单项选择题 An administrator receives reports from users in an office that their 802.11g wireless connectivity has been problematic since the installation of the new wireless phone system. At which of the following frequencies are both systems operating at to cause this issue?（）

多项选择题 An administrator needs to authenticate users to the network, authorize network activities, and account for activities done. Which of the following are services that will BEST meet these goals?（）(Select TWO).

单项选择题 Which of the following is a secure method of copying information over a public network?（）