1. [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
2. [单选题]After connecting a PC to an available port on a switch, you find that the PC can not access any of the resources on the LAN. No other PC's connected to the switch appear to be having any issues. What is the most likely cause for this problem?
A. The router lacks a routing table entry for the new host
B. The host switch port is assigned to the incorrect VLAN
C. The host MAC address is incorrectly configured
D. A STP instance for the new host has not been initialized
E. The switch does not have the MAC address hard coded in the CAM table.
3. [单选题]What kind of cable should be used to establish a trunked line between two Catalyst switches?
A. A straight-through cable
B. An EIA/TIA-232 serial cable
C. An auxiliary cable
D. A modem cable
E. A cross-over cable
4. [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
5. [单选题]Your network uses the172.12.0.0 class B address. You need to support 459 hosts per subnet, while accommodating the maximum number of subnets. Which mask would you use?
A. 255.255.0.0.
B. 255.255.128.0.
C. 255.255.224.0.
D. 255.255.254.0.
E. None of the above
6. [单选题]OSI七层模型中，数据链路层(data link layer)的数据封装名称为（）
A. 比特
B. 帧
C. 包
D. 段
7. [单选题]A Ezonexam switch is configured with all ports assigned to VLAN 2. In addition, all ports are configured as full-duplex FastEthernet. What is the effect of adding switch ports to a new VLAN on this switch?
A. The additions will create more collisions domains.
B. IP address utilization will be more efficient.
C. More bandwidth will be required than was needed previously.
D. An additional broadcast domain will be created.
E. The possibility that switching loops will occur will increase dramatically.
8. [单选题]如果网络中的路由器都是cisco路由器，则优先选择(priority selection)哪一个路由协议（）
A. RIP
B. EIGRP
C. IGRP
D. OSPF
9. [多选题]What are two characteristics of "store and forward" switching? (Select two answer choices)
A. Latency fluctuates regardless of frame. size.
B. The switch receives the complete frame. before beginning to forward it.
C. Latency through the switch varies with frame. length.
D. The switch checks the destination address upon receipt of headers.
10. [单选题]在路由器上，命令show access-list的功能是（）
A. 显示访问控制列表内容
B. 显示路由表内容
C. 显示端口配置信息
D. 显示活动配置文件
