DHCP Server Service May Stop Responding

• Microsoft Windows NT Server version 4.0

SYMPTOMS

The Dynamic Host Configuration Protocol (DHCP) server service may stop responding during administrative operations using the DHCP Manager application.

The specific operations that were found to make the service stop responding were adding reservations to active scopes and deleting scopes that had reservations defined. In each case, the server had to be extremely busy servicing DHCP client requests at the same time for it to stop responding.

CAUSE

This problem occurs when the DHCP server service deadlocks trying to acquire critical sections that guard access to the registry and the DHCP Jet database.

The deadlock occurs because, when a client issues a release request or a renew request, the DHCP server acquires the Jet database critical section and holds it while attempting to acquire the registry critical section. This causes a problem if it occurs at the same time as a DHCP administrative operation adds reservations in scopes or deletes entire scopes that contain reservations because these administrative operations acquire the registry critical section and hold it while attempting to acquire the Jet database critical section. Because client release or renew operations hold the Jet database critical section, the administrative operation cannot acquire it.

Likewise, because the administrative operation holds the registry critical section, the client release or renew operation cannot acquire it. This causes deadlock, and the DHCP server service stops responding.

RESOLUTION

The DHCP server service was modified so that contentions would not occur over the registry or Jet database critical sections during administrative operations.

To correct this problem, obtain the latest service pack for Windows NT 4.0 or obtain the hotfix mentioned below.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 4.0. This problem was corrected in the latest Microsoft Windows NT 4.0 U.S. Service Pack. 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