Rogue DHCP in My network

My network is 172.19.20.1, but some of the computers in the network occasionally pick 192.168.200.1 which stops the user from using a major application in the company. what do I do to Identify the devices dishing our this ip in my network since I can ping it. Kindly help.

A fairly easy three-step process:

• Find the MAC of the offending DHCP server. You should be able to find it on a computer that's assigned the wrong IP address, ping the DHCP server and then look in the MAC table
• Use the address tables in the switches on the LAN to find the physical port to which the offending server is connected
• Follow the cable coming out of the port on the switch and find the physical computer