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VLAN Trunking 3

November 24th, 2018 in SWITCH 300-115 Go to comments

Question 1


The “vlan dot1q tag native” command maintains the tagging on the native VLAN and drop untagged traffic -> B is correct.

Reference: http://www.cisco.com/web/techdoc/dc/reference/cli/nxos/commands/l2/vlan_dot1Q_tag_native.html

Question 2


Interface Gi5/1 is using 802.1q trunking which is an open standard protocol -> A is not correct while D is correct.

From the output we see the native VLAN of Gi5/1 interface is VLAN 1 so all untagged traffic should belong to VLAN 1 (using the default setting) -> B is not correct.

In this question we can only guess that “The device is configured with the default MST region” (also referred to as IST or Internal Spanning Tree). The “show interface trunk” command does not display any information about MST.

Answer E may be correct as interface Gi6/2 is in forwarding state for VLAN 36 so it may be the root port for VLAN 36.

So in conclusion there are two possibly correct answers but we have to choose one. We believe answer C is better than E so we choose it the best answer left.

Note: Answer F is not correct because VLAN 600 is the native VLAN on Gi6/2 does not mean untagged traffic is tagged with this VLAN. It only means “all untagged traffic belongs to VLAN 600”.

Question 3

Question 4


From the summary in the book of “Cisco Press’ SWITCH Foundation Learning Guide”:


We see an access port is formed when:

+ Both ports are in “Dynamic Auto”
+ One port in “Dynamic Auto” and the other port in “Access”
+ One port in “Dynamic Desirable” and the other port in “Access”
+ Both ports are in “Access”

Note: If you want to know what the result if one of the port is in “Nonegotiate” mode then this is the table you want:


Question 5

Question 6


Although Gi0/10 has been configured as trunk it it did not appear in the “show interfaces trunk” command so the most suitable reason is it is down (not administratively down but down for another reason).

Question 7


By entering the command “switch port trunk allowed vlan 2,3,4”, vlan 5 would be removed from allowed VLAN list. Both Workstations A & B are on VLAN 5 so they cannot communicate any more.

Note: If we want to add vlan 2 to 4 to the allowed VLAN list then we should use the “switchport trunk allowed vlan add 2,3,4”.

Question 8

Question 9

Question 10

  1. MaryCisco
    September 19th, 2017

    Why the answer on question 6 is D? I saw the configuration on interface FastEthernet0/2 (sw02) and on interface FastEthernet0/1 (sw01) that allows vlan 5…………….

  2. Nic
    September 21st, 2017

    Read Question carefully.
    it says “the effect of entering the switchport trunk allowed vlan 2,3,4 command”.

  3. WrittingSoon
    September 21st, 2017

    where are the questions?

  4. montu
    October 3rd, 2017

    where can i get latest dumps for CCNP switch
    have an exam in 15 days

  5. Rizwan
    October 10th, 2017

    in q6 if the gi0/10 port is trunk, why it is showing the the show vlan breif command? because in my practical preparation, the links marked as trunk are not shown in the show vlan commands, assist please

  6. switchy
    October 15th, 2017

    Q5 Why is the answer not “A”?

  7. switchy
    October 15th, 2017

    Q6 And Rizwan is right. The interface is showing on show vlan, wouldn’t that mean that the interface is active or up?

  8. swsw
    October 17th, 2017

    The Q4 is correct? The dynamic auto in both sides not will form a trunk port?

  9. superB
    October 19th, 2017

    @swsw – Q4. Dynamic Auto on both sides will form an ACCESS.

    Table 3-8 DTP Negotiated Interface Modes:

    TABLE,Dynamic Auto,Dynamic Desirable,Trunk,Access
    Dynamic Auto,Access,Trunk,Trunk,Access
    Dynamic Desirable,Trunk,Trunk,Trunk,Access
    Trunk,Trunk,Trunk,Trunk,Limited connectivity
    Access,Access,Access,Limited connectivity,Access

  10. switchy
    October 26th, 2017

    Q2 How do I know why the device is configured with the default MST region?

  11. switchy
    October 26th, 2017

    Q4 Should be A and D?

  12. switchy
    October 26th, 2017

    Q5 should be A, D right? O_o?
    B is wrong as it only allows VLAN 915 but not actually tag it with VLAN 915.

  13. switchy
    October 26th, 2017

    Q6 The interface is showing on Vlan 1 on “show vlan”.
    Why the heck is the answer “The interface is down”

  14. superB
    November 1st, 2017

    Q4 – correct answers are B,C. See Table 3-8 for details here, http://www.ciscopress.com/articles/article.asp?p=2181837&seqNum=8

    Q5 – correct answers are B,D. You need to review what “tag traffic” means. :)
    Option A has “switchport mode access”, therefore traffic is not tagged. A PC connected to that switchport will be in vlan 915, but it will never ‘know’ that. So, option A is wrong.
    Option B is correct because – switchport is in trunk mode and all traffic that is NOT NATIVE gets tagged.
    There is “switchport trunk allowed vlan 915” – so traffic on vlan 915 is allowed.
    There is NO “switchport trunk NATIVE vlan 915”. So, traffic on vlan 915 is allowed and tagged.

    In general – If there if you don’t see “switchport trunk NATIVE vlan XYZ” command, then vlan 1 is considered native vlan and traffic on that vlan 1 is NOT tagged.

    Q6 – “show interfaces trunk” has no output, so the interface is down, nothing is connected to that interface. In this case the port is listed under default vlan 1. If the interface is connected to another switch, Gi0/10 will be listed under “show interfaces trunk”, even if the other side is misconfigured.

  15. Stovepipe
    November 10th, 2017

    Q6- Interesting… I could be wrong, but I’m pretty sure the choices that I had were the following 1) The interface is shutdown, 2) the “switchport” command is missing from the configuration, 3) The interface is plugged into an access port on another switch, or 4) the “no shutdown” command is missing from the configuration. So, I am assuming that the best answer in this scenario would be that the interface is “shutdown”?

  16. Mago
    November 13th, 2017

    Is Q2 right?

  17. Anonymous
    November 15th, 2017

    Q6, if A “the interface is down” is correct, shouldn’t D “the interface needs no shutdown configured” be correct as well?

  18. Anonymous
    November 16th, 2017

    For Q6 with the outputs we have you know the interface is down, but you don’t know if its down due to being shut on the switch or on the the other side or even if the cable is broken/disconnect.
    So A “the interface is down” is the best choice in my opinion

  19. Addie
    December 4th, 2017

    What is the ans for question 3????

  20. RA
    December 6th, 2017

    Question 2, how do we know that The device is configured with the default MST region?

  21. ciptech
    December 6th, 2017

    @RA I think because of the last line, you see only all the configured VLANs running under the STP.
    Port —– Vlans in spanning tree forwarding state and not pruned:

  22. Jane
    January 2nd, 2018

    Q6 :: A and D are correct. However, the configuration for int Gi0/10 explicitly shows “no shutdown” is missing. Hence that would make D a better answer, imo

  23. Anonymous
    January 11th, 2018

    Q7 the answer is A. Both reside in Vlan 5 and both switches state ‘switchport trunk allowed vlan 5’

  24. Drj
    January 12th, 2018

    Q7 – i did this lab on pkt tracer… this question is not corret..
    I can ping normaly the pcs, so the correct answer is A

  25. MM
    January 18th, 2018

    about Question 2? Please, how I know that The device is configured with the default MST region? How can I check this information

  26. Doc
    January 30th, 2018

    Same question. Seriously Q2 is correct for MST region? I am not sure but it’s last one answer which could be possible. I not sure if it’s correct or not. Not know how to check but all of the others are invalid. I scheduled my exam for tomorrow so I would receive correct explanation if possible till 11:00 GMT ;-). Or I will believe you :-D

  27. Doc
    January 30th, 2018

    @MM I just received information from colleague which passed test 2w ago. There should be one more answer which is correct. So it is not MST region but something else. :-)

  28. Archangel
    March 1st, 2018

    Question 3 ans may be “D” because switchport encapsulation command missing, hence trunk will not create.

  29. Tinman
    March 11th, 2018

    Q4 – I believe C is wrong. The default switchport mode for newer Cisco switch Ethernet interfaces is dynamic auto. Note that if two Cisco switches are left to the common default setting of auto, a trunk will never form.

  30. Archangel
    March 12th, 2018

    i have problem with frame size of 802.1q, according Wikipedia “The minimum frame size is left unchanged at 64 bytes.[2] The maximum frame size is extended from 1,518 bytes to 1,522 bytes.”

    But according to CISCO Minimum size is “The 802.1Q tag is 4 bytes. Therefore, the resulting Ethernet frame can be as large as 1522 bytes. The minimum size of the Ethernet frame with 802.1Q tagging is 68 bytes. ”

    Please help

  31. Confuse guy
    March 15th, 2018


    Min frame size = 64
    Min frame size when encapsulated by 802.19 = 64 + 4 = 68

  32. Archangel
    March 19th, 2018

    hey, Confuse guy, thanks buddy

  33. lalaversa
    May 3rd, 2018

    Q3, the correct answer should be that the interface trunk is no active, but this answer in not present in the question. Then C should be the correct answer. If a side is a trunk port and the other side is an access port the connection remains down…

  34. lalaversa
    May 3rd, 2018

    Q3, on other certification sites the answer A shows “link is down” and not “link is shutdown”; in this case the correct answer is “A”…. (Q&A wrote bad ???)

  35. lalaversa
    May 3rd, 2018

    the Q9 does not make sense and the correct one seems to be the next one Q10 (D answer).

  36. lalaversa
    May 12th, 2018

    the question is “TO FORM AN ACCESS PORT”. DTP negotiate to form a Trunk port, then the question can be read also how “TO NO FORM A TRUNK PORT” !!!
    Then, correct answers are B and C
    B = Dynamic Desiderable and Access don’t form a trunk port, then it can form an access port.
    C = Dynamic auto and Dynamic auto don’t form a trunk port, then it can form an access port.

  37. madestro
    May 21st, 2018


    Q9 and Q10 are different questions. Q10 refers to using VLAN 99 as native. Q9 is talking about using that VLAN somewhere else when is already tagged on a trunk port, this would be assign it as an access VLAN on a different port.

  38. fasfasf64875
    May 30th, 2018

    100% valid CCNP Exam Questions


  39. Raito
    June 7th, 2018

    Q5 is a very strange question and I think there is only 1 correct answer here.

    Answer D, “encapsulation dot1q 915”, is a command I have never seen before and which does not work on my Cisco switches at home. I know some commands of the form “SWITCHPORT TRUNK ENCAPSULATION xxxx”, for example “switchport trunk encapsulation dot1q”, but you cannot add a VLAN afterwards to make it tagged. o.O

    To me the second best choice would be C, since voice vlan traffic is usually tagged. But it seems strange that the voice and the data VLAN are the same on this port.

  40. Kattmash
    June 19th, 2018

    For Q3, the correct answer is D, because

    when running show vlan brief , it was indicating that Vlan 1 default is still associated with interface Fx/x , this mean the switchport mode trunk was missing

  41. Kattmash
    June 19th, 2018

    Correcting my answer A or B, not D

  42. patzen
    July 11th, 2018

    Q2 I’m trying to look for some sensible information to support answer C

  43. patzen
    July 11th, 2018

    Q4 is correct, in case if someone is in doubts see the below link, table 3.8


  44. patzen
    July 11th, 2018

    @Jane and others the only correct answer for Q6 is A

    little setup on a pair of 2960s

    both ends are set us follows:

    interface FastEthernet0/1
    switchport trunk allowed vlan 10,20,30
    switchport mode trunk

    on switch A i issued shutdown on f0/1 which shows in running config

    interface FastEthernet0/1
    switchport trunk allowed vlan 10,20,30
    switchport mode trunk
    shutdown # this is showing in config

    int f0/1 both ends is down on switch A though it’s admin down, now on switch B

    interface FastEthernet0/1 # no shutdown present in running config of the int f0/1
    switchport trunk allowed vlan 10,20,30
    switchport mode trunk

    show vlan
    SwitchB#show vlan

    VLAN Name Status Ports
    —- ——————————– ——— ——————————-
    1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4 # interface shows in vlan 1
    Fa0/5, Fa0/6, Fa0/7, Fa0/8
    Fa0/9, Fa0/10, Fa0/11, Fa0/12
    Fa0/13, Fa0/14, Fa0/15, Fa0/16
    Fa0/17, Fa0/18, Fa0/19, Fa0/20
    Fa0/21, Fa0/22, Fa0/23, Fa0/24
    Gig0/1, Gig0/2

    SwitchB#show interfaces trunk # no out put

  45. patzen
    July 11th, 2018

    Q7 @DRJ please don’t confuse people here, check your lab as the only correct answer is D

    if vlan 5 was allowed on the trunk then yes the two workstations would be able to communicate one with another even without the gateway setup as they are on the same subnet

  46. hm3
    October 22nd, 2018

    Question 2: I would have actually assumed E over C. From the output of “show interface trunk,” we only see two ports being used as trunks. Only one of those ports is allowing VLAN 36. Therefore, that port must be the root port for VLAN 36 on this switch.


  47. hm3
    October 23rd, 2018

    re: Q2 I suppose it could be the root bridge … in which case it wouldn’t necessarily be the root port … just another FWD port. There simply isn’t enough information in this question (typical Cisco~)

  48. Q3
    February 14th, 2019

    Answer is B… I tested in a lab when the int is in shut down mode even if you config it in Trunk mode it will show it in vlan 1.. for the other answer if one side is access and the other side is trunk they still can communicate through native vlan and link wont be down!

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