单项选择题 Which of the following LAN technologies is considered fast Ethernet and uses two pairs of cabling,one pair for sending and the other pair for receiving?（）

单项选择题 A user reports being occasionally disconnected from the server. Which of the following tools couldthe technician use to determine if it is the client or the server that is dropping the connection?（）

单项选择题 A company needs strong wireless security enabled for minimal cost. Which of the following security measures is the BEST to use?（）