单项选择题
Which of the following wireless standards uses the 5GHz frequency?（）
A.802.11g B.802.2 C.802.11a D.802.3
单项选择题 Which of the following will cause a ghost image on a printout?（）
单项选择题 Which of the following commands would a technician use to view the active applicationconnections on a local PC to the network?（）
单项选择题 Which of the following protocols uses port 443 by default?（）
