单项选择题 What is the function of the command switchport trunk native vlan 999 on a switch?（）

单项选择题 Refer to the exhibit.Switch-1 needs to send data to a host with a MAC address of 00b0.d056.efa4.What will Switch-1 do with this data?（）

单项选择题 What value is primarily used to determine which port becomes the root port on each nonroot switch in a spanning-tree topology?（）