单项选择题
VLAN 3 is not yet configured on your switch. What happens if you set the switchport access vlan3 commmand interface configuration mode？（）
A.The command is accepted and the respective VLAN is added to vlan dat. B.The command is rejected. C.The command is accepted and you must configure the VLAN manually. D.The port turns amber.
判断题 ATM是一种面向链接的技术，为在交换式WAN或LAN主干网高速传输数据提供了通用的通信机制。
单项选择题 What occurs on a Frame Relay network when the CIR is exceeded?（）
单项选择题 下面属于物理层的设备是（）。
