CCNA 第二学期第九章答案

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思科考试第九章以太网答案

思科考试第九章以太⽹答案Cisco 考试第九章以太⽹答案CISCO考试2010-06-17 09:49:42 阅读219 评论0 字号：⼤中⼩1.将⼆进制数字10111010 转换为等值的⼗六进制数字。

请从下⾯选择正确的答案。

8590BAA1B31C2.以下哪些选项描述的是帧间隙？（选择两项）任何站点在发送另⼀帧前必须等待的最短时间间隔，以⽐特时间为测量单位任何站点在发送另⼀帧前必须等待的最长时间间隔，以⽐特时间为测量单位插⼊帧中的96 位负载填充位，⽤于使其达到合法的帧⼤⼩帧之间传输的96 位帧填充位，⽤于实现正确同步可以让速度较慢的站点处理帧并准备下⼀帧的时间站点在发送另⼀帧前不得超过的最长时间间隔，否则将视其为⽆法到达3.采⽤CSMA/CD 的⽹络中发⽣冲突时，需要传输数据的主机在回退时间到期后做何反应？主机恢复传输前侦听模式。

造成冲突的主机优先发送数据。

造成冲突的主机重新传输最后16 个帧。

主机延长其延迟时间以便快速传输。

4.发⽣以太⽹冲突之后调⽤回退算法时，哪种设备优先传输数据？涉⼊冲突的设备中MAC 地址最⼩的设备涉⼊冲突的设备中IP 地址最⼩的设备冲突域中回退计时器⾸先过期的任何设备同时开始传输的设备5.以下哪项是CSMA/CD 访问⽅法的缺点？冲突会降低⽹络性能。

⽐⾮确定性协议复杂。

确定性介质访问协议会减慢⽹络速度。

CSMA/CD LAN 技术只能以低于其它LAN技术的速度提供。

6.请参见图⽰。

交换机和⼯作站已针对全双⼯操作进⾏了管理配置。

下列哪项陈述准确反映了此链路的运⾏？此链路不会发⽣冲突。

每次只有⼀台设备能够传输。

交换机将优先传输数据。

如果发⽣过多冲突，设备将默认恢复半双⼯操作。

7.以太⽹⽹段中的主机发⽣冲突时，为何要在尝试传输帧之前随机延迟？随机延迟旨在确保⽆冲突链路。

每台设备的随机延迟值由制造商指定。

⽹络设备⼚商之间⽆法就标准的延迟值达成⼀致。

随机延迟有助于防⽌站点在传输期间再次发⽣冲突。

-最新+CCNA第二学期章节测试++第十章+答案

1.请参见图示。

网络192.168.0.0/28 断开。

Router2 会立即向Router1 和Router3 发送什么类型的数据包？查询网络192.168.0.0/28 的查询数据包到224.0.0.9 的确认数据包发送到255.255.255.255 的更新数据包包含R2 新路由表的数据包发送到192.168.1.1 和192.168.2.1 的单播更新数据包2.哪两种事件将会导致链路状态路由器向所有邻居发送LSP？（选择两项。

）30 秒计时器超时网络拓扑结构发生变化时运行贝尔曼-福特算法之后立即发送DUAL FSM 建立拓扑数据库之后立即发送路由器或路由协议初次启动时3.链路状态路由过程的最后一步是什么？将后继路由加入路由表中SPF 计算到达每个目的网络的最佳路径向所有邻居发送LSP 以收敛网络运行DUAL 算法以找出到达目的网络的最佳路径4.哪两项陈述正确描述了链路状态路由过程？（选择两项。

）区域中的所有路由器都有链路状态数据库区域中的每个路由器都将向所有邻居发送LSPLSP 使用保留的组播地址224.0.0.10 来访问邻居通过运行扩散更新算法(DUAL) 来防止路由环路可靠传输协议(RTP) 是用于发送和接收LSP 的协议5.请参见图示。

在从路由器JAX 发送到路由器ATL 的LSP 中，可以看到哪种类型的信息？跳数路由的正常运行时间链路的开销正在使用的所有路由协议的列表6.现代链路状态协议通过哪些功能来尽可能降低处理器和内存要求？将路由拓扑结构分割成更小的区域为路由计算分配较低的处理优先级使用更新计时器限制路由更新严格执行水平分割规则以减少路由表条目7.为使网络达到收敛，每台链路状态路由器会执行哪三个步骤？（选择三项。

）使用自动总结缩小路由表大小构建一个链路状态数据包(LSP)，其中包含每条直连链路的状态向所有邻居发送LSP，邻居随后把接收到的所有LSP 存储到数据库中按一定时间间隔发送Hello 数据包来发现邻居并建立相邻关系构建完整的拓扑图并计算到达每个目的网络的最佳路径使用DUAL FSM 选择有效且无环路的路径，并将路由插入到路由表中8.在使用链路状态路由的网络中，什么可以加速收敛过程？由网络变更触发的更新按固定间隔发送的更新仅发送给直连邻居的更新包含完整路由表的更新9.为什么使用链路状态路由的网络中很少发生路由环路？每台路由器都根据跳数建立起对网络的直观印象。

CCNA认证基础课程-课后作业.习题答案

CCNA认证基础-习题分析讲义第一部分第一章1. Convert the binary number 10111010 into its hexadecimal equivalent. Select thecorrect answer from the list below. （3）1) 852) 903) BA4) A15) B36) 1C2. Convert the Hexadecimal number A2 into its Base 10 equivalent. Select thecorrect answer from the list below. （4）1) 1562) 1583) 1604) 1625) 1646) 1663. Which binary number is a representation of the decimal number 248? （3）1) 111010002) 111101003) 111110004) 111110104. Which of the following will test the internal loopback of a node? （3）1) ping 10.10.10.12) ping 192.168.1.13) ping 127.0.0.14) ping 223.223.223.2235) ping 255.255.255.2555. What can be verified by successfully pinging the reserved loopback address ona host? （2）1) Connectivity exists between two hosts on the LAN.2) The TCP/IP stack of the local host is configured correctly.3) A connection exists between a host and the default gateway.4) The route a packet takes from the local host to a remote host is valid.6. Which of the following commands could be used on a Windows-basedcomputer to view the current IP configuration of the system? (Choose two.) （3，4）1) configip2) ifconfig3) ipconfig4) winipcfg5) Winipconfig7.Refer to the exhibit. What must be configured on Host B to allow it to communicate withthe Host C? (Choose three.) （2，4，6）1)the MAC address of RTA router interface connected to Switch 12) a unique host IP address3)the IP address of Switch 14)the default gateway address5)the MAC address of Host C6)the subnet mask for the LAN8. What are important characteristics to consider when purchasing a networkinterface card? (Choose two.) （2，3）1) security used on the network2) media used on the network3) system bus used on the computer4) software installed on the network5) diagnostic tools installed on the network第二章1. Select the necessary information that is required to compute the estimated timeit would take to transfer data from one location to another. (Choose two.) （1，5）1) file size2) data format3) network in use4) type of medium5) bandwidth of the link2. Using the data transfer calculation T=S/BW, how long would it take a 4MB file tobe sent over a 1.5Mbps connection? （2）1) 52.2 seconds2) 21.3 seconds3) 6.4 seconds4) 2 seconds5) 0.075 seconds6) 0.0375 seconds3. What are features of the TCP/IP Transport layer? (Choose two.) （3，5）1) path determination2) handles representation, encoding and dialog control3) uses TCP and UDP protocols4) packet switching5) reliability, flow control and error correction4. Which of the following is the Layer 4 PDU? （4）1) bit2) frame3) packet4) Segment5. What is important to remember about the data link layer of the OSI model whenconsidering Peer to Peer communication? (Choose three.) （3，4，5）1) It links data to the transport layer.2) It encapsulates frames into packets.3) It provides a service to the network layer.4) It encapsulates the network layer information into a frame.5) Its header contains a physical address which is required to complete the datalink functions.6) It encodes the data link frame into a pattern of 1s and 0s (bits) for transmissionon the medium.6. Which statement describes a star topology? （2）1) Each host in the network is connected to a backbone cable that is terminated atboth ends.2) Each host is connected to a hub or switch, either of which acts as a central pointfor all network connections.3) Each host is directly connected to two other hosts to form a long chain of hosts.4) Each host has a connection to all other hosts in the network.7. Which statements describe the logical token-passing topology? (Choose two.)（2）1) Network usage is on a first come, first serve basis.2) Computers are allowed to transmit data only when they possess a token.3) Data from a host is received by all other hosts. Electronic tokens are passedsequentially to each other.4) Token passing networks have problems with high collision rates.8. Which technologies are considered to be LAN technologies? (Choose two.) （2，5）1) DSL2) Token Ring3) Frame Relay4) ISDN5) Ethernet9.Refer to the exhibit. Host A wants to send a message to host B. Place the following stepsin the correct order so that the message can be sent. （4）A - add network layer addressesB - transmit bitsC - create application dataD - add data link layer addresses1) B, A, D, C2) D, A, C, B3) A, D, A, B4) C, A, D, B5) C, D, A, B6) C, B, A, D10.After an uns u ccessful ping to the local router, the technician decides to investigate therouter. The technician observes that the lights and fan on the router are not operational.In which layer of the OSI model is the problem most likely occurring? （4）1) transport2) network3) data link4) physical11. Refer t o the exhibit. What is the order of the TCP/IP Protocol Data Units as datais moved as indicated through the OSI model? （3）1) data, segments, frames, packets, bits2) data, packets, segments, frames, bits3) data, segments, packets, frames, bits4) data, packets, frames, segments, bits第三章1. Which combinations of charges will be repelled by electric force? (Choose two.)（4，6）1) neutral and neutral2) neutral and positive3) neutral and negative4) positive and positive5) positive and negative6) negative and negative2. Which of the following are considered the best media for use in data networkcommunications? (Choose three.) （2，3，6）1) glass2) fibers3) copper4) gold5) plastic6) silicon7) Silver3. Which of the following wireless standards increased transmission capabilitiesto 11 Mbps? （2）1) 802.11a2) 802.11b3) 802.11c4) 802.11d4. What is attenuation? （3）1) opposition to the flow of current2) measurement of electrical signals relative to time3) degradation of a signal as it travels along the medium4) amount or volume of traffic that is flowing on the medium5. Which cable specifications are indicated by 10BASE-T? （3）1) 10 Mbps transmission speed, baseband signal, 500 meter cable length, coaxialcable2) 10 Mbps transmission speed, broadband signal, 100 meter cable length, coaxialcable3) 10 Mbps transmission speed, baseband signal, 100 meter cable length,twisted-pair cable4) 10 Gbps transmission speed, broadband signal, 500 meter cable length,twisted-pair cable6. For which Ethernet installations would fiber optic rather than Cat5 UTP be abetter media choice? (Choose two.) （2，4）1) a 3 meter connection between two 10BASE-T hubs2) an environment with many potential sources of EMI and RFI3) a peer to peer connection between two NICs with RJ45 connectors4) an installation between two buildings that are located 500 meters apart5) a single building installation where installation costs are the major concern7. Refer to the exhibit. Which type of UTP cable should be used to connect Host Ato Switch1? （4）1) rollover2) console3) crossover4) straight-through8. Refer to the exhibit. Which type of Category 5 cable is used to make an Ethernetconnection between Host A and Host B? （3）1) coax cable2) rollover cable3) crossover cable4) straight-through cable第四章1. During cable testing, which of the following are used to calculate theinformation carrying capacity of a data cable? (Choose two.) （2，5）1) bit speed2) attenuation3) wire map4) saturation limit5) analog bandwidth2. What type of wiring problem is depicted in this sample of a cable tester? （3）1) a fault2) a short3) an open4) a split a good map3. In a new network installation, the network administrator has decided to use amedium that is not affected by electrical noise. Which cable type will best meet this standard? （5）1) coaxial2) screened twisted pair3) shielded twisted pair4) unshielded twisted pair5) fiber optic4. How does network cable length affect attenuation? （3）1) Category 5 cable that is run in metal conduit has the highest attenuation in theshortest distance.2) Shorter cable lengths have greater signal attenuation.3) Longer cable lengths have greater signal attenuation.4) The length of the cable has no effect on signal attenuation.第五章1. The highest capacity Ethernet technologies should be implemented in whichareas of a network? (Choose three.) （3，4，5）1) between workstation and backbone switch2) between individual workstations3) between backbone switches4) between enterprise server and switch5) on aggregate access links2. What device must be used between an AUI port of a networking device and themedia to which it is being connected? （3）1) a transducer2) a transmitter3) a transceiver4) a transponder5) a port replicator3. An ISDN Basic Rate Interface (BRI) is composed of how many signalingchannels? （1）1) 12) 23) 34) 44. Which layer of the OSI model covers physical media? （1）1) Layer 12) Layer 23) Layer 34) Layer 45) Layer 56) Layer 65. What type of network cable is used between a terminal and a console port? （3）1) cross-over2) straight-through3) rollover4) patch cable6. What is the recommended maximum number of workstations configured on apeer-to-peer network? （3）1) 252) 153) 104) 55) 27. Which of the following increases the potential for a collision to occur? （4）1) the use of an active hub instead of an intelligent hub2) the use of an intelligent hub instead of an active hub3) a reduction in the number of devices attached to the hub4) an increase in the number of devices attached to the hub8. What is the maximum length of a media segment used for 100BASE-TX? （1）1) 100 meters2) 185 meters3) 400 meters4) 500 meters9. Which cable diagram displays the end to end pinout for a crossover cable usedwith Cisco devices? （3）1) Cable A2) Cable B3) Cable C4) Cable D第六章1. What does the "10" in 10Base2 indicate about this version of Ethernet? （2）1) The version uses Base10 numbering within the frames.2) The version operates at a transmission rate of 10 Mbps.3) Frames can travel 10 meters unrepeated.4) The maximum frame length is 10 octets.2. How is a MAC address represented? （4）1) four groups of eight binary digits separated by a decimal point2) four Base10 digits separated by a decimal point3) six hexadecimal digits4) twelve hexadecimal digits5) twenty-four Base10 digits3. Which of the following statements are correct about CSMA/CD? (Choose three.)（1，3，6）1) It is a media access method used in LANs.2) It is a media access method used in FDDI WANs.3) When a device needs to transmit, it checks to see if the media is available.4) A device sends data without checking media availability because all deviceshave equal access.5) Multiple devices can successfully transmit simultaneously.6) Only one device can successfully transmit at a time.4. Which devices shown in the graphic must have a MAC address? （5）1) only PC2) only router3) PC and router4) PC, hub, and router5) PC, printer, and router第七章1. Which of the following items are common to all 100BASE technologies?(Choose three.) （1，4，5）1) frame format2) media3) connectors4) timing5) multi-part encoding2. Which of the following does 1000BASE-T use to accomplish gigabit speeds onCat 5e cable? （4）1) the use of four conductors in full-duplex mode2) the use of two multiplexed pairs of wires, simultaneously3) the use of three pairs of wires for data and the fourth for stabilization andforward error correction4) the use of all four pairs of wires in full-duplex mode, simultaneously3. For which of the following is Ethernet considered the standard? (Choose three.)（1，4，5）1) inter-building connection2) mid-length voice3) video conferencing4) vertical wiring5) horizontal wiring6) diagonal wiring4. To make sure timing limitations are not violated when implementing a 10 MbpsEthernet network involving hubs or repeaters, a technician should adhere to which rule? （4）1) the 4-5-3 rule2) the 6-4-2 rule3) the 3-4-5 rule4) the 5-4-3 rule5. What is the maximum distance that 10BASE-T will transmit data before signalattenuation affects the data delivery? （1）1) 100 meters2) 185 meters3) 300 meters4) 500 meters6. When using Category 5 UTP cable, which RJ-45 pin pairs are used to exchangedata between hosts on an Ethernet network? （2）1) 1 and 2; 4 and 52) 1 and 2; 3 and 63) 3 and 6; 7 and 84) 4 and 5; 7 and 8第八章1. John has been hired as the network administrator of a local company and hasdecided to add more hubs to the company's existing network. Which of the following has been caused by John's inexperience? （1）1) collision domain extended2) an increased number of collision domains3) increased network performance4) increased bandwidth5) extended bandwidth2. "CompA" is trying to locate a new computer named "CompB" on the network.Which of the following does "CompA" broadcast to find the MAC address of "CompB"? （2）1) MAC request2) ARP request3) ping4) Telnet5) proxy ARP3. Which of the following is a term associated with replacing hubs with switchesto increase the number of collision domains? （3）1) encapsulation2) latency3) segmentation4) layered model5) broadcast domain6) Extended4. The accumulation of traffic from which of the following can cause a networkcondition called broadcast radiation? (Choose three.) （3，5，6）1) anonymous FTP servers2) telnet sessions3) video over IP applications4) NAS services5) ARP requests6) RIP updates5. Which of the following describes the use of Spanning Tree Protocol (STP)? （4）1) resolve routing loops2) eliminate Split Horizon errors3) limit collisions4) resolve switching loops6. Which term describes the delay in time that occurs when a frame leaves itssource device and reaches its destination? （4）1) collision2) backoff3) attenuation4) latency5) broadcast7. Based on the graphic above, which of the following occurs as each host systemcomes on line in the topology? （2）1) The switch sends its MAC address to each host.2) The switch adds MAC address to the bridge table as each host sends a frame.3) Each host exchanges MAC addresses with each other.4) The switch listens for data traffic to block since the switch lacks an IP address. 8. Which devices segment collision domains? (Choose two.) （2，3）1) transceiver2) router3) switch4) hub5) media9. Which protocol is used to eliminate switching loops? （3）1) Transmission Control Protocol2) Routing Information Protocol3) Spanning Tree Protocol4) Interior Gateway Routing Protocol5) Internetworking Protocol10. Refer to the exhibit. A network associate needs to establish an Ethernetconnection between Host A and Host B. However, the distance between the two hosts is further than the cabling standards allow. Which two devices that operate at the physical layer of the OSI can be used to allow Host A and Host B to communicate? （2，5）1) switch2) hub3) bridge4) router5) repeater第九章1. Which term describes an ARP response by a router on behalf of a requestinghost? （3）1) ARP2) RARP3) Proxy ARP4) Proxy RARP2. Which protocol functions at the internet layer of the TCP/IP protocol suite? （4）1) File Transfer Protocol (FTP)2) Trivial File Transfer Protocol (TFTP)3) Transmission Control Protocol (TCP)4) Internet Protocol (IP)5) User Datagram Protocol (UDP)6) Simple Mail Transport Protocol (SMTP)3. Which of these workstation installation and setup tasks are concerned withnetwork access layer functions? (Choose two.) （2，4）1) configuring the e-mail client2) installing NIC drivers3) configuring IP network settings4) connecting the network cable5) using FTP to download application software updates4. Which part of an IP address identifies a specific device on a network? （4）1) first two octets2) third and fourth octets3) network portion4) host portion5) only the fourth octet5. Which of the following are features of the Internet Protocol (IP)? (Choose two.)（1，3）1) It is the most widely implemented global addressing scheme.2) It allows two hosts to share a single address on a local area network.3) It is a hierarchical addressing scheme allowing addresses to be grouped.4) It is only locally significant, used primarily on local area networks.6. Which of the following are useable Class A IP addresses with a default subnetmask? (Choose three.) （2，3，5）1) 127.0.39.12) 111.9.28.303) 123.1.2.1324) 128.50.38.25) 105.1.34.16) 0.23.92.37. Which application layer protocols use UDP at the transport layer? (Choose two.)（2，4）1) FTP2) SNMP3) Telnet4) DHCP5) SMTP第十章1. Which OSI layer encapsulates data into packets? （3）1) session2) transport3) network4) data link2. Which OSI layer defines the functions of a router? （3）1) physical2) data link3) network4) transport5) session3. Which of the following are Cisco proprietary routing protocols? (Choose two.)（2，6）1) RIPv22) IGRP3) OSPF4) BGP5) RIPv16) EIGRP4. A company with a Class B license needs to have a minimum of 1,000 subnetswith each subnet capable of accommodating 50 hosts. Which mask below is the appropriate one? （4）1) 255.255.0.02) 255.255.240.03) 255.255.255.04) 255.255.255.1925) 255.255.255.2245. A small company has a class C network license and needs to create five usablesubnets, each subnet capable of accommodating at least 20 hosts. Which of the following is the appropriate subnet mask? （3）1) 255.255.255.02) 255.255.255.1923) 255.255.255.2244) 255.255.255.2406. When a network administrator applies the subnet mask 255.255.255.248 to aClass A address, for any given subnet, how many IP addresses are available to be assigned to devices? （6）1) 10222) 5103) 2544) 1265) 306) 67. Host A is assigned the IP address 10.18.97.55 /21. How many more networkdevices can be assigned to this subnetwork if Host A is the only one that has an IP address assigned so far? （4）1) 2542) 5093) 10214) 20455) 40946) 81908.Refe r to the exhibit. The network administrator wants to create a subnet for thepoint-to-point connection between the two routers. Which subnetwork mask would provide enough addresses for the point-to-point link with the least number of wasted addresses?1) 255.255.255.1922) 255.255.255.2243) 255.255.255.2404) 255.255.255.2485) 255.255.255.2529. What is the correct number of usable subnetworks and hosts for the IP networkaddress 192.168.35.0 subnetted with a /28 mask?1) 6 networks / 64 hosts2) 14 networks / 32 hosts3) 14 networks / 14 hosts4) 30 networks / 64 hosts10. Which subnet masks would be valid for a subnetted Class B address? (Choosetwo.) （5，6）1) 255.0.0.02) 255.254.0.03) 255.224.0.04) 255.255.0.05) 255.255.252.06) 255.255.255.19211. Refer to the exhibit. How will the Fohi router dynamically learn routes to the192.168.16.16/28, 192.168.16.32/28, and 192.168.16.48/28 subnetworks? （3）1) with a static route2) with a routed protocol3) with a routing protocol4) with a directly connected route12. How many broadcast domains are shown in the diagram? （1）1) three2) four3) five4) six5) seven6) eight13. How many collision domains are shown in the diagram? （5）1) three2) four3) five4) six5) seven6) eight14. A router interface has been assigned an IP address of 172.16.192.166 with amask of 255.255.255.248. To which subnet does the IP address belong?1) 172.16.0.02) 172.16.192.03) 172.16.192.1284) 172.16.192.1605) 172.16.192.1686) 172.16.192.17615. Refer to the exhibit. Host A is sending data to Host B. Once R2 determines thatdata from Host A must be forwarded to R1 to reach Host B, which layer of the OSI model will R2 use to address and build the frames destined for R1?1) physical2) data link3) network4) transport5) session6) presentation16. Which type of address is 192.168.170.112/28?1) host address2) subnetwork address3) broadcast address4) multicast address17. Which type of address is 223.168.17.167/29?1) host address2) multicast address3) broadcast address4) subnetwork address18. Which combination of network id and subnet mask correctly identifies all IPaddresses from 172.16.128.0 through 172.16.159.255?1) 172.16.128.0 255.255.255.2242) 172.16.128.0 255.255.0.03) 172.16.128.0 255.255.192.04) 172.16.128.0 255.255.224.05) 172.16.128.0 255.255.255.19219. Refer to the exhibit. The internetwork in the exhibit has been assigned the IPaddress 172.20.0.0. What would be the appropriate subnet mask to maximize the number of networks available for future growth?1) 255.255.224.02) 255.255.240.03) 255.255.248.04) 255.255.252.05) 255.255.254.06) 255.255.255.0第十一章1. If a network administrator needed to download files from a remote server, whichprotocols could the administrator use to remotely access those files? (Choose two.) （3，5）1) NFS2) ASCII3) TFTP4) IMAP5) FTP6) UDP2. What is established during a connection-oriented file transfer betweencomputers? (Choose two.) （2，5）1) a temporary connection to establish authentication of hosts2) a connection used for ASCII or binary mode data transfer3) a connection used to provide the tunnel through which file headers aretransported4) a command connection which allows the transfer of multiple commands directlyto the remote server system5) a control connection between the client and server3. Which of the following protocols are used for e-mail transfer between clientsand servers? (Choose three.) （3，4，5）1) TFTP2) SNMP3) POP34) SMTP5) IMAP46) postoffice4. Which type of institution does the domain suffix .org represent? （4）1) government2) education3) network4) non-profit5. Which of the following services is used to translate a web address into an IPaddress? （1）1) DNS2) WINS3) DHCP4) Telnet6. Which part of the URL http://www.awsb.ca/teacher gives the name of thedomain? （4）1) www2) http://3) /teacher4) awsb.ca7. Which protocols are TCP/IP application layer protocols? (Choose two.) （2，4）1) UDP2) FTP3) IP4) SMTP5) TCP8. What are three characteristics of the TCP protocol? (Choose three.) （3，4，6）1) has less overhead than UDP2) is used for IP error messages3) forces the retransmission undelivered packets4) creates a virtual session between end-user applications5) carries the IP address of destination host in the TCP header6) is responsible for breaking messages into segments and reassembling9. Two peer hosts are exchanging data using TFTP. During the current session, adatagram fails to arrive at the destination. Which statement is true regarding the retransmission of the datagram? （2）1) Datagram retransmission requires user authentication.2) Datagram retransmission is controlled by the application.3) Datagram retransmission relies on the acknowledgements at transport layer.4) Datagram retransmission occurs when the retransmission timer expires in thesource host.案例学习1. 子网计算练习：Answer2. 子网号及广播地址计算练习Answer3. 子网规划练习：已知：给定一个C类地址201.16.5.0/24。

CCNA第二学期练习答案chapter1

1Which two statements correctly describe the components of a router? (Choose two.) RAM permanently stores the configuration file used during the boot sequence.ROM contains diagnostics executed on hardware modules.NVRAM stores a backup copy of the IOS used during the boot sequence.Flash memory does not lose its contents during a reboot.ROM contains the most current and most complete version of the IOS.Flash contains boot system commands to identify the location of the IOS.2Which interfaces in the exhibit could be used for a leased line WAN connection? (Choose tw1234563 If a router cannot find a valid configuration file during the startup sequence, what will occur?The startup sequence will reset.The router will prompt the user for a response to enter setup mode.The startup sequence will halt until a valid configuration file is acquired.The router will generate a default configuration file based on the last valid configuration.The router will monitor local traffic to determine routing protocol configuration requiremen4 Which of the following is the correct flow of routines for a router startup?load bootstrap, load IOS, apply configurationload bootstrap, apply configuration, load IOSload IOS, load bootstrap, apply configuration, check hardwarecheck hardware, apply configuration, load bootstrap, load IOS5 What is the default sequence for loading the configuration file?NVRAM, FLASH, ROMFLASH, TFTP,CONSOLENVRAM, TFTP, CONSOLEFLASH, TFTP, ROM6 From what location can a router load the Cisco IOS during the boot process? (Choose two.)RAMTFTP serverNVRAMsetup routineFlash memoryterminal7 Which are functions of a router? (Choose three.)packet switchingextension of network segmentssegmentation of broadcast domainsselection of best path based on logical addressingselection of best path based on physical addressing8 What three processes does a router execute when it receives a packet from one network thadestined for another network? (Choose three.)decapsulates the Layer 3 packet by stripping off the Layer 2 frame headeruses the destination MAC Address in the IP Header to look up the next-hop address in th tableleaves the Layer 2 frame header intact when decapsulating the Layer 3 packetuses the destination IP Address in the IP header to look up the next-hop address in the r tableencapsulates the Layer 3 packet into the new Layer 2 frame and forwards it out the exit iencapsulates the Layer 3 packet into a special Layer 1 frame and forwards it to the exit i 9 The network administrator needs to connect two routers directly via their FastEthernet ports.cable should the network administrator use?straight-throughrollovercross-overserial10Refer to the exhibit. What can be concluded from the output of the running-configuration of a The passwords are encrypted.The current configuration was saved to NVRAM.The configuration that is shown will be the one used on the next reboot.The commands that are displayed determine the current operation of the router.11 Which two statements describe characteristics of load balancing? (Choose two.)Load balancing occurs when a router sends the same packet to different destination netwLoad balancing occurs when the same number of packets are sent over static and dynamLoad balancing allows a router to forward packets over multiple paths to the same destin network.Unequal cost load balancing is supported by EIGRP.If multiple paths with different metrics to a destinations exist, the router cannot support lo balancing.12Refer to the exhibit. What can be concluded from the routing table output in the exhibit? (ChoThis router only has two interfaces.The router interfaces are not operational yet.This router is configured to forward packets to remote networks.The FastEthernet0/0 and Serial0/0/0 interfaces of this router were configured with an IP and the no shutdown command.An IP packet received by this router with a destination address of 198.18.9.1 will be forw of the Serial0/0/0 interface.13The serial connection shown in the graphic needs to be configured. Which configuration com must be made on the Sydney router to establish connectivity with the Melbourne site? (ChooSydney(config-if)# ip address 201.100.53.2 255.255.255.0Sydney(config-if)# no shutdownSydney(config-if)# ip address 201.100.53.1 255.255.255.224Sydney(config-if)# clock rate 56000Sydney(config-if)# ip host Melbourne 201.100.53.214 Passwords can be used to restrict access to all or parts of the Cisco IOS. Select the modesinterfaces that can be protected with passwords. (Choose three.)VTY interfaceconsole interfaceEthernet interfacesecret EXEC modeprivileged EXEC moderouter configuration mode15 What is the outcome of entering these commands?R1(config)# line vty 0 4R1(config-line)# password check123R1(config-line)# loginensures that a password is entered before entering user EXEC modesets the password to be used for connecting to this router via Telnetrequires check123 to be entered before the configuration can be savedcreates a local user account for logging in to a router or switch16Refer to the exhibit. The network administrator has configured the router with the interface IP addresses shown for the directly connected networks. Pings from the router to hosts on the c networks or pings between router interfaces are not working. What is the most likely problem The destination networks do not exist.The IP addresses on the router interfaces must be configured as network addresses and addresses.The interfaces must be enabled with the no shutdown command.Each interface must be configured with the clock rate command.17 A network administrator has just entered new configurations into Router1. Which command sexecuted to save configuration changes to NVRAM?Router1# copy running-config flashRouter1(config)# copy running-config flashRouter1# copy running-config startup-configRouter1(config)# copy running-config startup-configRouter1# copy startup-config running-configRouter1(config)# copy startup-config running-config18Refer to the exhibit. All routers have a route in its routing table to each network that is shown exhibit. Default routes have not been issued on these routers. What can be concluded about packets are forwarded in this network? (Choose two.)If RouterC receives a packet that is destined for 10.5.1.1, it will be forwarded out interfacIf RouterA receives a packet that is destined for 192.168.3.146, it will be forwarded out in S0/0/1.If RouterB receives a packet that is destined for 10.5.27.15, it will be forwarded out interf S0/0/1.If RouterB receives a packet that is destined for 172.20.255.1, it will be forwarded out int S0/0/0.If RouterC receives a packet that is destined for 192.16.5.101, it will be forwarded out int S0/0/1.19 What header address information does a router change in the information it receives from anEthernet interface before information is transmitted out another interface?only the Layer 2 source addressonly the Layer 2 destination addressonly the Layer 3 source addressonly the Layer 3 destination addressthe Layer 2 source and destination addressthe Layer 3 source and destination address20Refer to the exhibit. Host A pings host B. When R4 accepts the ping the Ethernet interface, what two pieces of header information are included? (Choose two.)s ource IP address: 192.168.10.129s ource IP address: BBBB.3333.5677s ource MAC address: 5555.AAAA.6666d estination IP address: 192.168.10.33d estination IP address: 192.168.10.134d estination MAC address: 9999.DADC.123421Refer to the exhibit. After host 2 is connected to the switch on the LAN, host 2 is unable to communicate with host 1. What is the cause of this problem?The subnet mask of host 2 is incorrect.Host 1 and host 2 are on different networks.The switch needs an IP address that is not configured.The router LAN interface and host 1 are on different networks.The IP address of host 1 is on a different network than is the LAN interface of the router.。

CCNA第二学期答案

.请参见图示。

对于发往的数据包，R2 会采取什么操作？它会丢弃数据包。

2.请参见图示。

R1 会使用哪一总结地址来向R2 通告其网络？3.请参见图示。

尽管R2 已配置正确，但主机A 还是无法访问Internet。

可以在R1 上配置哪两条可让主机 A 访问Internet 的静态路由？（选择两项。

ip route Fa0/1ip route4.请参见图示。

网络管理员已按图示配置了R1，并且所有接口都运作正常。

但从R1 ping 时失败。

造成此问题的原因可能是什么？默认路由配置有误。

5.请参见图示。

所有接口都已编址，并且运行正常。

网络管理员在主机A 上运行了tracert 命令。

得到这种输出的原因可能是什么？（选择两项。

）R2 的路由表中缺少的条目。

R1 的路由表中缺少的条目。

6.请参见图示。

从主机A 到主机B 的ping 成功，但从主机A ping 在Internet 上正常运行的主机却失败了。

此问题的原因是什么？未在这两台路由器上配置路由协议。

7.网络管理员使用RIP 路由协议在一个自治系统内实施路由。

下列哪两项是该协议的特征？（选择两项。

使用贝尔曼-福特算法确定最佳路径。

定期将完整的路由表发送给所有连接的设备。

8.请参见图示。

两台路由器无法建立相邻关系。

此问题的原因可能是什么？这两台路由器上的hello 间隔和dead 间隔不同9.在两台路由器能够使用OSPF 形成邻居邻接关系之前必须完成哪两项任务？（选择两项。

）路由器必须在网络类型方面达成一致。

路由器必须使用相同的dead 时间间隔。

10.下列关于链路状态路由协议的陈述，哪两项是正确的？（选择两项。

）运行链路状态协议的路由器可以建立完整的网络拓扑使用最短路径优先算法。

11.请参见图示。

下列关于Router1 路由表的陈述，哪三项是正确的？（选择三项。

）EIGRP 路由的AD 已经手动更改为默认值以外的其它值。

Router1 正同时运行着EIGRP 和OSPF 路由过程尚未配置任何默认路由。

CCNA第二学期练习答案chapter3

1Which two statements correctly describe the concepts of administrative distanc metric? (Choose two.)Administrative distance refers to the trustworthiness of a particular route.A router first installs routes with higher administrative distances.The value of the administarive distance can not be altered by the networkRoutes with the smallest metric to a destination indicate the best path.The metric is always determined based on hop count.The metric varies depending which Layer 3 protocol is being routed, such as2Refer to the exhibit. Which statement correctly describes how R1 will determinepath to R2?R1 will install a RIP route using network A in its routing table because theadministrative distance of RIP is higher than EIGRP.R1 will install a RIP route using network A in its routing table because the pafrom RIP is lower than EIGRP.R1 will install an EIGRP route using network B in its routing table because th administrative distance of EIGRP is lower than RIP.R1 will install an EIGRP route using network B in its routing table because th cost from EIGRP is lower than RIP.R1 will install an EIGRP route and a RIP route in its routing table and load b between them.3 Which two statements are true regarding classless routing protocols? (Choosesends subnet mask information in routing updatessends complete routing table update to all neighborsis supported by RIP version 1allows for use of both 192.168.1.0/30 and 192.168.1.16/28 subnets in the sareduces the amount of address space available in an organization4 Which command would the network administrator issue to determine if load balin effect on a router?s how ip protocolss how ip routes how ip interface briefs how ip interface5 Which two conditions would create a setting where the use of a distance-vectorprotocol would be efficient? (Choose two.)the network requires a special hierarchical designfast convergence of the network is crucialthe network is using a hub and spoke topologythe network is using a flat designthere are more than 15 hops between the most distant routers6 What is the purpose of a routing protocol?It is used to build and maintain ARP tables.It provides a method for segmenting and reassembling data packets.It allows an administrator to devise an addressing scheme for the network.It allows a router to share information about known networks with other route It provides a procedure for encoding and decoding data into bits for packet forwarding.7 Which of the following best describes the operation of distance vector routing pThey use hop count as their only metric.They only send out updates when a new network is added.They send their routing tables to directly connected neighbors.They flood the entire network with routing updates.8 What attribute is associated with link-state routing protocols?split horizonpoison reverselow processor overheadshortest-path first calculations9 Why is fast convergence desirable in networks that use dynamic routing protocRouters will not allow packets to be forwarded until the network has converg Hosts are unable to access their gateway until the network has converged.Routers may make incorrect forwarding decisions until the network has conv Routers will not allow configuration changes to be made until the network ha converged.10 Which of the following conditions must be met in order for a network to have conThe routers in the network are operating with dynamic routing protocols.The routers in the network are operating with compatible versions of IOS.The routers in the network are operating with the same routing tables.The routers in the network are operating with consistent routing knowledge.11 Which two statements are true regarding metrics? (Choose two.)RIP uses bandwidth as a metric.OSPF uses delay as a metric.EIGRP uses bandwidth as a metric.OSPF uses cost based on bandwidth as a metric.RIP uses delay as a metric.EIGRP uses hop count only as a metric.12 Which two statements are true regarding the advantages of the use of static routes? (Choosincreased securityreduced effort in configuring routesthe administrator maintains control over routingeasier to implement in a growing networkreduces the chance of routing errorsincreased router resource usage13 The following line of code is displayed in a routing table:R 209.165.201.0/24 [120/2] via 192.168.252.2, 00:00:16, S0/0/0What can be concluded from this output?A packet destined for host 192.168.252.2 will be forwarded out the interface connected t209.165.201.0/24.The value, 120, is used to determine the best path when a router has more than one rou protocol configured for the same destination network.This route was manually configured using the ip route command.192.168.252.2 is an interface on the router that produced this output.14 What will be the result of the following commands?ORL(config)# interface fastethernet 0/0ORL(config-if)# ip address 172.16.3.1 255.255.255.0ORL(config-if)# no shutdownThe 172.16.3.0 network will be routed by any dynamic routing protocol automatically.A routing table entry is made to the 172.16.3.0 network with a code of "C".A static route is required to route traffic to the 172.16.3.0 network.The commands will be saved to the startup-configuration automatically.15 An engineer creates a static route by entering the Router(config)# ip route 10.0.0.0 255.255192.168.1.2 command. What can be concluded about this route?The administrative distance of this route is 1.192.168.1.2 is the address of an interface on this router.This route will display as a directly connected network in the routing table.Packets with a destination IP address of 192.168.1.2 will be forwarded to the 10.0.0.0/24 first.16Refer to the exhibit. Router1 and Router2 are running EIGRP. All interfaces are operational a packets can be forwarded between all networks. What information will be found in the routing Router1?Router1 will have 6 directly connected networks.The administrative distance of the route to network 172.16.0.0 will be 90.The metric for routes to 172.16.0.0 will be 1.The interface that is used to forward packets to 172.16.0.0 will always be the S0/1 interfa 17 The following line of code is present in the routing table:O 10.16.1.0/27 [110/129] via 192.168.1.5, 00:00:05, Serial0/0/1What does the number 129 indicate in this output?The cost for this link has a value of 129.The clock rate on this serial interface is set to 129,000.The next-hop router is 129 hops away from this router.This route has been updated 129 times in this routing table.18 A growing medium-sized manufacturing company recently began to have routing instability iscompany uses static routes and has a mixture of over 30 Cisco and non-Cisco routers. The n administrator has decided to convert the network to dynamic routing. What characteristics of should be considered in this selection process?Distance vector routing protocols, such as RIP, converge more quickly than do link-state protocols.EIGRP can be used on all of the routers in the company.OSPF can be used between the routers.An exterior routing protocol, such as BGP, is recommended for growing companies.19Refer to the exhibit. If RIP is the routing protocol, what is the value metric from router A to network 192.168.5.0/24?345662472420 A router learns two paths with equal metrics to a destination network via the RIP routing protwill the router handle packets to the destination network?The router will install the first route it learned into the routing table.The router will install both routes in the routing table and load balance between the two.The router will put the first route in the routing table, and denote the second route as a ba route.The router will pick the path with the higher bandwidth and will place it in the routing tabl。

ccna章节与期末答案

第一章：正确答案：2.4.5•解析：由于不需要使用网络设备和专用服务器，对等网络易于创建，复杂性更低，且成本更少。

而且对等网络也没有集中管理。

这种网络安全性更低，不可扩展，而且那些同时充当客户端和服务器的设备可能性能更差正确答案：1解析：正确答案： 3.5解析：选择网络介质的条件包括：所选介质可以成功传送信号的距离、要安装所选介质的环境、必须传输的数据量和速度以及介质和安装的成本。

正确答案：3和4解析：终端设备上的应用程序可以生成数据，更改数据内容并且负责启动封装过程。

正确答案：1和4解析：终端设备会发出通过网络传输的数据。

中间设备会在链路发生故障时通过备用路径传输数据，并且会过滤数据传输以增强安全性。

网络介质提供网络消息的传输通道。

正确答案：4解析：外联网是公司外部的人或企业合作伙伴访问数据的网络区域。

内部网只描述通常仅供内部人员访问的网络区域。

当设备连接到有线网络时，有线LAN 会受BYOD（自带设备）影响。

使用大学无线LAN 的设备多为平板电脑和智能手机。

大学生主要使用无线WAN 来访问他们的手机运营商网络。

.正确答案：2解析：由于通过Internet 可以联系在线供应商，所以家庭用户通过Internet 进行网上购物。

内联网基本上是仅供内部使用的局域网。

外联网是外部合作伙伴访问组织内部特定资源的网络。

家庭用户并不一定使用LAN 来访问Internet。

例如，PC 可以通过调制解调器直接连接到ISP。

正确答案：1解析：内部网这个术语用于表示一个组织的私有局域网和广域网连接。

内部网的设计旨在仅允许该组织的成员、员工或其他获得授权的人员进行访问。

正确答案：2和4解析：电缆和DSL 均能实现高带宽、始终联网，并提供到主机计算机或LAN 的以太网连接。

10正确答案：2和3解析：移动电话连接需要使用移动电话网络。

卫星连接通常用于家庭或企业外部不便使用物理布线的位置。

11正确答案：2解析：当对网络资源的请求超出了可用容量时，网络就会变得拥堵。

计算机网络技术第9章习题参考答案

A. 保密性
B. 可选择性
C. 可用性
D. 审查性
⑹ [ D ]用来记录网络中被管理对象的状态参数值。
A. 管理对象
B. 管理协议
C. 管理进程
D. 管理信息库
⑺ [ B ]功能是用来评测网络运行状态的网络管理功能域。
A. 安全管理
B. 性能管理
C. 故障管理
D. 配置管理
⑻ [ A ]服务用来保证收发双方不能对已发送或接收的信息予以否认。
建议只在未加入域的计算机内建立本地用户账户而不要在成员服务器或已加入域的windows2000professional内建立本地用户账户因为无法通过域内其他任何一台计算机来访问这些账户设置这些账户的权限因此这些账户无法访问域上的资源同时域系统管理员也无法管理这些本地用户账户因此要访问域资源的用户账户应该被建立在域控制器的活动目录内
⑺ 什么是防火墙(Firewall)？防火墙能够用哪些方式防范网络内外的攻击？简述防火墙的基本功能及其技术分类。
答：防火墙通常是指设置在不同网络(例如，可信任的内部网络和不可信的外部网络)或网络安全域之间的一系列部件的组合。它是不同网络或网络安全域之间信息的唯一出入口，能根据网络安全政策控制(允许、拒绝、监测)出入网络的信息流，且本身具有较强的抗攻击能力。它是提供信息安全服务，实现网络和信息安全的基础设施。它有效地监控内部网和互联网之间的任何活动，保证内部网络的安全。防火墙一般具有以下功能：过滤进出网络的数据；管理进出网络的访问行为；封堵某些禁止的业务；记录通过防火墙的信息内容和活动；对网络攻击进行检测和报警。防火墙技术分类，数据包过滤、应用级网关、代理服务。
⑵ 请简述 SNMP 中的五种网络管理的请求/响应操作原语。答： SNMP 的工作方式：采用轮询监控的工作方式：管理者按一定时间间隔向代理请求管理信息，根据管理信息判断是否有异常事件发生；当管理对象发生紧急情况时，也可以使用 trap 信息的报文主动报告。特点：SNMP 提供了以下五个服务原语： ⑴ GetRequest ⑵ GetNextRequest ⑶ GetResponse ⑷ SetRequest ⑸ Trap

ccna第二学期练习答案中文

ERouting Chapter 1 - CCNA Exploration: 路由协议和概念(版本4.0)1口令可用于限制对Cisco IOS 所有或部分内容的访问。

请选择可以用口令保护的模式和接口。

（选择三项。

）VTY 接口控制台接口特权执行模式2路由器从相连的以太网接口收到消息后，会更改哪项报头地址，再将消息从另一个接口发送出去？第 2 层源地址和目的地址3请参见图示。

网络管理员已经为路由器连接到直连网络的接口配置了如图所示的IP 地址。

从路由器ping 相连网络上的主机口之间相互ping 都会遭到失败。

此问题最可能的原因是什么？必须使用no shutdown命令启用接口。

4请参见图示。

主机 A ping 主机B。

当R4 收到对以太网接口的ping 时，哪两块报头信息包括在内？（选择两项。

）目的IP 地址：192.168.10.134目的MAC 地址：9999.DADC.12345网络管理员刚把新配置输入Router1。

要将配置更改保存到NVRAM，应该执行哪一条命令？Router1# copy running-config startup-config6您需要配置图中所示的串行连接，必须在Sydney 路由器上发出以下哪条配置命令才能与Melbourne 站点建立连接？（选Sydney(config-if)# ip address 201.100.53.2 255.255.255.0Sydney(config-if)# no shutdownSydney(config-if)# clock rate 560007请参见图示。

从路由器的运行配置输出可得出什么结论？显示的命令决定了路由器的当前运行情况。

8请参见图示。

在主机 2 连接到LAN 上的交换机后，主机2 无法与主机 1 通信。

导致此问题的原因是什么？主机 1 和主机2 位于不同的网络中。

9输入以下命令的作用是什么？R1(config)# line vty 0 4R1(config-line)# password check123R1(config-line)# login设置通过Telnet 连接该路由器时使用的口令10以下哪一项正确描述了路由器启动时的顺序？加载bootstrap、加载IOS、应用配置11加载配置文件时的默认顺序是怎样的？NVRAM、TFTP、CONSOLE12请参见图示。

思科CCNA考试答案(全)

CCNA思科考试答案（全）第 1 章考试1一家拥有10 名员工的小型公司使用单个LAN 在计算机之间共享信息。

哪种类型连接适合此公司？由当地电话服务提供商提供的拨号连接能够使公司方便且安全地连接员工的虚拟专用网络通过当地服务提供商建立的私有专用线路通过当地服务提供商提供的宽带服务（如DSL）答案：4解析：对于这种小型办公室，比较适合通过被称为数字用户线路(DSL) 的常见宽带服务实现Internet 连接，这种服务由当地的电话服务提供商提供。

由于员工人数很少，带宽的问题并不突出。

如果公司较大，在远程站点有分支机构，则专用线路会更加适合。

如果公司员工需要通过Internet 与公司联系，则采用虚拟专用网。

2哪种网络情况需要使用WAN？员工工作站需要获取动态分配的IP 地址。

员工在出差时需要通过VPN 连接到公司电子邮件服务器。

分支机构的员工需要与同一园区网络上的另一座建筑物内的公司总部共享文件。

员工需要访问托管在其建筑物内DMZ 中的公司Web 服务器上的网页。

答案：2解析：当出差的员工需要通过WAN 连接到公司电子邮件服务器时，VPN 将通过WAN 连接在员工笔记本电脑与公司网络之间创建一个安全隧道。

通过DHCP 获取动态IP 地址是LAN 通信的功能。

在企业园区的不同建筑物之间共享文件可通过LAN 基础设施来实现。

DMZ 是企业LAN 基础设施内一个受保护的网络。

3以下哪项描述了WAN 的特征？WAN 和LAN 在同一地理范围内运行，但有串行链路。

WAN 网络归运营商所有。

所有串行链路均被视为WAN 连接。

WAN 可提供到园区主干网的终端用户网络连接。

答案：2解析：WAN 可用于将企业LAN 互连到远程分支机构站点LAN 和远程工作人员站点。

WAN 归运营商所有。

虽然WAN 连接一般通过串行接口实现，但并不是所有串行链路均连接至WAN。

LAN（而非WAN）可在组织中提供终端用户网络连接。

4电路交换WAN 技术的两个常见类型是什么？（请选择两项。

ccna第二学期练习答案

c c n a第二学期练习答案(总45页)--本页仅作为文档封面，使用时请直接删除即可----内页可以根据需求调整合适字体及大小--ERouting Chapter 1 - CCNA Exploration: 路由协议和概念(版本1口令可用于限制对 Cisco IOS 所有或部分内容的访问。

请选择可以用口令保护的模式和接口。

（选择三项。

）VTY 接口控制台接口特权执行模式2路由器从相连的以太网接口收到消息后，会更改哪项报头地址，再将消息从另一个接口发送出去第 2 层源地址和目的地址3请参见图示。

网络管理员已经为路由器连接到直连网络的接口配置了如图所示的 IP 地址。

从路由器 ping 相连网络路由器接口之间相互 ping 都会遭到失败。

此问题最可能的原因是什么必须使用no shutdown命令启用接口。

4请参见图示。

主机 A ping 主机 B。

当 R 网接口的 ping 时，哪两块报头信息包括在内（选择两项。

）目的 IP 地址：目的 MAC 地址：5网络管理员刚把新配置输入 Router1。

要将配置更改保存到 NVRAM，应该执行哪一条命令Router1# copy running-config startup-config6您需要配置图中所示的串行连接，必须在 Sydney 路由下哪条配置命令才能与 Melbourne 站点建立连接（选择三项）Sydney(config-if)# ip addressSydney(config-if)# no shutdownSydney(config-if)# clock rate 560007请参见图示。

从路由器的运行配置输出可得出什么结论显示的命令决定了路由器的当前运行情况。

8请参见图示。

在主机 2 连接到 LAN 上的交换机后，主主机 1 通信。

导致此问题的原因是什么主机 1 和主机 2 位于不同的网络中。

9输入以下命令的作用是什么？R1(config)# line vty 0 4R1(config-line)# password check123R1(config-line)# login设置通过 Telnet 连接该路由器时使用的口令10以下哪一项正确描述了路由器启动时的顺序加载 bootstrap、加载 IOS、应用配置11加载配置文件时的默认顺序是怎样的NVRAM、TFTP、CONSOLE12请参见图示。

CCNA 思科网络章节考试题及答案《网络规划和布线》

《网络规划和布线》在IPv4 环境中，路由器根据什么信息在不同的路由器接口之间转发数据包？目的网络地址源网络地址源MAC 地址公认端口目的地址OSI 第3 层封装期间添加什么信息？源MAC 地址和目的MAC 地址源应用程序协议和目的应用程序协议源端口号和目的端口号源IP 地址和目的IP 地址在无连接系统中，下列哪项陈述是正确的？发送数据包之前联系目的设备。

发送数据包之前不联系目的设备。

目的设备向源设备发送确认，表示已经收到数据包。

目的设备向源设备发送确认，请求发送下一个数据包。

IP 数据包的哪个字段用于防止无限循环？服务类型标识标志生存时间报头校验和路由器使用网络层地址的哪个部分转发数据包？主机部分广播地址网络部分网关地址请参见图示。

如果使用图示中的网络，下列哪一项将成为192.133.219.0 网络中主机A 的默认网关地址？192.135.250.1192.31.7.1192.133.219.0192.133.219.1如果主机上的默认网关配置不正确，对通信有何影响？该主机无法在本地网络上通信。

该主机可以与本地网络中的其它主机通信，但不能与远程网络上的主机通信。

该主机可以与远程网络中的其它主机通信，但不能与本地网络中的主机通信。

对通信没有影响。

默认网关有何作用？用于物理连接计算机和网络为计算机提供永久地址标识计算机所连接的网络标识网络计算机的逻辑地址，并且是网络中的唯一标识允许本地网络计算机和其它网络中的设备通信的设备标识哪种路由使用的信息需要手动输入路由表中？动态内部静态标准如果目的网络未列在Cisco 路由器的路由表中，路由器可能会采取哪两项措施？（选择两项）路由器发送ARP 请求以确定所需的下一跳地址。

路由器丢弃数据包。

路由器将数据包转发到ARP 表所示的下一跳。

路由器将数据包转发到源地址所示的接口。

路由器将数据包从默认路由条目所确定的接口发出。

将主机分组到同一个网络时应考虑哪些关键因素？（选择三项）网关用途物理编址软件版本地理位置所有权以下哪一项是路由表条目的组成部分？路由器接口的MAC 地址第 4 层目的端口号目的主机地址下一跳地址下列哪些中间设备可用于在网络之间实施安全保护？（选择两项）路由器集线器交换机防火墙接入点网桥大型网络存在哪三个常见问题？（选择三项）广播太少性能下降安全问题管理职责受限制主机标识协议兼容性请参见图示。

CCNA第二学期考试答案

以下是针对您未获得满分的试题给出的反馈。

某些交互式试题可能不显示您的答案。

分项分数：1与固定配置的交换机相比，模块化交换机具有哪两个优点？（请选择两项。

）正确响应您的响应每台交换机的成本更低可扩展性更高转发率更低需要的电源插座数目更少带宽聚合可以使用多个端口固定配置交换机价格较低，但是它具有指定数量的端口且不能添加端口。

它们提供的高速端口通常比较少。

为了在包含固定配置交换机的网络上扩展交换，需要购买更多的交换机。

这增加了需要使用的电源插座数量。

模块化交换机只需要购买额外的线卡便可以扩展。

带宽聚合也更容易，因为机箱的背板可以为交换机端口线卡提供所需的带宽。

此试题参考以下领域的内容：Routing and Switching Essentials• 1.1.2 交换网络2思科无边界架构接入层的基本功能是什么？正确响应您的响应聚合第 2 层广播域聚合第 3 层路由边界为用户提供访问权提供高可用性思科无边界架构接入层的功能是为用户提供网络访问。

第 2 层广播域聚合、第 3 层路由边界聚合和高可用性是分布层的功能。

也有说答案是聚合第 3 层路由边界此试题参考以下领域的内容：Routing and Switching Essentials• 1.1.1 融合网络3思科无边界架构分布层的基本功能是什么？正确响应您的响应充当主干聚合所有园区块聚合第 3 层路由边界为用户提供访问权思科无边界架构的分布层的一项基本功能是在不同的VLAN 之间路由。

充当主干和聚合园区块是核心层的功能。

为用户提供访问是接入层的功能。

此试题参考以下领域的内容：Routing and Switching Essentials• 1.1.1 融合网络4若将大端口密度、容错和低价作为重要指标，应使用哪个交换机外形因素？正确响应您的响应固定配置交换机模块化交换机可配备机架的1U 交换机可堆叠式交换机堆叠式交换机可以使用特殊电缆实现互联，从而在交换机之间提供高带宽的吞吐量，并像单个大型交换机一样运行。

ccna2答案第九章

ERouting Chapter 9 - CCNA Exploration: 路由协议和概念(版本4.0)1 窗体顶端在如图所示的网络中，主机192.168.1.66 无法ping 通主机192.168.1.130。

必须如何配置EIGRP 才能让这通？（选择两项。

）R1(config-router)# network 192.168.1.128R1(config-router)# auto-summaryR1(config-router)# no auto-summaryR2(config-router)# no auto-summaryR2(config-router)# auto-summaryR2(config-router)# network 192.168.1.642 窗体顶端EIGRP DUAL 算法在下列哪些表中存储到目的地的主路由？（选择两项。

）路由拓扑邻居路径最短路径哪两项陈述描述了EIGRP 的特性？（选择两项。

）EIGRP 是一种距离矢量路由协议。

EIGRP 支持无类路由和VLSM。

EIGRP 属于链路状态路由协议。

EIGRP 使用TCP 进行可靠的EIGRP 更新数据包传输。

EIGRP 使用抑制计时器来消除路径环路。

EIGRP 每30 分钟发送一次定期更新。

4 窗体顶端请参见图示。

根据show ip eigrp neighbors 的输出，Router1 和Router2 之间的邻接关系可能存在哪两个问两项。

）路由器上配置的EIGRP 进程ID 不同。

禁用了自动总结。

更改了R1 的hello 计时器。

两台路由器的串行接口位于不同的网络中。

未找到可行后继路由。

窗体底端请参见图示。

这是 2 个直连EIGRP 路由器的调试输出。

这两台路由器并未建立邻接关系。

原因是什么？其中一台路由器是非cisco 路由器它们的自治系统编号不同它们使用不同的序列号它们发送的hello 类型不正确窗体底端6 窗体顶端在运行EIGRP 的路由器上，什么数据库将维护可行后继路由的列表？路由表邻居表拓扑表邻接表窗体底端7 窗体顶端请参见图示。

CCNA第二学期第九章答案.

1 哪两项功能描述了访问控制列表的用途？（请选择两项。

）正确响应您的响应ACL 可以根据路由器上的始发 MAC 地址来允许或拒绝流量。

ACL 可以控制主机能够访问网络中的哪些区域。

ACL 可以帮助路由器确定到目的地的最佳路径。

标准 ACL 可限制对特定应用程序和端口的访问。

ACL 提供基本的网络安全性。

2 访问控制列表在企业网络中的可能用途是下列哪两项？（选择两项。

）正确响应您的响应控制路由器接口的物理状态控制调试输出允许通过路由器过滤第 2 层流量降低路由器上的处理负载控制虚拟终端对路由器的访问3 哪两个特征是标准 ACL 和扩展 ACL 共有的特征？（请选择两项。

）正确响应您的响应两者都可以通过使用描述性名称或号码创建。

两类ACL 都可以根据协议类型进行过滤。

两者都包含隐式 deny 作为最终 ACE。

两者都可以通过端口号允许或拒绝特定服务。

两者都可为特定目的主机 IP 地址过滤数据包。

4 下列哪项描述了标准 IPv4 ACL 的特点？正确响应您的响应创建它们时可以使用数字，但不可以使用名称。

它们是在接口配置模式下配置的。

可以根据源 IP 地址和源端口对过滤流量进行配置。

它们仅根据源 IP 地址过滤流量。

5 网络管理员需要配置标准 ACL，使得只有 IP 地址为 192.168.15.23 的管理员工作站能够访问主要路由器的虚拟终端。

哪两个配置命令可以完成该任务？（请选择两项。

）正确响应您的响应Router1(config)# access-list 10 permit 192.168.15.23 255.255.255.255Router1(config)# access-list 10 permit 192.168.15.23 0.0.0.0Router1(config)# access-list 10 permit 192.168.15.23 255.255.255.0Router1(config)# access-list 10 permit host 192.168.15.23 Router1(config)# access-list 10 permit 192.168.15.23 0.0.0.2556 哪一个 IPv4 地址范围包含由 172.16.2.0 指定的、与 ACL 过滤器匹配的、通配符掩码为 0.0.1.255 的所有 IP 地址？正确响应您的响应172.16.2.1 到 172.16.3.254172.16.2.1 到 172.16.255.255172.16.2.0 到 172.16.3.255172.16.2.0 到 172.16.2.2557 如果路由器有两个接口，并且路由 IPv4 和 IPv6 的流量，那么可以在其中创建并应用多少个 ACL？正确响应您的响应12616488 通常认为下列哪三项是安置 ACL 的最佳做法？（请选择三项。

计算机网络(第二版)课后习题答案第九章

计算机网络参考答案第九章（高教第二版冯博琴）1. 应用层协议对传输层协议选择的主要考虑因素是哪些？数据丢失、带宽需求、实时性2. 列出五个常用的因特网应用项目以及相关协议。

万维网：HTTP电子邮件：SMTP, POP, IMAP文件传输：FTP远程终端登录：TELNET域名服务：DNS3. 在两个主机的通信会话中，那个主机是服务器，哪个是客户端？答案：在两个主机的通信会话中，首先发起会话的一方为客户端，处于“倾听”状态的为服务器。

但是，通信会话成功的先决条件是服务器必须首先处于开机或“倾听”状态。

4. 一个运行在某台主机中的通信进程，需要那些信息来确定运行在另一台主机中的进程？答案：一个运行在某台主机中的通信进程，需要对方主机的IP地址、对方的端口号或服务访问点（SAP）来确定运行在该主机中的对等通信进程。

5. 列出常见的网络应用的用户代理程序。

答：万维网：IE, FIREFOX电子邮件：OE, FOXMAIL文件传输：IE, cuteFTP远程终端登录：telnet, IE多媒体视频：realplay6. 为什么HTTP、FTP、SMTP、POP和IMAP需要TCP的支持而不是UDP的？答：因为上述协议都是基于“文件”的网络应用，对数据丢失十分敏感，要求数据的完整和可靠、但对带宽需求、实时性的要求并不高，所以，TCP协议可以满足这样的要求。

7. 为什么大部分FTP服务器需要限制同时连接的客户端数量？答：实际上，所有的网络服务器都会对同时可接入的客户数量进行限制，其原因也十分简单，任何网上的服务资源都是有限的，但是这种情况，尤以FTP服务器表现的最为突出。

首先，因为FTP是一种十分普及的网络应用，使用客户众多；其次它是“面向连接”的应用，服务器需要保留登录用户的状态和根据用户权限控制用户对文件的访问，对于每一个FTP连接，一般需要两个通道进行才能进行有效的文件传输。

由于以上原因，FTP对服务器资源的占用是比较多的。

思科网院第二学期第九章答案

NAT 的主要目的是什么？•正确响应您的响应••节省IPv4 地址•增强网络性能•提高网络安全•允许对等文件共享开发NAT 以节省IPv4 地址。

一个附带优势是NAT 通过隐藏内部网络编址方案而增加了小等级的安全性。

然而，使用NAT 也有一些缺点。

它不允许真正的对等通信，并且会增加外部链接的延迟时间。

此试题参考以下领域的内容：Routing and Switching Essentials•9.1.1 NAT 的特性2 已启用PAT 的路由器使用哪种方法将传入数据包发送到正确的内部主机？2已启用PAT 的路由器使用哪种方法将传入数据包发送到正确的内部主机？•正确响应您的响应••它在传入数据包上使用源TCP 或UDP 端口号和目的IP 地址的组合。

•它在传入数据包上使用目的TCP 或UDP 端口号。

•它在传入数据包上使用源IP 地址。

它在传入数据包上使用源TCP 或UDP 端口号。

•已启用PAT 的路由器维护由内部本地IP 地址和TCP/UDP 端口号到外部本地地址和TCP/UDP 端口号映射组成的表。

当流量从公共网络返回路由器时，路由器会将目的端口与PAT 映射表进行比较，确定将流量发送到哪台内部主机。

此试题参考以下领域的内容：Routing and Switching Essentials•9.1.2 NAT 的类型3 技术人员必须配置边缘路由器，才能将每个会话的不同TCP 端口号用于互联网上的服务器。

应实现哪种类型的网络地址转换(NAT)？3技术人员必须配置边缘路由器，才能将每个会话的不同TCP 端口号用于互联网上的服务器。

应实现哪种类型的网络地址转换(NAT)？•正确响应您的响应••在本地地址和全局地址之间实现多对一地址映射•在本地地址和全局地址之间实现一对多地址映射•在本地地址和全局地址之间实现多对多地址映射•在本地地址和全局地址之间实现一对一地址映射端口地址转换也称为NAT 过载。

PAT 使用端口作为附加参数来实现乘数效应，从而可以将10 个内部全局地址中的任何一个最多重复使用65,536 次。

CCNA第二学期期末考试Final：Exam

路由器获知到的第一条路径仅使用路由器获知到的前两条路径路由器获知到的最后一条路径全部四条路径对于为防备路由环路而经过毒性反转实现的水平切割方法，哪两项表达正确？（选择两项。

）全部Cisco IOS都会默认启用此方法。

会将一个表示无量大胸怀的值分派给路由以将其毒化。

将毒化路由更新发回该更新的发送接口。

指示路由器将可能会影响路由的改正保持一段特定的时间。

限制数据包在被抛弃以前能够在网络中传输的跳数。

在两台路由器能够使用OSPF形成街坊毗邻关系以前一定达成哪两项任务？（选择两项。

）路由器一定选举出指定路由器。

路由器一定在网络种类方面达成一致。

路由器一定使用同样的dead时间间隔。

路由器一定互换链路状态恳求。

路由器一定互换数据库描绘数据包。

以下路由器组件和操作的配对中，哪两项是正确的？（选择两项。

）DRAM -加载bootstrapRAM -储存操作系统闪存- 启动时履行诊疗NVRAM -储存配置文件ROM -存贮备份配置文件POST -运转硬件模块诊疗以下对于无类路由协议的陈说，哪两项是正确的？（选择两项。

）无类路由协议可用于不连续子网。

无类路由协议可在路由更新中转发超网路由。

无类路由协议没法在路由表中实行有类路由。

无类路由协议仅使用跳数胸怀。

无类路由协议的路由更新中不包含子网掩码。

请拜见图示。

在图示的此中一台设施上运转了show cdp neighbors命令。

依据此信息，可推测出哪两项结论？（选择两项。

）在路由器上运转了该命令。

ABCD是一台非CISCO设施。

两台设施间存在第 3 层连通性。

ABCD支持路由功能。

ABCD连结到相邻设施的Fa0/0接口。

R3 。

图中显示了全部三台路由器的路由。

从该输出能够获得什么结论？请拜见图示。

网络连结有三台路由器：R1 、 R2 和R1和R3经过S0/0/0接口相连。

R1 S0/0/0接口的IP 地点为10.1.1.2 。

R2 S0/0/1接口的IP 地点为10.3.3.2 。