单项选择题 You have a network that supports VLSM and you need to reduce IP address waste in your point to point WAN links. Which of the masks below would you use?（）

单项选择题 You have a single Class C IP address and a point-to-point serial link that you want to implement VLSM on. Which subnet mask is the most efficient?（）

单项选择题 On the topic of VLSM, which one of the following statements best describes the concept of the route aggregation?（）