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1. [单选题]OSI七层模型中，网络层的数据封装名称为（）
A. 比特
B. 帧
C. 包
D. 段
2. [单选题]某台PC，能ping通路由器，但不能telnet到路由器，可能的原因是（）
A. PC的IP地址设置错误
B. 路由器端口IP设置错误
C. 路由器端口处于关闭状态
D. telnet密码未设置
3. [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
4. [多选题]CDP is being used throughout the Ezonexam network. What are two reasons why the Ezonexam network administrator would use CDP? (Choose two)
A. To determine the status of network services on a remote device
B. To obtain the IP Address of a connected device in order to telnet to the device
C. To verify the type of cable interconnecting two devices
D. To verify Layer 2 connectivity between two devices when Layer 3 fails
E. To obtain VLAN information from directly connected swticehs
F. F. To determine the status of the routing protocols between directly connected routers
G. G. To support automatic network failover during outages
5. [多选题]With regard to Ethernet media access methods, which of the following are true?(Choose all that apply.)
A. A device waits for an electronic signal before transmitting.
B. A device listens and waits until the media is not busy before transmitting.
C. All devices on an Ethernet segment see data that passes on the network medium.
D. Only the sender and the receiver devices see data that passes on the network medium.
E. Ethernet networks allow you to configured devises with higher transmission priority.
