Which statement about spanning-tree root-bridge election is true?
A. It is always performed automatically
B. Each VLAN must have its own root bridge
C. Each VLAN must use the same root bridge
D. Each root bridge must reside on the same root switch
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All the VLANs that a participating in a spanning-tree root-bridge election must have a ROOT-Bridge
A – is not always done automatically, you can manually select a root-bridge
B – All the VLANs that a participating in a spanning-tree root-bridge election must have their own ROOT-Bridge
C – Nonsense
D – Nonsense
Correct answer is B
I think, (and its only my opinion) that the “most true” is A.
Because: you can have a switch that does not permit vlan, or you are not using STP per Vlan. Therefore you’d have the same root bridge for all vlans.
You can participate on the election of the root by changing priorities, but the process is automatic anyway. You can’t go to a switch to select it manually as root. But, you can intermediate in the process…
“Description of the Technology
…Each VLAN must have its own root bridge because each VLAN is a separate broadcast domain.”
https://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/5234-5.html
The correct answer is B
Configure the bridge priority on each switch, then configure the trunks and the VTP root selection happens automatically. If the bridge priority is not configured the lowest mac address automatically selects the root switch. In a per VLAN it happens the same, per VLAN. A is correct.
You can manipulate and force a Switch to be the Root bridge by changing Priority, so it does not Always have to be automatic.
C and D are nonsense
Thus, I would say B is the best answer
The B is correct answer
But in the question the vlan it is NOT mentioned. That’s why, the correct answer is A.
Any opinion?