单项选择题 The ios of a north american cisco aironet 1230 series access point has become corrupt，  necessitating the need for a tftp firmware reload. Before you press and hold the mode button，what must the file be named in order for the reload to occur？（）

单项选择题 lightweight access point has been connected to a catalyst 3550 24-pwr switch， and on power-up the access point fails. What is the problem with the switch？（）

单项选择题 Two access points running the core feature set are connected to the same switch and are  providing guest services. if pspf is enabled. What must be enabled on the switch to prevent clients from seeing one another’s data？（）