Which spanning-tree enhancement prevents the spanning-tree topology from changing by blocking a port that receives a superior BPDU?

Which spanning-tree enhancement prevents the spanning-tree topology from changing by blocking a port that receives a superior BPDU?

• BDPU filter
• BPDU guard
• root guard
• PortFast

Explanation: Root guard prevents the placement of the root bridge from changing by blocking any port that receives a superior BPDU. A superior BPDU is one with a higher root bridge ID than the currently selected root bridge has.

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