Home > ICND1 – OSI Model

ICND1 – OSI Model

December 22nd, 2016 in ICND1 100-105 Go to comments

Note: If you are not sure about OSI Model, please read my OSI Model Tutorial.

Question 1

Question 2


CDP runs at Layer 2 (Data Link) of the OSI model -> E is correct.

Question 3


SMTP stands for Simple Mail Transfer Protocol. It’s a set of communication guidelines that allow software to transmit email over the Internet while File Transfer Protocol (FTP) is a standard network protocol used to transfer files from one host to another host over TCP-based network.

Note: Simple Network Management Protocol (SNMP) uses UDP as the transport protocol for passing data between managers and agents. SNMP uses UDP to help reduce the impact on your network’s performance. Although SNMP can be configured to run on TCP but we should only do it in special situations. SNMP uses the UDP port 161 for sending and receiving requests, and port 162 for receiving traps from managed devices.

DNS work on both the TCP and UDP protocols. DNS uses TCP for zone exchanges between servers and UDP when a client is trying to
resolve a hostname to an IP address. Therefore in most cases we say “DNS uses UDP”.

Question 4


The primary function of an access-layer is to provide network access to the end user.

The hardware and software attributes of the access layer that support high availability include security services for additional security against unauthorized access to the network through the use of tools such as 802.1x, port security, DHCP snooping, Dynamic ARP Inspection, and IP Source Guard.

Question 5


The picture below compares the two TCP/IP and OSI models:


Question 6


Transmission Control Protocol (TCP) has all the features mentioned above and TCP resides in Transport Layer (Layer 4) of the OSI model.

Flow control: A methodology used to ensure that receiving units are not overwhelmed with data from sending devices when buffers at a receiving unit are full, a message is transmitted to the sending unit to temporarily halt trans-missions until all the data in the receiving buffer has been processed and the buffer is again ready for action.

Sequencing: is used to number segments before sending so they can be put back together again in the correct order at the receiving side.

Acknowledgment: When the receiver gets the data, it sends a response telling the sender that the data have been safely arrived.

Question 7


In CCNA, the popular devices operate in Layer 1 are hub and repeater.

Comments (99) Comments
  1. Michael
    October 20th, 2013


    are you sure the answer to question 4 is A, B? I believe it should be B,D.

  2. Emran
    October 21st, 2013

    Even I think the answer to question 4 is B,D

  3. Mike
    October 23rd, 2013

    Please review question 7, this could be either B and C there should be a ‘choose two’

  4. jp.ccna
    October 24th, 2013

    Mike, a NIC operates at two layers and the question states “which device operates ONLY at Layer 1 of the OSI model.” You have to watch for those keywords. 🙂

  5. gufre
    October 25th, 2013
  6. DJ Anyweh
    October 30th, 2013

    I have a exam this evening on chapter 3 these questions really help.

  7. Kristof
    November 21st, 2013

    Answers to question 4 must be wrong. Why would an access layer switches support Layer3 (IP addresses) if the Ethernet operates at Layer2? I believe it’s B and D.

  8. needslipo
    November 26th, 2013

    I think Question 4 should be amended to “Choose 3”.

  9. Purple
    November 26th, 2013

    I was investigating and the answer of the question 4 is Security Port, VLAN and PoE http://www.ciscopath.com/content/61/

  10. Kristof
    November 28th, 2013

    RE question 4: i saw it somewhere else and the correct answers are B and D.
    Please change it.

  11. srinath
    November 29th, 2013

    It is enough to study the question from 200-120 or i want this part of questions ah????

  12. Michael Sanhueza
    December 3rd, 2013


    Access Layer In-Depth
    The building access layer aggregates end users and provides uplinks to the distribution layer. With the
    proper use of Cisco switches, the access layer may contain the following benefits:
    • High availability: The access layer is supported by many hardware and software features.
    System-level redundancy using redundant supervisor engines and redundant power supplies for
    critical user groups is an available option within the Cisco switch portfolio. Moreover, additional
    software features of Cisco switches offer access to default gateway redundancy using dual
    connections from access switches to redundant distribution layer switches that use first-hop
    redundancy protocols (FHRP) such as the hot standby routing protocol (HSRP). Of note, FHRP and
    HSRP features are supported only on Layer 3 switches; Layer 2 switches do not participate in
    HSRP and FHRP and forwarding respective frames.
    • Convergence: Cisco switches deployed in an access layer optionally support inline Power over
    Ethernet (PoE) for IP telephony and wireless access points, enabling customers to converge voice
    onto their data network and providing roaming WLAN access for users.
    • Security: Cisco switches used in an access layer optionally provide services for additional
    security against unauthorized access to the network through the use of tools such as port
    security, DHCP snooping, Dynamic Address Resolution Protocol (ARP) Inspection, and IP Source
    Guard. These features are discussed in later chapters of this book.

    En síntesis, debería ser PoE y también seguridad de puertos según lo descrito por el libro oficial de CCNP.

  13. Riccardo
    January 19th, 2014

    So in the Question 4 correct B and D? (Port Security and PoE) right?

  14. Anonymous
    January 20th, 2014


    B and D are port security and VLANs. Anyway, I totally agree to all that layer 3 support should not be the answer, but VLAN is also being used in distribution and core layer. For me, if its asking for 3, then definitley its B, D and E. But since its just asking to choose 2, I’ll put my money on B and E (port security and power over ethernet).

    @9tut – hope you can review this and provide more detailed explanation as to why its A and B.

  15. CCENT Someday
    January 31st, 2014


    I plan on taking exam next week. What other sims/labs did you get besides the OSPF 6 router?

    Thanks in Advance!

  16. Donathien Lagloire
    January 31st, 2014

    J’ai l’intention de prendre l’examen la semaine prochaine. Quels sont les autres sims?

  17. one day after reading
    February 4th, 2014

    Question 4 answer is B(port security) and E(POE)

  18. Culebro
    February 8th, 2014


    Why is the answer in question 4 A B and not B E?


  19. Marco Mwaimu
    February 18th, 2014

    My self for question 4,i could recommend B and D as the correct answers the network access layer is the combination of physical and datalink layer so how could it be A and B? A deals with ip address

  20. Marco Mwaimu
    February 18th, 2014

    Is this what you meant? Access layer: The main purpose of the access layer is to provide direct connection to devices on the network and controlling which devices are allowed to communicate over it. The access layer interfaces with end devices, such as PCs, printers, and IP phones, to provide access to the rest of the network. The access layer can include routers, switches, bridges, hubs, and wireless access points (AP).

    Switch features in the Access layer:

    Port security
    Fast Ethernet/Gigabit Ethernet
    Power over Ethernet (PoE)
    Link aggregation
    Quality of Service (QoS)

  21. Steve
    February 28th, 2014

    I searched the CISCO website, and found this description:

    At the same time as providing simple uncomplicated network access for users, the access layer provides the first line of security defense for the network, provide service differentiation based upon management policies and, providing power to support the deployment of specialized devices.

    The roles can be broken broadly into the following areas:

    •Access layer security
    •Access layer QoS
    •Access layer Power-over-Ethernet (PoE)

    Since CISCO’s definition is Security and PoE, I’d go with those two. B and E


  22. Farai
    March 6th, 2014

    Thnx 9tut u made it all possible, passed 947

  23. DC
    March 7th, 2014

    Question 4 is B, E. D is vague and depending on use, can be applied to distribution or access layer.

  24. Dalma
    March 9th, 2014

    Q4 is tricky. access layer main focus is connecting end devices to the rest of the network.

    I would say main goal is connection and security.

    connection is PoE and VLANs

    security is port security.

    If i had to choose, i would choose Port Sec and VLANs.

  25. JamesK
    April 4th, 2014

    Why is question 4 even here? It has to do with the Cisco hierarchical model , not the OSI model.

  26. Panfila
    April 9th, 2014

    Arriba Cruz Verde

  27. Ups
    April 9th, 2014

    Welcome to Potrero City

  28. Embo
    April 14th, 2014

    Question 4 should be B D

  29. Mustafa
    April 14th, 2014

    At access layer switches appears, so secuirty and Vlans comes in, Also we can not create vlans in routers, please correct me if I am wrong.

  30. fez
    April 24th, 2014

    Passed my 100-101 exam today and question 1, 3 and 6 was there.. all the best.

  31. wall cookie
    May 12th, 2014


    Answer is B D
    L3 support is designated at the distribution layer, not the access layer. Can you imagine a building with routing in every single switch closet? Access laeys is about 3 services: high availability, POE, and port security (security services).

    I hope this helps.

  32. Saavy Boy
    May 15th, 2014

    Question 4 should be B and D @9Tut why you not saying nothing?

  33. Manohar Tn
    May 16th, 2014

    Got 986/1000 Marks, {5/16/2014} 50 Questions, Ospf Sim, Security simlet, and Router and switch Simlet Was also there…..All questions From 9tut. and Examcollections…..Now Heading For Icnd2 And Blogging…..

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  34. 9tut
    May 17th, 2014

    @all: Q.4 the answers should be B D. Thanks for your detection. We updated it!

  35. Ibtu
    July 2nd, 2014

    @all:Q- 4 is now corrected it was a mistake i believe so.

    Shout out to 9tut… you are awesome

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    July 22nd, 2014

    This is awesome I’ve been looking for a site like this for days, now I got it watch the space CISCO CERTIFICATES. Thanks to all of you guys for your participation and also thank you 9tut

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    September 11th, 2014

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    Thanks for help

  40. Anonymous
    September 18th, 2014

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  41. I love this site
    September 29th, 2014

    Guys Q No.4 answer is A & B…..

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  43. GeoCes
    October 16th, 2014

    http://www.ciscopath.com/content/61/ does list Q4 having Ans: B, D, & E. The other 2 are listed as Layer 2 Distribution layer. Just saying.

    Switch features in the Access layer: I.Port security
    III.Fast Ethernet/Gigabit Ethernet
    IV.Power over Ethernet (PoE)
    V.Link aggregation
    VI.Quality of Service (QoS)

  44. Serg
    October 27th, 2014

    http://www.ciscopath.com/content/61/ tells about layer of The Hierarchical Network Model, but Question 4 ask about the Access layer of TCP/IP model. Please, attend!

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    November 22nd, 2014

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  47. samora
    December 8th, 2014

    Q4 should be C & E

  48. Deriq
    December 17th, 2014

    I can’t imagine the answer to question 4 has been debates for over a year now. 9tut help out here. What is the final answer?

  49. 9tut
    December 18th, 2014

    @Deriq: Q.4 the answers are B & D. Although PoE is not wrong but B & D are better choices.

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    January 14th, 2015

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  53. Techgique
    January 27th, 2015

    For Q4, it is referring to the hierarchical design model, which is NOT OSI and suggests the three layer topology of core, distribution, and access. I think that they simply grabbed a question that someone else provided and did their best. If we are referring to Layer 2, then sure, VLANS and Port Security. However, in the Access layer design it clearly states that implementing VLANs, Port Security, and PoE are all part of the puzzle. This is difficult because the distribution layer also utilizes the handling of VLAN traffic. If only left to two possible answers, I would still say VLANs and Port Security though. Has anyone seen this question on THE ACTUAL TEST, not a dump or practice test?

    @9tut, can you confirm what the question in Q4 is referring to, and if the three layer design, why PoE is less of a correct answer based on Cisco’s articles on their website? Thank you!

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  65. Bob
    May 26th, 2015

    Still confused why q4 is B/ D when it states:

    Figure 1-5 Access Layer
    The access layer serves a number of functions, including
    •Layer 2 switching
    •High availability
    •Port security
    •QoS classification and marking and trust boundaries
    •Address Resolution Protocol (ARP) inspection
    •Virtual access control lists (VACLs)
    •Spanning tree
    •Power over Ethernet (PoE) and auxiliary VLANs for VoIP


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  69. Boy-Cisco
    June 19th, 2015

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  72. 9tut
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  73. tasha
    July 18th, 2015

    why cant we see the questions

  74. 9tut
    July 18th, 2015

    @tasha: We had to remove the questions because of copyrighted issues. We can only keep the explanation. We are very sorry for the inconvenience we caused. You can download all the questions at: http://www.4shared.com/office/WXdZDq7Xce/ICND1_2_Questions_July_2015.html

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  76. khurisu
    July 31st, 2015

    How to make the questions appear? I see question number but no actual question.

  77. 9tut
    July 31st, 2015

    @khurisu: We had to remove the questions because of copyrighted issues. We can only keep the explanation. We are very sorry for the inconvenience we caused. You can download all the questions at: http://www.4shared.com/office/WXdZDq7Xce/ICND1_2_Questions_July_2015.html

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    February 3rd, 2016

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