20. Refer to the topology and router configuration shown in the graphic. A host on the LAN is accessing an FTP
server across the Internet. Which of the following addresses could appear as a source address for the packets
forwarded by the router to the destination server?
A. 10.10.0.1
B. 10.10.0.2
C. 199.99.9.33
D. 199.99.9.57
E. 200.2.2.17
F. 200.2.2.18
Answer: D
解释:这题考查NAT的知识,当源地址在10.10.0.0/24这个网段内的主机和外网进行通讯的时候
会产生NAT地址转换,转换成199.99.9.40到199.99.9.62这个地址尺里面的地址,所以答案是
199.99.9.40到199.99.9.62里面的一个地址,所以答案是D
21. A company is installing IP phones. The phones and office computers connect to the same device. To ensure
maximum throughput for the phone data, the company needs to make sure that the phone traffic is on a different
network from that of the office computer data traffic. What is the best network device to which to directly connect
the phones and computers, and what technology should be implemented on this device? (Choose two.)
A. hub
B. router
C. switch
D. STP
E. subinterfaces
F. VLAN
Answer: CF
解释:题目要求是将IP phone和PC连在一个设备上,并且将IP phone的流量和其他的流量分开,那么我们需要用VLAN的技术
通过VLAN的技术来把不同流量隔离,所用到的网络设备就是SWICH(交换机).
22. Refer to the exhibit. Which statement describes DLCI 17?
A. DLCI 17 describes the ISDN circuit between R2 and R3.
B. DLCI 17 describes a PVC on R2. It cannot be used on R3 or R1.
C. DLCI 17 is the Layer 2 address used by R2 to describe a PVC to R3.
D. DLCI 17 describes the dial-up circuit from R2 and R3 to the service provider.
Answer: C
解释:DLCI是数据链路控制标识符,是frame-relay里面的2层地址,题目中17是R2的一个DLCI号,
表示连接R3的一条PVC.所以答案是C
23. Which routing protocol by default uses bandwidth and delay as metrics?
A. RIP
B. BGP
C. OSPF
D. EIGRP
Answer: D
解释:用bandwidth和delay来进行metric度量的协议是EIGRP,EIGRP的metric度量是用:bandwidth,delay,可靠性,负载,MTU
RIP用的是hop,BGP用的是各种属性,OSPF用的是cost值,所以答案是D
