2022思科认证历年真题和解答6卷.docx

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1、2022思科认证历年真题和解答6卷2022思科认证历年真题和解答6卷 第1卷 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.缺省路由正确答案：ABC IGP包括如下哪些协议()A.RIPB.BGPC.IS-ISD.OSPF正确答案：ACD During startup, router VE1 displays the following error message:boot: cannot open flash:What will VE1 do next?A. It wi

2、ll attempt to locate the configuration file from a TFTP server. If this fails, it will initiate the setup dialog.B. It will attempt to locate the IOS from a TFTP server. If this fails, it will load a limited IOS from ROM.C. It will attempt to locate the configuration file from a TFTP server. If this

3、 fails, it will load a limited configuration from ROM.D. Because of damaged flash memory, the router will fail the POST.E. It will attempt to locate the IOS from a TFTP server. If this fails, it will initiate the setup dialog.F. None of the above正确答案：BB 解析：Explanation:The boot sequence of a Cisco ro

4、uter is shown below:Booting up the router and locating the Cisco IOS1. POST (power on self test)2. Bootstrap code executed3. Check Configuration Register value (NVRAM) which can be modified using the config-register command0 = ROM Monitor mode1 = ROM IOS2 - 15 = startup-config in NVRAM4. Startup-con

5、fig file: Check for boot system commands (NVRAM)If boot system commands in startup-configa. Run boot system commands in order they appear in startup-config to locate the IOSb. If boot system commands fail, use default fallback sequence to locate the IOS (Flash, TFTP, ROM)?If no boot system commands

6、in startup-config use the default fallback sequence in locating the IOS:a. Flash (sequential)b. TFTP server (netboot)c. ROM (partial IOS) or keep retrying TFTP depending upon router model5. If IOS is loaded, but there is no startup-config file, the router will use the default fallback sequence for l

7、ocating the IOS and then it will enter setup mode or the setup dialogue.6. If no IOS can be loaded, the router will get the partial IOS version from ROM Two stations on the Ezonexam LAN transmit at the same time, resulting in a collision. What happens when a collision occurs on the network? (Choose

8、all that apply)AEach device on the Ethernet segment stops transmitting for a short time.BA jam signal informs all devices that a collision occurred.CWhen data transmission resumes, the devices that were involved in the collision have priority to transmit.DThe devices that are involved in the collisi

9、on stops transmitting for a short time.EThe collision invokes a random back-off algorithm.正确答案：BDE解析：Explanation:When a host on an Ethernet LAN has information to send, the following steps are taken:1. A device with a frame. to send listens until Ethernet is not busy.2. When the Ethernet is not busy

10、, the sender begins sending the frame.3. The sender listens to make sure that no collision occurred.4. Once the senders hear the collision, they each send a jamming signal, to ensure that all stations recognize the collision.5. After the jamming is complete, each sender randomizes a timer and waits

11、that long.6. When each timer expires, the process starts over with step 1.Incorrect Answers:A. Only the stations involved in the collision stop transmitting for a short time, not all stations on the LAN.C. No priority is given to any stations once a collision has occurred. The network administrator

12、has configured port security on a Ezonexam switch. Why would a network administrator configure port security on this Ezonexam device?ATo prevent unauthorized hosts from getting access to the LANBTo limit the number of Layer 2 broadcasts on a particular switch portCTo prevent unauthorized Telnet or S

13、SH access to a switch portDTo prevent the IP and MAC address of the switch and associated portsENone of the above正确答案：A解析：Explanation:You can use the port security feature to restrict input to an interface by limiting and identifying MAC addresses of the stations allowed to access the port. When you

14、 assign secure MAC addresses to a secure port, the port does not forward packets with source addresses outside the group of defined addresses. If you limit the number of secure MAC addresses to one and assign a single secure MAC address, the workstation attached to that port is assured the full band

15、width of the port.If a port is configured as a secure port and the maximum number of secure MAC addresses is reached, when the MAC address of a station attempting to access the port is different from any of the identified secure MAC addresses, a security violation occurs. Also, if a station with a s

16、ecure MAC address configured or learned on one secure port attempts to access another secure port, a violation is flagged. IP地址为：192.168.50.70，掩码为：255.255.255.248，则该IP地址所在子网的子网有效IP为（）A.192.168.50.33-192.168.50.39B.192.168.50.41-192.168.50.50C.192.168.50.65-192.168.50.70D.192.168.50.66-192.168.50.75正

17、确答案：C 网络中经常使用“帧中继”服务，请选出帧中继的优点（）A.偷占带宽B.提供拥塞管理机制C.可以使用任意广域网协议D.灵活的接入方式正确答案：ABD Which of the following statements correctly describe the differences between half-duplex and full-duplex Ethernet? (Select two answer choices.)AFull-duplex Ethernet uses CSMA/CD to prevent collisions.BHalf-duplex Ethernet

18、 uses a loopback circuit to detect collisions.CA full-duplex Ethernet card allows 20Mbps for data transmission.DFull-duplex Ethernet makes use of two pairs of wires for data.EAn Ethernet hub can operate both half and full duplex simultaneously.正确答案：BD解析：Explanation:Half-duplex Ethernet send and rece

19、ives on the same line, so a loopback needs to be set to detect collisions. Alternatively, full-duple Ethernet doesnt have to because it uses two pairs of wire, one to send and the other to receive. Collisions are not possible on full duplex Ethernet networks.Incorrect Answers:A. Full duplex uses bot

20、h pairs of wires, so transmissions are sent on the first pair, and data that is received come in on the other pair. This prevents collisions.C. Full duplex allows for data to be sent and received at the same time. It will not double the amount of bandwidth at any given time. The speed of the Etherne

21、t link will remain at 10/100.E. Hubs are shared devices and can only support one mode, unlike switches.2022思科认证历年真题和解答6卷 第2卷 路由器“全局模式”的提示符为（）A.B.C.(config)D.(config-router)正确答案：C 禁止RIP协议的路由聚合功能的命令是()A.noripB.no-summanyC.noauto-summanyD.nonetwork 10.0.0.0正确答案：C Which of the following components must

22、be elected before the Spanning Tree Protocol can converge in a switched LAN?A. Designated ports.B. Duplex operating mode.C. Fast mode ports.D. Root bridge.E. Root ports.F. BDPU priority.正确答案：ADEA,D,E 解析：Explanation:Designated port: Either a root port or a port that has been determined as having the

23、best (lower) cost-a designated port will be marked as a forwarding port. Root bridge: The root bridge is the bridge with the best bridge ID. With STP, the key is for all the switches in the network to elect a root bridge that becomes the focal point in the network. All other decisions in the network

24、-like which port is to be blocked and which port is to be put in forwarding mode-are made from the perspective of this root bridge. Root port: Always the link directly connected to the root bridge, or the shortest path to the root bridge. If more than one link connects to the root bridge, then a por

25、t cost is determined by checking the bandwidth of each link. The lowest cost port becomes the root port. So these three components must be elected before the spanning tree protocol can converge in a switched LAN 为了使配置私有IP的设备能够访问互联网，应采用的技术是()A.NATB.VLANC.ACCESS-LISTD.DDR正确答案：A 下列选项不属于分组交换技术的广域网通信协议有(

26、)。A.X.25B.帧中继C.ATMD.PSTN正确答案：D Which two statements describe the operation of the CSMA/CD access method, which is in use on the Ezonexam network? (Choose two)A. After a collision, the station that detected the collision has first priority to resend the lost data.B. In a CSMA/CD collision domain, sta

27、tions must wait until the media is not in use before transmitting.C. In a CSMA/CD collision domain, multiple stations can successfully transmit data simultaneously.D. The use of hubs to enlarge the size of collision domains is one way to improve the operation of the CSMA/CD access method.E. After a

28、collision, all stations run a random backoff algorithm. When the backoff delay period has expired, all stations have equal priority to transmit data.F. After a collision, all stations involved run an identical backoff algorithm and then synchronize with each other prior to transmitting data.正确答案：BEB

29、,E 解析：Explanation:Ethernet networking uses Carrier Sense Multiple Access with Collision Detect (CSMA/CD), a protocol that helps devices share the bandwidth evenly without having two devices transmit at the same time on the network medium. CSMA/CD was created to overcome the problem of those collisio

30、ns that occur when packets are transmitted simultaneously from different nodes. And trust me, good collision management is crucial, because when a node transmits in a CSMA/CD network, all the other nodes on the network receive and examine that transmission. Only bridges and routers can effectively p

31、revent a transmission from propagating throughout the entire network! So, how does the CSMA/CD protocol work? Like this: when a host wants to transmit over the network, it first checks for the presence of a digital signal on the wire. If all is clear (no other host is transmitting), the host will th

32、en proceed with its transmission. But it doesnt stop there. The transmitting host constantly monitors the wire to make sure no other hosts begin transmitting. If the host detects another signal on the wire, it sends out an extended jam signal that causes all nodes on the segment to stop sending data

33、 (think, busy signal). The nodes respond to that jam signal by waiting a while before attempting to transmit again. Backoff algorithms determine when the colliding stations can retransmit. If collisions keep occurring after 15 tries, the nodes attempting to transmit will then time out. Which of the

34、following are types of flow control? (Choose three)ABufferingBCut-throughCWindowingDCongestion avoidanceELoad balancing正确答案：ACD解析：Explanation:Datatransmissionflowcontroloccursatlayer4withthehelpofbuffering,windowingandcongestionavoidance. 下列哪一条命令是用来保存交换机的配置信息()A.writeB.Copy running-config startup-co

35、nfigC.Write NVRAMD.Copy startup-config running-config正确答案：B2022思科认证历年真题和解答6卷 第3卷 You have a class B network with a 255.255.255.0 mask. Which of the statements below are true of this network? (Select all valid answers)A. There are 254 usable subnets.B. There are 256 usable hosts per subnet.C. There a

36、re 50 usable subnets.D. There are 254 usable hosts per subnet.E. There are 24 usable hosts per subnet.F. There is one usable network.正确答案：ADA,D 解析：Explanation:The default subnet mask for Class B is 255.255.0.0. Thus an extra 8 bits have been used for the network portion, leaving 8 for hosts. The 2n

37、- 2 formula (28 - 2 in this case for both the network and IP hosts) gives us 254 networks and 254 hosts per network.Incorrect Answers:B: We must remember to always subtract 2 (one for the network, and one for the broadcast) so the result is 254, not 256.C, E: No possible network mask would give us t

38、his exact number of subnets or hosts.F: This would be true if this were a class C network, not a class B. CDP is being used throughout the Ezonexam network. What are two reasons why the Ezonexam network administrator would use CDP? (Choose two)A. To determine the status of network services on a remo

39、te deviceB. To obtain the IP Address of a connected device in order to telnet to the deviceC. To verify the type of cable interconnecting two devicesD. To verify Layer 2 connectivity between two devices when Layer 3 failsE. To obtain VLAN information from directly connected swticehsF. To determine t

40、he status of the routing protocols between directly connected routersG. To support automatic network failover during outages正确答案：BDB,D 网络管理员输入router ospf 100命令，命令中数字100的作用是（）A.自治系统编号B.度量值C.进程IDD.管理距离正确答案：C 在该条路由信中，路由的度量值是多少（）R192.168.3.0/24120/10via192.168.2.2,00:00:30,Serial0/0A.5B.10C.24D.120正确答案：

41、B You are bringing up a new Ezonexam switch, and wish to connect it via a trunk to another switch from a different vendor, which uses the IEEE standard for the trunking method. When setting the encapsulation type on the trunk, what should you configure on the Cisco switch?ASwitch(config)# switchport

42、 trunk encapsulation islBSwitch(config)# switchport trunk encapsulation ietfCSwitch(config-if)# switchport trunk encapsulation islDSwitch(config-if)# switchport trunk encapsulation ietfESwitch(config-if)# switchport trunk encapsulation dot1q正确答案：E解析：Explanation:The only real choices for setting up s

43、witching trunks are ISL and 802.1Q. ISL is Cisco proprietary, while 802.1Q uses the IEEE defined standard for trunking between switches.To configure the 802.1Q standard, the keyword dot1q is used in Cisco switches.Incorrect Answers:A, B, D. These are not valid options in a Cisco switch.C. ISL is a C

44、isco proprietary method for setting up trunks, and will only work between Cisco switches. Ping命令和TCP/IP中哪一协议有关（）A.IGRPB.RIPC.ICMPD.RARP正确答案：C 把访问权限表应用到路由器端口的命令是：()A.permit access-list 101 outB.ip access-group 101 outC.apply access-list 101 outD.access-class 101 out正确答案：B A host computer has been cor

45、rectly configured with a static IP address, but the default gateway is incorrectly set. Which layer of the OSI model will be first affected by this configuration error?A. Layer 1B. Layer 2C. Layer 3D. Layer 4E. Layer 5F. Layer 6E. Layer 7正确答案：CC 解析：Explanation: IP Addressing and IP routing resides o

46、n the OSI Network layer, which is layer 3.2022思科认证历年真题和解答6卷 第4卷 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.RIPB.OSPFC.EIGRPD.IGRP正确答案：C What value is primarily used to determine which port becomes the root port on each nonroot switch in a spanning-tree topology?A. path costB. lowest p

47、ort MAC addressC. VTP revision numberD. highest port priority numberE. port priority number and MAC addressF. None of the above正确答案：AA 解析：Explanation:At the conclusion of the root bridge election process, the switches move on to selecting Root Ports. The Root Port of a bridge is the port that is closest to the Root Bridge in terms of Path Cost. Every non-Root Bridge must select one Root Port. Again, bridges use the concept of cost to measure closeness. As with some routing metrics, the measure of closeness using STP is not necessarily reflected by hop count. Specifically, bridges tra