Multiple Entries in Zone File Cause Memory Leak in Dnsadmin.exe

• Microsoft Windows NT Workstation version 4.0
• Microsoft Windows NT Server version 4.0

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 on how to do this, view the "Restoring the Registry" online Help topic in Regedit.exe or the "Restoring a Registry Key" online Help topic in Regedt32.exe.

SYMPTOMS

When a zone file contains a large number (approximately 100) of "A" records for a single host name (each one mapped to a different IP address), the user interface appears to stop responding (hang) when trying to display the zone information.

During this time, the amount of memory used by Dnsadmin.exe progressively increases until such time as the system displays a dialog box saying that the system is running low on virtual memory and instructing the user to increase the size of the paging file.

Several minutes later, the system displays another dialog box, this one stating that there is not enough memory to get all the records. An "out of memory" message is also displayed in the lower right hand corner of DNS Manager, followed by another message stating that the system is running low on virtual memory.

CAUSE

The DNS Admin tool hangs when there are a lot of records for a particular node because it is running out of the RPC buffer space.

RESOLUTION

To resolve this problem, edit the registry to increase the default RPC Buffer size for the DNS Admin:

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" online Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" online Help topics in Regedt32.exe. Note that you should back up the registry before you edit it.

1. Run Registry Editor (Regedt32.exe).

2. Go to the following key:

         HKEY_LOCAL_MACHINE\Software\Microsoft\DNS Administrator
   

3. On the Edit menu, click Add Value and use the following entry:

         Value Name: RpcBufferAlloc
         Data Type:  REG_Dword
         Value:      0-FFFFFFFF
         Default:    800(2048)
   
         Description: This parameter determines the Size of the RPC Buffer
                      Allocation used by the DNS Administrator.
   
   

4. Repeat steps 2 and 3 for the following key:

         HKEY_CURRENT_USER\Software\Microsoft\DNS Administrator
   

5. Increase the value of RpcBufferAlloc from 2048 to 16384.

6. Close Registry Editor.

STATUS

Microsoft is researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.