[单选题]TCP23是（）协议端口号；UDP69是（）端口号；TCP80是（）端口号。

正确答案 ：C

TELNET TFTP HTTP

[单选题]After working all night and successfully configuring a Cisco router for the Ezonexam network you save your changes on the startup config, reboot the router, and go out for a cigarette. When you return, none of your changes are active and the router boots to the initial configuration mode! Which of the choices below indicates the source of your problem?

正确答案 ：C

Router configuration-register set to bypass startup configuration

解析：解析：Explanation:

[单选题]After logging into a router and typing in a few show commands, you press the up arrow key. What will this do?

正确答案 ：A

It will recall the previous command line

解析：解析：Explanation:

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