| 1: | What is connectionless data networking? |
| A1: | Connectionless networking refers to transferring data in independent units referred to as packets, without the need to predefine the path of data flow. Instead, the packets are forwarded using a hop-by-hop routing paradigm between the source and destination. |
| 2: | Why is routing needed in a connectionless networking environment? List two means by which routers obtain information for routing packets toward their destinations. |
| A2: | The packets used in connectionless transfer of data have addressing information for their intended destination in packet headers. Routing is needed to provide information for forwarding packets along optimal paths to their target desti-nations. Various mechanisms exist for forwarding packets on Cisco routers. However, forwarding decisions ultimately are based on information in the routing table, which is populated manually with static routes or dynamically by routing protocols. |
| 3: | What is the difference between functionalities of Interior Gateway Protocols (IGPs) versus exterior gateway protocols (EGPs)? |
| A3: | IGPs exchange routes between routers belonging to a single network domain. EGPs support routing between domains. |
| 4: | List the two main groups of IP routing protocols based on the method of operation and routing algorithm. Also, list two examples of each type. |
| A4: | Distance vector and link-state protocols. RIP and Cisco IGRP are distance vector-based; OSPF and Integrated IS-IS are link-state protocols. EIGRP falls under yet a third group , called advance distance vector protocols. |
| 5: | Briefly describe the operation of link-state routing protocols. |
| A5: | Link-state routing protocols share and collect network topology information by means of link-state advertisements. Link-state information is stored in a database, which is fed as input to the shortest path algorithm for determining the best routes. |
| 6: | What is the key difference between classless and classful routing protocols? Give an example of each. |
| A6: | Classful protocols operate under the notion of the rigid boundaries of classful addressing, whereas classless protocols are more flexible in this, regarding allowing them to support VLSMs and CIDR. RIP is an example of a classful routing protocol. OSPF is an example of a classless protocol. |
| 7: | What is the use of routing protocol administrative distances on Cisco routers? |
| A7: | The concept of administrative distance is used to distinguish between routing sources and assign relative preferences between them. |
| 8: | What are the values of administrative distance of IS-IS and OSPF, respectively? |
| A8: | The administrative distance of IS-IS is 115; the administrative distance of OSPF is 110. |
| 9: | If a router is running both OSPF and IS-IS protocols and has the same route from each of them, which protocol's information will be used in the IP routing table? |
| A9: | The lower administrative distance is preferred, so only the OSPF route will make it into the IP routing table. |
