21年思科认证考试历年真题精选5章.docx

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1、21年思科认证考试历年真题精选5章21年思科认证考试历年真题精选5章 第1章 “ipaccess-group”命令在接口上缺省的应用方向是什么（）。A.inB.具体取决于接口应用哪个访问控制列表C.outD.无缺省值正确答案：C You are logged into a router and wish to view the layer 3 information about your neighboring Cisco routers. What IOS command gives layer 3 information for of the directly connected rout

2、er interfaces?A. show ip linksB. show cdp neighborC. show cdp neighbor detailD. show ip clientsE. show ip routeF. None of the above正确答案：CC 解析：Explanation:To display detailed information about neighboring devices discovered using Cisco Discovery Protocol (CDP), use the show cdp neighbors privileged E

3、XEC command.Detail - (Optional) Displays detailed information about a neighbor (or neighbors) including network address, enabled protocols, hold time, and software version.Incorrect Answers:A, D. These are invalid commands.B. The show cdp neighbor command, without the detail keyword will not display

4、 the additional layer 3 protocol information.E. This will show all routes from all other routers within the domain. We wish to see information from just the direct interface neighbors. 交换机上VLAN的功能描述中，正确的是（）A.可以减少广播域的个数B.可以减少广播对网络性能的影响C.可以减少冲突域的个数D.可以减小冲突域的容量正确答案：B While troubleshooting a connectivit

5、y issue from a PC you obtain the following information:Local PC IP address: 190.0.3.35/24Default Gateway: 190.0.3.1Remote Server: 190.0.5.250/24You then conduct the following tests from the local PC:Ping 127.0.0.1 - UnsuccessfulPing 190.0.3.35 - SuccessfulPing 190.0.3.1 - UnsuccessfulPing 190.0.5.25

6、0 UnsuccessfulWhat is the underlying cause of this problem?ATCP/IP not correctly installedBLocal physical layer problemCNIC not functioningDRemote physical layer problemENone of the above正确答案：A解析：Explanation:Every Windows based PC uses the 127.0.0.1 as the local loopback IP address. Every PC will re

7、spond to this local IP address if the TCP/IP stack is correctly installed and running on the machine. If you cannot ping the loopback address of 127.0.0.1, then something is wrong with the TCP/IP protocol stack. 在大型网络中选择OSPF而不选择RIP的原因是（）A.更快的路由收敛B.需要更少的路由器内存C.需要更少的CPU的资源D.更优的选路，路由无环路正确答案：AD OSPF在同一区

8、域内，下列说法正确的是（）A.每台路由器生成的LSA都是相同的B.每台路由器的LSDB(链路状态数据库)都是相同的C.每台路由器根据该LSDB计算出的最短路径树都是相同的D.每台路由器根据该最短路径树计算出的路由都是相同的正确答案：B21年思科认证考试历年真题精选5章 第2章 关于帧中继的说法，正确的是（）A.速率最大为1Mbit/sB.不提供差错校验功能C.可以偷占带宽D.数据传输质量高于DDN正确答案：C 以下（）两个机制用于在距离矢量的路由协议中避免环路。A.水平分割B.路由毒化C.划分区域D.链路状态宣告正确答案：AB OSPF在建立邻接关系的过程中使用了哪几类报文（）A.HELLO报

9、文B.DBD（数据库描述）报文C.LSR（链路状态请求）报文D.LSU（链路状态更新）报文正确答案：ABCD完成密码恢复过程并让路由器正常运行后,配置寄存器的值是什么?()A.0x2100B.0x2101C.0x2102D.0x2142答案：C 请参见图示。根据showipnattranslations命令的输出，此路由器上正在使用哪种地址转换()A.静态NATB.动态NATC.PATD.私有NAT正确答案：C 路由表中的直接路由(Direct)可能有以下几种来源()A.本路由器自身接口的主机路由B.本路由器自身接口所在的网段路由C.与本路由器直连的对端路由器的接口的主机路由D.缺省路由正确答

10、案：ABC21年思科认证考试历年真题精选5章 第3章 PPP中()为两次握手协议，它通过在网络上以明文的方式传递用户名及口令来对用户进行验证。A.PAPB.IPCPC.CHAPD.RADIUS正确答案：A OSPF协议中，ABR的不同端口可能运行在不同的area中，其中一定有接口运行在（)当中.A.area0B.area1C.area10D.area100正确答案：A 100baseT的速率是()Mbit/sA.1B.10C.100D.1000正确答案：C PAP验证属于双向认证。此题为判断题(对，错)。正确答案： A receiving host has failed to receive

11、all of the segments that it should acknowledge.What can the host do to improve the reliability of this communication session?AStart a new session using UDPBObtain a new IP address from the DHCP serverCUse a different source port for the sessionDDecrease the sequence numberEDecrease the window size正确

12、答案：E解析：Explanation:A TCP window the amount of outstanding (unacknowledged by the recipient) data a sender can send on a particular connection before it gets an acknowledgment back from the receiver that it has gotten some of it.For example if a pair of hosts are talking over a TCP connection that ha

13、s a TCP window size of 64 KB (kilobytes), the sender can only send 64 KB of data and then it must stop and wait for an acknowledgment from the receiver that some or all of the data has been received. If the receiver acknowledges that all the data has been received then the sender is free to send ano

14、ther 64 KB.One way to improve the reliability of the TCP connection is to reduce the window size that the receiver needs to receive before sending an acknowledgement. However, this will reduce throughput as more segments and acknowledgements will need to be sent in order to transfer the same amount

15、of data. You have configured a Ezonexam switch as shown below:Ezonexam3(config-if) switchport port-securityEzonexam3(config-if) switchport port-security mac-address stickySelect the action below that results from executing these commands.A. A dynamically learned MAC address is saved in the VLAN data

16、base.B. A dynamically learned MAC address is saved in the startup-configuration file.C. Statically configured MAC addresses are saved in the startup-configuration file if frames from that address are received.D. A dynamically learned MAC address is saved in the running-configuration file.E. Statical

17、ly configured MAC addresses are saved in the running-configuration file if frames from that address are received.F. None of the above正确答案：DD 解析：Explanation:With port security, the switch supports these types of secure MAC addresses:Static secure MAC addresses-These are manually configured by using t

18、he switchport port-security mac-address mac-address interface configuration command, stored in the address table, and added to the switch running configuration.Dynamic secure MAC addresses-These are dynamically configured, stored only in the address table, and removed when the switch restarts.Sticky

19、 secure MAC addresses-These are dynamically configured, stored in the address table, and added to the running configuration. If these addresses are saved in the configuration file, when the switch restarts, the interface does not need to dynamically reconfigure them.You can configure an interface to

20、 convert the dynamic MAC addresses to sticky secure MAC addresses and to add them to the running configuration by enabling sticky learning. To enable sticky learning, enter the switchport port-security mac-address sticky interface configuration command. When you enter this command, the interface con

21、verts all the dynamic secure MAC addresses, including those that were dynamically learned before sticky learning was enabled, to sticky secure MAC addresses. The interface adds all the sticky secure MAC addresses to the running configuration.The sticky secure MAC addresses do not automatically becom

22、e part of the configuration file, which is the startup configuration used each time the switch restarts. If you save the sticky secure MAC addresses in the configuration file, when the switch restarts, the interface does not need to relearn these addresses. If you do not save the sticky secure addre

23、sses, they are lost.21年思科认证考试历年真题精选5章 第4章 How could the Ezonexam corporation benefit from using VLANs on their network?(Select three answer choices.)A. VLANs allow access to network services based on department, not physical location.B. VLANs utilize packet filtering to enhance network security.C. V

24、LANs provide a low-latency, high bandwidth internetworking alternative.D. VLANs provide a method of communication between IP addresses in large networks.E. VLANs establish segmented broadcast domains in switched networks.F. VLANs can greatly simplify adding, moving, or changing hosts on the network.

25、正确答案：AEFA,E,F 解析：Explanation:VLANs establish broadcast domains in switched networks, so by virtue of having the option to create many efficient broadcast domains, congestion is reduced and network throughput is greatly enhanced. VLANs allow networks to be divided by department or resource needs, rat

26、her then by physical location. When people move departments, leave a department, or join a department, administration is easy and convenient with a few keystrokes.Incorrect Answers:B, D. These would be router functions at layer 3. Switches and VLANs operate at layer 2 of the OSI model.C. The use of

27、VLANs may actually increase the latency in some cases, as traffic from one VLAN to the other will need to be routed. 下面对Cisco2621路由器和Cisco2501路由器描述中，错误的是（）A.Cisco2621路由器的可扩展性优于Cisco2501路由器B.Cisco2621是模块化路由器C.Cisco2501上提供一个100Mbit/s的快速以太网端口D.Cisco2501是固定端口的路由器正确答案：C Using a subnet mask of 255.255.255

28、.224, which of the IP addresses below can you assign to the hosts on this subnet? (Select all that apply)A. 16.23.118.63B. 87.45.16.159C. 92.11.178.93D. 134.178.18.56E. 192.168.16.87F. 217.168.166.192正确答案：CDEC,D,E 解析：Explanation:Since the subnet mask is 255.255.255.224, the number of network hosts t

29、hat is available is 30. Every network boundary will be a multiple of 32. This means that every subnet will be a multiple (0, 32, 64, 96, 128, 160, 192, 224) and the broadcast address for each of these subnets will be one less this number (31, 63, 95, 127, 159, 191, 223). Therefore, any IP address th

30、at does not end in one of these numbers will be a valid host IP address.C. Valid Host in subnetwork 2 (92.11.178.64 to 92.11.178.95)D. Valid Host in subnetwork 1 (134.178.18.32 to 134.178.18.63)E. Valid Host in subnetwork 2 (192.168.16.64 to 192.168.16.95)Incorrect Answers:A. This will be the broadc

31、ast address for the 16.23.118.32/27 network.B. This will be the broadcast address for the 87.45.16.128/27 networkF. This will be the network address for the 217.168.166.192/27 network. What is the default configuration register setting on most Cisco routers?A. 0x2104B. 0x2022C. 0x2210D. 0x2102E. 0x2

32、142F. None of the above正确答案：DD 解析：Explanation:About 99 percent of the time someone uses a config-register, its more than likely because of a lost router password. Normally, the two config-registers for recovering passwords are 0x2102 and 0x2142.The first config-register, 0x2102, is the normal config

33、-register if you boot the router from internal Flash. You can see this config-register by using the show version command. In this output, youll notice the last line says, Configuration register is 0x2102. This is normal.将路由器的许可证删除包括哪两步?()A.使用命令erase flash:licenseB.重启系统C.使用命令license boot，并在末尾指定关键字dis

34、ableD.使用命令license clear将许可证清除答案：CD 路由器下“特权用户模式”的标识符是：()A.B.!C.D.(config-if)正确答案：C21年思科认证考试历年真题精选5章 第5章 配置路由器特权用户“加密密码”的命令是：()A.passwordB.enable passwordC.enable secretD.passwd正确答案：C Barney是子网10.1.1.0/24中一个具有IP地址10.1.1.1的主机。以下哪些操作时标准IPACL可配置来执行的（）A.匹配准确的源IP地址B.使用一个access-list命令匹配IP地址10.1.1.1到10.1.1.4

35、，而不匹配其他IP地址C.使用一个access-list命令匹配Barney的子网中的所有IP地址，而不匹配其他IP地址D.仅匹配包的目标IP地址正确答案：AC 路由器上端口fa0/0,其最大传输速率是（）Mbit/sA.128B.10C.100D.1000正确答案：C RIP用()作为度量值。A.管理距离B.带宽C.跳数D.时间正确答案：C “InsideGlobal”地址在NAT配置里表示的是什么()A.这个概括地址是所有的内部子网地址B.一个注册的地址是表示一个内部的主机到外部网络C.一个全局唯一，私有的ip地址被分配给一个内网的主机D.路由器的MAC地址被用做内部主机去连接这个互联网正确答案：B TELNET工作在OSI哪一层（）A.会话层B.表示层C.传输层D.应用层正确答案：D