Released Client IP Address Shows As Active in DHCP Server

 Last reviewed: September 5, 1996
Article ID: Q136951
The information in this article applies to:
  • Microsoft Windows NT Server versions 3.51

SYMPTOMS

If you run IPCONFIG/RELEASE (or WINIPCFG/RELEASE from Windows95) from a DHCP-enabled client computer and the client computer is located on a different subnet than the DHCP server, the IP address is released but the address shows up in the active lease database on the DHCP server.

CAUSE

This problem occurs because the DHCP server is not checking the DHCP release packet correctly. Because the release packet is sent directly to the server, the BOOTP relay agent does not add header information, but the client's IP address is in the CIADDR field of the packet. The DHCP server is not looking at the CIADDR field and assumes the packet is for a local scope. The DHCP server fails to find the client's UID and the release fails.

RESOLUTION

To work around this problem, manually delete the active lease using DHCP Manager.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 3.51. This problem has been corrected in the latest U.S. Service Pack for Windows NT version 3.51. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces): 

   S E R V P A C K

KBCategory: kbnetwork kbfix3.51.sp2
KBSubcategory: nttcp NTSrvWkst
Additional reference words: prodnt 3.51 tcpip dhcp unavailable

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Last reviewed: September 5, 1996
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