单项选择题 Refer to the exhibit. In the diagram, the switches are running IEEE 802.1w RSPT. On which ports should root guard be enabled in order to facilitate deterministic root bridge election under normal and failure scenarios? （）

单项选择题 Refer to the exhibit. In the diagram, the switches are running IEEE 802.1s MST. Which ports are in the MST blocking state?（）

多项选择题 WhattwofeaturesinCiscoswitcheshelppreventLayer2loops？（）