Server 2003 – DHCP is serving duplicate IP addresses …

Strange issue I would say .. I have my MS Windows Server 2003 setup and this server has also role as the DHCP server for network. Today for some reason I am having troubles on network with IP conflicts and I have started to investigate what the problem is.

1. The conflict is causing issue with server that has a static IP address and this IP is in reservation pool

2. Whatever device I plug in .. this new connected device will receive the same IP address as is on the on server that has the same IP assigned as a static IP

I have shut down the DHCP and power up .. nothing has been solved .. the IP is still being served and users on the servers are being for this reason disconnected …

Well, there is easy fix and I should do this right away when the problem started .. check if the IP address is in exclusion list so it cannot be assigned by the DHCP server to hosts on the network.

Microsoft has also reference KB for this issue here

To exclude the static IP address from the DHCP scope:

  • Turn off the DHCP client computer in conflict with the network device that has the static IP address.
  • On the DHCP server, exclude the static IP address from the scope of the DHCP IP address range.