Network to Network
On an IP network, the logical addresses on a segment must be matched. If the network segment is 192.168.1.0, all the hosts on that network must have addresses that start with 192.168.1. They will have unique identifiers for the last digit.
When a computer is moved from one segment to another, the IP address will have to be changed to make it a member of the new segment.
MAC addresses do not change when a host is moved to another segment.
A MAC address (physical) only changes when the NIC card inside the host is changed.