Microsoft KB Archive/261964

= DHCP Lease Grace Period Is Four Hours =

Article ID: 261964

Article Last Modified on 2/28/2007

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server

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This article was previously published under Q261964



SUMMARY
After a Dynamic Host Configuration Protocol (DHCP) client lease expires, it is not immediately scavenged from the database. A grace period of four hours is added to the end of the lease to prevent against clock drift between the DHCP client and server. On a Windows 2000-based DHCP server, leases are scavenged from the database if they meet the criteria of ( + 4 hours).



MORE INFORMATION
In Windows 2000, leases that are expired but fall within the grace period appear in Microsoft Management Console (MMC) as inactive leases. Statistically, they are counted with active and excluded leases as &quot;In Use.&quot; However, any lease that falls within the grace period (inactive) may be issued by the DHCP server if the available leases fall to 0.

This behavior may become apparent if you are using short lease times and short scavenge intervals. The DHCP snap-in in MMC may display Scope Full icons (with an exclamation point on the Scope and Server icons) and the event log may contain event ID 1020. These notifications are based on the number of &quot;In Use&quot; addresses and occur even though inactive leases may be available to be distributed to requesting clients.

Sample event ID 1020:

Event Type: Warning

Event Source: DhcpServer

Event Category: None

Event ID: 1020

Date: 5/11/2000

Time: 5:32:24 PM

User: N/A

Computer: WIN2000

Description: Scope, 10.1.1.0, is 100 percent full with only 0 IP addresses remaining.

For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

153072 Leases Retained in DHCP Database For One Day After Expiration

Keywords: kbdhcp kbinfo KB261964

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