My company's Windows NT 4.0 DHCP server displays several active leases as BAD_ADDRESS. What does this designation indicate, and how do I remove these records so that the server can reassign the corresponding IP addresses to our DHCP clients?

The BAD_ADDRESS marking is part of the duplicate—IP address detection scheme in NT 4.0 Service Pack 2 (SP2) and later. Before assigning an IP address to a client, the DHCP server detects whether that address is in use. If the server finds an existing allocation, it marks the address as BAD_ADDRESS. (For more information about this process, see the Microsoft article "DHCP: Detecting and Flagging Duplicate IP Addresses" at http://support.microsoft.com/default.aspx?scid=kb;en-us;q161430.) When you're sure that the address is no longer assigned to any host on the network, you can delete the lease. Run DHCP Administrator, highlight the applicable scope, then choose Scope, Active Leases from the menu bar to open the Active Leases dialog box. Select the BAD_ADDRESS record, then click Delete. Doing so permits DHCP to once again allocate the IP address to requesting DHCP clients.