CCNA 3 (v5.0.3 + v6.0) Chapter 8 Exam Answers 2020 – 100% Full

How to find: Press “Ctrl + F” in the browser and fill in whatever wording is in the question to find that question/answer. If the question is not here, find it in Questions Bank.

NOTE: If you have the new question on this test, please comment Question and Multiple-Choice list in form below this article. We will update answers for you in the shortest time. Thank you! We truly value your contribution to the website.

1. By default, what is the OSPF cost for any link with a bandwidth of 100 Mb/s or greater?

  • 100
  • 100000000
  • 1
  • 10000

OSPF uses the formula: Cost = 100,000,000 / bandwidth. Because OSPF will only use integers as cost, any bandwidth of 100 Mb/s or greater will all equal a cost of 1.

2. Which command will verify that a router that is running OSPFv3 has formed an adjacency with other routers in its OSPF area?

  • show ipv6 interface brief
  • show ipv6 ospf neighbor
  • show ipv6 route ospf
  • show running-configuration

The show ipv6 ospf neighbor command will verify neighbor adjacencies for OSPFv3 routers. The other options do not provide neighbor information.

3. Which OSPF component is identical in all routers in an OSPF area after convergence?

  • adjacency database
  • link-state database
  • SPF tree
  • routing table

Each OSPF router views the network differently as the root of a unique SPF tree. Each router builds adjacencies based on its own position in the topology. Each routing table in the area is developed individually through the application of the SPF algorithm. The link-state database for an area, however, must reflect the same information for all routers.

4. Which OPSF packet contains the different types of link-state advertisements?

  • DBD
  • LSR
  • hello
  • LSAck
  • LSU

Link-state update (LSU) packets contain different types of link-state advertisements (LSAs). The LSUs are used to reply to link-state requests (LSRs) and to announce new information.

5. Which three addresses could be used as the destination address for OSPFv3 messages? (Choose three.)

  • FF02::AFF02::1:2
  • 2001:db8:cafe::1
  • FE80::1
  • FF02::6
  • FF02::5

OSPFv6 messages can be sent to either the OSPF router multicast FF02::5, the OSPF DR/BDR multicast FF02::6, or the link-local address.

6. Fill in the blank.
OSPF uses _______ as a metric.Correct Answer: cost*

The OSPF metric is cost. The lowest cost path to a remote destination is the preferred path and is installed in the routing table.

7. What are the two purposes of an OSPF router ID? (Choose two.)

  • to enable the SPF algorithm to determine the lowest cost path to remote networks
  • to facilitate the establishment of network convergence
  • to uniquely identify the router within the OSPF domain
  • to facilitate router participation in the election of the designated router
  • to facilitate the transition of the OSPF neighbor state to Full

OSPF router ID does not contribute to SPF algorithm calculations, nor does it facilitate the transition of the OSPF neighbor state to Full. Although the router ID is contained within OSPF messages when router adjacencies are being established, it has no bearing on the actual convergence process.

8. A network administrator enters the command ipv6 router ospf 64 in global configuration mode. What is the result of this command?

  • The router will be assigned an autonomous system number of 64.
  • The router will be assigned a router ID of 64.
  • The reference bandwidth will be set to 64 Mb/s.
  • The OSPFv3 process will be assigned an ID of 64.

The basic command to implement OSPFv3 on a router uses the same process-id parameter as OSPFv2 to assign a locally-significant number to the OSPF process. OSPF does not use autonomous system numbers. Following the assignment of the process ID, a prompt will direct the user to manually assign a router ID. After the router ID is assigned, the reference bandwidth can be set.

9. What happens immediately after two OSPF routers have exchanged hello packets and have formed a neighbor adjacency?

  • They exchange DBD packets in order to advertise parameters such as hello and dead intervals.
  • They request more information about their databases.
  • They exchange abbreviated lists of their LSDBs.
  • They negotiate the election process if they are on a multiaccess network.

During the exchange of hello packets, OSPF routers negotiate the election process and set the OSPF parameters. DBD packets are exchanged after that step has been completed. DBD packets contain abbreviated lists of link-state information. After that information has been exchanged, OSPF routers exchange Type 3 LSR packets to request further information.

10. Open the PT Activity. Perform the tasks in the activity instructions and then complete the task. What message is displayed on

  • Completion!
  • Success!
  • Converged!
  • Finished!

The correct configuration on R1 is:
router ospf 10
network area 0
network area 0

The correct configuration on R2 is:
router ospf 10
network area 0
network area 0
network area 0

11. What are two reasons that will prevent two routers from forming an OSPFv2 adjacency? (Choose two.)

  • a mismatched Cisco IOS version that is used
  • one router connecting to a FastEthernet port on the switch and the other connecting to a GigabitEthernet port
  • use of private IP addresses on the link interfaces
  • mismatched OSPF Hello or Dead timers
  • mismatched subnet masks on the link interfaces

There may be several reasons why two routers running OSPF will fail to form an OSPF adjacency, including these:
The subnet masks do not match, causing the routers to be on separate networks.
OSPF Hello or Dead Timers do not match.
OSPF network types do not match.
There is a missing or incorrect OSPF network command.
Mismatched IOS versions, the use of private IP addresses, and different types of interface ports used on a switch are not causes for an OSPF adjacency failing to form between two routers.

12. What does a Cisco router use automatically to create link-local addresses on serial interfaces when OSPFv3 is implemented?

  • the MAC address of the serial interface, the FE80::/10 prefix, and the EUI-64 process
  • an Ethernet interface MAC address available on the router, the FE80::/10 prefix, and the EUI-64 process
  • the FE80::/10 prefix and the EUI-48 process
  • the highest MAC address available on the router, the FE80::/10 prefix, and the EUI-48 process

Since serial interfaces do not have MAC addresses, OSPFv3 automatically assigns a link-local address to them derived from the first available MAC address from the pool of Ethernet interface addresses on the router. A FE80::/10 prefix is added. The router then applies the EUI-64 process to the MAC address by inserting FFFE into the middle of the existing 48-bit address and flipping the seventh bit.

13. Single area OSPFv3 has been enabled on a router via the ipv6 router ospf 20 command. Which command will enable this OSPFv3 process on an interface of that router?

  • ipv6 ospf 20 area 20
  • ipv6 ospf 0 area 0
  • ipv6 ospf 0 area 20
  • ipv6 ospf 20 area 0

The command to enable an OSPFv3 process on a router interface is ipv6 ospf process-id area area-id. In the case the process ID is 20 and the area ID is 0.

14. Fill in the blank.The election of a DR and a BDR takes place on _________ networks, such as Ethernet networks.
Correct Answer: multiaccess

There is no need to have a DR/BDR election on a point-to-point link.

15. Which command will provide information specific to OSPFv3 routes in the routing table?

  • show ip route ospf
  • show ipv6 route
  • show ipv6 route ospf
  • show ip route

The show ipv6 route ospf command gives specific information that is related to OSPFv3 routes in the routing table. The show ipv6 route command will show the entire routing table. The show ip route and show ip route ospf commands are used with OSPFv2.

16. Which command should be used to check the OSPF process ID, the router ID, networks the router is advertising, the neighbors the router is receiving updates from, and the default administrative distance?

  • show ip ospf neighbor
  • show ip ospf
  • show ip protocols
  • show ip ospf interface

The show ip ospf neighbor command is used to verify that the router has formed an adjacency with its neighboring routers. The show ip ospf command displays the OSPF process ID and router ID, the OSPF area information, as well as the last time the SPF algorithm was calculated. The show ip ospf interface command provides detailed information about every OSPF-enabled interface.

17. What is the metric that is used by OSPF?

  • cost
  • distance
  • hop count
  • delay

OSPF uses cost as a metric. OSPF calculates cost inversely to the bandwidth of an interface. The higher the interface bandwidth, the lower the cost of the interface.

18. What function is performed by the OSPF designated router?

  • summarizing routes between areas
  • dissemination of LSAs
  • maintaining the link-state database
  • redistribution of external routes into OSPF

OSPF designated routers are elected on multiaccess networks to disseminate LSAs to other OSPF routers. By having a single router disseminate LSAs, the exchanging of LSAs is more efficient.

19. What is used to create the OSPF neighbor table?

  • adjacency database
  • link-state database
  • forwarding database
  • routing table

Explanation: The adjacency database is used to create the OSPF neighbor table. The link-state database is used to create the topology table, and the forwarding database is used to create the routing table.

20. When a network engineer is configuring OSPFv3 on a router, which command would the engineer issue immediately before configuring the router ID?

  • clear ipv6 ospf process
  • interface serial 0/0/1
  • ipv6 router ospf 10
  • ipv6 ospf 10 area 0

The OSPFv3 router ID is configured in the IPv6 router configuration mode. The clear ipv6 ospf process privileged EXEC command forces OSPF on the router to renegotiate neighbor adjacencies. The interface serial 0/0/1 command causes the router to enter interface configuration mode where OSPFv3 is enabled by issuing the ipv6 ospf process-id area area-id command.

21. What will an OSPF router prefer to use first as a router ID?

  • the highest active interface that participates in the routing process because of a specifically configured network statement
  • the highest active interface IP that is configured on the router
  • any IP address that is configured using the router-id command
  • a loopback interface that is configured with the highest IP address on the router

The first preference for an OSPF router ID is an explicitly configured 32-bit address. This address is not included in the routing table and is not defined by the network command. If a router ID that is configured through the router-id command is not available, OSPF routers next use the highest IP address available on a loopback interface, as loopbacks used as router IDs are also not routable addresses. Lacking either of these alternatives, an OSPF router will use the highest IP address from its active physical interfaces.

22. Match the OSPF state with the order in which it occurs. (Not all options are used.)

Modules 1 - 2: OSPF Concepts and Configuration Exam

Modules 1 – 2: OSPF Concepts and Configuration Exam

The active and passive states are used by EIGRP.

23. Match each OSPF packet type to how it is used by a router. (Not all options are used.)

24. By order of precedence, match the selection of router ID for an OSPF-enabled router to the possible router ID options. (Not all options are used.)

Cisco routers determine the OSPF router ID based on the preferential order of configured router ID, IPv4 addresses of loopback interfaces, and IPv4 addresses of active physical interfaces.

25. Match the information to the command that is used to obtain the information. (Not all options are used.)

Older Version

26. Refer to the exhibit. All networks are active in the same EIGRP routing domain. When the auto-summary command is issued on R3, which two summary networks will be advertised to the neighbors? (Choose two.)


27. Refer to the exhibit. Router R3 is receiving multiple routes through the EIGRP routing protocol. Which statement is true about the implementation of summarization in this network?CCNA3_Ch8_02

  • Automatic summarization has been enabled only for the network.
  • Automatic summarization is disabled on R3.
  • Automatic summarization is enabled on neighboring routers.
  • Automatic summarization is disabled on a per-interface basis.

28. Refer to the exhibit. Which statement is supported by the output?CCNA3_Ch8_09

  • A static default route has been manually configured on this router.
  • Summarization of routes has been manually configured.
  • A default route is being learned through an external process.
  • The route to represents the configuration of a loopback interface.

29. Which three statements are advantages of using automatic summarization? (Choose three.)

  • It maximizes the number of routes in the routing table.
  • It increases the size of routing updates.
  • It reduces the frequency of routing updates.
  • It ensures that traffic for multiple subnets uses one path through the internetwork.
  • It improves reachability in discontiguous networks.
  • It decreases the number of entries in the routing table.

30. Refer to the exhibit. Which two routes will be advertised to the router ISP if autosummarization is disabled? (Choose two.)


31. Which address best summarizes the IPv6 addresses 2001:DB8:ACAD::/48, 2001:DB8:9001::/48, and 2001:DB8:8752::/49?

  • 2001:DB8:8000::/34
  • 2001:DB8:8000::/36
  • 2001:DB8:8000::/47
  • 2001:DB8:8000::/48

32. What is a characteristic of manual route summarization?

  • requires high bandwidth utilization for the routing updates
  • reduces total number of routes in routing tables
  • cannot include supernet routes
  • has to be configured globally on the router

33. Refer to the exhibit. Which statement accurately reflects the configuration of routing on the HQ router?CCNA3_Ch8_11

  • A static default route was configured on this router.
  • A static default route was learned via EIGRP routing updates.
  • The static default route should be redistributed using the default-information originate command.
  • The IP address assigned to the GigabitEthernet0/0 interface is

34. Refer to the exhibit. A network administrator has attempted to implement a default route from R1 to the ISP and propagate the default route to EIGRP neighbors. Remote connectivity from the EIGRP neighbor routers to the ISP connected to R1 is failing. Based on the output from the exhibit, what is the most likely cause of the problem?CCNA3_Ch8_04

  • The command default-information originate has not been issued on R1.
  • There are no EIGRP neighbor relationships on R1.
  • The ip route command must specify a next-hop IP address instead of an exit interface when creating a default route.
  • The command redistribute static has not been issued on R1.
  • The network statement for the ISP connection has not been issued.

35. In which IOS CLI mode must a network administrator issue the maximum-paths command to configure load balancing in EIGRP?

  • global configuration mode
  • interface configuration mode
  • privileged mode
  • router configuration mode

36. Two routers, R1 and R2, share a 64 kb/s link. An administrator wants to limit the bandwidth used by EIGRP between these two routers to 48 kb/s. Which command is used on both routers to configure the new bandwidth setting?

  • ip bandwidth-percent eigrp 100 48
  • ip bandwidth-percent eigrp 64 48
  • ip bandwidth-percent eigrp 100 64
  • ip bandwidth-percent eigrp 100 75
  • ip bandwidth-percent eigrp 75 100

37. Refer to the exhibit. A network administrator has issued the shown commands. The EIGRP routing domain has completely converged and a network administrator is planning on configuring EIGRP authentication throughout the complete network. On which two interfaces should EIGRP authentication be configured between R2 and R3? (Choose two.)CCNA3_Ch8_03

  • serial 0/0/1 of R2
  • serial 0/1/0 of R2
  • gig 0/0 of R3
  • serial 0/0/1 of R3
  • serial 0/1/0 of R4

38. Refer to the exhibit. A network administrator has configured EIGRP authentication between routers R1 and R2. After the routing tables are reviewed, it is noted that neither router is receiving EIGRP updates. What is a possible cause for this failure?

  • The same key chain name must be used on each router.
  • The same number of key strings must be used on each router.
  • The key string should be used in interface mode instead of the key chain.
  • The same autonomous system numbers must be used in the interface configurations of each router.
  • The authentication configuration is correct, issue the show ip eigrp neighbors command to troubleshoot the issue.

39. Two routers, R1 and R2, have established an EIGRP neighbor relationship, but there is still a connectivity problem. Which issue could be causing this problem?

  • an authentication mismatch
  • an access list that is blocking advertisements from other networks
  • automatic summarization that is disabled on both routers
  • a process ID mismatch

40. Refer to the exhibit. Remote users are experiencing connectivity problems when attempting to reach hosts in the /24 network. Using the output in the exhibit, what is the most likely cause of the connectivity problem?CCNA3_Ch8_07

  • The passive-interface command is preventing neighbor relationships on interface GigabitEthernet 0/0.
  • The hello timer has been modified on interface GigabitEthernet 0/1 of R3 and not on the neighbor, causing a neighbor adjacency not to form.
  • The GigabitEthernet 0/1 interface is not participating in the EIGRP process.
  • The GigabitEthernet interfaces are not limiting the flow of EIGRP message information and are being flooded with EIGRP traffic.

41. Refer to the exhibit. After the configuration shown is applied on router R1, the exhibited status message is displayed. Router R1 is unable to form a neighbor relationship with R2 on the serial 0/1/0 interface. What is the most likely cause of this problem?CCNA3_Ch8_08

  • The passive-interface command should have been issued on serial 0/1/0.
  • The hello interval has been altered on serial 0/1/0 and is preventing a neighbor relationship from forming.
  • The network statement used for EIGRP 55 does not enable EIGRP on interface serial 0/1/0.
  • The IPv4 address configured on the neighbor that is connected to R1 serial 0/1/0 is incorrect.
  • The networks that are configured on serial 0/0/0 and serial 0/1/0 of router R1 are overlapping.

42. Refer to the exhibit. Routers R1 and R2 are directly connected via their serial interfaces and are both running the EIGRP routing protocol. R1 and R2 can ping the directly connected serial interface of their neighbor, but they cannot form an EIGRP neighbor adjacency. What action should be taken to solve this problem?CCNA3_Ch8_13

  • Enable the serial interfaces of both routers.
  • Configure EIGRP to send periodic updates.
  • Configure the same hello interval between the routers.
  • Configure both routers with the same EIGRP process ID.

43. Fill in the blank. Do not use abbreviations.
The passive-interface command causes an EIGRP router to stop sending hello packets through an interface.

44. What is the purpose of a Null0 route in the routing table?

  • to redistribute external routes into EIGRP
  • to prevent routing loops
  • to act as a gateway of last resort
  • to prevent the router from sending EIGRP packets

45. Which administrative distance is used to advertise routes learned from other protocols that are redistributed into EIGRP?

  • 170
  • 90
  • 115
  • 5

Explanation: Routes learned from other routing protocols that are redistributed into EIGRP are known as external routes and are assigned an administrative distance of 170.

46. Refer to the exhibit. Which two conclusions can be drawn from the exhibited configuration? (Choose two.)

  • The configuration supports equal-cost load balancing.
  • The configuration supports unequal-cost load balancing.
  • Any EIGRP-learned route with a metric less than 3 times the successor metric will be installed in the local routing table.
  • Any EIGRP-learned route with a metric equal to 3 times the successor metric will be installed in the local routing table.
  • The network statements require subnet masks to prevent autosummarization.

47. Which command would limit the amount of bandwidth that is used by EIGRP for protocol control traffic to approximately 128 Kb/s on a 1.544 Mb/s link?

  • ip bandwidth-percent eigrp 100 8
  • maximum-paths 8
  • variance 8
  • traffic-share balanced

48. By default, how many equal-cost routes to the same destination network will EIGRP install in the routing table?

  • 2
  • 4
  • 6
  • 8

49. Refer to the exhibit. Router CiscoVille has been partially configured for EIGRP authentication. What is missing that would allow successful authentication between EIGRP neighbors?

  • The interfaces that will use EIGRP authentication must be specified.
  • The same key number must be used on any EIGRP neighbor routers.
  • The keychain for EIGRP authentication must be configured on the interfaces.
  • The CiscoVille router requires a second keychain to function correctly when using two interfaces for EIGRP authentication.

The ip authentication key-chain eigrp 1 EIGRP_key command for EIGRP authentication has not been applied on each interface that participates in EIGRP authentication. EIGRP authentication steps include the creation of a keychain, a key ID, and a key string that is the equivalent of a password. EIGRP authentication is used on interfaces by selecting the interface to configure and then enabling MD5 authentication. Finally, EIGRP authentication is activated when the keychain to be used is issued on the interface.

50. What two statements are correct regarding EIGRP authentication? (Choose two.)

  • EIGRP authentication uses the MD5 algorithm.
  • EIGRP authentication uses a pre-shared key.
  • EIGRP authentication requires that both routers have the same key chain name.
  • EIGRP authentication uses varying levels of WEP to encrypt data exchanged between routers.
  • EIGRP authentication can be configured on one router and updates from this router are protected; whereas a neighbor router can be without the authentication configuration and its updates are unprotected.

51. Which EIGRP parameter must match between all routers forming an EIGRP adjacency?

  • hello timer
  • variance
  • autonomous system number
  • hold timer
  • administrative distance

Explanation: EIGRP routers must belong to the same autonomous system for an adjacency to be successful. The autonomous system number is specified at the end of the router command.

52. Which command can be issued on a router to verify that automatic summarization is enabled?

  • show ip eigrp interfaces
  • show ip protocols
  • show ip interface brief
  • show ip eigrp neighbors

53. Fill in the blank. Do not use abbreviations.
What is the command that should be issued on a router to verify that EIGRP adjacencies were formed?​ show ip eigrp neighbors

54. Open the PT Activity. Perform the tasks in the activity instructions and then answer the question.
R1 and R2 could not establish an EIGRP adjacency. What is the problem?​

  • EIGRP is down on R1.
  • EIGRP is down on R2.
  • R1 Fa0/0 and R2 Fa0/0 are on different networks.
  • R1 Fa0/0 is not configured to send hello packets.
  • R1 Fa0/0 link local address is wrong.

55. Refer to the exhibit. Considering that R2, R3, and R4 are correctly configured, why did R1 not establish an adjacency with R2, R3, and R4?

  • because the automatic summarization is enabled on R1
  • because the IPv4 address on Fa0/0 interface of R1 is incorrect
  • because the Fa0/0 interface of R1 is declared as passive for EIGRP
  • because there is no network command for the network on R1

56. In which scenario will the use of EIGRP automatic summarization cause inconsistent routing in a network?

  • when there is no common subnet that exists between neighboring routers
  • when the routers in an IPv4 network have mismatching EIGRP AS​ numbers
  • when there is no adjacency that is established between neighboring routers
  • when the routers in an IPv4 network are connected to discontiguous networks with automatic summarization enabled

57. Which OSPF data structure is identical on all OSPF routers that share the same area?

  • forwarding database
  • routing table
  • link-state database
  • adjacency database

58. Which command will selectively display IPv6 routes that are learned from a remote network?

  • show ip route
  • show ipv6 route ospf
  • show ip route ospf
  • show ipv6 route

Download PDF File below:

Notify of

Inline Feedbacks
View all comments
4 years ago

Which OPSF packet contains the different types of link-state advertisements?
– LSU*
– LSAck
– hello

*correct answer

5 years ago

Which OSPF data structure is identical on all OSPF routers that share the same area?

forwarding database

routing table

link-state database*

adjacency database

5 years ago

Which command will selectively display IPv6 routes that are learned from a remote network?

show ip route

show ipv6 route ospf*

show ip route ospf

show ipv6 route

6 years ago