Modules 1 – 2: OSPF Concepts and Configuration

to discover neighbors and build adjacencies between them

1. What is a function of OSPF hello packets?

LSU

2. Which OSPF packet contains the different types of link-state advertisements?

It is a link-state database that represents the network topology.

3. Which three statements describe features of the OSPF topology table? (Choose three.)

When converged, all routers in an area have identical topology tables.

3. Which three statements describe features of the OSPF topology table? (Choose three.)

The table can be viewed via the show ip ospf database command.

3. Which three statements describe features of the OSPF topology table? (Choose three.)

routers that have the same link-state information in their LSDBs

4. What does an OSPF area contain?

the use of multiple areas

5. What is used to facilitate hierarchical routing in OSPF?

link-state database

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

exchanges link-state advertisements

7. Which step does an OSPF-enabled router take immediately after establishing an adjacency with another router?

The dead interval will now be 60 seconds.

8. 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 R1 dead timer expires between hello packets from R2.

9. Refer to the exhibit. A network administrator has configured the OSPF timers to the values that are shown in the graphic. What is the result of having those manually configured timers?

dead interval

10. To establish a neighbor adjacency two OSPF routers will exchange hello packets. Which two values in the hello packets must match on both routers? (Choose two.)

hello interval

10. To establish a neighbor adjacency two OSPF routers will exchange hello packets. Which two values in the hello packets must match on both routers? (Choose two.)

1

11. What is the default router priority value for all Cisco OSPF routers?

database description

12. Which type of OSPFv2 packet contains an abbreviated list of the LSDB of a sending router and is used by receiving routers to check against the local LSDB?

when the routers are interconnected over a common Ethernet network

13. In an OSPF network when are DR and BDR elections required?

every 30 minutes

14. When an OSPF network is converged and no network topology change has been detected by a router, how often will LSU packets be sent to neighboring routers?

any IP address that is configured using the router-id command

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

to uniquely identify the router within the OSPF domain

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

to facilitate router participation in the election of the designated router

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

192.168.1.100

17. Refer to the exhibit. If no router ID was manually configured, what would router Branch1 use as its OSPF router ID?

the OSPF process ID on R1

18. A network technician issues the following commands when configuring a router:

R1(config)# router ospf 11 R1(config-router)# network 10.10.10.0 0.0.0.255 area 0

What does the number 11 represent?

router(config-router)# network 172.16.1.0 255.255.255.0 area 0

19. An OSPF router has three directly connected networks; 172.16.0.0/16, 172.16.1.0/16, and 172.16.2.0/16. Which OSPF network command would advertise only the 172.16.1.0 network to neighbors?

R3 will be elected BDR.

20. Refer to the exhibit. Which three statements describe the results of the OSPF election process of the topology that is shown in the exhibit? (Choose three.)

The R4 router ID is 172.16.1.1.

20. Refer to the exhibit. Which three statements describe the results of the OSPF election process of the topology that is shown in the exhibit? (Choose three.)

R2 will be elected DR.

20. Refer to the exhibit. Which three statements describe the results of the OSPF election process of the topology that is shown in the exhibit? (Choose three.)

Router R4 will become the DR and router R1 will become the BDR.

21. Refer to the exhibit. If the switch reboots and all routers have to re-establish OSPF adjacencies, which routers will become the new DR and BDR?

1

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

65

23. Refer to the exhibit. What is the OSPF cost to reach the router A LAN 172.16.1.0/24 from B?

R0-A

24. Refer to the exhibit. On which router or routers would a default route be statically configured in a corporate environment that uses single area OSPF as the routing protocol?

show ip ospf neighbor

25. What command would be used to determine if a routing protocol-initiated relationship had been made with an adjacent router?

R1# show ip ospf interface serial0/0/1

26. Refer to the exhibit. Which command did an administrator issue to produce this output?

show ip protocols

27. 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?​

Interface Fa0/0 has not been activated for OSPFv2 on router R2.

28. Refer to the exhibit. A network administrator has configured OSPFv2 on the two Cisco routers but PC1 is unable to connect to PC2. What is the most likely problem?

Configure a value using the router-id command.

29. What is the recommended Cisco best practice for configuring an OSPF-enabled router so that each router can be easily identified when troubleshooting routing issues?

executing the SPF algorithm

30. Which step in the link-state routing process is described by a router running an algorithm to determine the best path to each destination?

0.0.1.255

31. An administrator is configuring single-area OSPF on a router. One of the networks that must be advertised is 192.168.223.0 255.255.254.0. What wildcard mask would the administrator use in the OSPF network statement?

a 32-bit number formatted like an IPv4 address

32. What is the format of the router ID on an OSPF-enabled router?

DUAL is the algorithm used by EIGRP. In multiarea OSPF, OSPF is implemented using multiple areas, and all of them must be connected to the backbone area.

33. Question as presented:

HQ# clear ip ospf process

34. After modifying the router ID on an OSPF router, what is the preferred method to make the new router ID effective?

It tells the router which interface to turn on for the OSPF routing process.

35. In an OSPFv2 configuration, what is the effect of entering the command network 192.168.1.1 0.0.0.0 area 0 ?

to more accurately reflect the cost of links greater than 100 Mb/s

36. What is the reason for a network engineer to alter the default reference bandwidth parameter when configuring OSPF?

Change the subnet mask of interface FastEthernet 0/0 to 255.255.255.0.

37. 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?