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Article ID: 196432 - Last Review: June 11, 2012 - Revision: 3.0

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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


It is not possible to change the following default DNS Start of Authority (SOA) values:

  • Serial Number
  • Minimum TTL
  • Expire Timer
  • Retry Timer
  • Refresh Timer
For more information, please see the following article in the Microsoft Knowledge Base:

163971  ( ) The Structure of a DNS SOA Record


To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to:
  • 152734  ( ) how to obtain the latest windows nt 4.0 service pack
For information on obtaining the individual software update, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:;EN-US;CNTACTMS (;EN-US;CNTACTMS)


Microsoft has confirmed this to be a problem in Windows NT version 4.0. This problem was first corrected in Windows NT version 4.0 Service Pack 5.


Some organizations, responsible for registering DNS domain names, demand specific DNS SOA values to be used when registering DNS domains. This is to make sure that these values adapt well to the requirements of the Internet.

The following is an example of the values that were requested by one of these organizations:

  • serial number is not in YYYYMMDDxx format
  • minimum ttl should fit the 40000-345600 range
  • expire timer should fit in the 604800-360000 range
  • retry timer does should fit in the 1800-28800 range
  • refresh timer should fit in the 10000-86400 range
Changing these values through DNS Admin is possible, but very labor- intensive when creating lots of zones. Therefore the following registry entries have been made to make these values configurable for all zones that are created.

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.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\Parameters ForceSoaSerial (REG_DWORD) ForceSoaMinimumTtl (REG_DWORD) ForceSoaRefresh (REG_DWORD) ForceSoaRetry (REG_DWORD) ForceSoaExpire (REG_DWORD)

NOTE: Be sure to click Decimal in Registry Editor when entering values.
These registry keys:

  • Overwrite the appropriate SOA value of every primary zone that loads on the computer.
  • Serve as default values for any new zone written
Using these registry entries will lock down the values; changing them through the DNS Admin Tool is still possible, but on the next restart of the DNS server, these SOA values are rewritten from the above registry entries.

NOTE: ForceSoaSerial should only be used for registration purposes as described above. After registering, this key should be deleted to ensure normal serial number functionality. If this key is not deleted, on every DNS server restart, the serial number is reset using the ForceSoaSerial value.

  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 4.0 Standard Edition
  • Microsoft Windows NT Server 4.0 Enterprise Edition
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