单项选择题
A.PVST+reduces the CPU cycles for all the switches in the network
B.PVST+automatically selects the root bridge location,to provide optimized bandwidth usage.
C.PVST+allow the root switch location to be optimized per vlan.
D.PVST+supports Layer 3 load balancing without loops.
单项选择题 Refer to the exhibit. What switch proves the spanning-tree designated port role for the network segment that services the printers?（）
单项选择题 Refer to the exhibit.The network administrator normally establishes a telnet session with the switch from host A.However,host A is unavailable.The administrator′s attempt to the switch from host B fails,but pings to the other two hosts are successful.what is the issue?（）
多项选择题 Which two of these are characteristics of the 802.1Q protocol?（）