Network Picking up another network ip address

[Amallia]

I have two networks here, and they both have there on ip range.

 

Both networks are picking up the other networks IP addresses.

 

Both of these network are link together but can see each other.

 

It has been fine for 4 years now all of sudden this happens.

 

Does anybody know what could be causing this

 

Thanks

Amallia

[tech_guy]

Has someone plugged a cable in where they shouldn't in a cabinet? Do you have comms cabinets accessible in public areas where people can fiddle?

[Amallia]

Only me and the technician have key to the cupboards where the cabinets are

[CISCODISCO]

Interesting.... the cable seems very likely. Are these on VLAN's or something maybe someone has changed the switch configuration.............

 

Have you checked the DHCP server see what's happening.

[cpjitservices]

or it could be a statically assigned IP somewhere, I'd Wireshark it and try to se what is being broadcast could be a spyware/malware issue.

[cpjitservices]

check DHCP logs see whats been doled out and where to and also see if it's you can see any traffic coming from/to the network showing up.