单项选择题
Which of the following WAN protocols is a circuit switching technology?（）
A. ISDN B. SONET C. Frame Relay D. ATM
单项选择题 Which of the following wireless standards has a MAXIMUM throughput, by default, of 11Mbps?（）
单项选择题 Which of the following protocols is commonly used by ping?（）
单项选择题 The "1000" in 1000BaseT cabling represents which of the following?（）
