单项选择题
A. ping
B. hello
C. get request
D. echo request
单项选择题 Which command displays the IPNCP parameters for all connected PPPoA subscribers?（）
单项选择题 Which CLI command displays the currently connected PPPoA subscribers?（）
单项选择题 End users are failing to log in to the network. Which command is used on the ERX Edge Router to validate communications with the RADIUS server?（）