1. [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?
A. Hardware failure in NVRAM prevents the router from loading the config
B. Startup-config in flash is corrupt and cannot be analyzed
C. Router configuration-register set to bypass startup configuration
D. Startup-config in NVRAM is corrupt and cannot be analyzed
E. None of the above
2. [单选题]路由器上“水平分割”的功能是：()
A. 分离端口
B. 阻止路由环路
C. 简化配置
D. 方便故障处理
3. [单选题]OSI七层模型中，“段”是哪一层数据封装的名称（）
A. 物理层
B. 数据链路层
C. 网络层
D. 传输层
