2016年CCNA第二学期第二章考试答案课案

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ccna第二章答案

1. Which statements correctly identify the role of intermediary devices in the network? (Choose three.)determine pathways for data 确定数据通路initiate data communicationsretime and retransmit data signals 重分发originate the flow of datamanage data flows 管理数据final termination point for data flow2. Select the statements that are correct concerning network protocols. (Choose three.)define the structure of layer specific PDU'sdictate how to accomplish layer functionsoutline the functions necessary for communications between layers limit the need for hardware compatibilityrequire layer dependent encapsulationseliminate standardization among vendors3. What are two functions of encapsulation? (Choose two.)tracks delay between end devicesenables consistent network paths for communicationallows modification of the original data before transmissionidentifies pieces of data as part of the same communicationensures that data pieces can be directed to the correct receiving end device4. What is a primary function of the trailer information added by the data link layer encapsulation?supports error detection 支持错误检测‘ensures ordered arrival of dataprovides delivery to correct destinationidentifies the devices on the local networkassists intermediary devices with processing and path selection5. Which statements correctly identify the role of intermediary devices in the network? (Choose three.)determine pathways for datainitiate data communicationsretime and retransmit data signalsoriginate the flow of datamanage data flowsfinal termination point for data flow6. What is a PDU?corruption of a frame during transmissiondata reassembled at the destinationretransmitted packets due to lost communicationa layer specific encapsulation 一个具体的封装层7. Which characteristic correctly refers to end devices in a network?manage data flowsoriginate data flow 原数据流retime and retransmit data signalsdetermine pathways for data8.Refer to the exhibit. "Cell A" at IP address 10.0.0.34 has established an IP session with "IP Phone 1" at IP address 172.16.1.103. Based upon the graphic, which device type best describes the function of wireless device "Cell A?"the destination devicean end devicean intermediate devicea media device9.Refer to the exhibit. Which three labels correctly identify the network types for the network segments that are shown?(Choose three.)Network A -- WANNetwork B -- WANNetwork C -- LANNetwork B -- MANNetwork C -- WANNetwork A -- LAN10. Which three statements best describe a Local Area Network (LAN)? (Choose three.)A LAN is usually in a single geographical area.The network is administered by a single organization.The connection between segments in the LAN is usually through a leased connection.The security and access control of the network are controlled by a service provider.A LAN provides network services and access to applications for users within a common organization.Each end of the network is generally connected to a Telecommunication Service Provider (TSP).11.Refer to the exhibit. Which networking term describes the data interleaving process represented in the graphic?pipingPDUstreamingmultiplexingencapsulation12. What is the primary purpose of Layer 4 port assignment?to identify devices on the local mediato identify the hops between source and destinationto identify to the intermediary devices the best path through the network to identify the source and destination end devices that are communicating to identify the processes or services that are communicating within the end devices13. What device is considered an intermediary device?1．file serve2.IP phone ptop 4.printer 5.switch14.Refer to the exhibit. Which term correctly identifies the device type that is included in the area B? sourceendtransferintermediary 中间设备15.Refer to the exhibit. What type of network is shown?WANMANLANWLAN16. Which layer encapsulates the segment into packets?physicaldata linknetwork 网络层封装的是数据包transport17. What can be identified by examining the network layer header?the destination device on the local mediathe destination host address 网络层头部封装目的主机的地址the bits that will be transferred over the mediathe source application or process creating the data18. What is the purpose of the TCP/IP Network Access layer?path determination and packet switchingdata presentationreliability, flow control, and error detectionnetwork media control 接入层控制网络媒体the division of segments into packets19. During the encapsulation process, what occurs at the data link layer? No address is added.The logical address is added.The physical address is added. 数据链路层添加一个物理地址The process port number is added.20.Refer to the exhibit. Which set of devices contains only end devices? A, C, DB, E, G, HC, D, G, H, I, JD, E, F, H, I, JE, F, H, I, J21. What is the proper order of the layers of the OSI model from the highest layer to the lowest layer?4physical, network, application, data link, presentation, session, transportapplication, physical, session, transport, network, data link, presentationapplication, presentation, physical, session, data link, transport, networkapplication, presentation, session, transport, network, data link, physicalpresentation, data link, session, transport, network, physical, application22. Which two layers of the OSI model have the same functions as the TCP/IP model Network Access Layer? (Choose two.)34NetworkTransportPhysicalData Link TCP/IP 工作在第一层和第二层Session。

ccna第二章练习答案.docx

yy1 ・ Refer to the exhibit・ Identify the devices labeled A, B, C, and D in the network physical documentation. 匚A=bridge, B=switch, C=router, D=hubK A=bridge, B=hub, C=router, D=switchC A=bridge, B=router, C=hub, D=switchc A=hub, B=bridge, C=router, D=switch2 The central hub has malfunctioned in the network. As a result, the entire network is down. Which type of physical network topology is implemented?匚busE starC ring匚mesh3. A switch has failed in the network. As a result, only one segment of the network is down. Which type of physical network topology is implemented?C busC ring匚starE extended star4. Which three features apply to LAN connections? (Choose three.)厂operate using serial in terfacesV make network connection using a hubV limited to operation over small geographic areas厂 provide part-time connectivity to remote servicesV typically operate under local administrative control厂provide lower bandwidth services compared to WANs5. What is one advantage of defining network communication by the seven layers of the OSI model? 【:It in creases the ban dwidth of a n etwork.E It makes networking easier to learn and understand・It eliminates many protocol restrictions.匚It increases the throughput of a network.c It reduces the need for testing network connectivity.6. What makes it easier for different networking vendors to design software and hardware that willin teroperate?E OSI modelc proprietary desig ns匚IP addressing schemec standard logical topologies匚standard physical topologies7. Which term describes the process of adding headers to data as it moves down OSI layers?匚division匚encoding匚separation匚segmentationE encapsulation8. What is the term used to describe the transport layer protocol data unit?匚bits c packetsE segments匚framesc data streams9. Which of the following are layers of the TCP/IP model? (Choose three.)▽ Applicati onr PhysicalV Internet0 Network Access厂Prese ntation10. Which of the following are data link layer encapsulation details? (Choose two.)0 A header and trailer are added・厂Data is con verted into packets ・V Packets are packaged into frames・厂Frames are divided into segments.厂Packets are changed into bits for Internet travel.11. Which layer of the OSI model provides network services to processes in electronic mail and file transfer programs?匚data link匚transport匚n etworkE application12. Which two features apply to WAN connections? (Choose two.)V operate using serial interfacesP make network connection using a hub厂limited to operation over small geographic areasI- typically operate under local administrative control▽provide lower bandwidth services compared to LANs13. Which of the following are ways that bandwidth is commonly measured? (Choose three.)厂GHzps▽kbpsV Mbps厂Nbps厂MHzpsV Gbps14. Refer to the following list. Choose the correct order of data encapsulation when a device sends information. segments bits packetsdata frames匚1 -3-5-4-2C 2- 1-3-5-4C 2-4-3-5-1匚4-3-1-2-5E 4-1 -3-5-2C 3-5-1-2-415. Which of the following are factors that determine throughput? (Choose two.)厂types of passwords used on servers厂type of Layer 3 protocol usedV n etwork topologywidth of the network cable0 number of users on the network16. Refer to the exhibit・ Which column shows the correct sequenee of OSI model layers?E D17. Which layer of the OSI model provides connectivity and path selection between two end systems where routing occurs?c physical layer匚data link layerE network layer匚transport layer18. Which best describes the function of the physical layer?E Defines the electrical and functional specifications for the link between end systems・匚Provides reliable transit of data across a physical link.匚Provides connectivity and path selection between two end systems・匚Concerned with physical addressing, network topology and media access.。

CCNA第二单元考试内容

CCNA第二单元考试内容CCNA第二单元考试内容1.STP的主要特点是什么？（实施VLAN和中继）a.允许架设中继，以提供冗余b.可以使交换网络的冗余最小化c.可以使错误配置和配置不一致的情况最小化d.允许在单个中继上运行几个VLAN2.STP如何选择网段上的指定端口？（使用生成树来提高性能）a.到根桥的开销最低路径b.到最近的非根桥的开销最高路径c.到最近的非根桥的开销最低路径d.到根桥的开销最高路径3.以下哪三种方法可以用于缓解配置问题？（交换网络故障排除）a.保护未使用的端口b.了解您有什么，然后开始c.保护配置。

d.验证更改，然后保存。

4.在故障排除商品访问问题时哪一个Cisco IOS 命令最有用？（交换机网络故障排除）a.b.I p address5.RSTP可解决哪种交换网络问题？（使用生成树来提高性能）a.收敛速度b.网络规模c.网络安全d.冗余拓扑6.有集线器的功能描述，哪两项是正确的？（了解共享LAN的挑战）a.集线器降低了冲突域的规模。

b.添加一个集线器以消除用户在网段上争用同一带宽的需求。

c.集线器可以增强数据信号，之后再重新传输。

d.集线器是一种数据链路层设备。

e.集线器可以扩展以太网LAN.7.如何通知Cisco设备解析和执行生个输入的命令？（Cisco IOS软件的操作）a.按Enter键b.在命令的结尾添加一个空格c.办理入命令后等待5秒钟。

d.按Send键8.当从VTP域删除VLAN时，应在何处进行更改？（实施LAN和中继）a.在每个交换机上，与VTP模式无关b.在处于VTP透明模式的交换机上c.在处于VTP客户端模式的每个交换机上d.在处于VTP服务器模式的交换机上9.下列哪两项可能会被认为是物理威胁？（保护交换机安全）a.有人关掉了交换器电源，从而阻止了网络访问。

b.用户密码遗忘在桌面上c.有人关掉了网络柜中的空调系统d.有人非法闯入了包含网络文档的机箱10.故障排除介质问题时哪一个Cisco IOS命令最有用？（交换网络故障排除）a.Show countersb.S how interfacec.Show rund.S how controller11.交换机A处于VTP客户端模式，并且其VLAN数据库具有VLAN1至VLAN5.交换机B处于VTP服务器模式，且被添加到相同的VTP域，其VLAN数据具有VLAN6至VLAN10那么当交换机B被添加到网络之后，交换机A和交换B的VLAN数据库会出现什么情况？（交换机故障排除）a.两个VLAN数据库均有VLAN6至VLAN10b.两个VLAN数据库均有VLAN1至VLAN10c.取决于哪台交换机具有更高的修订版号d.两个VLAN数据库均有VLAN1至VLAN512.当Cisco设备启动时，运行哪一项来检查其硬件？（Cisco IOS软件的操作）a.RAMb.T FTPc.POSTd.F lash13.VMPS将什么映射到VLAN分配？（实施VLAN和中继）a.IP地址b.M AC地址c.主机IDd.用户名14.下列哪一贡是远程访问网络设备的最安全的方法？（保护交换机安全）a.Telnetb.R MONc.SSHd.S NMPe.HTTP15.Show vlan命令会显示以下哪种信息？（实施VLAN和中继）a.配置为中继的端口b.V MPS服务器配置参数c.VLAN的名称和分配到VLAN的端口的名称d.V TP域参数16.哪一项Cisco IOS特征可用于vtp端口的访问？（保护交换机安全）a.访问列表b.端口安全性c.防火墙d.关闭17.哪三项陈述最好地描述了冲突？（了解共享LAN的挑战）a.向网络添加一个集线器可以发送冲突问题b.在一个冲突中，帧被破坏，网段中的每个站开始一个随机的计数器，该计数器在尝试重新传输数据之前完成c.冲突是共享LAN的副产品。

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。

CCNA-Exploration-网络基础知识-第二章练习及答案

CCNA Exploration：网络基础知识第二章练习题及答案A．B．C．D．E．F．G．□○1．下列哪些陈述正确指出了中间设备在网络中的作用？（选择三项）□确定数据传输路径□发起数据通信□重新定时和重新传输数据信号□发送数据流□管理数据流□数据流最后的终止点Option 1, Option 3, and Option 5 are correct.2．请选择关于网络协议的正确陈述。

（选择三项。

）□定义特定层 PDU 的结构□规定实现协议层功能的方式□概述层与层之间通信所需的功能□限制了对硬件兼容性的需要□需要取决于协议层的封装过程□杜绝厂商之间的标准化Option 1, Option 3, and Option 5 are correct.3.封装的两个功能是什么？（选择两项）□跟踪终端设备之间的延迟□为通信提供统一的网络路径□在传输前可以修改原始数据□标识属于同一通信的数据片段□确保数据片段可以转发到正确的接收端设备Option 4 and Option 5 are correct.4. 数据链路层封装添加的报尾信息有何主要功能？○支持差错校验○确保数据按照顺序到达○确保送达正确目的○标识本地网络中的设备○帮助中间设备进行处理和路径选择2 points for Option 15. OSI 模型哪两层的功能与 TCP/IP 模型的网络接入层相同？（选择两项）□网络层□传输层□物理层□数据链路层□会话层Option 3 and Option 4 are correct.6. 什么是 PDU？○传输期间的帧损坏○在目的设备上重组的数据○因通信丢失而重新传输的数据包○特定层的封装2 points for Option 47. 以下哪种特征正确代表了网络中的终端设备？□管理数据流□发送数据流□重新定时和重新传输数据信号□确定数据传输路径2 points for Option 28. 请参见图示。

IP 地址为 10.0.0.34 的“手机 A”已经与 IP 地址为 172.16.1.103 的“IP 电话 1”建立了 IP 会话。

CCNA第二学期

CCNA 2 - Module 1If a router cannot find a valid configuration file during the startup sequence, what will occur?The router will prompt the user for a response to enter setup mode.Refer 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 connected networks or pings between router interfaces are not working. What is the most likely problem?The interfaces must be enabled with the no shutdown command.Refer to the exhibit. What can be concluded from the routing table output in the exhibit? (Choose two.) The FastEthernet0/0 and Serial0/0/0 interfaces of this router were configured with an IP address and the no shutdown command.An IP packet received by this router with a destination address of 198.18.9.1 will be forwarded out of the Serial0/0/0 interface.Refer to the exhibit. The frame shown in the exhibit was received by the router. The router interfaces are operational. How will the router process this frame? (Choose two.)The router will change the frame type to one supported by the WAN link before forwarding the frame.The frame was received on the Fa0/0 interface of the router and will be s witched to the S0/0/0 interface.Passwords can be used to restrict access to all or parts of the Cisco IOS. Select the modes and interfaces that can be protected with passwords. (Choose three.)VTY interfaceconsole interfaceprivileged EX EC modeWhich two statements correctly describe the components of a router? (Choose two.)ROM contains diagnostics executed on hardware modules.Flash memory does not lose its contents during a reboot.Refer 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 LA N 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.Which are functions of a router? (Choose three.)packet s witchingsegmentation of broadcast domainsselection of best path based on logical addressingRefer to the exhibit. A ll routers have a route in its routing table to each network that is shown in the exhibit. Default routes have not been issued on these routers. What can be concluded about how packets are forwarded in this network? (Choose two.)If RouterA receives a packet that is destined for 192.168.3.146, it will be forwarded out interface S0/0/1.If RouterB receives a packet that is destined for 10.5.27.15, it will be forwarded out interface S0/0/1.The serial connection shown in the graphic needs to be configured. Which configuration commands must be made on the Sydney router to establish connectivity with the Melbourne site? (Choose three.) Sydney(config-if)# ip address 201.100.53.2 255.255.255.0Sydney(config-if)# no shutdownSydney(config-if)# clock rate 56000Refer to the exhibit. What can be concluded from the output of the running-configuration of a router? The commands that are dis played determine the current operation of the router.Refer to the exhibit. Host A pings host B. When R4 accepts the ping into the Ethernet interface, what two pieces of header information are included? (Choose two.)destination IP address: 192.168.10.134destination MAC address: 9999.DADC.1234What is the outcome of entering these commands?R1(config)# line vty 0 4R1(config-line)# password check123R1(config-line)# loginsets the password to be used for connecting to this router via T elnetWhich of the following is the correct flow of routines for a router startup?load bootstrap, load IOS, apply configurationWhat three processes does a router execute when it receives a packet from one network that is destinedfor another network? (Choose three.)decapsulates the Layer 3 packet by stripping off the Layer 2 frame headeruses the destination IP Address in the IP header to look up the next-hop address in the routing tableencapsulates the Layer 3 packet into the new Layer 2 frame and forwards it out the exit interfaceThe network administrator needs to connect two routers directly via their FastEthernet ports. What cable should the network administrator use?cross-overWhich two statements describe characteristics of load balancing? (Choose two.)Load balancing allows a router to forward packets over multiple paths to the same destination network.Unequal cost load balancing is supported by EIGRP.What information about the router and its startup process can be gathered from the output of the show version command? (Choose three.)the last restart methodthe configuration register settingsthe location from where the IOS loadedWhich interfaces in the exhibit could be used for a leased line WAN connection? (Choose two.)14From what location can a router load the Cisco IOS during the boot process? (Choose two.)TFTP serverFlash memoryA network administrator has just entered new configurations into Router1. Which command should be executed to save configuration changes to NVRAM?Router1# copy running-config startup-configWhat is the default sequence for loading the configuration file?NVRAM, TFTP, CONSOLEWhat header address information does a router change in the information it receives from an attached Ethernet interface before information is transmitted out another interface?the Layer 2 source and destination addressCCNA 2 - Module 2Which of the following are displayed by the Router# show cdp neighbors command? (Choose three.)platformholdtimelocal interfaceWhy is it advisable to enter a next-hop IP address when creating a static route whose exit interface is an Ethernet network?In a multi-access network, the router cannot determine the next-hop MAC address for the Ethernet frame without a next-hop address.The output of the Router# show interfaces serial 0/1 command displays the following: Serial0/1 is up, line protocol is down.What is the most likely cause for the line protocol being down?No clock rate has been set.A static route that points to the next hop IP will have what administrative distance and metric in the routing table?administrative distance of 1 and metric of 0Refer to the exhibit. What two commands will change the next-hop address for the 10.0.0.0/8 network from 172.16.40.2 to 192.168.1.2? (Choose two.)A(config)# no ip route 10.0.0.0 255.0.0.0 172.16.40.2A(config)# ip route 10.0.0.0 255.0.0.0 192.168.1.2Refer to the exhibit. A company network engineer is assigned to establish connectivity between the two Ethernet networks so that hosts on the 10.1.1.0/24 subnet can contact hosts on the 10.1.2.0/24 subnet. The engineer has been told to use only static routing for these company routers. Which set of commands will establish connectivity between the two Ethernet networks?R1(config)# ip route 10.1.1.0 255.255.255.0 192.168.0.2R2(config)# ip route 10.1.2.0 255.255.255.0 192.168.0.1Refer to the exhibit. Which static route should be configured on Router1 so that hostA will be able to reach hostB on the 172.16.0.0 network?ip route 172.16.0.0 255.255.0.0 S0/0/0Which address can be used to summarize networks 172.16.0.0/24 thru 172.16.7.0/24?172.16.0.0/21Refer to the exhibit. What is the significance of the /8 in the route to the 10.0.0.0 network?It indicates the number of consecutive bits, from the left, in the destination IP address of a packet that must match 10.0.0.0 to use that route.What two devices are responsible for converting the data from the WAN service provider into a form acceptable by the router? (Choose two).a modema CSU/DSU deviceA network administrator enters the following command into Router1: ip route 192.168.0.0 255.255.255.0 S0/1/0. Router1 then receives a packet that is destined for192.168.0.22/24. After finding the recently configured static route in the routing table, what does Router1 do next to process the packet?encapsulates the packet into a frame for the WAN link and forwards the packet out the S0/1/0 interfaceWhich piece of information is available from examining the output of the command show ip interface brief?Interface IP addressWhich of the following is true regarding CDP and the graphic shown?By default, Router A will receive CDP advertisements from routers B and C.Which two statements describe functions or characteristics of CDP? (Choose two.)It starts up automatically and allows the device to detect directly connected neighbor devices that use CDP.It allows systems to learn about each other even if different network layer protocols are configured.Hosts on two separate subnets cannot communicate. The network administrator suspectsa missing route in one of the routing tables. Which three commands can be used to help troubleshoot Layer 3 connectivity issues? (Choose three.)pingtracerouteshow ip routeWhat happens to a static route entry in a routing table when the outgoing interface is not available?The route is removed from the table.The routers in the diagram use the subnet assignments shown. What is the most efficient route summary that can be configured on Router3 to advertise the internal networks to the cloud?192.1.1.0/25Refer to the exhibit. How will packets destined to the 172.16.0.0 network be forwarded? Router1 will perform recursive lookup and packet will exit S0/0.A router has one static route configured to each destination network. Which two scenarios would require an administrator to alter the static routes that are configured on that router? (Choose two.)The destination network no longer exists.A topology change occurs where the existing next-hop address or exit interface is not accessible.Refer to the exhibit. Given the output in the exhibit, how would a clock rate be determined for this link?The rate configured on the DCE determines the clock rate.Refer to the exhibit. Which set of commands will configure static routes that will allow the WinterPark and the Altamonte routers to deliver packets from each LAN and direct all other traffic to the Internet?WinterPark(config)# ip route 0.0.0.0 0.0.0.0 192.168.146.1Altamonte(config)# ip route 10.0.234.0 255.255.255.0 192.168.146.2Altamonte(config)# ip route 0.0.0.0 0.0.0.0 s0/1Refer to the exhibit. What two commands are required to provide connectivity betw een the 192.168.1.0 and 10.0.0.0 networks without requiring recursive lookup? (Choose two.)A(config)# ip route 10.0.0.0 255.0.0.0 s 0/1/0B(config)# ip route 192.168.1.0 255.255.255.0 s 0/0/0CCNA 2 - Module 3Which two statements correctly describe the concepts of administrative distance and metric? (Choose two.)Administrative distance refers to the trustworthiness of a particular route.Routes with the smallest metric to a destination indicate the best path.Refer to the exhibit. Which statement correctly describes how R1 will determine the best path to R2?R1 will install an EIGRP route using network B in its routing table because the administrative distance of EIGRP is lower than RIP.Which two statements are true regarding classless routing protoc ols? (Choose two.) sends subnet mask information in routing updatesallows for use of both 192.168.1.0/30 and 192.168.1.16/28 subnets in the same topologyWhich command would the network administrator issue to determine if load balancing is in effect on a router?show ip routeWhich statement is true regarding routing protocols?EIGRP uses DUAL to calculate the shortest path and can be configured to do unequal cost load balancing.Which two conditions would create a setting where the use of a distance-vector routing protocol would be efficient? (Choose two.)the network is using a hub and spoke topologythe network is using a flat designWhat is the purpose of a routing protocol?It allows a router to share information about known networks with other rou ters.Which of the following best describes the operation of distance vector routing protocols? They send their routing tables to directly connected neighbors.Which of the following is associated with link-state routing protocols?shortest-path first calculationsWhy is fast convergence desirable in networks that use dynamic routing protocols? Routers may make incorrect forwarding decisions until the network has converged.Which of the following conditions must be met in order for a network to have con verged The routers in the network are operating with consistent routing knowledge.Which two statements are true regarding metrics? (Choose two.)EIGRP uses bandwidth as a metric.OSPF uses cost based on bandwidth as a metric.Which two statements are true regarding the advantages of the use of static routes? (Choose two).increased securitythe administrator maintains control over routingThe 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?The value, 120, is used to determine the best path when a router has more than one routing protocol configured for the same destination network.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 shutdownA routing table entry is made to the 172.16.3.0 network with a code of "C".An engineer creates a static route by entering the Router(config)# ip route 10.0.0.0 255.255.255.0 192.168.1.2 command. What can be concluded about this route?The administrative distance of this route is 1.Refer to the exhibit. Router1 and Router2 are running EIGRP. All interfaces are operational and packets can be forwarded between all networks. What information will be found in the routing table for Router1?The administrative distance of the route to network 172.16.0.0 will be 90.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.A growing medium-sized manufacturing company recently began to have routing instability issues. The company uses static routes and has a mixture of over 30 Cisco and non-Cisco routers. The network administrator has decided to convert the network to dynamic routing. What characteristics of protocols should be considered in this selection process?OSPF can be used between the routers.Refer to the exhibit. If RIP is the routing protocol, what is the value of the metric from router A to network 192.168.5.0/24?3A router learns two paths with equal metrics to a destination network via the RIP routing protocol. How will the router handle packets to the destination network?The router will install both routes in the routing table and load balance between the two.CCNA 2 - Module 4Which event will cause a triggered update?a route is installed in the routing tableThree routers running a distance-vector routing protocol lost all power, including the battery backups. When the routers reload, what will happen?They will send updates that include only directly connected routes to their directly connected neighbors.What does the RIP holddown timer do?instructs routers to ignore updates, for a specified time or event, about possible inaccessible routesWhich two statements are true regarding the function of the RIPv1 routing updates? (Choose two).updates are broadcast at regular intervalsbroadcasts are sent to 255.255.255.255Which of the following statements are correct about RIP?will send out an update if there is a failure of a linkWhich two statements describe EIGRP? (Choose two.)EIGRP sends triggered updates whenever there is a change in topology that influences the routing information.EIGRP sends a partial routing table update, which includes just routes that have been changed.Which statement is true regarding cisco’s RIP_JITTER variable?It prevents the synchronization of routing updates by subtracting a random length of time ranging from 0% to 15% of the specified interval time from the next routing update interval.What actions will occur after RouterA loses connectivity to network 114.125.16.0? (Choose two.)RouterB will include network 123.92.76.0 and 136.125.85.0 in its update to RouterA.Router C will learn of the loss of connectivity to network 114.125.16.0 from RouterB.Which of the following methods does split horizon use to reduce incorrect routing information?Information learned from one source is not distributed back to that source.The graphic shows a network that is configured to use RIP routing protocol. Router2 detects that the link to Router1 has gone down. It then advertises the network for this link with a hop count metric of 16. Which routing loop prevention mechanism is in effect?route poisoningWhat is the purpose of the TTL field in the IP header?limits the time or hops that a packet can traverse through the network before it should be discardedWhich of the following can exist in a distance vector network that has not converged? (Choose three.)routing loopsinconsistent traffic forwardinginconsistent routing table entriesRefer to the exhibit. The routers in this network are running RIP. Router A has not received an update from Router B in over three minutes. How will Router A respond?The Invalid timer will mark the route as unusable if an update has not been received in 180 seconds.A network administrator is evaluating RIP versus EIGRP for a new network. The network will be sensitive to congestion and must respond quickly to topology changes. What are two good reasons to choose EIGRP instead of RIP in this case? (Choose two.)EIGRP only updates affected neighbors.EIGRP updates are partial.Refer to the exhibit. What path will packets from the 192.168.1.0/24 network travel to reach the 10.0.0.0/8 network if RIP is the active routing protocol?The path will be router A -> router D -> router E.Which three routing protocols are distance vector routing proto cols? (Choose three).RIPv1EIGRPRIPv2What is a routing loop?a condition where a packet is constantly transmitted within a series of routers without ever reaching its intended destinationWhich two conditions are most likely to cause a routing loop? (Choose two.)inconsistent routing tablesincorrectly configured static routesWhat metric does the RIP routing protocol consider to be infinity?16What does a router running RIP do first with a new route that is received from an advertisement?adjusts the metric for the new route to show the added distance for the routeRefer to the exhibit. If all routers are using RIP, how many rounds of updates will occur before all routers know all networks?3CCNA 2 - Module 5Refer to the exhibit. The network that is shown is running RIPv1. The 192.168.10.0/24 network was recently added and will only contain end users. What command or set of commands should be entered on Router1 to prevent RIPv1 updates from being sent to the end user devices on the new network while still allowing this new network to be advertised to other routers?Router1(config-router)# passive-interface fastethernet 0/0The following line was displayed in the output of the show ip route command.R 192.168.3.0/24 [120/3] via 192.168.2.2, 00:00:30, Serial0/0What is the value of the routing metric?3Which of the following is considered a limitation of RIP v1?RIP v1 does not send subnet mask information in its updates.Refer to the exhibit. The Ethernet interface on Router2 goes down and the administrator notices that the route is still in the Router1 routing table. How much longer will Router1 keep the down network in its routing table before marking it as possibly down?155 secondsRefer to the exhibit. Router1 is running RIPv1. What command was entered into Router1 to configure the gateway of last resort?ip route 0.0.0.0 0.0.0.0 S0/0/1What are three characteristics of the RIPv1 routing protocol? (Choose three.)uses hop count as a metricconsiders a metric of 16 as infinitycalculates metrics using the Bellman Ford algorithmWhich of the following would be the correct command sequence to enable RIP on Router B for all connected networks?RouterB(config)# router ripRouterB(config-router)# network 198.16.4.0RouterB(config-router)# network 210.36.7.0RouterB(config-router)# network 220.17.29.0What is the default update period in seconds for the RIP routing protocol?30Refer to the exhibit. What can be concluded from the routing table output of router B? The default-information originate command has been entered on A.Refer to the exhibit. A network consists of multiple routers. What can be verified when the show ip protocols command is issued on one of the routers in the network? routing protocol configuration in use for IP on this routerRefer to the exhibit. All routers are configured with valid interface addresses in the indicated networks and are running RIPv1. The network is converged. Which routes are present in the routing tables?All routers have all /30 routes. Routers A and E also have some of the /24 routes in their routing table.Which two statements are true regarding the characteristics of RIPv1? (Choose two). It is a distance vector routing protocol.The data portion of a RIP message is encapsulated into a UDP segment.Which command or set of commands will stop the RIP routing process?RouterB(config)# no router ripRefer to the exhibit. All routers in the exhibit are running RIP v1. The network administrator issues the show ip route command on router A. What routes would ap pear in the routing table output if the network is converged? (Choose two).R 192.168.2.0/24 [120/1]R 10.10.1.0/24 [120/2]Which command will display RIP activity as it occurs on a router?debug ip ripRefer to the output from the show ip route command. What can be concluded from the output of this router command?There are two equal cost paths to network 1.0.0.0.Refer to the exhibit. Router1 and Router2 are running the RIPv1 protocol. The network administrator configures the command network 10.1.0.0 on Router1. What network will Router1 advertise to Router2?10.0.0.0/8Refer to the exhibit. Pings between the serial interfaces of the routers are successful. Hosts on each LAN can ping the Fa0/0 interface of the router to which they are directlyconnected through the switch. However, pings between hosts on the 10.1.1.0/24 and 10.1.2.0/24 networks are unsuccessful. What is a likely cause of this problem?RIP is configured incorrectly on R1.What will happen if an interface IP address is entered for the address portion of the network command in a RIPv1 configuration instead of a network address?All interfaces in the same classful network as the configured address will be included in the RIPv1 routing process.Refer to the exhibit. All routers that are shown are running the RIP routing protocol. All unknown IP traffic must be forwarded to the ISP. What router or set of routers are recommended to have both a default route and the default-information originate command issued to implement this forwarding policy?only the gateway routerCCNA 2 - Module 6What two advantages does CIDR provide to a network? (Choose two.)reduced routing table sizereduced routing update trafficRefer to the exhibit. The network administrator wants to create a subnet for the po int-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?255.255.255.252Refer to the exhibit. A network engineer is summarizing the two groups of routes on router R1 shown in the exhibit. Which summarization will work for all the subnets?192.168.0.0/21Which of the following are contained in the routing updates of classless routing protocols? (Choose two.)32-bit addresssubnet maskWhich of the following problems does VLSM help to alleviate?the shortage of IP addressesWhat does VLSM allow a network administrator to do?utilize multiple subnet masks in the same IP address spaceRefer to the exhibit. What subnet mask will be applied if Router A sends a RIPv1 update for the network 172.16.1.0 to Router B?24Refer to the exhibit. The network administrator wants to minimize the number of entries in Router1’s routing table. What should the administrator implement on the network?CIDRA router has a summary route to network 192.168.32.0/20 installed in its routing table. What range of networks are summarized by this route?192.168.32.0 – 192.168.47.0/24A network administrator is tasked with dividing up a class C network among the QA, Sales, and Administration departments. The QA department is made up of 10 people, the Sales is made up of 28 people, and the Administration has 6. Which two subnets masks adequately address the QA and Sales departments? (Choose two.)255.255.255.224 for Sales255.255.255.240 for QAIn the network shown in the graphic, three bits were borrowed from the host portion of a Class C address. How many valid host addresses will be unused on the three point-to-point links combined if VLSM is not used?84A Class C address has been assigned for use in the network shown in the graphic. Using VLSM, which bit mask should be used to provide for the number of host addresses required on Router A, while wasting the fewest addresses?/27An additional subnet is required for a new Ethernet link between Router1 and Router2 as shown in the diagram. Which of the following subnet addresses can be configured in this network to provide a maximum of 14 useable addresses for this link while wasting the fewest addresses?192.1.1.224/28Which three interior routing protocols support VLSM? (Choose three.)OSPFRIP v2EIGRPRefer to the exhibit. The number of required host addresses for each subnet in a network is listed in the exhibit. This number includes the host address requirements for all router ports and hosts on that subnet. After all device and router port address assignments are determined, what will be the total number of unused host addresses available?29Refer to the exhibit. In the network that is shown, the router interfaces are assigned the first address ineach subnet. Which IP address would be usable for a host on one of the LANs in this network?192.168.2.130/25Refer to the exhibit. Which address is a broadcast address for one of the subnets that are shown in the exhibit?192.168.4.15/29Refer to the exhibit. A network administrator needs to create two subnetworks from 10.0.0.0/8 for a router running RIPv2. The Admin subnet requires 120 hosts and the Sales subnet requires 58 hosts. The network administrator assigned 10.0.1.128/25 to the Admin subnet. The Sales subnet i s given 10.0.1.192/26. What will be the result of this addressing scheme?Because RIPv2 does not support VLSM, the subnet masks will not be allowed.The subnets overlap and will be rejected by the router.Refer to the exhibit. A network technician enters the static route in R1 needed to reach network 10.1.1.0/24. A ping from the S0/0/0 interface on R1 to host B fails. The technician begins testing the network and has the following results:1. pings from R1 to the S0/0/0 interface on R2....successful2. pings from R1 to the Fa0/0 interface on R2....successful3. pings from host B to hosts on the 10.1.1.0/24 network....successful4. pings from host B to the Fa0/0 interface on R2....successful5. pings from R2 to host B....successful.The default gateway on host B is not correctly set.What is a supernet?a summarization of classful addressesCCNA 2 - Module 7Refer to the exhibit. If all routers are running RIP version 2, why is there no route for the 192.168.1.32/27 network?Rip version 2 will auto summarize routes by default.Refer to the exhibit. Which two statements are true? (Choose two.)Router1 will install a route to 192.168.0.0/20Router2 will not install a route to 192.168.16.0/20Refer to the exhibit. Which command on which router will allow Router1 to learn about the 192.168.0.0/20 network?Router2(config-router)# version 2What are two reasons to implement RIP version 2 rather than RIP version 1? (Choose two.)RIP version 2 supports VLS M.。

CCNA路由和交换网络简介第章探索网络练习和答案(二)

CCNA路由和交换网络简介第章探索网络练习和答案(二)CCNA路由和交换网络简介第章探索网络练习和答案本文将为大家介绍CCNA路由和交换网络简介第章探索网络练习和答案，帮助大家更好地了解网络知识。

一、练习题1. 什么是计算机网络？2. 什么是协议？3. OSI模型中，每一层的作用是什么？4. 什么是TCP/IP协议？5. 什么是IP地址？6. 什么是子网掩码？7. 什么是路由器？8. 什么是交换机？二、答案解析1. 计算机网络是指两台或两台以上计算机通过通信设备和通信线路连接起来，以实现信息交换和资源共享的系统。

2. 协议是计算机网络中用于规定通信双方之间的通信规则和格式的一种约定。

3. OSI模型中每一层的作用如下：- 应用层：提供应用程序之间的通信和数据交换服务。

- 表示层：负责处理数据格式的转换、数据加密和解密等。

- 会话层：负责建立、管理和终止会话。

- 传输层：负责数据的传输和流量控制。

- 网络层：负责数据的路由和寻址。

- 数据链路层：负责数据的传输和错误检测。

- 物理层：负责数据的传输和物理连接。

4. TCP/IP协议是一种网络协议，它是互联网的基础协议，包括TCP和IP两个部分。

TCP负责数据的分段和重组，IP负责数据的路由和寻址。

5. IP地址是指互联网协议地址，它是用于标识网络上设备的一种地址，由32位二进制数表示。

6. 子网掩码是一种用于划分网络的地址掩码，它与IP地址一起使用，用于确定网络地址和主机地址的范围。

7. 路由器是一种网络设备，它负责将数据包从一个网络传输到另一个网络，是网络中的重要组成部分。

8. 交换机是一种网络设备，它负责在局域网中转发数据包，是局域网中的重要组成部分。

以上就是本文为大家介绍的CCNA路由和交换网络简介第章探索网络练习和答案，希望对大家有所帮助。

网络管理2016版第二章课后习题答案(可编辑修改word版)

1、表示层的功能是什么？抽象语法和传输语法各有什么作用？
表示层的功能是提供统一的网络数据表示。

ASN.1(抽象语法表示)：一种形式语言，提供统一的网络数据表示，通常用于定义应用数据的抽象语法和应用层协议数据单元的结构
传输语法：把抽象数据变换成比特串的编码规则
2、用ASN.1 表示一个协议数据单元（例如，IEEE802.3 的帧）。

GetRequest-
PDU::=SEQUENCE{ request-id
INTEGER,
error-status INTEGER,
error-index INTEGER,
variable-bindings VarBind
}
VarBind::=SEQUENCE{
name OBJECT IDENTIFIER,
value NULL
}
3、用基本编码规则对长度字段L 编码：L=18,L=180,L=1044。

L=18，00010010；L=180，10000001 10110100；L=1044，10001000 10010100
4、用基本编码规则对下面的数据编码：标签值＝1011001010，长度＝255.
标签编码：×××11111 1000 0101 11001010；长度编码：10000001 11111111
5、为什么要用宏定义?怎样由宏定义得到宏实例？
使用宏定义的目的是为了简化类型定义的方法。

用具体的值代替宏定义中的变量可以产生宏实例。

ccna第二章章节习题加答案

第1章路由和数据包转发介绍1.下面哪些路由器的组成和它的功能是匹配的？DA.Flash：永久的储存bootstrap程序B.ROM：永久地存储启动配置文件C.NVRAM：永久地存储操作系统镜像D.RAM：存储路由表和ARP缓存2.哪两个命令可以用来检查给路由器串行接口分配的IP地址？A、EA.show interfacesB.show interfaces ip briefC.show controllers allD.show ip configE.show ip interface brief3.下面哪些命令可以设置特权模式口令为“quiz”？AA.R1（config）# enable secret quizB.R1（config）# password secret quizC.R1（config）# enable password secret quizD.R1（config）# enable secret password quiz4.哪个路由原理是正确的？CA.如果一个路由器在它的路由表中具有确定的信息，那么所有邻接的路由也拥有同样的信息B.从一个网络到另外一个网络路径的路由信息意味着存在着反向（或返回）路径的路由信息C.每个路由器根据它自己路由表中的信息，独立作出路由判断D.每个路由器根据它自己和邻居路由表中的信息，独立作出路由判断5.动态路由协议执行哪两个任务？B、DA.发现主机B.更新和维护路由表C.传播主机默认网关D.网络发现E.分配IP地址6.网络工程师正在配置一个新的路由器。

接口已经配置好了IP地址，并且已经激活。

但是还没有配置路由协议或静态路由。

这时路由表中出现的是什么路由？CA.默认路由B.广播路由C.直接路由D.没有路由，路由表也是空的7.下面哪两个对于路由器转发数据包的描述是正确的？B、DA.如果数据包是去往远程网络的，那么路由器会向所有到这个网络的下一跳接口发送该数据包B.如果数据包是去往直连网络的，那么路由器会向路由表中所指示的外出接口发送C.如果数据包是去往远程网络的，那么路由器会根据路由主机表来发送该数据包D.如果数据包是去往远程网络的，那么路由器会向路由表中所指示下一跳IP发送E.如果数据包是去往直连网络的，那么路由器会根据目的MAC地址发送该数据包F.如果数据包是去往直连网络的，那么路由器会转发数据包到下一跳VLAN的交换机8.关于路由协议使用的度量的哪个描述是正确的？AA.度量是路由协议用来检测给定路由的一个测量值B.度量是思科专有的用来转换距离到标准单元的方法C.度量表示了对于所有路由协议中发生的数据包丢失的数量的一个统计值D.路由器使用度量lai 决定哪些包是错误的和要被丢失的9.网络管理员在路由器上配置了ip rout 0.0.0.0 0.0.0.0 serial 0/0/0命令。

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。

ccna第2学期第2章答案

Router# show interfaces serial 0/1 命令的输出显示了如下内容：Serial0/1 is up, line protocol is down.线路协议为down（关闭）的原因最可能是什么？Serial0/1 为关闭状态。

路由器未连接电缆。

远程路由器正在使用serial 0/0 接口。

尚未设置时钟频率。

2 points for Option 4下列哪一个地址可以用来总结网络172.16.1.0/24、172.16.2.0/24、172.16.3.0/24 和172.16.4.0/24？172.16.0.0/21172.16.1.0/22172.16.0.0 255.255.255.248172.16.0.0 255.255.252.02 points for Option 1请参见图示。

目的地为172.16.0.0 网络的数据包会被如何转发？Router1 会执行递归查找，数据包将从S0/0 接口发出。

Router1 会执行递归查找，数据包将从S0/1 接口发出。

没有与172.16.0.0 网络关联的匹配接口，因此数据包将被丢弃。

没有与172.16.0.0 网络关联的匹配接口，因此数据包将采用“最后选用网关”，从S0/2 接口发出。

2 points for Option 1指向下一跳IP 的静态路由在路由表中会显示怎样的管理距离和度量？管理距离为0，度量为0管理距离为0，度量为1管理距离为1，度量为0管理距离为1，度量为12 points for Option 3两个独立子网上的主机之间无法通信。

网络管理员怀疑其中一个路由表中缺少路由。

可以使用哪三条命令来帮助排查第 3 层连通性问题？（选择三项。

）pingshow arptracerouteshow ip routeshow interfaceshow cdp neighbor detailOption 1, Option 3, and Option 4 are correct.请参见图示。

CCNA第二学期官方章节考试题之《距离矢量路由协议》(附答案)46doc

数据包在路由器的两个环回接口之间来回传递
从目的地返回的路径与出发路径不同而形成
数据包在一系列路由器间不断传输却始终无法到达其真正的目的地的情况路由从一种路由协议到另一种路由协议的分布
2
用于在发送到其它路由器的更新中将路由标记为不可达
防止定期更新消息错误地恢复已经不可用的路由
防止从收到更新的接口通告同一网络
限制数据包在被丢弃之前在网络中传输的时间或跳数
通过设置最大跳数来为每一距离矢量路由协议定义最大度量值
4以
路由环路
不一致的流量转发
除非系统收敛，否则不会转发任何流量
路由表条目不一致
路由表更新被发送到错误的目的地
6运
立即将其加入路由表中
调整新路由的度量以显示增加的路由距离
将该路由从其传入接口以外的所有其它接口通告出去
发送
8下
它会在更新从路由器接口送出时缓冲更新，以此防止路由更新同步。

它会从下一次路由更新间隔中减去随机时间段（大小为指定间隔时间的
它会使路由器跳过每一个其它计划更新时间，以此防止路由更新同步。

它会强制路由器在发送自身更新之前侦听链路上的其它更新是何时发送的，以此防止路由更新同步10
13以15水
17R
19哪
抑制计时器将等候
如果在
更新计时器将请求有关从路由器Hello。

(完整版)计算机网络(第二章)课后答案

第二章应用层(课后习题和问题部分题目和参考答案)复习题：1.列出5种非专用的因特网应用及它们所使用的因特网协议。

答案：Web应用和HTTP协议、电子邮件应用和SMTP（简单邮件传输协议）、因特网的目录服务DNS和DNS协议、P2P应用和P2P协议、远程终端访问和Telnet、文件传输和FTP。

3.对两进程之间的通信会话而言，哪个进程是客户机，哪个进程是服务器？答案：在给定的一对进程之间的通信会话中，发起通信（即在该会话开始时与其他进程联系）的进程被标示为客户机，在会话开始时等待联系的进程是服务器。

6．假定你想尽快的处理从远程客户机到服务器的事务，应使用UDP 还是TCP？为什么？答案：UDP，因为TCP是面向连接的可靠数据传输服务，使用TCP 协议时，在应用层数据报文开始流动之前，其客户机程序和服务器程序之间互相交换运输层控制信息，完成握手阶段。

TCP的三次握手，以及拥塞控制机制和分组都有开销。

UDP没有拥塞控制机制，所以发送端可以以任何速率向其下面的层（网络层）注入数据。

7.在日常生活中你或许会使用Web浏览器和邮件阅读器。

你或许还会用到FTP用户代理，Telnet用户代理，音频/视频播放器用户代理（比如Real Networks player），即时信息代理，P2P文件共享代理。

答案：无。

8.列出运输协议能够提供的4种宽泛类型的服务。

对于每种服务类型，指出是UDP还是TCP（或这两种协议）提供这样的服务。

答案：1.可靠数据传输，TCP提供了可靠的端到端数据传输服务，而UDP没有。

2.吞吐量，TCP和UDP均为提供此服务。

3.定时，TCP和UDP均为提供此服务。

4.安全性，TCP在应用层可以很容易地通过SSL来提供安全服务,而UDP没有。

10.握手协议的作用是什么？答案：提示客户机和服务器做好传输分组的准备。

15．为什么说FTP在“带外”发送控制信息？答案：因为FTP 使用两个并行的TCP连接来传输文件，一个是控制连接，一个是数据连接。

CCNA最新中文版题库第二学期第二单元 (2)

1.Router# show interfaces serial 0/1 命令的输出显示了如下内容：Serial0/1 is up, line protocol is down.线路协议为 down（关闭）的原因最可能是什么？Serial0/1 为关闭状态。

路由器未连接电缆。

远程路由器正在使用 serial 0/0 接口。

尚未设置时钟频率。

2.哪一个地址可以用来总结从到的所有网络？3.请参见图示。

目的地为网络的数据包会被如何转发？Router1 会执行递归查找，数据包将从 S0/0 接口发出。

Router1 会执行递归查找，数据包将从 S0/1 接口发出。

没有与网络关联的匹配接口，因此数据包将被丢弃。

没有与网络关联的匹配接口，因此数据包将采用“最后选用网关”，从 S0/2 接口发出4指向下一跳 IP 的静态路由在路由表中会显示怎样的管理距离和度量？管理距离为 0，度量为 0管理距离为 0，度量为 1管理距离为 1，度量为 0管理距离为 1，度量为 15.两个独立子网上的主机之间无法通信。

网络管理员怀疑其中一个路由表中缺少路由。

可以使用哪三条命令来帮助排查第 3 层连通性问题？（选择三项。

）pingshow arptracerouteshow ip routeshow controllersshow cdp neighbor6.请参见图示。

为使主机 A 能够连接到网络上的主机 B，应在 Router1 上配置哪种静态路由？ip routeip routeip route S0/0/1ip route S0/0/07.Router# show cdp neighbors 命令会显示下列哪些内容？（选择三项。

）负载平台可靠性保持时间本地接口8.为什么在创建送出接口为以太网络的静态路由时输入下一跳 IP 地址是明智之举？添加下一跳地址将使路由器在转发数据包时不再需要在路由表中进行任何查找。

在多路访问网络中，如果没有下一跳地址，路由器将无法确定以太网帧的下一跳MAC 地址。

CCNA网络学院第二学期第二章试题及答案

ERouting Chapter 2 - CCNA Exploration: 路由协议和概念 (版本 4.0)1当外发接口不可用时，路由表中的静态路由条目有何变化？该路由将从路由表中删除。

路由器将轮询邻居以查找替用路由。

该路由将保持在路由表中，因为它是静态路由。

路由器将重定向该静态路由，以补偿下一跳设备的缺失。

2 哪两种设备负责将来自 WAN服务提供商的数据转换为路由器可以接受的形式？（选择两项。

）路由器的串行端口调制解调器交换机路由器的以太网端口CSU/DSU 设备DTE 设备3请参见图示。

要使WinterPark 和Altamonte 路由器能够传送来自每个LAN 的数据包并将所有其它流量转到Internet，应命令来配置静态路由？WinterPark(config)# ip route 0.0.0.0 0.0.0.0 192.168.146.1Altamonte(config)# ip route 10.0.234.0 255.255.255.0 192.168.146.2Altamonte(config)# ip route 0.0.0.0 0.0.0.0 s0/1WinterPark(config)# ip route 0.0.0.0 0.0.0.0 192.168.146.1Altamonte(config)# ip route 10.0.234.0 255.255.255.0 192.168.146.2Altamonte(config)# ip route 198.18.222.0 255.255.255.255 s0/1WinterPark(config)# ip route 172.191.67.0 255.255.255.0 192.168.146.1WinterPark(config)# ip route 0.0.0.0 0.0.0.0 192.168.146.1Altamonte(config)# ip route 10.0.234.0 255.255.255.0 192.168.146.2WinterPark(config)# ip route 172.191.67.0 255.255.255.0 192.168.146.1Altamonte(config)# ip route 10.0.234.0 255.255.255.0 192.168.146.2Altamonte(config)# ip route 0.0.0.0 0.0.0.0 s0/04路由器配置有到达每个目的网络的静态路由。