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VLAN Questions

May 23rd, 2017 Go to comments

Note: If you are not sure about Virtual Local Area Network (VLAN), please read our Virtual Local Area Network VLAN Tutorial.

Question 1

Question 2

Question 3

Question 4

Question 5


On an Ethernet connection, a duplex mismatch is a condition where two connected devices operate in different duplex modes, that is, one operates in half duplex while the other one operates in full duplex. Duplex mismatch can easily cause collision domain issue as the device that operates in full duplex mode turns off CSMA/CD. So it is eager to send data immediately without checking if the link is free to use -> A is correct.

An “inband path” is the path which provides path for management traffic (like CDP, VTP, PAgP…) but we are not sure why congestion on the switch inband path can cause collision domain issues. Maybe congestion on inband path prevents the JAM signal (sent when a collision occurs on the link) to be sent correctly on the link.

Question 6


If we configure an access port as follows:

Switch(config)#interface fa0/1
Switch(config-if)#switchport mode access

Then this interface, by default, will belong to VLAN 1. Of course we can assign another VLAN to this port via the “switchport access vlan {vlan-number}” command.

Question 7


Traffic on the native VLAN is untagged -> Answer B is not correct.

Control plane traffic (like CDP, VTP, STP…) runs on VLAN 1 by default. They are not blocked on the native VLAN -> Answer C is not correct.

If the answer says “the native VLAN should be set so that no real traffic running on it for security reasons” then it is correct but the native VLAN is not typically disabled -> Answer D is not correct.

CDP runs on VLAN 1 by default and the native VLAN is also VLAN 1 by default so answer A is the best choice here.

Question 8


With the configuration above, when we type “do show vlan” we would not see VLAN 10 in the VLAN database because it has not been created yet. VLAN 10 is only created when we exits VLAN configuration mode (with “exit” command).

Question 9


IEEE 802.1Q is the networking standard that supports virtual LANs (VLANs) on an Ethernet network. When a frame enters the VLAN-aware portion of the network (a trunk link, for example), a VLAN ID tag is added to represent the VLAN membership of that frame. The picture below shows how VLAN tag is added and removed while going through the network.


Question 10


When using VLAN the number and size of collision domains remain the same -> A is not correct.

VLANs allow to group users by function, not by location or geography -> B is correct.

VLANs help minimize the incorrect configuration of VLANs so it enhances the security of the network -> C is correct.

VLAN increases the size of broadcast domains but does not decrease the number of collision domains -> D is not correct.

VLANs increase the number of broadcast domains while decreasing the size of the broadcast domains which increase the utilization of the links. It is also a big advantage of VLAN -> E is correct.

VLANs are useful but they are more complex and need more administration -> F is not correct.

Question 11

Question 12

Question 13


The default Ethernet VLAN is VLAN 1. It is a security best practice to configure all the ports on all switches to be associated with VLANs other than VLAN 1. All used ports are associated with VLANs distinct from VLAN 1.

Reference: http://www.ciscopress.com/articles/article.asp?p=2181837&seqNum=11

All control/management traffic (like CDP, VTP, DTP…) is sent on VLAN 1 and we should separate management and user data traffic. Another reason is by default, the native VLAN is also VLAN 1 which is untagged on trunk links so it may cause a security hole.

Question 14


The native VLAN must match on both sides of the trunk link for 802.1Q; otherwise the link will not work. If there is a native VLAN mismatch, Spanning Tree Protocol (STP) places the port in a port VLAN ID (PVID) inconsistent state and will not forward on the link -> STP can detect native VLAN mismatch.

Note: Cisco Discovery Protocol (CDP) version 2 passes native VLAN information between Cisco switches. If you have a native VLAN mismatch, you will see CDP error messages on the console output -> CDP can detect native VLAN mismatch.

Reference: http://www.ciscopress.com/articles/article.asp?p=29803&seqNum=3

Question 15

Question 16


Answer A is not correct because when a packet is received from an 802.1Q trunk, it always carries VLAN ID information in the VLAN tag portion so the switch does not need to look up its source MAC address table to determine the VLAN ID of that packet.

Question 17

Question 18

Comments (31) Comments
  1. Anonymous
    February 6th, 2017

    when you passed ccna???

  2. CCNA_Std
    February 12th, 2017

    Where can I find the questions ?

  3. Ttepi
    February 16th, 2017

    Q8. You cannot set a VLAN on a router so presumably the question should show a switch (or it is actually a switch with its hostname set to “Router” !).

    Also, the answer should be D. The VLAN 10 is added to the database (and will be displayed by #do show vlan) this happens before you exit the VLAN configuration

  4. asdf
    February 17th, 2017

    @CCNA_Std Become premium member allows you to access:

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  5. lexis
    February 18th, 2017

    @asdf, can you give me the link to become a premium member since i cannot see the log on page here, all i see is answers. Thank you

  6. star
    February 19th, 2017

    @Ttepi I second his comment.. I ave added Vlan on switch and before exiting the vlan mode i checked with do show Vlan and puff new vlan was added in database. So the correct option should be “D”

  7. Sisi
    February 21st, 2017

    You should change Q8!

  8. Neil
    February 22nd, 2017

    Question 8 I have tested (in packet tracer not on physical yet) and the answer should be D not C?

    @Ttepi you can add VLANs to routers we use 881s and 887s in some parts of our environment which support 8 VLANs (tied to dot1q sub-interfaces)

  9. Pindan
    February 25th, 2017

    Please fix q8

  10. Anonymous
    February 27th, 2017

    pls correct question 8

  11. banay
    March 2nd, 2017

    thanks guys for following up in Q8

  12. Kuchulu
    April 13th, 2017

    guys i checked Q8 on 3850 switch ,the correct answer is C.

  13. mikiko
    April 19th, 2017

    @9tut …
    got confused on Q8
    I assumed the answer should be D or both C and D are correct …

  14. logic
    April 22nd, 2017

    I agreee with question 7 here. But in the exam pdf the answer says B is the answer. There are lots of wrong answers.

  15. Mizlan
    April 23rd, 2017

    Any body has the latest 200-125 CCNA dumps …?

  16. Anymous777
    May 3rd, 2017

    Question 8 as listed is correct. Answer C. I have a cisco 3550 layer 3 switch and tried this out. Does not save vlan before you exit vlan mode.

  17. Anonymous
    May 4th, 2017

    Q3. This question (and the diagram) is not set up correctly. If each host is on a different VLAN, how can Host B Ping Hosts A & C if there is no appropriate default gateway? And how can Host B Ping Host C, when Host C’s IP is not in the same subnet as the sub interface (for Host C’s subnet) on the Router? B could be the correct answer if the question was written correctly.

  18. ishan
    May 26th, 2017

    can anybody tell me how to start ccna exam ?
    coz i dont under from where shuold i need to start for dumbs

    please, help me on {email not allowed}


  19. Pradeep_SL
    June 1st, 2017

    Hay guys,

    i am going to sit for exam sooner, can somebody tell me where are the questions , only answers with explanations available here. please help me somebody….


  20. soniaravindh@gmail.com
    June 6th, 2017

    send me dumps pls

  21. Boyce
    June 13th, 2017

    Sitted the exam last week, happily i can say “I passed it”. Used the dumps from itlibraries and 9tut. Study hard and practice the labs since the ips can be changed on the exam.

  22. LadyAggy
    June 13th, 2017

    @CCNA_Std; Pradeep-SL, Ishan

    Become premium member allows you to access:(Membership register at top right corner of this page) STudy hard to grab the concepts then review damps and practice labs.

    + All tutorials in the CCNA Knowledge section. See example.
    + Flash-based questions to check your knowledge with each topic of CCNA.
    + Flash-based questions on all topics of CCNA to help you fully prepare for the CCNA exam. See example.
    + Practice popular lab sims with our simulators.

  23. Jewel
    June 19th, 2017
  24. akash
    June 20th, 2017

    Where can we find questions ?

  25. dugdik
    June 20th, 2017

    am looking for a vce player that will support 200-125 vce file.
    send email dugdik17 @ g mail.co m

  26. Vin
    June 20th, 2017

    For question 5, the correct answer are A and D.
    Congestion on the switch inband path is responsible for Slow IntraVLAN (Broadcast Domain) issues.
    Reference: http://www.cisco.com/c/en/us/support/docs/lan-switching/virtual-lans-vlan-trunking-protocol-vlans-vtp/23637-slow-int-vlan-connect.html

  27. JD
    June 21st, 2017

    For Q7 I would choose “typically disabled” answer explaining that:

    – Traffic on the native vlan is not tagged by default
    – CDP travels on vlan 1 no matter if vlan 1 is native or not
    – Control plane traffic has nothing to do with vlans (or has it?)

    I think that what Cisco meant by “typically disabled” is that You should set native vlan to the one “not used” and “not vlan 1”.

  28. JD
    June 21st, 2017

    To all people confused with Q8:

    Vlan is typically added to the database when exiting the vlan configuration. This is the default behavior on most devices. I don’t know what fancy switches did You guys have that the vlan was added instantly, but the “normal” operation is described with answer C. If You just tested it on Packet Tracer then this is not trustworthy.


  29. osman
    July 10th, 2017

    these dumps https://drive.google.com/open?id=0B5mAFqgydmCzc3BmR214LWFuTDg for CCNAX. i need CCNA ROUTING and SWITCHING 210-260

  30. Haris
    July 18th, 2017

    Passed 8xx,
    A few new questions but it’s still very easy to pass. Only got 8xx is due to my laziness ,used the it-libraries dumps.

  31. Mack
    July 19th, 2017

    Where are the questions ? Cannot find the question list !