单项选择题
You have been asked to come up with a subnet mask that will allow all three web servers to be on the same network while providing the max number of subnets.Which network address and subnet mask meet this requirement?（）
A. 192.168.252.8 255.255.255.248 B. 192.168.252.8 255.255.255.252 C. 192.168.252.16 255.255.255.240 D. 192.168.252.0 255.255.255.252 E. 192.168.252.16 255.255.255.252
单项选择题 Which command displays the CHAP authentication process as it occurs between two routers?（）
单项选择题 At which layer of the OSI model dose PPP perform?（）
单项选择题 Which command is used to display the collection of OSPF link states?（）
