Microsoft KB Archive/255880

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Article ID: 255880

Article Last Modified on 11/1/2006


  • Microsoft Windows NT Server 4.0 Standard Edition
  • Microsoft Windows NT 4.0 Service Pack 1
  • Microsoft Windows NT 4.0 Service Pack 2
  • Microsoft Windows NT 4.0 Service Pack 3
  • Microsoft Windows NT 4.0 Service Pack 4
  • Microsoft Windows NT 4.0 Service Pack 5
  • Microsoft Windows NT 4.0 Service Pack 6
  • Microsoft Windows NT 4.0 Service Pack 6a

This article was previously published under Q255880

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


In DNS Manager, when you try to manually add any of the following reverse lookup zones

you may receive the following error message:

The new zone couldn't be created because there is already a zone by this name.
Verify that the zone name was entered correctly or choose a new zone name.

The process is terminated by DNS and the zone is not created. In addition, the following entry is displayed in the system log of Event Viewer:

Event ID: 1540
Source: DNS
Type: Error
Description: DNS Server unable to create domain node.


This behavior can occur for one of the following reasons:

  • The Show Automatically Created Zones check box (click Options, and then click Preferences) is cleared (by default) or the ShowAutoCreatedZones registry value is set to 0.

NOTE: When a DNS server is created, these three reverse lookup zones are automatically created (in memory only and not stored in a zone file) by default. However, in DNS Manager the Show Automatically Created Zones option is disabled by default, and the automatically created zones are therefore not displayed. This may lead you to believe that those zones are not created.

  • When the DisableAutoReverseZones registry value is accidentally set to 1 or a non-zero value.


To resolve this issue, use the appropriate method.

Method 1

  1. In DNS Manager, click to select the Show Automatically Created Zones check box or set the ShowAutoCreatedZones registry value to a non-zero value.
  2. In DNS Manager, right-click the server name, and then click Update Server Data Files.
  3. Right-click the server name again, and then click Refresh.

Method 2

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.

If the DisableAutoReverseZones value exists, make sure it is set to 0.


The ShowAutoCreatedZones value is located in the following registry key:


Value: ShowAutoCreatedZones
Type: Reg_DWORD (Boolean)
Default: 1 (SP5 or earlier), 0 (SP6 and SP6a)
Value Range: 0 (False) or 1 (True)
Function: Determines if the server shows the automatically created zones, including the standard reverse lookup zones

The DisableAutoReverseZones value is located in the following registry key:


Value: DisableAutoReverseZones
Added in: Windows NT 4.0
Type: Reg_DWORD (Boolean)
Default: NoKey (Create automatic reverse lookup zones)
Value Range: 0 (False) or 1 (True)
Function: Determines if the server automatically creates standard reverse lookup zones

NOTE: If the DisableAutoReverseZones value does not exist or if it is set to 0, the DNS server automatically creates these zones with the correct entries (except for a PTR for to localhost). If the DisableAutoReverseZones value is set to non-zero, the server does not create these zones.

Every DNS server should be authoritative for three reverse lookup zones according to RFC:

These zones are used for localhost lookups/queries such as, (loopback), and (broadcast).

By being authoritative for the zones corresponding to these queries, the DNS server avoids unnecessary recursions to the root servers on these queries, so they should always exist on the DNS server. Therefore, the DisableAutoReverseZones value should normally not be enabled because if the zones do not exist, lookup to any of the zones is sent to a root server.

If you need to modify the localhost (127.0.0.x) reverse lookup zone, you must manually create it. The correct name for this zone is

Additional query words: domain node

Keywords: kberrmsg kbnetwork kbprb kbui KB255880