1. [单选题]网关的功能（）
A. 过滤数据包
B. 不同网段通信
C. 校验数据帧
D. 把数据封装成“段”
2. [单选题]IP扩展访问列表的数字标示范围是多少（）。
A. 0-99
B. 1-99
C. 100-199
D. 101-200
3. [单选题]备份路由器IOS的命令是：()
A. copy flash tftp
B. copy running-configt ftp
C. copy IOS tftp
D. copy startup-configt ftp
4. [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.
5. [单选题]对于运行OSPF协议的路由器来说，RouterID是路由器的唯一标识，所以协议规定：必须保证RouterID在如下范围之内唯一（）。
A. 网段内
B. 区域内(intra-region)
C. 自治系统内
D. 整个因特网
