单项选择题 The network administrator is asked to configure 113 point-to-point links. Which IP addressing scheme best defines the address range and subnet mask that meet the requirement and waste the fewest subnet and host addresses？（）

判断题 X.25作为国际通用标准的广域网协议，内置的差错纠正，流量控制和丢包重传机制使之具有高度的可靠性，由于数据吞吐率很低，包时延较大，故不适于在质量差的信道上传输数据。

单项选择题 What is the difference between a CSU/DSU and a modem?（）