CCNA 3 Chapter 5: Dynamic Routing (v5.0.3 + v6.0) Exam Answers – 100% Result

Q1. Which routing protocol is designed to use areas to scale large hierarchical networks?

• RIP
• OSPF
• EIGRP
• BGP

Explanation:  OSPF works best for a large hierarchical network, because OSPF supports a multiarea design, which provides a much better scaling capability compared with EIGRP

Discussion

Q2. Which routing protocol uses link-state information to build a map of the topology for computing the best path to each destination network?

• RIP
• RIPng
• OSPF
• EIGRP

Explanation:  OSPF is a link-state routing protocol and as such it uses a link-state database to construct a topology map of the network to calculate the best path to destination networks. RIP, RIPng, and EIGRP are distance vector routing protocols.

Discussion

Q3. After a network topology change occurs, which distance vector routing protocol can send an update message directly to a single neighboring router without unnecessarily notifying other routers?

• IS-IS
• RIPv1
• RIPv2
• EIGRP
• OSPF

Explanation:  RIPv2 and EIGRP support updating neighboring routers via the use of multicasting. EIGRP is the only distance vector protocol that can support updating a specific neighbor by using unicast. OSPF and ISIS are link state protocols.

Discussion

Q4. Which dynamic routing protocol was developed as an exterior gateway protocol to interconnect different Internet providers?

• EIGRP
• RIP
• OSPF
• BGP

Explanation:  BGP is a protocol developed to interconnect different levels of ISPs as well as ISPs and some of their larger private clients.

Discussion

Q5. A network administrator is researching routing protocols for implementation in a critical network infrastructure. Which protocol uses the DUAL algorithm to provide almost instantaneous convergence during a route failover?

• RIP
• BGP
• OSPF
• EIGRP

Explanation:  EIGRP is commonly the fastest IGP to converge because it maintains alternate routes. A switchover to an alternate route is immediate and does not involve interaction with other routers.

Discussion

Q6. Which routing protocol sends a routing update to neighboring routers every 30 seconds?

• RIP
• BGP
• OSPF
• EIGRP

Explanation:  Regardless of topology changes, RIP sends a periodic update to all neighboring routers every 30 seconds.

Discussion

Q7. Which statement is an incorrect description of the OSPF protocol?

• Multiarea OSPF helps reduce the size of the link-state database.
• When compared with distance vector routing protocols, OSPF utilizes less memory and less CPU processing power.
• OSPF builds a topological map of the network.
• OSPF has fast convergence.

Explanation:  Link-state protocols require more memory to create and maintain the link-state database.

Discussion

Q8. What happens when two link-state routers stop receiving hello packets from neighbors?

• They create a default route to the adjacent router.
• They continue to operate as normal and are able to exchange packets.
• They consider the neighbor to be unreachable and the adjacency is broken.
• They will flood their database tables to each other.

Explanation:  Hello packets serve a keepalive function to monitor the state of an adjacent router.

Discussion

Q9. What are two features of the OSPF routing protocol? (Choose two.)

• has an administrative distance of 100used primarily as an EGP
• uses Dijkstra’s algorithm to build the SPF tree
• automatically summarizes networks at the classful boundaries
• calculates its metric using bandwidth

Explanation:  Characteristics of OSPF include the following:
Interior gateway protocol
Link-state
Classless
Cost metric based on bandwidth
Dijkstra algorithm
Builds topological map
Event-driven updates
Hierarchical design
Requires additional memory, CPU processing, and more initial bandwidth than other protocols

Discussion

Q10. What is maintained within an EIGRP topology table?

• the hop count to all networks
• all routes received from neighbors
• the area ID of all neighbors
• the state of all links on the network

Explanation:  The EIGRP topology table maintains all the routes received from neighbors, not just the best paths. DUAL can use backup routes from the topology table to provide instantaneous route failover in the EIGRP routing table.

Discussion

Q11. What is the difference between interior and exterior routing protocols?

• Interior routing protocols are used to route on the Internet. Exterior routing protocols are used inside organizations.
• Exterior routing protocols are used only by large ISPs. Interior routing protocols are used by small ISPs.
• Exterior routing protocols are used to administer a single autonomous system. Interior routing protocols are used to administer several domains.
• Interior routing protocols are used to communicate within a single autonomous system. Exterior routing protocols are used to communicate between multiple autonomous systems.

Explanation:  Interior gateway protocols (IGPs) are used for routing within an organization having a common administration or autonomous system (AS). Exterior gateway protocols (EGPs) are used by service providers and sometimes by large companies.

Discussion

Q12. An OSPF enabled router is processing learned routes to select best paths to reach a destination network. What is the OSPF algorithm evaluating as the metric?

• The amount of traffic and probability of failure of links.
• The amount of packet delivery time and slowest bandwidth.
• The number of hops along the routing path.
• The cumulative bandwidth that is used along the routing path.

Explanation:  The OSPF routing protocol uses the cumulative bandwidth as the metric for route computations.

Discussion

Q13. Question

Explanation:  No answer description available for this question

Discussion

Q14. Which two components of an LSP enable an OSPF router to determine if the LSP that is received contains newer information than what is in the current OSPF router link-state database? (Choose two.)

• hellosquery
• aging information
• sequence numbers
• acknowledgements

Explanation:  Information such as sequence numbers and aging information is included in an LSP to help manage the flooding process. This information can assist a router in determining if it has already received the LSP from another router or if the LSP has newer information than what is already contained in the link-state database.

Discussion

Q15. What are two purposes of dynamic routing protocols? (Choose two.)

• discover remote networks
• provide network security
• reduce network traffic
• provide a default route to network hosts
• select best path to destination networks

Explanation:  The purpose of dynamic routing protocols include the following:
Discover remote networks
Maintain up-to-date routing information
Choose the best path to a destination network
Find a new best path if the current path is not available

Discussion

Q16. What is the first step taken by a newly configured OSPF router in the process of reaching a state of convergence?

• It floods LSP packets to neighboring routers.
• It builds the topological database.
• It learns about directly connected links in an active state.
• It exchanges hello messages with a neighboring router.

Explanation:  Before OSPF can form a neighbor adjacency and start the Hello protocol, it detects which interfaces are in an up and active state.

Discussion

Q17. Question

Explanation:  No answer description available for this question

Discussion

Q18. In the context of routing protocols, what is a definition for time to convergence?

• a measure of protocol configuration complexity
• the amount of time a network administrator needs to configure a routing protocol in a small- to medium-sized network
• the amount of time for the routing tables to achieve a consistent state after a topology change
• the capability to transport data, video, and voice over the same media

Explanation:  Time to convergence defines how quickly the routers in the network topology share routing information and reach a state of consistent knowledge.

Discussion

Q19. Which two requirements are necessary before a router configured with a link-state routing protocol can build and send its link-state packets? (Choose two.)

• The router has constructed an SPF tree.
• The router has determined the costs associated with its active links.
• The router has established its adjacencies.
• The router has built its link-state database.
• The routing table has been refreshed.

Explanation:  Once a router has established its adjacencies, it can build its link-state packets (LSPs) that contain the link-state information, including the link cost. A router can only build a link-state after it has received link-state packets from adjacent routers. It then constructs its SPF tree from the least cost routes to remote networks which are used to populate its routing table.

Discussion

Q20. Which two routing protocols are classified as distance vector routing protocols? (Choose two.)

• EIGRP
• RIP
• BGP
• OSPF
• IS-IS

Explanation:  RIP and EIGRP are classified as distance vector routing protocols, OSPF and IS-IS are classified as link-state, and BGP is classified as a path-vector routing protocol.

Discussion

Q21. Which two events will trigger the sending of a link-state packet by a link-state routing protocol? (Choose two.)

• the router update timer expiring
• the requirement to periodically flood link-state packets to all neighbors
• a change in the topology
• the initial startup of the routing protocol process
• a link to a neighbor router has become congested

Explanation:  An LSP (link-state packet) is only sent during initial startup of the routing protocol process on a router; and whenever there is a change in the topology, including a link going down or coming up, or a neighbor adjacency being established or broken. Data traffic congestion does not directly influence routing protocol behavior. LSPs are not flooded periodically, and update timers are not relevant to LSPs.

Discussion

Q22. Which feature provides secure routing updates between RIPv2 neighbors?

• keepalive messages
• routing protocol authentication
• adjacency table
• unicast updates

Explanation:  The RIPv2 routing protocol supports routing protocol authentication to secure routing table updates between neighbors.

Discussion

Q23. Which two protocols are link-state routing protocols? (Choose two.)

• OSPF
• EIGRP
• RIP
• IS-IS
• BGP
• IGP

Explanation:  OSPF and IS-IS are link-state protocols. EIGRP and RIP are distance vector protocols.

Discussion

Q24. What is a disadvantage of deploying OSPF in a large single area routing environment?

• OSPF uses a topology database of alternate routes.
• OSPF uses excessive LSP flooding.
• OSPF uses a metric of bandwidth and delay.
• OSPF uses multicast updates.

Explanation:  Link-state protocols have the following disadvantages:
Memory Requirements – Creating and maintaining the link-state database and SPF tree.
Processing Requirements – The SPF algorithm requires more CPU time than distance vector algorithms because link-state protocols build a complete map of the topology.
Bandwidth Requirements – Link-state packet flooding can adversely affect the available bandwidth on a network.

Discussion

Q25. Question

Explanation:  No answer description available for this question

Discussion

Q26. Which two pieces of information are used by the OSPF MD5 algorithm to generate a signature? (Choose two.)

• secret key
• OSPF message
• OSPF router ID
• router hostname
• interface IP address

Explanation:  No answer description available for this question

Discussion

Q27. A network administrator has just changed the router ID on a router that is working in an OSPFv2 environment. What should the administrator do to reset the adjacencies and use the new router ID?

• Configure the network statements.
• Change the interface priority.
• Issue the clear ip ospf process privileged mode command.
• Change the OSPFv2 process ID.

Explanation:  No answer description available for this question

Discussion

Q28. Question

Explanation:  No answer description available for this question

Discussion

Q29. When checking a routing table, a network technician notices the following entry: O*E2 0.0.0.0/0 [110/1] via 192.168.16.3, 00:20:22, Serial0/0/0 What information can be gathered from this output?

• This route is a propagated default route.
• The route is located two hops away.
• The metric for this route is 110.
• The edge of the OSPF area 0 is the interface that is addressed 192.168.16.3.

Explanation:  No answer description available for this question

Discussion

Q30. Which command will a network engineer issue to verify the configured hello and dead timer intervals on a point-to-point WAN link between two routers that are running OSPFv2?

• show ip ospf neighbor
• show ip ospf interface serial 0/0/0
• show ipv6 ospf interface serial 0/0/0
• show ip ospf interface fastethernet 0/1

Explanation:  No answer description available for this question

Discussion

Q31. A network engineer has manually configured the hello interval to 15 seconds on an interface of a router that is running OSPFv2. By default, how will the dead interval on the interface be affected?

• The dead interval will now be 15 seconds.
• The dead interval will now be 30 seconds.
• The dead interval will now be 60 seconds.
• The dead interval will not change from the default value.

Explanation:  No answer description available for this question

Discussion

Q32. A network engineer suspects that OSPFv3 routers are not forming neighbor adjacencies because there are interface timer mismatches. Which two commands can be issued on the interface of each OSFPv3 router to resolve all timer mismatches? (Choose two.)

• no ipv6 ospf hello-interval
• no ipv6 ospf dead-interval
• ip ospf hello-interval 10
• ip ospf dead-interval 40
• no ipv6 ospf cost 10
• no ipv6 router ospf 10

Explanation:  No answer description available for this question

Discussion

Q33. Question

Explanation:  No answer description available for this question

Discussion

Q34. Why do OSPF serial interfaces usually require manual bandwidth configuration?

• OSPF uses the bandwidth value to compute routes for its routing table.
• Each side of an OSPF serial link should be configured with a unique value.
• All serial interfaces default to a value of 1.544 Mb/s.
• Bandwidth value affects the actual speed of the link.

Explanation:  No answer description available for this question

Discussion

Q35. Question

Explanation:  No answer description available for this question

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Q36. Question

Explanation:  No answer description available for this question

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Q37. Why is MD5 authentication more secure than simple authentication for OSPF updates?

• MD5 does not send the password to the neighbor router.
• MD5 requires passwords that are at least 8 characters long.
• MD5 uses both a username and a password to authenticate the neighbor.
• MD5 employs IPsec to keep the updates from being intercepted.

Explanation:  MD5 does not send the configured password across the network. MD5 generates a special hash, or signature, that is attached to the messages and sent to the neighbor. This signature is used to validate the neighbor instead of the password. MD5 does not use a username and does not enforce a minimum length on the password. While IPsec tunnels can be used to keep updates secure, they are not used specifically by MD5.

Discussion

Q38. A network engineer is troubleshooting convergence and adjacency issues in an OSPFv2 network and has noted that some expected network route entries are not displayed in the routing table. Which two commands will provide additional information about the state of router adjacencies, timer intervals, and the area ID? (Choose two.)

• show ip protocols
• show ip ospf interface
• show ip route ospf
• show ip ospf neighbor
• show running-configuration

Explanation:  The show ip ospf interface command will display routing table information that is already known. The show running-configuration and show ip protocols commands will display aspects of the OSPF configuration on the router but will not display adjacency state details or timer interval details.

Discussion

Q39. A network engineer is troubleshooting convergence and adjacency issues in an OSPFv2 network and has noted that some expected network route entries are not displayed in the routing table. Which two commands will provide additional information about the state of router adjacencies, timer intervals, and the area ID? (Choose two.)

• show ip protocols
• show ip ospf interface
• show ip route ospf
• show ip ospf neighbor
• show running-configuration

Explanation:  The show ip ospf interface command will display routing table information that is already known. The show running-configuration and show ip protocols commands will display aspects of the OSPF configuration on the router but will not display adjacency state details or timer interval details.

Discussion

Q40. When OSPFv2 neighbors are establishing adjacencies, in which state do they elect a DR and BDR router?

• Exchange state
• Init state
• Two-Way state
• Loading state

Explanation:  Down state: No hello packets are received.
Attempt: No recent information received by NBMA router, but still trying to communicate.
Init state: Hello packets received, but bidirectional communication not established.
2-way state: Bidirectional communication is established and if needed, a DR/BDR election occurs.
ExStart state: Negotiate master/slave role for LSDB synchronization.
Exchange state: Exchange of DBD packets occurs.
Loading state: Request for additional information is sent.
Full state: Routers converged and neighbors are fully adjacent.

Discussion

Q41. A network engineer is troubleshooting an OSPFv2 network and discovers that two routers connected by a point-to-point WAN serial link are not establishing an adjacency. The OSPF routing process, network commands and area ID are all confirmed as correct, and the interfaces are not passive. Testing shows that the cabling is correct, that the link is up, and pings between the interfaces are successful. What is most likely the problem?

• The subnet masks on the two connected serial interfaces do not match.
• A clock rate has not been set on the DCE interface of the serial link.
• The OSPFv2 process IDs on each router do not match.
• A DR election has not taken place.

Explanation:  The establishment of an OSPF adjacency between connected routers requires each interface of the link to be in the same subnet. This requires each interface to be configured with correct IP addresses and the same subnet mask. Pings across serial links can be successful with correct IP addresses and different subnet masks. Successful pings verify that a clock rate has been set on the DCE interface of the serial link. The OSPFv2 process IDs on each router are local and do not need to match. A DR election does not take place across point-to-point serial links between OSPF routers.

Discussion

Q42. A network engineer is troubleshooting OSPFv2 routing issues on two connected routers. Which two requirements to form an adjacency need to be verified? (Choose two.)

• Verify that one of the interfaces that connects the two routers is active and the other passive.
• Verify that one of the routers is the DR or BDR and the other router a DRother.
• Verify that the interfaces that connect the two routers are in the same subnet.
• Verify that the interfaces that connect the two routers are in the same area.
• Verify that both routers are using the same OSPFv2 process ID.

Explanation:  The OSPFv2 process ID is local to each router and does not have to be common. Neither interface on the link connecting the two routers can be passive. Both must be participating in the OSPF area. The DR, BDR, and DROTHER status of the router has no bearing on the adjacency relationship.

Discussion

Q43. Which command is used to verify that OSPF is enabled and also provides a list of the networks that are being advertised by the network?

• show ip protocols
• show ip ospf interface
• show ip interface brief
• show ip route ospf

Explanation:  The command show ip ospf interface verifies the active OSPF interfaces. The command show ip interface brief is used to check that the interfaces are operational. The command show ip route ospf displays the entries that are learned via OSPF in the routing table. The command show ip protocol s checks that OSPF is enabled and lists the networks that are advertised.

Discussion

Q44. Question

Explanation:  No answer description available for this question

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Q45. Question

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Q46. Question

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Q47. Question

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Discussion

Q48. Fill in the blank. Do not use abbreviations.

When IPv4 and OSPFv2 are being used, the command show ip ospf neighbor is used to verify that a router has formed an adjacency with its neighboring routers.

Explanation:  No answer description available for this question

Discussion

Q49. Question

Explanation:  No answer description available for this question

Discussion

Q50. What is a recommended method of authentication for OSPFv3?

• MD5 authentication
• IPsec to secure routing updates
• the passive-interface command
• a VPN tunnel between each OSPF neighbor adjacency

Explanation:  No answer description available for this question

Discussion

Q51. A fully converged five router OSPF network has been running successfully for several weeks. All configurations have been saved and no static routes are used. If one router loses power and reboots, what information will be in its routing table after the configuration file is loaded but before OSPF has converged?

• All routes for the entire network will be present.
• Directly connected networks that are operational will be in the routing table.
• Because the SPF algorithm has not completed all calculations, no routes will be in the table.
• A summary route for all previously learned routes will automatically appear in the routing table until all LSPs have been received by the router.

Explanation:  No answer description available for this question

Discussion

Q52. During verification or troubleshooting of the OPSFv3 configuration on a router, which three parameters are displayed by the show ipv6 ospf interface command? (Choose three.)

• the hello and dead intervals
• the global unicast IPv6 address of the interface
• the metric of the route that is attached to the interface
• the OSPFv3 area that the interface is in
• the process ID that is assigned to the interface
• the number of interfaces in the area

Explanation:  The number of interfaces in the area is displayed by the show ipv6 ospf command. The metric of the route that is attached to the interface is displayed by the show ipv6 route command. The interface global unicast IPv6 address is displayed in the show running-configuration command output.

Discussion

Q53. The PT initialization was skipped. You will not be able to view the PT activity. Open the PT Activity. Perform the tasks in the activity instructions and then answer the question. Which task has to be performed on Router 1 for it to establish an OSPF adjacency with Router 2?

• Issue the clear ip ospf process command.
• Remove the passive interface command from interface FastEthernet 0/0.
• Add the network 10.0.1.0 0.0.0.255 area 0 command to the OSPF process.
• Change the subnet mask of interface FastEthernet 0/0 to 255.255.255.0.

Explanation:  No answer description available for this question

Discussion

Q54. Question

Explanation:  No answer description available for this question

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Q55. Question

Explanation:  No answer description available for this question

Discussion

Q56. A network engineer is researching dynamic routing protocols and how much time it takes for a network to converge. What does it mean for a router to achieve convergence?

• The amount of time it takes a router to share information, calculate best paths, and update the routing table
• The capability to transport data, video, and voice over the same media
• The amount of time a network administrator needs to configure a routing protocol in a small- to medium-sized network
• The capability to forward traffic between hosts on a local network

Explanation:  No answer description available for this question

Discussion