You might get some clues from the notes on modifying the registry. This information on Windows Server 2003 might be helpful, if not exact.
You have to modify the registry. However, serious problems might occur if you modify the registry even slightly incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the (322756) article in the Microsoft Knowledge Base:
DHCP checks for expired leases by using the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DhcpServer\Parameters\DatabaseCleanupInterval
By default, when the DHCP Server service is running on Windows Server 2003-based computers, the DatabaseCleanupInterval value is set to 60 (1 hour). When the DHCP Server service is running on a Windows 2000-based computer, the DatabaseCleanupInterval value is set to 1440 (1 day). When the DHCP lease is released, the DHCP server unregisters the DNS record.
You can configure the client's DHCP lease to expire automatically when the client computer is shut down for Windows 2000-based DNS clients or for later versions of DNS clients. To do this, follow these steps:
1. Click Start, point to Administrative Tools, then click DHCP
2. Expand the scope for which you want to change the DHCP expiration lease, right-click Scope Options, then click Configure Options.
3. Click the Advanced tab.
4. Click the list that is next to Vendor Class, then click Microsoft Windows Options.
5. Click to select the 002 Microsoft Release CHCP Lease on Shutdown Option check box, then click