geeksforgeeks.org/routing-tables-in-computer-network/

We have 4 hosts: juliet, romeo, ophelia, hamlet and othello, and 3 routers: router-1 , router-2 andn router-3. We have 4 network segments: 4 physical points of connection between network interfaces. (color - network segments). We have labelled each interface, i.e. each attachment to its network segment with its IP address. We have labeled the network address with bold text.

Each interface is with a netmask of 255.255.255.0

Red: network address is 10.10.0.0/24 so each network interface attached to it should have IP address like 10.10.0.x(free), where ‘/24’ means.

Similar with all other three network segment.

4.1 Exercises with IP address and subnet mask in a single segment network

In a previous experiment, we saw that when a host needs to send an IP packet, it uses ARP to resolve the destination IP address to a MAC address. We observed three possible outcomes of this process:

• a host already has the destination IP address in its ARP table. In this case, it will directly send the IP packet with the destination host’s MAC address (from the ARP table) in the destination address field of the Layer 2 header.
• a host does not already have the destination IP address in its ARP table, it sends an ARP request to resolve the address, and it receives an ARP reply. Then, it will send the IP packet with the destination host’s MAC address (from the ARP reply) in the destination address field of the Layer 2 header.
• a host does not already have the destination IP address in its ARP table, and it sends an ARP request to resolve the address, but does not receive an ARP reply. Then, it will send itself an ICMP Destination Unreachable: Host Unreachable message, indicating that it cannot reach the destination IP address. The IP packet is not sent.

However, these three scenarios only occur if the host first checks its routing table, and determines that the route that matches this destination address is a directly connected route.