1. [单选题]帧中继环境下，为了区分虚电路，应该使用的地址是（）
A. IP地址
B. MAC地址
C. DLCI
D. IPX地址
2. [单选题]What kind of cable should be used to establish a trunked line between two Catalyst switches?
A. A straight-through cable
B. An EIA/TIA-232 serial cable
C. An auxiliary cable
D. A modem cable
E. A cross-over cable
3. [单选题]查看路由表的命令是：()
A. show interface
B. show run
C. show ip route
D. show table
