思科认证考试真题5节.docx

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1、思科认证考试真题5节思科认证考试真题5节 第1节 为查看控制器状态，你需要输入哪个命令?（）A.show running-configB.show startup-configC.show versionD.show controllers正确答案：D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disableD.使用命令license clear将许可证清除答案：CD 扩展ACL和标准ACL的区别（）。A.标准的ACL在禁止和允许方面比扩展的ACL更高的精度B.扩展的ACL核查数据包的

2、源地址和目标地址和端口号C.他们都可以查端口号D.他们都可以查特殊协议和其他参数正确答案：B 以下哪些路由表项要由网络治理员手动配置()A.静态路由B.直接路由C.动态路由D.以上说法都不正确正确答案：A 距离-向量路由算法最优路径计算的复杂度要比链路-状态路由算法最优路径计算的复杂度大。此题为判断题(对，错)。正确答案： 路由器重新启动并进入设置模式。此问题的原因是什么（）A.IOS映像损坏B.闪存中缺少CiscoIOSC.NVRAM中缺少配置文件D.POST过程检测到硬件故障正确答案：C Which of the following are types of flow control? (

3、Choose three)ABufferingBCut-throughCWindowingDCongestion avoidanceELoad balancing正确答案：ACD解析：Explanation:Datatransmissionflowcontroloccursatlayer4withthehelpofbuffering,windowingandcongestionavoidance. An administrator would like to configure a switch over a virtual terminal connection from locations

4、 outside of the local LAN. Which of the following are required in order for the switch to be configured from a remote location? (Choose two)A. The switch must be reachable through a port connected to its management VLAN.B. The switch console port must be connected to the Ethernet LAN.C. The switch m

5、ust be fully configured as an SNMP agent.D. The switch must be configured with an IP address, subnet mask, and default gateway.E. The switch management VLAN must be created and have a membership of at least one switch port.F. The switch must be connected to a router over a VLAN trunk.正确答案：ADA,D 解析：E

6、xplanation:In order the telnet to any Cisco device, the device must be reachable from the remote location. For a Cisco switch to be reachable from remote locations, it must have an IP address, subnet mask, and default gateway assigned.Communication with the switch management interfaces is through th

7、e switch IP address.The IP address is associated with the management VLAN, which by default is VLAN 1思科认证考试真题5节 第2节 A Ezonexam Ethernet switch receives a unicast frame. with a destination MAC that is listed in the switch table. What will this switch do with the frame?A. The switch will forward the f

8、rame. to a specific portB. The switch will forward the frame. to all ports except the port on which it was receivedC. The switch will return a copy of the frame. out the source portD. The switch will not forward unicast framesE. The switch will remove the destination MAC from the switch tableF. None

9、 of the above.正确答案：AA 解析：Explanation:How Does the Switch Find Host MACs?Lets use the diagram below to help us understand how address learning process takes place.Lets assume that we have just powered on the switch. It has nothing in its MAC table. We connect the cables from the hosts on the switch i

10、nterfaces as shown in the diagram. Host A initiates a connection towards Host D, and the following takes place:1. Host A (interface fe0/0) sends a frame. to Host D (MAC address:0000.43c5.334c).2. The switch inspects the Source Address in the frame. and notes in its table the MAC address of Host A al

11、ong with the Interface number from which the frame. originated.3. The switch inspects the Destination Address in the frame. Since it does not have Hosts D MAC address in its table, it constructs a broadcast frame. and forwards out all interfaces except the interface from where the original frame. ar

12、rived.4. Host D identifies itself as the expected recipient and responds back to Host A. The switch receives the respond frame. on interface fe0/11 and places the SA in its table along with the interface number where the frame. came from.5. From now on, further communication between the two hosts wi

13、ll be switched to the appropriate interfaces based on the MAC tables entries.This process takes place every time a new host is attached on the switch and initiates traffic. The switch tries to keep its MAC table up-to-date, therefore if some hosts do not initiate traffic for a certain amount of time

14、, the switch removes them from its table and reinserts them when they begin sending traffic. A host computer has been correctly 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

15、. 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 on the OSI Network layer, which is layer 3. 缺省路由是最后一条被使用的特殊的静态路由。此题为判断题(对，错)。正确答案： 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 什么时候选用PPP而不选用HDLC作为串行线路的二层封装（）A.工作在多厂商环境中B

16、.工作在纯Cisco设备环境中C.需要在同一个线路上同时传输IP和IPX协议时D.必须配置CHAP时正确答案：AD 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 What is the subnet for the host IP address 201.100.5.68/28?A. 201.100.5.0B. 201.100.5.32C. 201.100.5.64D. 201.100.5.65E. 201.100.5.31F. 201.100.5.1正确答案：CC 解析

17、：Explanation:This question is much easier then it appears when you convert it to binary and do the Boolean operation as shown below:IP address 201.100.5.68 = 11001001.01100100.00000101.01000100/28 mask = 11111111.11111111.11111111.11000000AND result = 11001001.01100100.00000101.01000000AND in decima

18、l= 200. 100. 5. 64 如果一个内部网络对外的出口只有一个，那么最好配置()A.缺省路由B.主机路由C.动态路由D.静态路由正确答案：A思科认证考试真题5节 第3节 What is the maximum number of IP addresses that can be assigned to hosts on a Ezonexam subnet that uses the 255.255.255.224 subnet mask?A. 14B. 15C. 16D. 30E. 31F. 32正确答案：DD 解析：Explanation:The subnet mask 255.2

19、55.255.224 means that there are 27 network bits. The remaining 5 bits are the host bits. The maximum possible combinations with 5 bits are 25 = 32. As all zeros and all ones hosts are not allowed so, maximum number of valid hosts with the mask 255.255.255.224 are 25 -2 =32-2 = 30 Hosts You need to c

20、onfigure an 802.1Q link on a Ezonexam switch. Which commands, when used together, would do this? (Select two answer choices)A. Switch(vlan) mode trunkB. Switch(config) switchport access mode trunkC. Switch(config-if) switchport mode trunkD. Switch(config-if) switchport trunk encapsulation dot1qE. Sw

21、itch(config) switchport access mode 1F. Switch(vlan) trunk encapsulation dot1q正确答案：CDC,D 解析：Explanation:Creating this trunk link is a two step process. First you have to set the switchport mode to trunk, and then you configure the encapsulation. The giveaway on this question is the fact that to crea

22、te a trunk on an interface, you have to be in interface configuration mode. So switchport mode trunk sets the trunk, and switchport trunk encapsulation dot1q sets the encapsulation. Which fields are included in the TCP header? (Choose three).A. Source PortB. Acknowledgement NumberC. Request NumberD.

23、 Destination AddressE. WindowF. Data正确答案：ABEA,B,E 解析：Explanation:TCP header:Source Port: 16 bits.Destination Port: 16 bits.Sequence Number: 32 bits.The sequence number of the first data byte in this segment. If the SYN bit is set, the sequence number is the initial sequence number and the first data

24、 byte is initial sequence number + 1.Acknowledgment Number: 32 bits.If the ACK bit is set, this field contains the value of the next sequence number the sender of the segment is expecting to receive. Once a connection is established this is always sent.Data Offset: 4 bits.The number of 32-bit words

25、in the TCP header. This indicates where the data begins. The length of the TCP header is always a multiple of 32 bits.Reserved: 3 bits.Must be cleared to zero.ECN, Explicit Congestion Notification: 3 bits.Added in RFC 3168.Control Bits: 6 bits.Window: 16 bits, unsigned.The number of data bytes begin

26、ning with the one indicated in the acknowledgment field which the sender of this segment is willing to accept.Checksum: 16 bits.This is computed as the 16-bit ones complement of the ones complement sum of a pseudo header of information from the IP header, the TCP header, and the data, padded as need

27、ed with zero bytes at the end to make a multiple of two bytes.Urgent Pointer: 16 bits, unsigned.If the URG bit is set, this field points to the sequence number of the last byte in a sequence of urgent data.Options: 0 to 44 bytes.Options occupy space at the end of the TCP header. All options are incl

28、uded in the checksum. An option may begin on any byte boundary. The TCP header must be padded with zeros to make the header length a multiple of 32 bits.Data: Variable length. Assuming you build networks to exact specifications, what is the recommended maximum length a 10BaseT cable can be before it

29、 has to be segmented or repeated?A100 metersB100 feetC100 yardsD200 metersENone of the above正确答案：A解析：Explanation:The distance standards are in meters and 10BaseT has a distance restriction of 100 meters. If you go further then that, you compromise data integrity. 10BastT is the predominant cable typ

30、e used in Ethernet networks. 在相距几百英里的路由器之间使用租用线路的点到点WAN链路上，下列哪个设备室DTE设备A.路由器B.CSU/DSUC.电话局中心机房设备D.路由器处理器上的芯片正确答案：A Which VTP mode should a Cisco switch be set to if this switch is to add or delete VLANs to a management domain?ATransparentBServerCAutoDClientEUser正确答案：B解析：Explanation:VTPModes:Ifyouint

31、endtomakeaswitchpartofaVTPmanagementdomain,eachswitchmustbeconfiguredinoneofthreepossibleVTPmodes.TheVTPmodeassignedtoaswitchwilldeterminehowtheswitchinteractswithotherVTPswitchesinthemanagementdomain.ThethreeVTPmodesthatcanbeassignedtoaCiscoswitchincludeservermode,clientmode,andtransparentmode.Each

32、oftheserolesisoutlinedbelow:ServerMode:OnceVTPisconfiguredonaCiscoswitch,thedefaultmodeusedisServerMode.InanygivenVTPmanagementdomain,atleastoneswitchmustbeinServerMode.WheninServerMode,aswitchcanbeusedtoadd,delete,andmodifyVLANs,andthisinformationwillbepassedtoallotherswitchesintheVTPmanagementdoma

33、in.ClientMode:WhenaswitchisconfiguredtouseVTPClientMode,itissimplytherecipientofanyVLANsadded,deleted,ormodifiedbyaswitchinServerModewithinthesamemanagementdomain.AswitchinVTPclientmodecannotmakeanychangestoVLANinformation.TransparentMode:AswitchinVTPTransparentModewillpassVTPupdatesreceivedbyswitch

34、esinServerModetootherswitchesintheVTPmanagementdomain,butwillnotactuallyprocessthecontentsofthesemessages.WhenindividualVLANsareadded,deleted,ormodifiedonaswitchrunningintransparentmode,thechangesarelocaltothatparticularswitchonly,andarenotpassedtootherswitchesintheVTPmanagementdomain.Basedontherole

35、sofeachVTPmode,theuseofeachshouldbemoreorlessobvious.Forexample,ifyouhad15Ciscoswitchesonyournetwork,youcouldconfigureeachofthemtobeinthesameVTPmanagementdomain.AlthougheachcouldtheoreticallybeleftinthedefaultServerMode,itwouldprobablybeeasiertoleaveonlyoneswitchinthisconfiguration,andthenconfigurea

36、llremainingswitchesforVTPClientMode.Then,whenyouneedtoadd,delete,ormodifyaVLAN,thatchangecanbecarriedoutontheVTPServerModeswitchandpassedtoallClientModeswitchesautomatically.Incaseswhereyouneedaswitchtoactinarelativelystandalonemanner,ordonotwantittopropagateinformationaboutitsconfiguredVLANs,useTra

37、nsparentMode.IncorrectAnswers:A.AswitchinVTPTransparentModewillpassVTPupdatesreceivedbyswitchesinServerModetootherswitchesintheVTPmanagementdomain,butwillnotactuallyprocessthecontentsofthesemessages.C,E.ThesearenotvalidVTPmodes.D.ClientmodemerelyacceptschangesmadebytheswitchthatisconnectedandinSERVE

38、Rmode. 子网172.16.0.0/22有（）个可用的IP地址A.1022B.1024C.256D.254正确答案：A You are a senior network administrator at Ezonexam, and while performing the password recovery procedure on your 2500 series Cisco router, you type in the following command:o/r 0x2142What is the purpose of this command?AIt is used to rest

39、art the router.BIt is used to bypass the configuration in NVRAM.CIt is used to enter ROM Monitor mode.DIt is used to view the lost password.EIt is used to save the changes to the configuration.正确答案：B解析：Explanation:Theo/r 0x2142 command changes the value of config-register to 2142 in a Cisco 2500 ser

40、ies router, so that the Router ignores the NVRAM contents and reverts to the initial setup configuration mode when it boots.思科认证考试真题5节 第4节 下列哪项对OSI第1层协议主要功能的描述最准确（）A.成帧B.将比特从一台设备传递到另一台设备C.编址D.DLCI正确答案：B OSI物理层定义了用于创建物理网络以及通过物理网络发送比特的标准和协议。此题为判断题(对，错)。正确答案： Which of the following a true statements re

41、garding the use of VLANs to segment a network? (Select three)A. They increase the size of collision domainsB. They allow logical grouping of users by function.C. They can enhance network security.D. They increase the size of the broadcast domain while decreasing the number of collision domains.E. Th

42、ey increase the number of broadcast domains while decreasing the size of the broadcast domains.F. They simplify switch administration.正确答案：BCEB,C,E 解析：Explanation:VLANs are used to segment a LAN into multiple, smaller LANs. This can be used to enhance security as local traffic from one VLAN will not

43、 be passed to users in other VLANS.Incorrect Answers:A. VLANs are used to decrease the size of a collision domain, not increase it.D. The opposite is true.F. The default operation of a switch is to allow all traffic and to enable all ports in VLAN1. The use of VLANs will increase the complexity of t

44、he switch environment, making for more difficult administration.在哪种情况下,可能在交换型LAN中传输单播帧的多个副本?()A.流量很高时B.断开的链路重建后C.上层协议要求可靠性极高时D.未妥善实现冗余拓扑时答案：D 路由器上激活端口的命令是（）A.shutdownB.no shutdownC.upD.noup正确答案：B Which one of the following protocols allows the information about the configuration of a new VLAN to be

45、distributed across entire switched network?A. STPB. VTPC. EIGRPD. SNMPE. CDPF. None of the above正确答案：BB 解析：Explanation:Sybex CCNA Study Guide 4th Edition states on page 359:The basic goals of VLAN Trunking Protocol (VTP) are to manage all configured VLANs across a switched internetwork and to mainta

46、in consistency throughout that network. VTP allows an administrator to add, delete, and rename VLANs-information that is then propagated to all other switches in the VTP domain.Incorrect Answers:A. STP is the Spanning Tree Protocol, used to prevent bridging loops in a LAN.C. EIGRP is a routing proto

47、col used to exchange routing information, not VLAN information.D. SNMP is the Simple Network Management Protocol, used to provide information to remote network management stations.E. CDP is the Cisco Discovery Protocol, which is used to exchange information between Cisco devices. It can only be used between Cisco routers and switches. 在RIP路由协议中，以下有关减少路由自环的方法正确的是()A.触发更新是从减少路由自环发生的概率方面来考虑问题的B.水平分割的方法只对消除两台路由器之间的自环有作用C.设置抑制时间的方法可能导致路由的慢收敛D.为了减轻路由自环产生的后果，RIP协议规定了最大跳数正确答案：ABCD When files are transferred between a host and