1. [单选题]下列哪一个通配符掩码与子网172.16.64.0/27的所有主机匹配（）。
A. 255.255.255.0
B. 255.255.224.0
C. 0.0.0.31
D. 0.0.31.255
2. [单选题]VLAN主干协议VTP的默认工作模式是()
A. 服务器模式
B. 客户端模式
C. 透明模式
D. 以上三者都不是
3. [单选题]A Ezonexam technician is troubleshooting connectivity problems between two routers that are directly connected through the serial line. The technician notices that the serial line is up but cannot see any neighbors displayed in the output of the show cdp neighbors command.In which OSI layer is the problem most likely occurring?
A. Physical
B. Data link
C. Network layer
D. Transport layer
E. Application layer
4. [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
5. [单选题]路由器“路由模式”的提示符号是（）
B. (config)
C. (config-if)
D. (config-router)
