2021思科认证历年真题6章.pdf

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1、2021思 科 认 证 历 年 真 题 6章 第 1章 什 么 命 令 允 许 你 查 看 RAM中 的 配 置()A.show startup-configB.show RAM-configC.show running-configD.show config正 确 答 案：C-台 运 行 O SPF的 路 由 器，它 的 两 个 正 常 工 作 的 接 口 一 个 属 于 区 域 0,另 一 个 属 于 区 域 9,并 且 重 分 布 5 条 静 态 路 由 进 入 OSPF,则 该 路 由 器 一 定 会 始 发 哪 些 L S A()A.Router LSA(T y p e=l)；B.N

2、etwork LSA(Type=2)；C.Network Summary LSA(Type=3)；D.ASBR Summary LSA(Type=4)；E.ASE xternal LSA(Type=5)；正 确 答 案：ACDEIP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 号 为()A.192.168.50.32B.192.168.80.64C192.168.50.96D.192.168.50.71正 确 答 案：B对 于 以 下 ACL语 句 描 述 正 确 的 是()RI(c o n fig)#ip

3、a c c e s s-l i s t sta n d a rd TELNETRI(c o n fig_std T ia c l)#p e rin it 192.168.4.2 0.0.0.0R1(c if ig)#1ine y ty 0 4RI(c o n fig-1 in e)#a c c e ss-c la s s TELNET inA.只 允 许 192.168.4.2的 数 据 流 穿 过 RIB.只 允 许 192.168.4.2 对 RI 进 行 TELNETC.只 允 许 192.168.4.2对 R I进 行 TELNET并 拒 绝 其 它 流 量 D.只 允 许 192.1

4、68.4.0/24网 段 的 数 据 流 穿 过 R1正 确 答 案：B要 显 示 由 产 品 ID和 路 由 器 序 列 号 组 成 的 唯 一 设 备 标 识 符，可 使 用 哪 个 命 令?()A.show licenseB.show license featureC.show license udiD.show version答 案：C2021思 科 认 证 历 年 真 题 6章 第 2 章 During the boot sequence,a Ezonexam 2800 series router needs to locateand load an operating system

5、.What is the default order the router uses to findan operating system?A.ROM,TFTP server,FlashB.Flash,TFTP server,ROMC.Flash,NVRAM,TFTP serverD.Flash,ROM,TFTP serverE.Flash,TFTP server,RAM正 确 答 案：B解 析：Explanation:BootinguptheRouter:CiscorouterscanbootCiscoIOSsoftwarefromtheselocations:!.Flashmemory2.

6、TFTPserver3.ROM(notfullCiscoIOS)Multiplesourceoptionsprovideflexibilityandfallbackalternatives.PPP验 证 可 选 的 验 证 方 式 有 0。A.MD5B.PAPC.CHAPDJPSec正 确 答 案：BCR IP路 由 协 议 每 隔()秒 进 行 路 由 更 新。A.30B.60C.120D.180正 确 答 案：A把 访 问 权 限 表 应 用 到 路 由 器 端 口 的 命 令 是：()A.permit access-list 101 outB.i p access-group 101 o

7、utC.apply access-list 101 outD.access-class 101 out正 确 答 案：B请 参 见 图 示 图 中 显 示 了 在 路 由 器 R 1上 发 出 show ip route命 令 后 的 输 出 对 于 发 往 192.168.1.5的 数 据 包，该 路 由 器 会 采 取 什 么 操 作()Ri#show ip rowteCodes:C-connected/S-s t a t ic，I-IGRf,R-RIP.M-Mobile B-B G FD-E1GFP,E X-extern al,0 OSIP,U-03”in tec areaVI 05FF

8、 V S SA extetn al type A,N2 OSFF V3SA extetn al type 2EI-OSPF external type 1.E2 O SFF external type 2,E G P1-IS-I34 LI-IS-I5 L2-IS-I3 la-IS-IS intK 3”-c g d id a s d ete u lt,U-pec-u9ec o-T-p eriod ic downloaded v ta tic tout*Getevay of 1 9 t te so c t is not se t17 2.1 6.0.0/2 4 i s subnetted/3 su

9、baetjS 172.16.1.0(1/0 v ia 172.16.2.2C 172.16.2.0 is d ic t c d y com ecttd,SetialO/O/OC 172.16.3.0 1*d iceccly com ected,FaJtEthernetO/0S 192.168.1.0/24 1/0 v ia 172.16.2.2S 192.168.2.0/24 i s d lz e c tly connecs%SKlal0/0/0Sw 0.0.0.0/0 i s d ite c c ly connected,FajtEthem ec0/05-A.它 会 丢 弃 数 据 包 B.

10、它 会 将 数 据 包 转 发 到 接 口 Serial 0/0/0c.它 会 通 过 路 由 协 议 为 数 据 包 确 定 路 由 D.它 会 将 数 据 包 转 发 到 默 认 网 关 正 确 答 案：B2021思 科 认 证 历 年 真 题 6章 第 3章 在 大 型 网 络 中 选 择 O SPF而 不 选 择 R IP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：ADThe network administrator has conf

11、igured port security on a Ezonexamswitch.Why would a network administrator configure port security on thisEzonexam device?A.To prevent unauthorized hosts from getting access to the LANB.To limit the number of Layer 2 broadcasts on a particular switch portC.To prevent unauthorized Telnet or SSH acces

12、s to a switch portD.To prevent the IP and MAC address of the switch and associated portsE.None 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 limitingand identifying MAC addresses of the stations allowed to access the port.Whenyou assi

13、gn secure MAC addresses to a secure port,the port does not forwardpackets with source addresses outside the group of defined addresses.If youlimit the number of secure MAC addresses to one and assign a single secureMAC address,the workstation attached to that port is assured the full bandwidthof the

14、 port.If a port is configured as a secure port and the maximum number of secure MACaddresses is reached,when the MAC address of a station attempting to accessthe port is different from any of the identified secure MAC addresses,a securityviolation occurs.Also,if a station with a secure MAC address c

15、onfigured orlearned on one secure port attempts to access another secure port,a violation isflagged.You need to configure an 802.IQ link on a Ezonexam switch.Whichcommands,when used together,would do this?(Select two answer choices)A.Switch(vlan)mode trunkB.Switch(config)switchport access mode trunk

16、C.Switch(config-if)switchport mode trunkD.Switch(config-if)switchport trunk encapsulation dotlqE.Switch(config)switchport access mode 1F.Switch(vlan)trunk encapsulation dotlq正 确 答 案：CDC,D 解 析：Explanation:Creating this trunk link is a two step process.First you have to set the switchportmode to trunk

17、,and then you configure the encapsulation.The giveaway on thisquestion is the fact that to create a trunk on an interface,you have to be ininterface configuration mode.So switchport mode trunk sets the trunk,andswitchport trunk encapsulation dotlq sets the encapsulation.You need to decide on which t

18、runking method to implement in theEzonexam network.What is a characteristic of ISL and 802.1q frame,tagging in aswitched LAN environment?A.They are used to find the best path through a network.B.They allow the exchange of filtering tables.C.They specify different implementations of the Spanning-Tree

19、 Protocol.D.They allow the exchange of routing tablesE.They provide inter-switch VLAN communication.正 确 答 案：E解 析:Explanation:A trunk link is the other type of Layer 2 port supported onCisco switches.When a trunk port is configured,it begins marking frames as theyexit the port to indicate which VLAN

20、each frame,is associated with.The trunk port can also read the markings,called tags,as they enter the trunkport.This enables the switch to send a frame,only to the ports for the givenVLAN associated with the incoming frame.The main purpose of trunking is tocarry traffic between switches and maintain

21、 the VLAN information.Unlike an access link,the trunk link does not belong to a single VLAN but insteadcan carry traffic from several VLANs over a point-to-point link between twodevices that understand the protocol.Two forms of trunking are used for Ciscoswitches on Ethernet networks:An IEEE industr

22、y standard called IEEE 802.IQ.This is a frame-tagging mechanism that adds a VLAN identifier to the frame.byinserting a tag at Layer 2.Another form.of trunking on Cisco switches is calledInter-Switch Link QSL),which is a Cisco proprietary trunking mechanism.ISL usesa frame.encapsulation method that a

23、dds a header to identify the VLAN.Incorrect Answers:A,D.These are the functions of routers,not switches.B.Filtering tables can be used on certain Catalyst switches via the use of VLANaccess control lists,but this information is never shared between switches.C.A separate STP instance is created for e

24、ach VLAN；but the STP implementationremains the same.要 确 保 交 换 机 成 为 VLAN30的 根 网 桥，可 使 用 下 面 哪 两 个 命 令 之 一?()A.spanning-tree vlan 30 priority 0B.spanning-tree vlan 30 priority 16384C.spanning-tree vlan 30 root guaranteeD.spanning-tree vlan 30 root primary答 案：AD2021思 科 认 证 历 年 真 题 6章 第 4 章 命 令 ip nat

25、pool aaa 192.1.1.2 192.1.1.10 netmask 255.255.255.0 的 作 用 是()A.指 定 可 访 问 地 址 B.定 义 地 址 池 C.指 定 路 由 D.定 义 哪 些 地 址 可 以 进 行 地 址 转 换 正 确 答 案：BYou want to influence the root bridge selection within the Ezonexam LAN.Which two values are used by spanning tree protocol to elect a root bridge?(Choose two.)A.

26、Amount of RAMB.Speed of the linksC.IOS VersionD.MAC AddressE.Bridge PriorityF.IP AddressG.Router ID正 确 答 案：DED,EA receiving host has failed to receive all of the segments that it shouldacknowledge.What can the host do to improve the reliability of this communicationsession?A.Start a new session usin

27、g UDPB.Obtain a new IP address from the DHCP serverC.Use a different source port for the sessionD.Decrease the sequence numberE.Decrease the window size正 确 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 be

28、fore it gets anacknowledgment 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 has a TCPwindow size of 64 KB(kilobytes),the sender can only send 64 KB of data and thenit must stop and wait for an acknowledgment from the receiv

29、er that some or allof the data has been received.If the receiver acknowledges that all the data hasbeen received then the sender is free to send another 64 KB.One way to improve the reliability of the TCP connection is to reduce the windowsize that the receiver needs to receive before sending an ack

30、nowledgement.However,this will reduce throughput as more segments and acknowledgementswill need to be sent in order to transfer the same amount of data.介 质 工 作 在 O SI的 哪 一 层（）A物 理 层 B.数 据 链 路 层 C.网 络 层 D.传 输 层 正 确 答 案：A请 参 见 图 示。公 司 的 新 安 全 策 略 允 许 来 自 工 程 部 LAN的 所 有 IP流 量 访 问 Internet,但 对 于 来 自 营 销

31、 部 LAN的 流 量，则 只 允 许 其 中 的 w eb流 量 访 问 Internet,.为 实 施 新 的 安 全 策 略，可 在 营 销 部 路 由 器 的 SerialO/1接 口 的 出 站 方 向 上 应 用 哪 一 ACLQA.access-list 197 permit ip 192.0.2.0 0.0.0.255 any access-list 197 permit ip198.18.112.0 0.0.0.255 any eq wwwB.access-list 165 permit ip 192.0.2.0 0.0.0.255 any access-list 165 p

32、ermit tcp198.18.112.0 0.0.0.255 any eq www access-list 165 permit ip any anyC.access-list 137 permit ip 192.0.2.0 0.0.0.255 any access-list 137 permit tcp198.18.112.0 0.0.0.255 any eq wwwD.access-list 89 permit 192.0.2.0 0.0.0.255 any access-list 89 permit tcp198.18.112.0 0.0.0.255 any eq www正 确 答 案

33、：C2021思 科 认 证 历 年 真 题 6章 第 5章 R IP的 管 理 距 离 为()。A.0B.lC.110D.120正 确 答 案：D你 使 用 命 令 copy running-config startup-config保 存 路 由 器 的 配 置，并 重 启 路 由 器，但 路 由 器 启 动 后 没 有 任 何 运 行 配 置。请 问 可 能 出 现 了 什 么 问 题?()A.启 动 路 由 器 时 使 用 的 命 令 不 对 B.NVRAM 受 损 G配 置 寄 存 器 的 设 置 不 正 确 D.新 升 级 到 的 IO S与 路 由 器 硬 件 不 兼 容 E.保

34、存 的 配 置 与 硬 件 不 兼 容 答 案：C下 列 对 访 问 控 制 列 表 的 描 述 不 正 确 的 是()。A.访 问 控 制 列 表 能 决 定 数 据 是 否 可 以 到 达 某 处 B.访 问 控 制 列 表 可 以 用 来 定 义 某 些 过 滤 器 C.一 旦 定 义 了 访 问 控 制 列 表，则 其 所 规 范 的 某 些 数 据 包 就 会 严 格 被 允 许 或 拒 绝D.访 问 控 制 列 表 可 以 应 用 于 路 由 更 新 的 过 程 当 中 正 确 答 案：D基 本 IP访 问 权 限 表 的 表 号 范 围 是：（）A.1100B.1-99C.100

35、-199D.800-899正 确 答 案：BAt which OSI layer is a logical path created between two host systems namedVE1 and VE2 on the Ezonexam LAN?A.PhysicalB.SessionC.Data linkD.TransportE.NetworkF.ApplicationG.Presentation正 确 答 案：EE2021思 科 认 证 历 年 真 题 6章 第 6 章 The Ezonexam network administrator needs to a switch na

36、med VE1 tobecome the root bridge for a redundant path switched network.What can bedone to ensure that VE1 will always assume the role as the root bridge?A.Assign the switch a higher MAC address than the other switches in thenetwork haveB.Establish a direct link from the switch to all other switches

37、in the networkC.Configure the switch full-duplex operation and configure the otherswitches for half-duplex operationD Configure the switch so that it has lower priority than other switches inthe networkE.None of the above正 确 答 案：DA Ezonexam switch is configured with all ports assigned to VLAN 2.Inad

38、dition,all ports are configured as full-duplex FastEthernet.What is the effect ofadding switch ports to a new VLAN on this switch?A.The additions will create more collisions domains.B.IP address utilization will be more efficient.C.More bandwidth will be required than was needed previously.D.An addi

39、tional broadcast domain will be created.E.The possibility that switching loops will occur will increase dramatically.正 确 答 案：D解 析：Explanation:A VLAN is a group of hosts with a common set of requirements thatcommunicate as if they were attached to the same wire,regardless of theirphysical location.A

40、VLAN has the same attributes as a physical LAN,but it allowsfor end stations to be grouped together even if they are not located on the sameLAN segment.Networks that use the campus-wide or end-to-end VLANs logically segment aswitched network based on the functions of an organization,project teams,or

41、applications rather than on a physical or geographical basis.For example,allworkstations and servers used by a particular workgroup can be connected to thesame VLAN,regardless of their physical network connections or interaction withother workgroups.Network reconfiguration can be done through softwa

42、re instead of physicallyrelocating devices.Cisco recommends the use of local or geographic VLANs thatsegment the network based on IP subnets.Each wiring closet switch is on its ownVLAN or subnet and traffic between each switch is routed by the router.Thereasons for the Distribution Layer 3 switch an

43、d examples of a larger networkusing both the campus-wide and local VLAN models will be discussed later.A VLAN can be thought of as a broadcast domain that exists within a defined setof switches.Ports on a switch can be grouped into VLANs in order to limitunicast multicast,and broadcast traffic flood

44、ing.Flooded traffic originating froma particular VLAN is only flooded out ports belonging to that VLAN,includingtrunk ports,so a switch that connects to another switch will normally introducean additional broadcast domain.ICMP is often used in troubleshooting and verifying network.Whatstatements are

45、 true regarding ICMP packets?(Choose two)A.They acknowledge receipt of TCP segments.B.They guarantee datagram delivery.C.They can provide hosts with information about network problems.D.They are encapsulated within IP datagrams.E.They are encapsulated within UDP datagrams.F.They are encapsulated wit

46、hin TCP datagrams.正 确 答 案：CDC,D 解 析：Explanation:ping may be used to find out whether the local machines are connected to thenetwork or whether a remote site is reachable.This tool is a common networktool for determining the network connectivity which uses ICMP protocol insteadof TCP/IP and UDP/IP.Th

47、is protocol is usually associated with the networkmanagement tools which provide network information to network administrators,such as ping and traceroute(the later also uses the UDP/IP protocol).ICMP is quite different from the TCP/IP and UDP/IP protocols.No source anddestination ports are included

48、 in its packets.Therefore,usual packet-filteringrules for TCP/IP and UDP/IP are not applicable.Fortunately,a special signatureknown as the packets Message type is included for denoting the purposes of theICMP packet.Most commonly used message types are namely,0,3,4,5,8,11,and 12 which represent echo

49、 reply,destination unreachable,source quench,redirect,echo request,time exceeded,and parameter problem respectively.Incorrect AnswersICMP is an IP protocol so A and E are incorrect.ICMP doesnt guarantee datagram delivery so B is wrong as well.You are an administrator of the Ezonexam switched network

50、 and your goal isto reduce some of the administrative overhead on your network.You plan onachieving this by configuring a new VLAN for each department in the Ezonexamnetwork.However,you need to share the VLAN information across numerousswitches.Which of the following would allow you accomplish this?