DHCP Client Continues to Function After IP Lease Expires

• Microsoft Windows NT Workstation version 4.0
• Microsoft Windows NT Server version 4.0

SYMPTOMS

Dynamic host configuration protocol (DHCP) clients may continue to use their IP address information for up to five minutes after the lease has expired. DHCP

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 4.0. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

The following is a small section of RFC 1541 that governs lease expiration behavior:

4.4.4 Reacquisition and expiration ...

   In both RENEWING and REBINDING state, if the client receives no
   response to its DHCPREQUEST message, the client should wait one-half
   the remaining time until the expiration of T1 (in RENEWING state) and
   T2 (in REBINDING state) down to a minimum of 60 seconds, before
   retransmitting the DHCPREQUEST message.

   If the lease expires before the client receives a DHCPACK, the client
   moves to INIT state, MUST immediately stop any other network
   processing and requests network initialization parameters as if the
   client were uninitialized. If the client then receives a DHCPACK
   allocating that client its previous network address, the client SHOULD
   continue network processing. If the client is given a new network
   address, it MUST NOT continue using the previous network address and
   SHOULD notify the local users of the problem.