CCNA – 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
Which of the following statements below best describe the process identifier that is used to run OSPF on a router? (Choose two)
A – It is an optional parameter required only if multiple OSPF processes are running on the router
B – It is locally significant
C – It is needed to identify a unique instance of an OSPF database
D – All routers in the same OSPF area must have the same process ID if they are to exchange routing information
Answer: B C
Question 2:
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
Answer: C D
Explanation:
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 flag
Question 3:
Which items are correct about the routing protocol OSPF? (Choose three)
A – Support VLSM
B – Increase routing overhead on the network
C – Confine network instability to one area of the network
D – Allow extensive control of routing updates
Answer: A C D
Explanation:
Routing overhead is the amount of information needed to describe the changes in a dynamic network topology. All routers in an OSPF area have identical copies of the topology database and the topology database of one area is hidden from the rest of the areas to reduce routing overhead because fewer routing updates are sent and smaller routing trees are computed and maintained (allow extensive control of routing updates and confine network instability to one area of the network).
Question 4:
Which three features are of OSPF routing protocol? (Choose three)
A – Converge quickly
B – OSPF is a classful routing protocol
C – Identify the best route by use of cost
D – Before exchanging routing information, OSPF routers find out neighbors
Answer: A C D
Question 5:
OSPF routing uses the concept of areas. What are the characteristics of OSPF areas? (Chose three)
A – Each OSPF area requires a loopback interface to be configured
B – Areas may be assigned any number from 0 to 65535
C – Area 0 is called the backbone area
D – Hierarchical OSPF networks do not require multiple areas
E – Multiple OSPF areas must connect to area 0
F – Single area OSPF networks must be configured in area 1
Answer: B C E
Explanation:
I used to think the answers should be C D E and here is my explanation:
OSPF can use an active interface for its router ID, so a loopback interface is not a must -> A is incorrect.
OSPF Area is a 32-bit number so we can use up to 232 – 1 = 4294967296 – 1 (since Area 0 is the first area). Remember that only process ID is a 16-bit number and ranges from 1 to 65535 -> B is incorrect.
F is incorrect too because single area OSPF netwoks must be configured in Area 0, which is called the backbone area.
For answer D, it is a bit hard to guess what they want to say about “hierarchical” but we should understand “Hierarchical OSPF networks” as “OSPF networks”. D is correct bercause we can only have one area (area 0 – the backbone area) for our networks.
But TT commented on 01-11-2010:
Especially to note on choice B, D, and E:
Choice B: we all know that The areas can be any number from 0 to 4.2 billion and 1 to 65,535 for the Process ID. As choice B specifies ‘area’ (be aware, it’s not saying ‘process id), there is no reason to say that we cannot assign numbers from 0 to 65535 for area # (it is using ‘may be’, not ‘have to be’ or ‘ought to be’). Hence, we do not worry about assigning ’0′.
Choice E: as Area 0 is the backbone, we all understand that any areas in a OSPF network have to be connected to it. And actually this is implicitly saying that multiple areas form a hierarchical OSPF network, as Area 0 being a root and others being its leaves.
Choice D: when it specifies ‘Hierarchical’, at least 2 areas should be required to form such topology (of course that includes Area 0)
Although Choice B is not an absolutely accurate statement since it not only can be assigned up to 65535, it is still a correct answer. And again, it specifies ‘area’, not ‘process id’, so ’0′ can be included. Finally, it would be meaningless to call OSPF a hierarchical network if no more than one area is present.
—————————————————————————————————-
I reviewed the question and think it is a more suitable solution with choice B than choice D, surely it is a tricky question!
Question 6:
Part of the OSPF network is shown below:
Configuration exhibit:
R1 routing commands:
ip route 0.0.0.0 0.0.0.0 serial0/0
router ospf 1
network 172.16.100.0 0.0.0.3 area 0
network 172.16.100.64 0.0.0.63 area 0
network 172.16.100.128 0.0.0.31 area 0
default-information originate
You work as a network technician, study the exhibits carefully. Assume that all router interfaces are operational and correctly configured. In addition, assume that OSPF has been correctly configured on router R2. How will the default route configured on R1 affect the operation of R2?
A – Any packet destined for a network that is not directly connected to router R2 will be dropped immediately
B – Any packet destined for a network that is not directly connected to router R1 will be dropped
C – Any packet destined for a network that is not directly connected to router R2 will be dropped immediately because of the lack of a gateway on R1
D – The network directly connected to a router R2 will not be able to communicate with the 172.16.100.0, 172.16.100.28 and 172.16.100.64 subnetworks.
E – Any packet destined for a network that is not referenced in the routing table of router R2 will be directed to R1. R1 will then send that packet back to R2 and a routing loop will occur
Answer: E
Explanation:
First, notice that the more-specific routes will always be favored over less-specific routes regardless of the administrative distance set for a protocol. In this case, because we use OSPF for three networks (172.16.100.0 0.0.0.3, 172.16.100.64 0.0.0.63, 172.16.100.128 0.0.0.31) so the packets destined for these networks will not be affected by the default route.
The default route configured on R1 “ip route 0.0.0.0 0.0.0.0 serial0/0″ will send any packet whose destination network is not referenced in the routing table of router R1 to R2, it doesn’t drop anything so answers A, B and C are not correct. D is not correct too because these routes are declared in R1 and the question says that “OSPF has been correctly configured on router R2″, so network directly connected to router R2 can communicate with those three subnetworks.
As said above, the default route configured on R1 will send any packet destined for a network that is not referenced in its routing table to R2; R2 in turn sends it to R1 because it is the only way and a routing loop will occur.
I cant understand Q6 please help me ?
thanks
Q 6 last statement -Default Information Originate will cause loops
Helo!
About question 5:
“OSPF Area is a 32-bit number so we can use up to 232 – 1 = 4294967296 – 1 (since Area 0 is the first area). Remember that only process ID is a 16-bit number and ranges from 1 to 65535 -> B is incorrect”
So alternative B is not correct to question 5!!!
Tahnks :)
Angelo
Why do you put the answers directly underneath the question?!?!?!?!?
How does it help me try and solve the problem if I can already see the answer in front of me?
Sonny Keogan: use the slide bar of ur Browser in such a way tht only the question part is visible to u …
From Cisco site, OSPF desing, about 5th question:
” …The area-id is the area number we want the interface to be in. The area-id can be an integer between 0 and 4294967295 or can take a form similar to an IP address A.B.C.D. … ”
“B” is correct …
OSPF has special restrictions when multiple areas are involved. If more than one area is configured, one of these areas has be to be area 0. This is called the backbone. When designing networks it is good practice to start with area 0 and then expand into other areas later on.
The backbone has to be at the center of all other areas, i.e. all areas have to be physically connected to the backbone. The reasoning behind this is that OSPF expects all areas to inject routing information into the backbone and in turn the backbone will disseminate that information into other areas
HI 9tut, about Q6
Answer E said : “Any packet destined for a network that is not referenced in the routing table of router R2 will be directed to R1!”
How is that possible when R2 will not form a neighbor relationship with R1????
If you notice, the default route in R1 is directed back to R2 (serial 0/0)… therefor, a routing loop should occur.
Letter E is the appropriate answer for this case.
Hi all!
In my hand I had a hard copy of question. Unfortunately, I am unable to draw the topology in this plane, sorry, OSPF topology.
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 the examining the router resources , the ospf DRs need to be known.All the router ospf priorities at the default and the router IDs are shown with each route.Which routers are likely to have been elected as DR?
A.corp-1
B.Corp-2
C.Corp3
D.Corp-4
E.Branch-1
F.Branch-2
Ans D and F
My answer Is E and F
because of Mac address 10.2.10.10 (br-1′s ) greater than 10.1.40.40( corp4′s)
Please give the answer? why not ?
Instead of topology I used my maximum utilities:
There are 6 routers and one more router for the ISP router:
Isp Router (provider)
Corp 1-R1(10.1.10)
Corp 2 R-2(10.1.20.20) switch 1 corp-(10.1..40.40)
corp-3(10.1.30.30)
branch-1-R Switch2 (10.2.20.20) Branch2
(10.2.10.10)
Above was given OSPF topology with area 0
Ip address is given in brackets
Isp connected with corp-1( 1-connection)
corp1 connected with switch 1(1-connection)
switch1 connected with both corp2 and corp 4 ( respectively)
also connected with corp3( switch 1 itself had a 3 connection)
corp-3 connected with branch-1 ( 1-connection)
branch 1 connected with switch 2( 2-connection)
Finally switch 2 connected with branch 2- (only 1 connection)
I am really appreciated the answer.
Sorry for the above Q: Ip address instead of Mac add, apologized.
My answer Is E and F
because of IP address 10.2.10.10 (br-1′s ) greater than 10.1.40.40( corp4′s) ??
Is that right :
Ip address 10.2.10.10 (br-1′s ) greater than 10.1.40.40( corp4′s) ??
If not, please give brief description.
Right answer is (D and F)..
I have done this question….in this scenario we have pTOp and broadcase networks togather so consider them separate then choose DR …
Hi @ stevan!
Thank you for your answer.I am not satisfied with your answer,please. because You have mentioned point-to-point and frame-relay.
In my understanding, They do not provide any dlci numbers or they explicitly said it is ospf, is not it?. If you can give me more detail, I’ll happy. Although, you may have q: page #83/328 , on the left hand up saying:
‘ The safer, easier way to help you pass any It exams’.
minor correction:
ip for corp-1 is 10.1.10.10
thank you in advance
Again about Q6 , there is something just I cant understand , Since R1 is configured with default not R2 , why R2 had to send back to R1 , wht does not drop the packet, since it does not have any default configured .and the default originate statement is configured on R1 , does not say anything about R2 , if that case for sure OSPF will send it .
More clarification on this one will be great . Thanks
I think I found the answer for this question 6 , we suppose just that the R2 will send any packet that is not found on its table to R1 .and the loop will occur , since R1 will send it back as has default route configured and assume as well for R2 according to the answer (E)
and more comment or explanation will be great .
sorry stevan, i did typing mistake…but i said there are two networks “1.PtP and 2.shared network or broadcast network(via switch )”…..
i could not explain exactly because i didnt find question ..better u put n/w picture somewhere….
i got my exam yesterday and passed with 974. especial thanks for the 9tut. pass4sure & testinside dumps are still valid. sims are eigrp,vtp & access-list only the ip addresses are changed. in access-list the the pc also changed. again thanks for the 9tut and all of the contributors
if any one need help from me pls email to
hasy_001@yahoo.com
Thanks a lot to 9tut.com. I got my exam today and passed with 932. Sims are eigrp,vtp & access-list.
Cisco Certified Network Associate CCNA
Pass4sure 640-802 Exam
Questions and Answers: 430 Q & A
Updated: Dec 21, 2010
pleas mail me zulfiqarsoomro@yahoo.com
this update version of p4s
Please help me with this question.
Which statment about RIPng is true?
A: RIPng uses broadcast to exchange routes.
B: RIPng is enabled on each interface separately.
C: There can be only one RIPng process per router.
D: RIPng allows for route up to 30 hops.
In pass4sure B is the correct answer, but I don’t get it. I think the answer is A can anyone help me with this question?
If I am wrong then whats the reason?
@JOHN
RIPng Is ipv6 based it does not support IPV4 .the concept of broadcasting is eliminated in IPV6 hence RIPng can not use broadcast to exchnage updates .
RIPng is not an extension of RIPv2 ,Its an entirely separate protocol.However RIPng uses the same timers, procedures, and message types as RIPv2 .
In response for Q5 B is correct “Areas may be assigned any number from 0 to 65535″
It emphasis NOT on area NUMBERS but on the process IDs .It should be read as areas may be assigned any Process Id (NUMBER) from 0 to 65535 .The term NUMBER does not realte to AREA number instead it means process IDS .
sorry if i have made any mistake.
Hi Guys
Learn some usefull tips for ccna and ccnp at youtube
Learn Frame Relay and ip help-address
http://www.youtube.com/watch?v=hHortaLwjn8
Switch——————-Network devise A———————–Switch
|
| |
| |
|
10.1.0.36(host) 10.1.1.70(host)
which 3 statement describe the network A
A-with a network wide mask of 255.255.255.128 each interface does not require an ip address
B- – – – – – – each interface does require an ip address on the unique subnet
C- – – – – 255.255.255.0, must be a layer 2 device for the pcs to communicate with each other.
D- – – – – – – – ,- – – 3 device for the pcs to communicate with each other.
E- – – – – 255.255.255.254 each interface doen not require an ip address.
Answer are B,D,E
please explain why?
A little bit misunderstanding about question 6:
R1 has configured with default route. That means if packet is for destination that is not in his routing table router sends that packet over interface of default route.
R2 is configured with OSPF. That mean if R2 got packet that destination is not in his routing table, packet will be droped.
That mean there is not routing loop between R1 and R2.
++++++++++++++++
If on R2 is configured default route then we got routing loop.
But that is not mentioned in the question.
Default route is configured for s0/0 interface (that means for ISP router), not for R2.
?
That mean packets with unknown destination will go through ISP router.
Default route ain’t gonna affect router R2.
From the diagram of Question 6 we can assume that all unknown routes on R2 will be forwarded to R1 because the ISP router is connected to R1. With that being said, with the static route on R1, all unknown routes will be forwarded to R2 creating a routing loop.
Hmm.
A little bit a problem.
“default-information originate” – injects OSPF default route into OSPF domain.
That mean that R2 will know about default route on R1. (Default route is advertised from R2 to R1) Packets with destination address different than routes in routing table of R2 will be forwarded to R1.
And then what?
why routing loop will be created?
?
Is this related with question that is not added
“ip classless”
command after configuring default route on router R1?
If someone knows I appreciate your thinking about this.
Refer question 6 schematic…
A. Router R2 will not form a neighbor relationship with R1.
B. Router R2 will obtain a full routing table, including a default route, from R1.
C. R2 will obtain OSPF updates from R1, but will not obtain a default route from R1.
D. R2 will not have a route for the directly connected serial network, but all other directly
connected networks will be present, as well as the two Ethernet networks connected to R1.
The Answer says A, but I think ACMEs answer is not correct. for me it is answer B is it correct? Can someone helpme with this question?
Refer to the exhibit. The output that is shown is generated at a switch. Which three of these statements are true? (Choose three.)
A:All ports will be in a state of discarding, learning, or forwarding.
B:Thirty VLANs have been configured on this switch.
C:The bridge priority is lower than the default value for spanning tree.
D:All interfaces that are shown are on shared media.
E:All designated ports are in a forwarding state.
F:This switch must be the root bridge for all VLANs on this switch.
Answers: C, E, F
WHY is F correct? how can we ashume that this switch is the root bridge of all other VLANs?
please HELP
I passed CCNA today.
It was really hard exam for me, so many new questions.
There was not questions about STP (RSTP), OSPF,
But in the exam were just
CCNA VTP SIM Question
and Question 3: Troubleshooting 2
from 9tut.
Anyway I think that there a lot of great questions on this site.
It was helpful for me.
Thanks.
Salam Guys
I have given My CCNA paper 640-802 paper on 18th Jan.and i got 987 marks.There is 1 question which is being changed from dumps
1)-Switch A is connected to Switch C and there are 767 CRC Errors between it.What you will do to troublshoot and what is reason for it
a)-there is straight through cable b/w two switches
b)-check the duplex settings for switch A
c)- check the duplex settings on Switch C
d)- there is physical layer issue
Answer……b check the duplex setting on the other end i.e Switch C.As we are currently on SwitchA.
This quest is changed from last dumps……
Dear All,
I want to take CCNA exam & i need dumps… Kindly guide Where could i get……????
hey waheed can u give me your mob no. for some guidence
the ans of Q5 is may be option A b/c it not use the word must or like shoud
Why answer on Q1 is B,C? It’s maybe A,B, because OSPF is locally significant & for multiple OSPF instance.
@Mehmood
To clear the exam do ACME/Mashti dumps and all the questions and sims from this site 9tut.com
thnks 9tut for your support
Can anyone explain why the answer to this OSPF question is ‘A’? Thanks
Refer to the exhibit. Assume that all of the router interfaces are operational and configured correctly. How will router R2 be affected by the configuration of R1 that is shown in the exhibit?
Exhibit: http://i56.tinypic.com/4jqfev.jpg
A. Router R2 will not form a neighbor relationship with R1.
B. Router R2 will obtain a full routing table, including a default route, from R1.
C. R2 will obtain OSPF updates from R1, but will not obtain a default route from R1.
D. R2 will not have a route for the directly connected serial network, but all other directly connected networks will be present, as well as the two Ethernet networks connected to R1.
@b,
I think the ans is C.
R2 will not be affected by default route on R1. except the fact that all unknown traffic will be send to it.
Aalhamdulillah,
Hi Everyone,
I M Just here to say thank u so much to 9tut and all who post there valuable comment on this website.
I took mah Exm on 4th Feb’11 and I hv pass d Exm with scoring 923.
All d best to u all who is gonna be appeare dr exm.
@9tut……….plz explain this question
http://img831.imageshack.us/i/29974088.jpg/
@punit: If the priorities are the same among these routers then the router with highest (active) IP will be chosen.
In the future, please post your questions at http://certprepare.com/forum our team will try the best to help you.
Question 6 Clarification.
E is the correct answer.
default-information originate statement notifies all routers in the area that default route is through R1.
R2 sends unknown routes to R1.
When R1 receives the packet, it then Forwards packet out its s0/0 interface.
Packet hits R2, R2′s route table says to go to R1. Hence a routing loop.
In a real world scenario, and following network on the image, the default route on R1 SHOULD have been through s0/1. Not s0/0
This question is designed to test knowledge of what default-information originate does.
Follow the packet and its easy.
Anyone knows?
Refer to the exhibit. Assume that all of the router interfaces are operational and configured correctly. How will router R2 be affected by the configuration of R1 that is shown in the exhibit?
Exhibit: http://i56.tinypic.com/4jqfev.jpg
A. Router R2 will not form a neighbor relationship with R1.
B. Router R2 will obtain a full routing table, including a default route, from R1.
C. R2 will obtain OSPF updates from R1, but will not obtain a default route from R1.
D. R2 will not have a route for the directly connected serial network, but all other directly connected networks will be present, as well as the two Ethernet networks connected to R1.
Please anyone ans to the above question ?? why A is right as per test inside….
Hi pratik, B is the right one, period.
This question has been discussed over and over, and outdated dumps mark A as right when it isn’t.
Router R2 will clearly obtain a full routing table, including a default route, from R1, the problem is there a loop will occur if when a packet reaches R1 and has to use the default route. For instance, if one packet is destined to the Internet (any Outside Global address aka public address), it will use the default route, which means R1 will send it back to R2 (because of the misconfigured default route, it should be “ip route 0.0.0.0 0.0.0.0 serial 0/1″), R2 will send it back to R1, R1 to R2 and so on until the TTL expires and the packet is finally discarded.
Regards.
Regarding Q2. Will configuring EIGRP effect whether or not two OSPF routers establish a neighbour relationship. I think not. I understand that EIGRP routes will appear in the routing table as opposed to OSPF routes because they have a lower AD. However, this should not affect the OSPF process of identifying and forming neighbor relationships. Any thoughts? I do agree that answer A is incorrect though. I’m just questioning the reason as to why they suggest A is wrong!
my email id : krishchand_niit@rediff.com
Hi everybody!
I’ve got a question: There is the lab 8.6.1 in CCNA Exploration course, we’ve got 4 routers (HQ, B1, B2, B3) connected through the Frame Relay cloud and EIGRP routing between them. HQ router have a default route to ISP. My network working good with only EIGRP inside, but author Asks to configure all of branch routers with a default route to HQ. Why? Isn’t it enough just EIGRP using?
thanx 9tut.
have cleared my ccna on 5/3/11 with 910 marks…
each n every question were from 9tut without the change in ip address also..
thanx alot…