单项选择题 You download a file from an FTP site on the Internet. What is the highest layer in the OSI model used in this FTP operation?（）

单项选择题 While troubleshooting a connectivity problem on the network, you issue the ping command from your PC command prompt, but the output shows "request times out."At which OSI layer is this problem associated with?（）

单项选择题 You are logged into a router and with to view the layer 3 information about your neighboring Cisco routers. What IOS command gives layer 3 information for of the directly connected router interfaces?（）