When a device on your network is assigned an IP address that is on the same subnet as another device on the Internet or external network, the result is overlapping networks.
This is a common result when two companies merge together.
It is possible to allow communication between two overlapping networks without having to renumber any devices by using Network Address Translation (NAT).
Note: The internal host must initiate the connection to the external host by the domain name, rather than by the IP address.
For a configuration example, refer to Using NAT in Overlapping Networks.