OSPF Questions
Here you will find answers to OSPF Questions
Note: If you are not sure about OSPF, please read my OSPF tutorial
Question 1
After the network has converged, what type of messaging, if any, occurs between R3 and R4?
A. No messages are exchanged.
B. Hellos are sent every 10 seconds.
C. The full database from each router is sent every 30 seconds.
D. The routing table from each router is sent every 60 seconds.
Answer: B
Explanation
HELLO messages are used to maintain adjacent neighbors so even when the network is converged, hellos are still exchanged. On broadcast and point-to-point links, the default is 10 seconds, on NBMA the default is 30 seconds.
Although OSPF is a link-state protocol but the full database from each router is sent every 30 minutes (not seconds) -> C and D are not correct.
Question 2
R1 is configured with the default configuration of OSPF.
From the following list of IP addresses configured on R1, which address will the OSPF process select as the router ID?
A. 192.168.0.1
B. 172.16.1.1
C. 172.16.2.1
D. 172.16.2.225
Answer: A
Explanation
The Router ID (RID) is an IP address used to identify the router and is chosen using the following sequence:
+ The highest IP address assigned to a loopback (logical) interface.
+ If a loopback interface is not defined, the highest IP address of all active router’s physical interfaces will be chosen.
+ The router ID can be manually assigned
In this case, because a loopback interface is not configured so the highest active IP address 192.168.0.1 is chosen as the router ID.
Question 3
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
Answer: A C
Question 4
R1 is unable to establish an OSPF neighbor relationship with R3. What are possible reasons for this problem? (Choose two)
A. All of the routers need to be configured for backbone Area 1.
B. R1 and R2 are the DR and BDR, so OSPF will not establish neighbor adjacency with R3.
C. A static route has been configured from R1 to R3 and prevents the neighbor adjacency from being established.
D. The hello and dead interval timers are not set to the same values on R1 and R3.
E. EIGRP is also configured on these routers with a lower administrative distance.
F. R1 and R3 are configured in different areas.
Answer: D F
Explanation
To become OSPF neighbors, routers must meet these requirements: Hello interval, Dead interval and AREA number -> D and F are correct.
Question 5
ROUTER# show ip route
192.168.12.0/24 is variably subnetted, 9 subnets, 3 masks
C 192.168.12.64 /28 is directly connected, Loopback1
C 192.168.12.32 /28 is directly connected, Ethernet0
C 192.168.12.48 /28 is directly connected, Loopback0
O 192.168.12.236 /30 [110/128] via 192.168.12.233, 00:35:36, Serial0
C 192.168.12.232 /30 is directly connected, Serial0
O 192.168.12.245 /30 [110/782] via 192.168.12.233, 00:35:36, Serial0
O 192.168.12.240 /30 [110/128] via 192.168.12.233, 00:35:36, Serial0
O 192.168.12.253 /30 [110/782] via 192.168.12.233, 00:35:37, Serial0
O 192.168.12.249 /30 [110/782] via 192.168.12.233, 00:35:37, Serial0
O 192.168.12.240/30 [110/128] via 192.168.12.233, 00:35:36, Serial 0
To what does the 128 refer to in the router output above?
A. OSPF cost
B. OSPF priority
C. OSPF hop count
D. OSPF ID number
E. OSPF administrative distance
Answer: A
Explanation
The first parameter is the Administrative Distance of OSPF (110) while the second parameter is the cost of OSPF.
Question 6
Which of the following describe the process identifier that is used to run OSPF on a router? (Choose two)
A. It is locally significant.
B. It is globally significant.
C. It is needed to identify a unique instance of an OSPF database.
D. It is an optional parameter required only if multiple OSPF processes are running on the router.
E. All routers in the same OSPF area must have the same process ID if they are to exchange routing information.
Answer: A C
Question 7
Open Shortest Path First (OSPF) is a routing protocol developed for Internet Protocol (IP) networks by the Interior Gateway Protocol (IGP) working group of the Internet Engineering Task Force (IETF). What is the default administrative distance of the OSPF routing protocol?
A. 90
B. 100
C. 110
D. 20
E. 130
F. 170
Answer: C
Question 8
The internetwork infrastructure of company XYZ consists of a single OSPF area as shown in the graphic.
There is concern that a lack of router resources is impeding internetwork performance.
As part of examining the router resources the OSPF DRs need to be known.
All the router OSPF priorities are at the default and the router IDs are shown with each router.
Which routers are likely to have been elected as DR? (Choose two)
A. Corp-1
B. Corp-2
C. Corp-3
D. Corp4
E. Branch-1
F. Branch-2
Answer: D F
Explanation
There are 2 segments on the topology above which are separated by Corp-3 router. Each segment will have a DR so we have 2 DRs.
To select which router will become DR they will compare their router-IDs. The router with highest (best) router-ID will become DR. The router-ID is chosen in the order below:
+ The highest IP address assigned to a loopback (logical) interface.
+ If a loopback interface is not defined, the highest IP address of all active router’s physical interfaces will be chosen.
In this question, the IP addresses of loopback interfaces are not mentioned so we will consider IP addresses of all active router’s physical interfaces. Router Corp-4 (10.1.40.40) & Branch-2 (10.2.20.20) have highest “active” IP addresses so they will become DRs.
Question 9
Which address are OSPF hello packets addressed to on point-to-point networks?
A. 224.0.0.5
B. 172.16.0.1
C. 192.168.0.5
D. 223.0.0.1
E. 254.255.255.255
Answer: A
Question 10
Which statements describe the routing protocol OSPF? (Choose three)
A. It supports VLSM.
B. It is used to route between autonomous systems.
C. It confines network instability to one area of the network.
D. It increases routing overhead on the network.
E. It allows extensive control of routing updates.
F. It is simpler to configure than RIP v2.
Answer: A C E
Question 11
R1 is unable to establish an OSPF neighbor relationship with R3
What are possible reasons for this problem? (Choose two)
A. All of the routers need to be configured for backbone Area 1
B. R1 and R2 are the DR and BDR, so OSPF will not establish neighbor adjacency with R3
C. A static route has been configured from R1 to R3 and prevents the neighbor adjacency from being established.
D. The hello and dead interval timers are not set to the same values on R1 and R3
E. EIGRP is also configured on these routers with a lower administrative distance
F. R1 and R3 are configured in different areas
Answer: D F
Question 12
RouterD# show ip interface brief
Given the output for this command, if the router ID has not been manually set, what router ID will OSPF use for this router?
A. 10.1.1.2
B. 10.154.154.1
C. 172.16.5.1
D. 192.168.5.3
Answer: C
Question 12 is Incorrect, correct answer should be D
Question 12 is correct, the answere is indeed C. OSPF uses the highest IP address of the loopback interfaces first. If ther are no loopback interfaces then OSPF will use the highest IP address of the active interfaces.
The answer is C loppback0
Could someone explain the answer given for the question 8. In my understanding the DR will be the router with the highest IP as the other settings are defaults( priority , no router id set and no loopback) . In the topology routers Branch 2(10.2.20.20) and Branch 1 (10.2.10.10)are the ones having higest IP .
Comments please !
There is a wan link dividing the network, so I think we are meant to assume they are different networks 10.1.0.0 and 10.2.0.0
Branch 2 (10.2.20.20) has the highest IP on its network, so it becomes a DR for the 10.2.0.0 network.
Corp4 (10.1.40.40) has the highest IP on its network, so it becomes the DR for the 10.1.0.0 network.
I could be wrong, but I believe that is how it works. Hope that helps.
Could anyone plz explain question 9?
as i know that the chosen address is for multicast to point to point so plzzz verify
http://en.wikipedia.org/wiki/Multicast_address
A is the right answer.
Thank you
)
On Q4 should it not be backbone area 0? I also thought I had seen that question elsewhere and it showed a topology diagram of r1-r2-r3
Thanks.
By the way in my comment above I was not implying that A should be th correct answer, and after thinking about it some more I guess it doesn’t really matter what it says on a wrong answer.
As mentioned above by Frerot about Q#8,
@tut or someone can plz explain the answer bcoz this Q was in the 640-816 exam.
thanks.
@sam: I added explanation to Q#8, kindly check.
@tut Thanks for that quick response.
but you know what, the Q says 2 DRs and same network cannot have 2 DRs at a time atleast that should have come to my mind in the test
I would still appreciate if you can explain a little more about what you mean by segment and how it is defined in this scenario.
@sam: segment here means a “broadcast domain”. In this question there are 2 segments:
+ Segment 1: limited by Corp1,Corp2,Corp3,Corp4
+ Segment 2: limited by Corp3, Branch1, Branch2
Each segment requires a DR so we can have 2 DRs in this question.
Q9) if the question specifically says point to point which means there are only two host(sender and receiver)involved why should it use a muticast ip …?
Why not a unicast..?
Q2 and Q8 This question was there for my exam… on 28th July…
Questions 1,2, 6 and 10 were on test today (8/5/11). Passed with 920
could anyone explain Q6. for me. I dnt understand why E is not correct
@dferra
the name says it all: *process identifier*
the process is local, it doesn’t affect any other devices except the router it is running on.
i believe you mixed up the EIGRP A.S. number and the OSPF process ID…
EIGRP A.S. number – global importance, must be the same on all routers in the autonomous system
OSPF process ID – can be any number from 0 to 65535 (don’t quote me on the numbers). it has importance only on the router.
Test test today ICND 2… Q1 , Q2, Q4, Q8, Q11, Q12 were on the test
Re: Q1 on exam…they also ask how many routes are placed by OSPF on the R1 routing table. I believe the highest is 7 routes, but also offers 1 route,2 routes,5 routes.
Anyone know/remember the answer to that one?
Grr, also saw that on on the ICND2 testr a couple of weeks ago. I was not ready for that test.
How many routes are placed on the R1 routing table in
question 1. I also answered 7, but believe It is wrong, just cannot wrap my head around that one. And I know it is easy.
Grr, and anyone else. Question #1 was asked as this,
OSPF is configured using default classful addressing.
With all routers and interfaces operational, how many networks will be in the routing table of router 1, that are indicated to be learned by OSPF.
answers are
2,3, 4, 5, 6,7
Correct Answer is 4 (Thanks to VCE from Xallax)
Reason “Learned by OSPF” If you look at the router 1 how many routes does it need to learn? It already knows about its directly connected ones, only those not directly connected are “Learned by OSPF”
I’ve been trying to figure this out all week.
@CrazyDude, you gotta change your nick dude. You’re starting to make sense…
Can I suggest SensibleDude?
@crazydude
I got this question. I think I got this wrong though. I think I answered 4 because it is classful addressing (I think three class C addresses were used for OSPF and a public one for the ISP). Using it here, I would say router 1 knows about the 172.16.0.0 network and 192.168.0.0 network so I would chose 2. The question asks how many networks are in the routing table of router 1 so it should include those directly connected. Again, not sure with this one.
Just read that OSPF does not support auto-summarization so it should learn 4 (not including those directly connected). I just read my comment and it is wrong! I really hate this question.
took my icnd1 and 2 today.
questions 1, 2, 7 and 8 were there on todays exam.
passed both.
thank you all
The answer to Q1 is wrong. It should be: A…no messages are exchanged. I just labbed it up in GNS3 and ran a debug ip ospf hello…the only messages exchanged are between full neighbors.
Disregard my last post…Q1 is right as the two routers have their FastEthernet ports connected to a switch on the same network which allows them to become neighbors. Great site! Taking my ICND2 tomorrow morning.
Can some pliz convince me on Question 3.
@nkuba
“Hello protocol – The OSPF Hello protocol provides dynamic neighbor discovery and maintains neighbor relationships. Hello packets and Link State Advertisements(LSAs) build and maintain the topological database.
Link State advertisement – A Link State Advertisement(LSA) is an link-state protocol data packet containing link-state and routing information that’s shared among OSPF routers. There are different types of LSA packets, and I’ll go into these shortly. An link-state protocol router will exchange LSA packets only with routers to which it has established adjacencies.”
I got the question 2 today on the exam today. within the same diagram on question 2, there was questions as Crazydude mentioned.
OSPF is configured using default classful addressing.
With all routers and interfaces operational, how many networks will be in the routing table of router 1, that are indicated to be learned by OSPF.
answers are
2,3, 4, 5, 6,7
I picked 4 but not sure.
also the same diagram question which command will you use to load balance R3 and R4. I picked ip ospf priority but i am not positive. anybody have answers?
int fa0/0
ip ospf cost
the costs must be the same for load balancing to happen
I had diagram from 1,2 question. 4 questions.
Question about load balansing from R2 to sw-a network + how match routes R1 will lern from R2 on OSPF.
Q1,Q2 on my exam today
Hi 9TUT,
I didnot understand the question 11?Can anybody explain to me??
Passed ICND2 today with 944!! I had questions #1 and #2 on my test today
Congratulations WKC. I sit Wednesday. Was the exam like these tests?
Where there areas not stated here. What labs did you get?
Cheers
Cryptkeeper, I’m currently writing up my whole experience with details, it will be kind of long so stay tuned, will have it up soon.
Took ICND2 today and passed with 944! Every single question I had came from either 9tuts CCNA pool of questions or their ICND2 pool of questions on their site, although the majority of my questions came from the CCNA portion so make sure you study both sites. Also, know your theory because if you just memorize dumps and can’t apply it on the job then you won’t keep a job very long. I only had one SIM to do which was the VTP sim. I had the Frame Relay Simlet and a couple of Drag and Drops. The rest were just questions from these sites. It was not near as hard as I was expecting after studying for the last 6 months. I think I over prepared but it paid off for me. I finished the test and still had about 25 minutes to spare. These are the questions I had and what sections they came from on 9tut.
CCNA-Cisco IOS Questions #1 #3 #5 — CCNA-Cisco IOS Questions 2 #2 #10
CCNA- Show Command Questions #7 –CCNA- WAN #1 –CCNA-IP Routing Questions 2 #10
CCNA-RIP Questions #13 –CCNA-OSPF Questions #4 #6 –CCNA-OSPF Questions 2 #2 #6
CCNA-EIGRP Questions #1 #2 –CCNA-Security Questions #2 #5 #10
CCNA-NAT and PAT Questions #4 –CCNA-Drag and Drop 1 #1 #4
CCNA-Drag and Drop 4 #2 –CCNA-Switch Questions #10 #12 #13
CCNA-Hotspot Frame Relay Simlet –CCNA-STP Questions #1 –CCNA-STP Questions 2 #5
CCNA-IPV6 Questions #7 –CCNA-Subnetting #3 –CCNA-Subnetting Questions 4 #1
CCNA-Operations 1 #5 #12 –CCNA-Troubleshooting 1 #6
ICND2 Labsim VTP Configuration –ICND2-VTP&VLAN Questions #5
ICND2-EIGRP Questions #6 –ICND2-EIGRP 2 #6 #7 –ICND2-OSPF #1 #2
INCD2-OSPF Questions 2 #2 #3 #5 #9 #12
Study Material:
8 Years of on the job experience
5 Week CCNA course at local Vocational School
Wendell Odem Books
Chris Bryant http://www.thebryantadvantage.com/ and also his Youtube channel
VCE’s
9tut
WKC. thats awsome, thanks fella (fellerette)
Are there any Route Summarization questions on the exam? I noticed this wasn’t touched upon on the site. Thanks