.



CAUSE
When a DNS server boots, it needs a list of root server "hints" -- NS and A records for the servers -- historically called the cache file. Traditionally DNS administrators could keep this file current by downloading a new copy from the InterNIC. This method works adequately when the root servers stay fairly static, but does require attention on the part of the administrator when updates and changes are made (for example, the massive renaming in late 1995).

The Microsoft DNS server has a feature to allow the server to attempt to write back a new cache file based on the response from the root servers.

If the AutoCacheUpdate key does NOT exist or is non-zero, the Microsoft DNS server will rewrite the cache file based on the data received from querying the root DNS servers on startup.



RESOLUTION
WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).

If the key is zero, the DNS server does not do this update.

NOTE: This change will only take affect after restarting the DNS service.

After you add the key and set the value to 0, copy the Cache.dns file from the \System32\Dns\Backup over the one that just contains the bad entries, typically in the \System32\Dns folder.

NOTE: The AutoCacheUpdate is turned off by default in Windows NT Service Pack 4.

Additional query words: kbDSupport

Keywords: kbprb KB195811

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