1. [单选题]A receiving host has failed to receive all of the segments that it should acknowledge.What can the host do to improve the reliability of this communication session?
A. Start a new session using UDP
B. Obtain a new IP address from the DHCP server
C. Use a different source port for the session
D. Decrease the sequence number
E. Decrease the window size
2. [单选题]路由器“特权模式”的提示符是：（）
A. >
B.
C. (config)
D. (config-if)
3. [单选题]IP地址为：192.168.50.70，掩码为：255.255.255.248，则该IP和掩码结合划分子网时，每个子网的容量为（）
A. 8
B. 4
C. 12
D. 6
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]工作在OSI第三层(layer 3)的设备是：()
A. 网卡
B. 路由器
C. 交换机
D. 集线器
6. [单选题]The Ezonexam network administrator has just issued the "switchport trunk native vlan 998" command on switch VE2. What is the function of this command?
A. It designates VLAN 998 as the default for all unknown tagged traffic
B. It designates VLAN 998 for untagged traffic
C. It blocks VLAN 998 traffic from passing on the trunk
D. It creates a VLAN 998 interface
E. None of the above
7. [单选题]While troubleshooting a connectivity problem on the network, you issue the ping command from your PC command prompt, but the output shows "request times out."At which OSI layer is this problem associated with?
A. The data link layer
B. The application layer
C. The access layer
D. The session layer
E. The network layer
8. [单选题]混合型协议既具有“距离矢量路由协议”的特性，又具有“链路状态路由协议”的特性，下列协议中属于混合型协议的是：()
A. RIP
B. OSPF
C. EIGRP
D. IGRP
9. [单选题]路由器下，由一般用户模式进入特权用户模式的命令是：（）
A. enable
B. config
C. interface
D. router
10. [单选题]网关的功能（）
A. 过滤数据包(packet)
B. 不同网段通信
C. 校验数据帧
D. 把数据封装成“段”
