单项选择题
A. 6, 9, 12, 18
B. 1, 2, 5.5, 6
C. 5.5, 6, 9, 11
D. 1, 2, 5.5, 11
单项选择题 Which port state is introduced by Rapid-PVST?（）
单项选择题 What is the name of the VTP mode of operation that enables a switch to forward only VTP advertisements while still permitting the editing of local VLAN information?（）
单项选择题 Which command will show the MAC addresses of stations connected to switch ports?（）