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MST Questions

November 21st, 2019 in SWITCH 300-115 Go to comments

Question 1


Instead of using Per-VLAN Spanning Tree (PVST) or Rapid PVST which runs a separate STP instance for each active VLAN (there will have 20 STP instances for 20 VLANs), Multiple Spanning Tree (MST) maps multiple VLANs into a spanning tree instance, thereby reducing the number of spanning-tree instances needed. MST also reduces switch resources and managerial burdens.

Question 2


Besides two MST instances 1 & 2, Instance 0 is a special instance for a region, known as the Internal Spanning Tree (IST). The IST always exists on all ports; you cannot delete the IST. By default, all VLANs are assigned to the IST. All other MST instances are numbered from 1 to 4094. The IST is the only STP instance that sends and receives BPDUs. All of the other MSTI information is contained in MST records (M-records), which are encapsulated within MST BPDUs.

+ The Common Spanning Tree (CST) interconnects the MST regions and any instance of 802.1D and 802.1w STP that may be running on the network
+ A Common and Internal Spanning Tree (CIST) is a collection of the ISTs in each MST region.

Question 3


Unlike Per-VLAN Spanning Tree (PVST) which maintains a spanning tree instance for each VLAN configured in the network, Multiple Spanning Tree (MST) maps multiple VLANs into a spanning tree instance, thereby reducing the number of spanning-tree instances needed. MST also reduces switch resources and managerial burdens.

Question 4

Question 5

  1. Matrix
    October 3rd, 2017

    @Jer: congratulations. Is it 100% valid?

  2. Anonymous
    October 15th, 2017

    Hello Guys,

    I am taking my ccnp switch next week please could your share latest dumps with me : norway.dublin at gmail . com

  3. oz
    November 22nd, 2017


    i got like 2 or 3 new questions today, some of the questions seems similar but with new options. the only i can remember is:

    1. how to enable the root for vlans 10 and 20 on MST 1 .

    they give you the commands but they are tricky.

    by studing only this material you won’t pass, go a little beyond.

    Good Luck.

  4. I like butter on my butter
    December 4th, 2017

    For those wondering, here is a sample MST configuration:
    spanning-tree mode mst
    spanning-tree mst configuration
    name MYMSTCONFIGLOL (this is optional)
    revision 1
    !! Here is where you define the VLAN configurations !!
    instance 1 vlan XX, YY, ZZ
    instance 2 vlan AA, BB, CC

    This will run MST into 2 instances (3 if you count the IST). Instance 1 would be VLANS XX, YY, and ZZ. I’m sure you can figure out the rest.

  5. Anonymous
    January 24th, 2018

    how i can enable MST in packet tracer?

  6. Archangel
    March 12th, 2018

    Please FYI—— VTP propagation of MST information Catalyst switches

    mst and pvst is for spanning-tree mode while server, client, and transparent is for vtp mode. it doesn’t matter what spanning-tree mode you use as long as you have a server – client relationship on your vtp domain you would always propagate the vtp info.

    if you are talking about MST INSTANCE info then you would have to configure it to all the switches. it doesn’t get propagated LIKE VTP info

  7. Retire2020
    April 17th, 2018

    found mst config in switch lab manual page 62, version 7 ccnp lol

  8. Anonymous
    June 17th, 2018

    No MST in Packet tracer, use GNS 3 or real equipment for CCNP

  9. RED1
    August 15th, 2018

    can somebody try to add the new questions (2 or 3) about MST configuration.
    For the future, for the others,
    Dont forgot:
    The Today’s actions will facilitate the tomorrow live

  10. Due_Diligence
    December 16th, 2018

    Question 5
    Which two statements about MST are true? (Choose two)
    A. It can operate without a root bridge
    B. It supports one STP instance per VLAN
    C. It is vendor neutral
    D. All VLANs must reside in a single MST region
    E. It can map multiple VLANs to a single STP instance

    Answer (from pdf): C E

    Why not C & D, considering that option E mentions STP instance rather than MST instance

  11. Switcher
    December 27th, 2018

    Question: 5 – Answer is C and E.

    – MST operates with a root bridge for an MST region – A is not correct.
    – PVST operates one STP instance per VLAN; whereas MST operates one STP instance per MST region – B is not correct.
    – MST is vendor-neutral – C is correct.
    – All VLANs need not reside in a single MST region. Of course, by default MST 0 region contains all the VLANs. After you configure MST regions and attach VLANs to them, all the left behind VLANs will be part of the MST 0 region – D is not correct.
    – MSTs are made to map multiple VLANs to single STP instances, thereby optimize Switch resources – E is correct.

  12. @switch_basics
    August 14th, 2019

    hey 9tut, please provide latest questions and answers please. thanks.

  13. Easy_Q4
    November 16th, 2019

    Can you guys elaborate more about the QUESTION 4

    Why does MST enable RSTP and uses BPDU type 2 ??

    Thank you

  14. Zisla
    December 21st, 2019

    Your can take this Question like this, Enabling MST also enables RSTP which uses the Type 2 BPDU (version 2) to better detect Legacy STP BPDUs. MST can support 65 (including Instance 0) instances inside a region. There is no maximum/limitations to how many regions you can have .


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