DHCP in IOS not returning NAK

[oben]

I have a problem using the IOS DHCP server option.

When clients roam from network to network they retain their old address and do not get a new address in the new subnet.

Checking with sniffer this behaviour against our normal DHCP server I find that the Cisco IOS device (an MSFC in this case) does not return NAK when the client does a DHCP request on the new subnet with the old IP and the client (Win2K or XP) then keeps the old address.

Please advise how to solve this.

Thanks

[glen.grant]

In the MSF make sure there is not a specific broadcast address defined such as 150.XXX.XXX.255 . A broadcast address does not need to be defined and will cause the symptoms you are describing as we went thru this and it took us a week to figure out why .