Test Your Knowledge Is On CCNA – OSPF Questions 2
Welcome back to another quiz which aims to boost your studies for your Cisco Certified Network Associate, where we’ll be taking another look at the routing protocol known as Open Shortest Path First (OSPF). What can you tell us about this protocol and how it works? Let’s take a look. .
- 1.
Why R1 can’t establish an OSPF neighbor relationship with R3 according to the following graphic? (Choose two)
- A.
Configure EIGRP on these routers with a lower administrative distance
- B.
All routers should be configured for backbone Area 1
- C.
R1 and R3 have been configured in different areas
- D.
The hello and dead interval timers are not configured the same values on R1 and R3
Correct Answer(s)
C. R1 and R3 have been configured in different areas
D. The hello and dead interval timers are not configured the same values on R1 and R3Explanation
A is not correct because configure EIGRP on these routers (with a lower administrative distance) will force these routers to run EIGRP, not OSPF.
B is not correct because the backbone area of OSPF is always Area 0.
C and D are correct because these entries must match on neighboring routers:
- Hello and dead intervals
– Area ID (Area 0 in this case)
– Authentication password
– Stub area flagRate this question:
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- 2.
Which parameter or parameters are used to calculate OSPF cost in Cisco routers?
- A.
Bandwidth, Delay and MTU
- B.
Bandwidth
- C.
Bandwidth and MTU
- D.
Bandwidth, MTU, Reliability, Delay and Load
Correct Answer
B. BandwidthExplanation
The well-known formula to calculate OSPF cost is
Cost = 108 / Bandwidth
so B is the correct answer.Rate this question:
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- 3.
A network administrator is troubleshooting the OSPF configuration of routers R1 and R2. The routers cannot establish an adjacency relationship on their common Ethernet link. The graphic shows the output of the show ip ospf interface e0 command for routers R1 and R2. Based on the information in the graphic, what is the cause of this problem?
- A.
The OSPF area is not configured properly.
- B.
The priority on R1 should be set higher.
- C.
The cost on R1 should be set higher.
- D.
The hello and dead timers are not configured properly.
- E.
A backup designated router needs to be added to the network.
- F.
The OSPF process ID numbers must match.
Correct Answer
D. The hello and dead timers are not configured properly.Explanation
D is correct because these entries must match on neighboring routers:
- Hello and dead intervals
– Area ID (Area 0 in this case)
– Authentication password
– Stub area flag
In this case Ethernet0 of R1 has Hello and Dead Intervals of 5 and 20 while R2 has Hello and Dead Intervals of 10 and 40 -> R1 and R2 cannot form OSPF neighbor relationship.Rate this question:
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- 4.
What information does a router running a link-state protocol use to build and maintain its topological database? (Choose two)
- A.
Hello packets
- B.
SAP messages sent by other routers
- C.
LSAs from other routers
- D.
Beacons received on point-to-point links
- E.
Routing tables received from other link-state routers
- F.
TTL packets from designated routers
Correct Answer(s)
A. Hello packets
C. LSAs from other routersExplanation
A router running a link-state protocol uses hello packets to establish and maintain neighbor relationships with other routers. These hello packets allow routers to exchange information about their presence and capabilities. Additionally, the router uses LSAs (Link State Advertisements) from other routers to build and maintain its topological database. LSAs contain information about the router's directly connected links and their state, which helps the router to construct a map of the network topology.Rate this question:
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- 5.
Which command is used to display the collection of OSPF link states?
- A.
Show ip ospf link-state
- B.
Show ip ospf lsa database
- C.
Show ip ospf neighbors
- D.
Show ip ospf database
Correct Answer
D. Show ip ospf databaseExplanation
The correct answer is "show ip ospf database". This command is used to display the collection of OSPF link states. It provides information about the OSPF database, which includes information about the OSPF routers, networks, and link states in the OSPF domain. By using this command, network administrators can view the OSPF link state database and gather information about the OSPF network topology.Rate this question:
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- 6.
When running OSPF, what would cause router A not to form an adjacency with router B?
- A.
The loopback addresses are on different subnets.
- B.
The values of the dead timers on the routers are different.
- C.
Route summarization is enabled on both routers.
- D.
The process identifier on router A is different than the process identifier on router
Correct Answer
B. The values of the dead timers on the routers are different.Explanation
To form an adjacency (become neighbor), router A & B must have the same Hello interval, Dead interval and AREA number.Rate this question:
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- 7.
Which is true about OSPF router-id? (Choose two)
- A.
It is used for type 1 router LSA
- B.
Highest IP address of the loopback is used
- C.
Router-id needs to be matched on ospf neighbors
- D.
Router-id is 16 bit
Correct Answer(s)
A. It is used for type 1 router LSA
B. Highest IP address of the loopback is usedExplanation
OSPF LSA Type 1 (or Router LSA) is generated by all routers in an area to describe their directly attached links. An example below shows this type of LSA:Rate this question:
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- 8.
Which two statements about the OSPF Router ID are true? (Choose two)
- A.
It identifies the source of Type 1 LSA
- B.
It should be the same on all routers in an OSPF routing instance
- C.
By default, the lowest IP address on the router becomes the OSPF router ID
- D.
The router automatically chooses the IP address of a loopback as the OSPF Router ID
- E.
It is created using the MAC Address of the loopback interface
Correct Answer(s)
A. It identifies the source of Type 1 LSA
D. The router automatically chooses the IP address of a loopback as the OSPF Router IDExplanation
From the output of the “show ip ospf database”:Rate this question:
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- 9.
What are two benefits of using a single OSPF area network design? (Choose two)
- A.
It is less CPU intensive for routers in the single area.
- B.
It reduces the types of LSAs that are generated.
- C.
It removes the need for virtual links.
- D.
It increases LSA response times.
- E.
It reduces the number of required OSPF neighbor adjacencies.
Correct Answer(s)
B. It reduces the types of LSAs that are generated.
C. It removes the need for virtual links.Explanation
A single OSPF area network design reduces the types of Link State Advertisements (LSAs) that are generated. In a single area, only one type of LSA, known as Type 1 LSA, is generated. This simplifies the network design and reduces the complexity of OSPF routing. Additionally, a single area design removes the need for virtual links. Virtual links are used to connect non-backbone areas through the backbone area. By using a single area design, the need for virtual links is eliminated, which further simplifies the network and reduces potential configuration errors.Rate this question:
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Mar 21, 2023Quiz Edited by
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Mar 23, 2015Quiz Created by
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