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VLAN Questions

February 6th, 2017 Go to comments

Question 1

Question 2

Question 3

Question 4

Question 5

Explanation

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

Explanation

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

Explanation

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

Explanation

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

Explanation

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.

VLAN_tag_added_removed.jpg

Question 10

Explanation

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

Comments (11) 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:

    + 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.

  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