1. [多选题]Which of the following statements correctly describe the differences between half-duplex and full-duplex Ethernet? (Select two answer choices.)
A. Full-duplex Ethernet uses CSMA/CD to prevent collisions.
B. Half-duplex Ethernet uses a loopback circuit to detect collisions.
C. A full-duplex Ethernet card allows 20Mbps for data transmission.
D. Full-duplex Ethernet makes use of two pairs of wires for data.
E. An Ethernet hub can operate both half and full duplex simultaneously.
2. [单选题]The 201.145.32.0 network is subnetted using a /26 mask. How many networks and IP hosts per network exists using this subnet mask?
A. 4 networks and 64 hosts
B. 64 networks and 4 hosts
C. 4 networks and 62 hosts
D. 62 networks and 2 hosts
E. 6 network and 30 hosts
3. [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
4. [单选题]OSPF的度量值是什么()
A. 跳数
B. 接口开销
C. 矢量距离
D. 链路状态
5. [单选题]在路由表中到达同一网络的路由有：静态路由、RIP路由、IGRP路由，OSPF路由，则路由器会选用哪条路由传输数据：()
A. 静态路由
B. RIP路由
C. IGRP路由
D. OSPF路由
6. [单选题]RIP路由协议认为“网络不可到达”的跳数是：()
A. 8
B. 16
C. 24
D. 100
7. [单选题]The network administrator has configured port security on a Ezonexam switch. Why would a network administrator configure port security on this Ezonexam device?
A. To prevent unauthorized hosts from getting access to the LAN
B. To limit the number of Layer 2 broadcasts on a particular switch port
C. To prevent unauthorized Telnet or SSH access to a switch port
D. To prevent the IP and MAC address of the switch and associated ports
E. None of the above
8. [单选题]关于PPP和HDLC的说法中，错误的是（）
A. PPP是通用协议，HDLC是CISCO私有协议
B. PPP有验证功能，HDLC无验证功能
C. PPP效率低，HDLC效率高
D. 在配置ISDN时，广域网协议不能封装成PPP，但可以封装成HDLC
9. [单选题]把指定端口添加到VLAN的命令是：()
A. vlan
B. vlan-member ship
C. vtp
D. switch port
10. [单选题]介质工作在OSI的哪一层（）
A. 物理层
B. 数据链路层(data link layer)
C. 网络层
D. 传输层
