## Question: Interpreting show stp (1)

To analyze Spanning Tree for #CCNA, you need to think about the root switch, then the root ports on the non-root switches, and then designated ports. That analysis usually begins with the show spanning-tree command – a command that packs an incredible amount of meaning into its relatively short output. Mastering every tidbit of meaning from show spanning-tree is a great place to avoid mistakes and pick up points on the exam. Here’s a new practice question that gives you some exercise.

## Question

Which answers show facts confirmed by the output from local switch SW4 about the root switch and the listed port G0/1?

```SW4> show spanning-tree vlan 1

VLAN0001
Spanning tree enabled protocol rstp
Root ID    Priority    24577
Cost        4
Port        2 (GigabitEthernet0/1)
Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec```
1. The local switch (SW4) is the root switch
2. Some other switch is the root switch
3. The output does not confirm whether the local switch (SW4) is the root switch or not
4. Port G0/1 is a port on the root switch
5. Port G0/1 is a port on the local switch (SW4)
6. Port G0/1 is a port on some other switch that may or may not be the root switch

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It is B, since the cost is 4 we can say that the interface in a GIG interface !!

and the other in E, Because it is a local interface on the switch that is connected to the root with the cost of 4 !!

Choices:- A, and, E.

Reasons:- for, (A). Low bridge priority value.

(E). Path cost 4 is a GEthernet port cost. G0/1 is in fact a port from local switch to the root switch. This port listed in the output of show spanning tree, command, is in accordance with the network topology, of this question.

1-The local switch (SW4) is the root switch
Answer: false, because Root has a cost of 4 and is connected through G0/1.

2-Some other switch is the root switch
Answer: True, the Root is connected through G0/1 and has the MAC fa16.3e9a.25be

3-The output does not confirm whether the local switch (SW4) is the root switch or not
Answer: False, because the output is confirming that Root exist through G0/4, therefore SW4 wouldn’t be root.

4-Port G0/1 is a port on the root switch
Answer: false, is a port in SW4.

5-Port G0/1 is a port on the local switch (SW4)

6-Port G0/1 is a port on some other switch that may or may not be the root switch

I’m not 100% sure of these answer, hope they’re rightn.

Now… time to compare in the answer of this question 🙂