1. [单选题]路由器上，命令“show int s0”的显示结果为：Serial0 is up,line protocol is down出现该结果的可能原因是（）
A. 端口处于关闭状态
B. 物理端口被烧毁
C. 两端设备协议不一致
D. 路由表中无路由
2. [单选题]After working on a router, some problems arise and you wish to view the commands that you recently entered. Which IOS command opens the history buffer and displays the most recently entered commands?
A. Show history
B. Show buffers
C. Show typed commands
D. Show terminal buffer
E. Show command
F. F. None of the above
3. [单选题]You are a senior network administrator at Ezonexam, and while performing the password recovery procedure on your 2500 series Cisco router, you type in the following command:o/r 0x2142
A. What is the purpose of this command?
B. It is used to restart the router.
C. It is used to bypass the configuration in NVRAM.
D. It is used to enter ROM Monitor mode.
E. It is used to view the lost password.
F. It is used to save the changes to the configuration.
