Using DHCPCMD to Modify a Reservation Converts It to a Lease

Article translations Article translations
Article ID: 198541 - View products that this article applies to.
This article was previously published under Q198541
Expand all | Collapse all


When you use the DHCPCMD command ADDRESERVEDIP to modify an existing reservation, error 20022 (ERROR_DHCP_RESERVEDIP_EXISTS) is returned. When you subsequently inspect the reservation using DHCP ADMIN, the reservation has been turned into an active lease. If DHCPCMD is run again to modify the lease, it works correctly and is turned back into a reservation.


This is a problem in DHCP server, which incorrectly handles the modification of an existing reservation, causing the reservation to be partially deleted. This results in the remaining data looking like an active lease.

Running the same command again causes the reservation to be correctly re- added.


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:
  • Windows Service Pack Center -or-

  • 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


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.


Article ID: 198541 - Last Review: June 11, 2012 - Revision: 2.0
  • Microsoft Windows NT Server 4.0 Standard Edition
  • Microsoft Windows NT Server 4.0 Enterprise Edition
kbhotfixserver kbqfe kbbug kbfix KB198541

Give Feedback


Contact us for more help

Contact us for more help
Connect with Answer Desk for expert help.
Get more support from