Connecting two hosts with the same IP address but different subnet masks

Generally speaking, no two devices should have the same IP address unless they are behind a NAT device. Computers need routers to communicate with devices that are not on their same logical subnet. When one computer prepares to communicate with another, it basically goes through three steps to determine if the communication is local or gets addressed to the router. This routing information can be seen by issuing the "route print" command from the cmd prompt. These three steps include:

1. Are both addresses the same class?

   Source 200 120 3 72
   Target 200 120 3 41

   YES

2. Do both share the same network address?

   Source 200 120 3 72
   Mask 255 255 255 224
   Target 200 120 3 41
   Mask 255 255 255 224
   Binary = 11100000

   YES

3. Are both on the same logical subnet?

   Source 1st Address 72 = 01001000
   Mask 224 = 11100000
   Target 2nd Address 41= 00101001

   NO

Since the first three bits listed above do not match, the sending computer now knows that the computer it wishes to communicate with is not local, therefore the router will receive the data and is responsible for delivery. I hope this helps you better understand the routing process.