单项选择题
What is a valid option when using the ping command?（）
A. packet loss B. packet size C. CRC D. TCP port
单项选择题 Which command do you use to show active alarms?（）
单项选择题 Which command do you use to display the messages seen during the last system boot?（）
单项选择题 Which command displays the amount of space available on the storage media?（）
