Q2C.Justify the usage of a MAC address at datalink layer along with IP address at network layer in the TCP/IP protocol suite. Consider a LAN with 4 hosts A,B,C,D and a default router R1 implemented...

Extracted text: Q2C.Justify the usage of a MAC address at datalink layer along with IP address at network layer in the TCP/IP protocol suite. Consider a LAN with 4 hosts A,B,C,D and a default router R1 implemented with a switch S1.Suppose Host A would like to send an IP datagram to Host B, and neither A's ARP cache contains B's MAC address nor does B's ARP cache contain A's MAC address. Further suppose that the switch S1's forwarding table contains entries for Host B and router R1 only. Give the actions That will Host A and switch S1 perform to send the ARP request message to B. Once Host B receives this ARP request message, it will send back to Host A an ARP response message. But will it send an ARP query message to ask for A's MAC address? Why? What will switch S1 do once it receives an ARP response message from Host B?