Question : DHCP Strangeness

I'm having an odd issue at one of my client sites with DHCP addresses being assigned outside the DHCP Scope. The Scope itself runs from 192.168.122.1-192.168.123.254 using a 23-bit netmask. There are multiple exclusions of ranges for static addresses assigned to server and network gear and reservations for some of the medical equipment and printers.

I had an issue this morning with two devices at a remote office (the network is flat and remote sites are connected via Metro Ethernet) picking up addresses of 192.168.125.x and 192.168.126.x. I had the person on-site power cycle the devices and I could see them connect to the Cisco AP and then watched as they picked up the ssame two out of scope addresses.

I added reservations for these devices to the DHCP scope and once cycled they picked up the reserved addresses without a problem and were then able to connect to the server to upload the data.

DHCP Server is a Server 2003 R2 box and is the PDC for the domain. The scope reconciles without error and is 33% available. There are no entries in the Event logs on either the client or the server. There are no other DHCP Servers running on the network and this happens with both wireless and wired clients. This has me scratching my head.

Anybody seen this behavior before?

Answer : DHCP Strangeness

Try using the following tool to see if there are rogue DHCP server floating about on the remote network:

http://www.softpedia.com/get/Network-Tools/Network-IP-Scanner/DHCPExplorer.shtml