Part - B: Answer any three questions. Each question carries FOUR Marks. (34=12 Marks) 21. Briefly discuss about Area border router, Back bone router, ASBR and Internal router. 22. Discuss the types of OSPF tables. 23. Describe the following: functions of a router, CIDR and Super netting 24. Write down the usage of the following components of a router: NV-RAM, FLASH, RAM, AUI and Console, 25. Explain about the four fundamental design goals