Which STP feature can prevent other switches on the network from becoming the root switch, but still allow that interface to participate in STP otherwise?
A . Root Guard
B . Loop Guard
C . BPDU Guard
D . BPDU Filter
Answer: A
Explanation:
When a port only has a host device connected to it, we will enable portfast, this will speed up the port initialization process and put the port into forwarding state straight away. This eliminates 30 seconds of delay that would have been encountered if STP was not bypassed and the port went through the Listening and Learning states. Because host is a workstation, it sends no BPDUs and so disabling Spanning Tree on a port like this is not an issue.
If we removed this end host of this port and connected a switch. This new switch will start to generate BPDUs and could take over as been the Root Bridge for the network, or it could cause a loop in our network if it has another link connected into another part of the network.
http://ericleahy.com/index.php/bpdu-guard-bpdu-filter-root-guard-loop-guard-udld/
BPDU Guard is used to prevent unauthorized switches, its configured on end-user ports. If switch sees BPDU packet on the port where BPDU guard is configured it will shut port down.
The question said “but still allow that interface to participate in STP” so BPDU guard cannot be an answer.
has only one answer – ROOT Guard.
https://vceguide.com/which-stp-feature-can-prevent-other-switches-on-the-network-from-becoming-the-root-switch-but-still-allow-that-interface-to-participate-in-stp-otherwise/
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