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How can I enable conflict detection on my DHCP server?

A. You can configure the DHCP server to determine whether an address is in use before the server allocates it to a client. Doing so is useful in scenarios in which you've set up a new DHCP server to take over for a failed DHCP scope for which no backup exists. This method helps alleviate concerns that the new DHCP server will give out addresses that were allocated when the scope was used on the previous server.

If the DHCP server checks to determine whether the address is in use before giving it to a client, you shouldn't see many allocation problems, assuming that you've configured clients to renew their lease at start-up to alleviate problems with clients that were turned off when the DCHP server performed the check. When you restart clients that were turned off during the DHCP server check, and they use the existing lease rather than trying to renew their lease, address-conflict problems will arise.

To enable conflict detection on your DHCP server, perform these steps:

  1. Start the Microsoft Management Console (MMC) DHCP snap-in (Start, Programs, Administrative Tools, DHCP).
  2. Right-click the DHCP server and select Properties.
  3. Select the Advanced tab.
  4. By default, "Conflict detection attempts" is set to 0. Increase the value to 1 or 2, as the figure shows. Setting it higher than 2 isn't recommended because each attempt takes as long as 1 second.
  5. Click OK.
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