CCNA 3 v7

Modules 1 – 2: OSPF Concepts and Configuration Exam Answers

Modules 1 – 2: OSPF Concepts and Configuration Exam Answers


1. What is one use of the router ID in OSPF routing?

  • The router ID indicates the router priority value.
  • The router ID identifies the OSPF area.
  • The router ID can be used to break a tie in the election process.
  • The router ID indicates the highest IPv4 address of all routers that are participating in OSPF routing.

2. What is the first criterion used by OPSF routers to elect a DR?

  • highest priority
  • highest IP address
  • highest router ID
  • highest MAC address

3. Which command could be used on a router to ensure that an OSPF adjacency is formed with another router?

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

4. A router in an OSPF enterprise network has a default static route that has been configured via the interface that connects to the ISP. Which command would the network administrator apply on this router so that other routers in the OSPF network will use this default route?

  • redistribute static
  • redistribute connected
  • redistribute static subnets
  • default-information originate

5. A router is participating in an OSPFv2 domain. What will always happen if the dead interval expires before the router receives a hello packet from an adjacent DROTHER OSPF router?

  • OSPF will run a new DR/BDR election.
  • SPF will run and determine which neighbor router is “down”.
  • A new dead interval timer of 4 times the hello interval will start.
  • OSPF will remove that neighbor from the router link-state database.

6. What is the order of packet types used by an OSPF router to establish convergence?

  • Hello, LSAck, LSU, LSR, DBD
  • LSAck, Hello, DBD, LSU, LSR
  • Hello, DBD, LSR, LSU, LSAck
  • LSU, LSAck, Hello, DBD, LSR

7. What is a feature of the OSPF routing protocol?​

  • The SPF algorithm chooses the best path based on 30-second updates​.
  • OSPF authentication is configured in the same way on IPv4 and IPv6 networks.​
  • It scales well in both small and large networks.
  • Routers can be grouped into autonomous systems to support a hierarchical system.

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

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

9. What is identical on all OSPF routers within a single area?

  • routing table
  • link-state database
  • neighbor table
  • static routes

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

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

11. What are two reasons for creating an OSPF network with multiple areas? (Choose two.)

  • to provide areas in the network for routers that are not running OSPF
  • to ensure that an area is used to connect the network to the Internet
  • to reduce SPF calculations
  • to reduce use of memory and processor resources
  • to simplify configuration

12. At which OSPF state are neighbor routers converged and able to exchange routing updates?

  • Two-Way
  • ExStart
  • Exchange
  • Full

13. The OSPF hello timer has been set to 15 seconds on a router in a point-to-point network. By default, what is the dead interval on this router?

  • 15 seconds
  • 30 seconds
  • 45 seconds
  • 60 seconds

14. 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 negotiate the election process if they are on a multiaccess network.
  • They request more information about their databases.
  • They exchange abbreviated lists of their LSDBs.

15. Which statement is correct about multiarea OSPF?

  • OSPF can consolidate a fragmented OSPF area into one large area.
  • All routers are in one area called the backbone area (area 0).
  • Arranging routers into areas partitions a large autonomous system in order to lighten the load on routers.
  • OSPF multiarea increases the frequency of SPF calculation.

16. Which criterion is preferred by the router to choose a router ID?

  • the IP address of the highest configured loopback interface on the router
  • the IP address of the highest active interface on the router
  • the router-id rid command
  • the IP address of the highest active OSPF-enabled interface

17. Which wildcard mask would be used to advertise the 192.168.5.96/27 network as part of an OSPF configuration?

  • 0.0.0.32
  • 0.0.0.31
  • 255.255.255.224
  • 255.255.255.223

18. The following three networks are directly connected to an OSPF router; 192.168.0.0/24, 192.168.1.0/24, and 192.168.2.0/24. Which OSPF network command would advertise only the 192.168.1.0 network to neighbors?

  • router(config-router)# network 192.168.1.0 0.0.0.255 area 0
  • router(config-router)# network 192.168.0.0 0.0.15.255 area 0
  • router(config-router)# network 192.168.1.0 255.255.255.255 area 0
  • router(config-router)# network 192.168.1.0 0.0.0.0 area 0

19. Which three parameters should match in order for a pair of routers to form an adjacency when running OSPFv2? (Choose three.)

  • router ID
  • OSPFv2 process number
  • OSPFv2 type of network
  • hello timer
  • interface priority
  • subnet mask

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

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

21. A router with two LAN interfaces, two WAN interfaces, and one configured loopback interface is operating with OSPF as its routing protocol. What does the router OSPF process use to assign the router ID?

  • the IP address of the interface that is configured with priority 0
  • the OSPF area ID that is configured on the interface with the highest IP address
  • the loopback interface IP address
  • the highest IP address on the LAN interfaces
  • the highest IP address that is configured on the WAN interfaces

22. Which verification command would identify the specific interfaces on a router that were configured with the passive-interface command?

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

23. Which command, if applied on an OSPF router, would give a Gigabit Ethernet interface a lower cost than a Fast Ethernet interface?

  • (config-if)# bandwidth 100
  • (config-router)# auto-cost reference-bandwidth 1000
  • (config-if)# ip ospf cost 100
  • (config-if)# ip ospf priority 1

24. 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.

25. Which command can be used to view the OSPF hello and dead time intervals?

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

26. What does the SPF algorithm consider to be the best path to a network?

  • The path with the least number of hops.
  • The path with the smallest delays.
  • The path that includes the fastest cumulative bandwidth links.
  • The path that includes the fastest single bandwidth link.

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