You are currently using VLAN IDs 2 through 300 within your Layer 2 domain and you need to configure VSTP to prevent loops. You must ensure that all VLANs are loop free. In this scenario, which statement is correct?
A.
You must ensure that the VLANs are balanced between two different root bridges.
B.
You must enable RSTP to account for all VLANs.
C.
You must ensure that the bridge priority is set to the lowest value on all switches in the Layer 2 domain.
D.
You must enable all VLANs, 2 through 300, under the VSTP configuration.
This is a bit of a trick question.
Now this exam is for ELS switches, so in theory the maximum is 510 VLANs - however, non-ELS switches only support up to 253, any VLANs that you can't specify in VSTP should be specified in RSTP (Well, they will all be associated with RSTP and associated under the same Bridge Calculations).
However, the confusing element is that in the course material, it tells you that it can only support up to 253 VLANs, it's only by reading through the DOCs you see that 510 is the limit on ELS switches.
I think the answer is B based on explanation from Plinkity and this link: https://www.juniper.net/documentation/en_US/junos18.3/topics/topic-map/spanning-tree-configuring-vstp.html
This is configuration to prevent loops with VSTP. Implies that VLANs are included into VSTP configuration..
https://www.juniper.net/documentation/en_US/junos/topics/topic-map/spanning-tree-loop-protection.html
Include the bpdu-timeout-action statement with either the block or log option
For all VSTP instances on a physical interface configured at the global level or a the VLAN level:
content_copy zoom_out_map
[edit]
protocols {
vstp {
interface interface-name {
bpdu-timeout-action (log | block);
}
vlan vlan-id {
interface interface-name {
bpdu-timeout-action (log | block);
}
}
}
}
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Hyde
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