CCNA – OSI Model Questions
Here you will find answers to OSI Questions
Note: If you are not sure about OSI Model, please read my OSI tutorial.
Question 1
Which of the following correctly describe steps in the OSI data encapsulation process? (Choose two)
A. The transport layer divides a data stream into segments and may add reliability and flow control information.
B. The data link layer adds physical source and destination addresses and an FCS to the segment.
C. Packets are created when the network layer encapsulates a frame with source and destination host addresses and protocol-related control information.
D. Packets are created when the network layer adds Layer 3 addresses and control information to a segment.
E. The presentation layer translates bits into voltages for transmission across the physical link.
Answer: A D
Explanation
The transport layer segments data into smaller pieces for transport. Each segment is assigned a sequence number, so that the receiving device can reassemble the data on arrival.
The transport layer also use flow control to maximize the transfer rate while minimizing the requirements to retransmit. For example, in TCP, basic flow control is implemented by acknowledgment by the receiver of the receipt of data; the sender waits for this acknowledgment before sending the next part.
-> A is correct.
The data link layer adds physical source and destination addresses and an Frame Check Sequence (FCS) to the packet (on Layer 3), not segment (on Layer 4) -> B is not correct.
Packets are created when network layer encapsulates a segment (not frame) with source and destination host addresses and protocol-related control information. Notice that the network layer encapsulates messages received from higher layers by placing them into datagrams (also called packets) with a network layer header -> C is not correct.
The Network layer (Layer 3) has two key responsibilities. First, this layer controls the logical addressing of devices. Second, the network layer determines the best path to a particular destination network, and routes the data appropriately.
-> D is correct.
The Physical layer (not presentation layer) translates bits into voltages for transmission across the physical link -> E is not correct.
Question 2
Which layer of the OSI reference model uses the hardware address of a device to ensure message delivery to the proper host on a LAN?
A. physical
B. data link
C. network
D. transport
Answer: B
Explanation
The hardware address of a device or the Media Access Control (MAC) address is added in the Data Link layer. An Ethernet MAC address is a 48-bit binary value expressed as 12 hexadecimal digits (for example: 00:15:A4:CB:03:CA).
Question 3
Which layer of the OSI reference model uses flow control, sequencing, and acknowledgments to ensure that reliable networking occurs?
A. data link
B. network
C. transport
D. presentation
E. physical
Answer: C
Question 4
Which layer in the OSI reference model is responsible for determining the availability of the receiving program and checking to see if enough resources exist for that communication?
A. transport
B. network
C. presentation
D. session
E. application
Answer: E
Question 5
Data transfer is slow between the source and destination. The quality of service requested by the transport layer in the OSI reference model is not being maintained. To fix this issue, at which layer should the troubleshooting process begin?
A. presentation
B. session
C. transport
D. network
E. physical
Answer: D
Question 6
Which protocols are found in the network layer of the OSI reference model and are responsible for path determination and traffic switching?
A. LAN
B. routing
C. WAN
D. network
Answer: B
Question 7
Refer to the exhibit. An administrator pings the default gateway at 10.10.10.1 and sees the output as shown. At which OSI layer is the problem?
| C:\> ping 10.10.10.1 Pinging 10.10.10.1 with 32 bytes of data: Request timed out. Request timed out. Request timed out. Request timed out. Ping statistics for 10.10.10.1: Packets: sent – 4, Received = 0, Lost – 4 (100% loss) |
A. data link layer
B. application layer
C. access layer
D. session layer
E. network layer
Answer: E
Explanation
The Network layer is responsible for network addressing and routing through the internetwork. So a ping fails, you may have an issue with the Network layer (although lower layers like Data Link & Physical may cause the problem).
Question 8
Which of the following are types of flow control? (Choose three)
A. buffering
B. cut-through
C. windowing
D. congestion avoidance
E. load balancing
Answer: A C D
Explanation
Three types of flow control are buffering, windowing & congestion avoidance:
+ Buffering: If a device receives packets too quickly for it to handle then it can store them in a memory section called a buffer and proceed them later.
+ Windowing: a window is the quantity of data segments that the transmitting device is allowed to send without receiving an acknowledgment for them. For example:
With the window size of 1, the sending device sends 1 segment and the receiving device must reply with 1 ACK before the sending device can send the next segment. This “waiting” takes some time.
By increasing the window size to 3, the sending device will send up to 3 segments before waiting an ACK -> helps reduce the waiting time.
+ Congestion avoidance: lower-priority traffic can be discarded when the network is overloaded -> minimize delays.
Question 9
A network administrator is verifying the configuration of a newly installed host by establishing an FTP connection to a remote server. What is the highest layer of the protocol stack that the network administrator is using for this operation?
A. application
B. presentation
C. session
D. transport
E. internet
F. data link
Answer: A
Explanation
FTP belongs to Application layer and it is also the highest layer of the OSI model.
Question 10
A receiving host computes the checksum on a frame and determines that the frame is damaged. The frame is then discarded. At which OSI layer did this happen?
A. session
B. network
C. physical
D. data link
E. transport
Answer: D
Explanation
When using the term “frame” we can easily recognize it belongs to the Data Link layer. In this layer, an Frame Check Sequence (FCS) field is added to the frame to verify that the frame data is received correctly.
Question 11
As a frame leaves a Layer 3 device, the Layer 2 encapsulation information is changed from what it was when it entered the device. For what two reasons can this happen? (Choose two)
A. The data is moving from 10BASE-TX to 100BASE-TX.
B. The WAN encapsulation type has changed.
C. The data format has changed from analog to digital.
D. The source and destination hosts are in the same subnet.
E. The source and destination MAC addresses have changed.
Answer: B E
Question 12
Acknowledgement, Sequencing, and Flow control are characteristics of which OSI layer?
A. Layer 2
B. Layer 3
C. Layer 4
D. Layer 5
E. Layer 6
F. Layer 7
Answer: C
Taking the CCNA in a week. I see other’s here requesting updated dumps. Are the dumps on the site not upgraded?
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Thank to Jehovah !
Yesterday was my CCNA exam…and I passed with 986/1000 score. Lab’s: VTP(Four questions from this page, really the same questions); EIGRP( The same question and the passive interface in the ISP link that we don’t have to take) and the ACL 2 (this lab you should learn the subject “ACL” because the questions are variated a lot but with the same essence from lab 9tut). My personal TIP: 1º you should choose just one dump(in my case it was the Jericho 632) and repeat its untill you reaching between 900 and 1000. 2º step: You should viewing all questions from the 9tut’s link and keep doing the dump. Everyday step 1º plus 2º step. And the 3º step is select the betther dumps and select 50 questions with 30 minuts to response them. You should alternate the dumps. With 4 months you will be completely prepared. Understand the questions, you shouldn´t memorize them. Read the tutorials and the some literature. Good Luck and good preparation! Question 1 and 7 it were in my exam!
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at which layer logical path created between two host systems? for dis I m thinking answer is transport layer.. but in dumps it was network layer, can any one help me ab. dis
Question 7 is an interesting one. It asks, what OSI layer is the problem. Well, it could be layers 1-3. Layer one (cabling), layers two (bad arp), etc…I am sure its all in the wording, but it is one of *those* questions that cisco loves to throw in there just to screw you over.
Hi 9tut,
I see that there are a few requesting updated dumps. Please could you send some to regigee@hotmail.co.uk My exam is next week…
today i got Q4 from this slide..
here is cisco’s listing of show commands
http://www.cisco.com/en/US/docs/ios/fundamentals/command/reference/cf_s1.html#wp1175770
Hi all, I am taking CCNA 640-802 exam first time on 30/05/2012. Could anyone please send me latest dumps which are valid for UK? My e-mail address is puneet_gill84@yahoo.co.uk. Many thanks.
I’m planning to take CCNA 640-802 end of this month…Can u please send me the latest dumps to Romeo_bahrain@hotmail.com . Thank you.
hi jehova
just wondering how did you manage to open those dumps, i have trial version, can only view 5 questions
hi jehova
just wondering how did you manage to open those dumps, i have trial version, can only view 5 questions, my email rohit.kum@bigpond.com
hi!
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Hi for Question 1,
I tot shld be C because :
Packets are created because it encapsulate the frames not the segments.
Please explain. Tks
The order should be like the below:
Frames —> Packets —–> Segments
I PASSED CCNA EXAM TODAY THANKS TO ALL MIGHTY ALLAH
960/1000
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Hi guys can i know ho you got the answer of question 5. why it is network layer? thx
Hi all, I am having my CCNA (640-802) exams this week. Can anyone please send me latest dumps: allient@post.sk
Thank you ;)
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http://www.examcollection.com/cisco/Cisco.ActualTests.640-802.v2012-06-08.by.Anonymous.641q.vce.file.html
http://www.examcollection.com/cisco/Cisco.Acme.640-802.v2012-05-31.by.suresh.521.vce.file.html
For Question 7.
The Default Gateway is the same network as the host is.
So there does not exist any job for network layer or any higher layers to reach there.
A ping does not reach coz of Data link layer problem.
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Hello everyone
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in q 1 please correct this :The Physical layer (presentation layer) translates bits into voltages for transmission across the physical link -> E is not correct.
The Physical layer ( NOT presentation layer) !!
thanks
@zohreh mesripour: Yes, thanks for your detection. I updated it!
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Thank you ;)
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@9tut, @Xallax , i want to say thank you so much for this site.!!!. I pass my CCNA today 881/1000 and I know if i did not have this site I would have failed.(EIGRP, VTP,Acess-List 2 and question 1 was in exam). For the lastest dumps go to http://www.examcollection.com, read the comments that people leave to learn the best dumps to use, I use Jericho , Collisio and off course 9TUT!!!.
@Marvel
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Heloo people I pass the exam with 960 on 27 this moht the questions are from 9tut and I study from Cisco.ActualTest.640-802.v2012-02-26.by.Jericho.632q .vce the simulations are acl2,eigrp,vtp the same from 9tut with difrent ip addresss. Thahks to 9tut
I am doing ccna in the 3 semester so thanx
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16. Which area of the OSI model and the TCP/IP stack is most diverse?
network layer
transport layer
application layer
data-link layer
my answer is application layer
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Data transfer is slow between the source and destination. The quality of service requested by the transport layer in the OSI reference model is not being maintained. To fix this issue, at which layer should the troubleshooting process begin?
A. presentation
B. session
C. transport
D. network
E. physical
Answer: D
CAn anyone please explain this answer?
Anita, QoS is a configurable option in the router. “the quality of serice requested by the transport layer”….layer 3, the network layer.
hiiiiiii……i will pass ccna today al hamdo llah. thanks for god ..thanks for my family.. thanks 9tut. i got 920.
Hi for Question 1,
I tot shld be C because :
Packets are created because it encapsulate the frames not the segments.
Please explain. Tks
The order should be like the below:
Frames —> Packets —–> Segments
Passed CCNA exam.. thank u 9tut & exam collection!
Got 947/1000..
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@ Dobs
I wonder the same thing, because the question states,
“Data transfer is slow between the source and destination. The quality of service requested by the transport layer in the OSI reference model is not being maintained. To fix this issue, at which layer should the troubleshooting process begin?”
So why wouldn’t we look at that layer? Or if we’re going to break down the troubleshooting process then why wouldn’t we look at the physical layer first?
I know that packet drops are layer 3. But MPLS is layer 2 and 3. And a lot of the time when we were looking at packet loss that could be from any number of different problems.