Enable IP Address Conflict Detection
Applies To: Windows Server 2008
You can use this procedure to specify how many times the DHCP server tests an IP address before leasing it to a client.
Membership in the Administrators or DHCP Administrators group is the minimum required to complete this procedure.
To enable address conflict detection
Open DHCP.
In the console tree, click the applicable DHCP server.
On the Action menu, click Properties.
Click the Advanced tab.
For Conflict detection attempts, type a number greater than 0 (zero) and less than 6, and then click OK.
The number you type determines how many times the DHCP server tests an IP address before leasing it to a client.
Additional considerations
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. A value of no greater than 2 for ping attempts is recommended.