DHCP: IP address conflict detection should have a value of less than 4

  • Article

Applies To: Windows Server 2008 R2, Windows Server 2012

This topic is intended to address a specific issue identified by a Best Practices Analyzer scan. You should apply the information in this topic only to computers that have had the Dynamic Host Configuration Protocol Best Practices Analyzer run against them and are experiencing the issue addressed by this topic. For more information about best practices and scans, see Best Practices Analyzer (https://go.microsoft.com/fwlink/?LinkId=122786).

Operating System

Windows Server 2008 R2, Windows Server 2012

Product/Feature

Dynamic Host Configuration Protocol (DHCP)

Severity

Warning

Category

Configuration

Issue

DHCP: IP Address conflict detection should have a value of less than 4.

Impact

Conflict detection with a value greater than 3 can lead to slow performance of the DHCP server.

Resolution

Set the IP address conflict detection value to 3 or less using the DHCP MMC

When conflict detection attempts are set, the DHCP server uses the ping process to test available scope IP addresses before including these addresses in DHCP lease offers to clients.

A successful ping means the IP address is in use on the network. Therefore, the DHCP server does not offer to lease the address to a client. If the ping request fails and times out, the IP address is not in use on the network. In this case, the DHCP server offers to lease the address to a client.

Each additional conflict detection attempt delays the DHCP server response by a second while waiting for the ping request to time out. This increases the load on the server.

Membership in the Administrators or DHCP Administrators group is the minimum required to complete this procedure.

To change the address conflict detection value

  1. Click Start, point to Administrative Tools and then click DHCP.

  2. In the console tree, expand the applicable DHCP server, right click IPv4, right-click the applicable scope and then click Properties.

  3. Click Advanced, type 1, 2 or 3 in Conflict detection attempts: and then click OK.

Additional references

For updated detailed IT pro information about DHCP and selectively enabling or disabling DHCP server bindings, see the Windows Server 2008 R2 documentation on the Microsoft TechNet Web site.