now in this setup we have a connection that will be between the host A and B and the interface R1 within a switch so same as previously they should be in the same subnet so the same mask so all we need to do is write on all their mask the same mask and based on it we choose the ips left.

How Communication Works in This Network:

1. Within the Switch (Local Communication):
   • Host A and Host B can communicate directly through the switch if:
     • Both hosts are in the same subnet.
     • They use unique IP addresses and share the same subnet mask.
   • Example:
     • Host A: 192.168.1.2 / 255.255.255.0
     • Host B: 192.168.1.3 / 255.255.255.0
     • Interface r1: 192.168.1.1 / 255.255.255.0 (router as the gateway for this subnet).
2. Between Subnets (Router Communication):
   • For Host A or Host B to communicate with a device in another subnet (connected to r2 or r3), traffic must be routed through the router.
   • Example:
     • Interface r2: Connected to a second network (e.g., 74.149.118.1/25).
     • Interface r3: Connected to a third network (e.g., 74.149.118.224/26).
   • If Host A wants to communicate with a device in the 74.149.118.224/26 subnet:
     • Host A sends the packet to its gateway (192.168.1.1).
     • The router forwards the packet to Interface r2, which sends it to the destination device.