单项选择题
While troubleshooting a connectivity problem, a network administrator notices that a port status LED on a Cisco Catalyst series switch is alternating green and amber. Which condition could this indicate（）。
A.The port is experiencing errors B.The port is administratively disabled C.The port is blocked by spanning tree D.The port has an active link with normal traffic activity
多项选择题 下列哪些接口可作逻辑通道？（）
多项选择题 What are some of the advantages of using a router to segment the network?（）
单项选择题 OSI中，哪些不是表示层功能？（）
