单项选择题 The network administrator is in a campus building distant from Building B. WANRouter is hosting a newly installed WAN link on interface S0/0. The new link is not functioning and the administrator needs to determine if the correct cable has been attached to the S0/0 interface. How can the administrator accurately verify the correct cable type on S0/0 in the most efficient manner（）。

多项选择题 Refer to the topology shown in the exhibit. Which ports will be STP designated ports if all the links are operating at the same bandwidth? （）

多项选择题 What are three valid reasons to assign ports to VLANs on a switch? （）