ccna第二章答案

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计算机网络第二章习题解答

计算机网络第二章习题解答

计算机网络第二章习题解答1. 问题描述:解释什么是分组交换?分组交换是一种网络传输技术,其中数据被分成较小的块(或分组)进行传输,而不是以连续的比特流进行传输。

在分组交换中,每个分组都会独立地通过网络传输,并且可以根据网络条件选择最佳路径来传输分组。

2. 问题描述:什么是电路交换?请列出其优点和缺点。

电路交换是一种传输技术,其中通信路径在建立连接时被预先分配。

在电路交换中,通过建立一个持续的、专用的通信路径来实现端到端的数据传输。

优点:- 传输效率高,数据传输过程稳定;- 可保障数据传输的实时性,适用于需求严格的应用场景,如电话通信;缺点:- 通信链路建立时间较长;- 通信路径在建立时就被预留,即使在通信过程中没有数据传输也会占用资源;- 在链路建立的过程中,若链路中断,需要重新建立连接。

3. 问题描述:什么是存储转发交换?请列出其特点。

存储转发交换是一种分组交换的方式,其中每个分组在传输之前需要完全接收,并存储在交换机的缓冲区中,然后根据目的地址选择合适的端口进行转发。

存储转发交换的特点包括:- 可以处理不同大小的分组,适用于各种应用场景;- 由于分组在接收端进行存储和处理,因此可以对接收到的分组进行差错检测和纠正;- 可以在网络拥塞时进行流量控制,防止分组丢失。

4. 问题描述:简要解释虚电路交换和数据报交换的区别?虚电路交换和数据报交换都是分组交换的方式,但两者存在一些区别。

虚电路交换中,发送端和接收端在通信之前会建立一个虚电路,路由器会记录这个虚电路,将后续的分组沿着虚电路转发。

在传输过程中,每个分组都有一个虚电路号标识,使得分组能够按照特定的路径到达目的地。

虚电路交换类似于电路交换,在传输过程中,分组的到达顺序和给定路径的稳定性都得到了保证。

而数据报交换中,每个分组都是独立地通过网络传输,每个分组都包含了目的地址等信息,因此路由器根据分组的目的地址来选择最佳的传输路径。

数据报交换类似于存储转发交换,分组可以通过不同的路径进行传输,灵活性较高。

思科认证CCNA认证试题与答案中文版

思科认证CCNA认证试题与答案中文版
(A) 224. 0. 0.5 (B) 127. 32. 5. 62 (0202. 112.5.0 (D) 162. 111. 111. Ill
答案:D 注释:这个题目不是太严谨,应该加上子网掩码. A:224. 0. 0. 5 是多播地址 B: 127. 0.0. 0 保留作为测试使用 C:网络地址 26、 设置主接口由 up 转 down 后延迟 30 秒切换到备份接口,主 接口 由 down 转 up 后 60 秒钟切换回主接口的配置为()
忍一句,息一怒,饶一着,退一步。——《增广贤文》
人之为学,不日进则日退,独学无友,则孤陋而难成;久处一方,则习染而不自觉。——《顾炎武》
答案:D 注释:255. 255. 255. 255 是全网广播,DHCP 客户端发送全网广播来 查 找 DHCP 服务器. 24、 下而有关 NAT 叙述正确的是() (A) NAT 是英文“地址转换”的缩写,又称地址翻译 (B) XAT 用来实现私有地址与公用网络地址之间的转换 (C) 当内部网络的主机访问外部网络的时候,一定不需要 NAT (D) 地址转换的提出为解决 IP 地址紧张的问题提供了一个有效途 径 答案:ABD 25、 以下属于正确的主机的 IP 地址的是()
(A) arp-a (B) traceroute (C) routeprint (D) displayiprouting-table
答案:D 23、 D0. 0. 0 (B) 10. 0. 0. 1 (0127. 0. 0. 1 (D)255. 255. 255. 255
192. 168. 1. 1
答案:D 注释:PC 的'默认网关要指向路由器的以太网口的 IP 地址. 28、 ISDNB 信道速率是()
(A) 16kbps (B) 64kbps

CCNA2第二章路由器基础

CCNA2第二章路由器基础

第二章路由器基础1、cisco IOS 软件内置在几乎所有的cisco路由器和catalyst交换机上。

提供下列服务:基本的路由选择和交换功能;对联网资源可靠和安全的访问;网络的可扩展性。

2、命令行界面CLI3、CLI环境可通过以下几种方式访问:通过控制台会话;通过AUX端口的调制解调器或者零调制解调器;通过telnet作为虚拟终端连接到路由器(需要给一个端口配置IP地址,为各个虚拟终端会话配置登录并设定口令)。

4、路由器的用户界面模式:分级机构;EXEC命令执行者;出于安全考虑EXEC会话分成2个级别:“用户EXEC模式”和“特权EXEC模式”。

5、用户EXEC模式:“>”,用于监视网络,不允许改变路由器配置。

6、特权EXEC模式:“#”,可到达配置模式,进行路由器修改。

7、cisco IOS软件版本的命名约定:该映像所运行的平台;该映像所支持的特定功能;该映像在哪里运行,以及它是否是被压缩的。

8、选择cisco IOS的一个主要问题是该映像与路由器的Flash和RAM存储器是否兼容。

而兼容主要指的是容量够不够。

9、会阻止路由器正确启动的情况:缺少配置文件或者boot system语句不正确;不正确的配置寄存器值;受损的Flash映像;硬件故障。

10、路由器状态命令:show version 显示系统软硬件版本名称和来源,启动映像的配置,显示系统最近一次重启的原因;show processes 显示关于活动进程的信息;show protocols显示所配置的各种协议,显示所配置的任何一种第三层协议状态;show memory显示路由器内存信息,包括对空闲内存池的统计信息;show stacks 监视进程和中断例程对堆栈的使用情况;show buffers 提供路由器上缓冲池的统计信息;show flash 显示关于Flash存储器设备的信息;show running-config 显示活动配置文件;show startup-config 显示备份配置文件;show interface 显示所配置的所有接口的统计信息。

CCNA学习指南第2章复习题中英文翻译版

CCNA学习指南第2章复习题中英文翻译版

CCNA学习指南第2章复习题中英文翻译版1. What are the decimal and hexadecimal equivalents of the binary number 10011101?(Choose two.)1. 二进制数10011101等效的十进制和十六进制数分别是多少?(选择两项。

)A. 159B. 157C. 185D. 0x9DE. 0xD9F. 0x1592. Which of the following allows a router to respond to an ARP request that is intended for a remote host?2. 下列哪一项允许路由器对远端主机的ARP请求做出响应?A. Gateway DP网关DPB. Reverse ARP (RARP)反向ARPC. Proxy ARP代理ARPD. Inverse ARP逆向ARPE. Address Resolution Protocol (ARP)地址解析协议3. You want to implement a mechanism that automates the IP configuration, including IP address, subnet mask, default gateway, and DNS information. Which protocol will you use to accomplish this?3. 你想实现自动IP配置,包括IP地址,子网掩码,默认网关和DNS信息。

你应该使用什么协议来完成这?A. SMTP简单邮件传输协议B. SNMP简单网络管理协议C. DHCP动态主机控制协议D. ARP地址解析协议4. What protocol is used to find the hardware address of a local device?4. 什么协议用来找本地设备的硬件地址?A. RARPB. ARPC. IPD. ICMPE. BootP5. Which of the following are layers in the TCP/IP model? (Choose three.)5. 下列哪些层属于TCP/IP模型?(选择三项。

ccna第二学期练习题中文答案..

ccna第二学期练习题中文答案..

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 接口控制台接口以太网接口加密执行模式特权执行模式路由器配置模式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?仅第 2 层源地址仅第 2 层目的地址仅第 3 层源地址仅第 3 层目的地址第 2 层源地址和目的地址第 3 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 相连网络上的主机之间相互ping 都会遭到失败。

此问题最可能的原因是什么?目的网络不存在。

路由器接口的IP 地址必须配置为网络地址而非主机地址。

必须使用no shutdown命令启用接口。

每个接口都必须使用clock rate命令配置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。

)源IP 地址:192.168.10.129源IP 地址:BBBB.3333.5677源MAC 地址:5555.AAAA.6666目的IP 地址:192.168.10.33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 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-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)# ip address 201.100.53.1 255.255.255.224Sydney(config-if)# clock rate 56000Sydney(config-if)# ip host Melbourne 201.100.53.27请参见图示。

CCNA1_2_English答案

CCNA1_2_English答案

Which method of interacting with an operating system involves typing commands at a command prompt?CLIGUIredirectorkernel translatorWhat are two ways that a user can interact with an operating system shell? (Choose two.)CLIOSGUINICkernelWhat are three characteristics of an operating system that is released under the GPL (GNU Public License)? (Choose three.)full access to source codesoftware often available freestructured development cyclecan be expensive to purchaselimits what end-user can do with codesupport normally user-based and often freeWhich three resource specifications are given by the manufacturer to ensure that an operating system performs as designed? (Choose three.)type of keyboardprinter requirementsrequired video memoryrequired hard disk spaceprocessor type and speedrecommended amount of RAMYou must select an operating system for the faculty at a college. All of the questions below would be logical for you to ask except one. Determine the illogical question.How much does the operating system cost and does the college have funding?Is the technical support staff at the college able to support the operating systems being considered?Do the operating systems being considered have the ability to support the ports available on the faculty computers?What types of applications do the faculty use and are they compatible with the operating systems being considered?An operating system is severely damaged. All data on the partition needs to be deleted, and all application software must be reinstalled. Which installation method should be used to correct the problem?clean installupgrademulti-bootvirtualizationWhich two statements should be included in a pre-installation checklist when upgrading an operating system? (Choose two.)Verify that the hardware resources have multiple partitions.Verify that the hardware resources meet or exceed the published minimum requirements. Complete a full backup of all important files and data.Overwrite any data currently contained on the drive to remove all contents.Verify that the hardware resources are certified to work with the existing operating system prior to upgrading.Which two statements are true about drive partitions? (Choose two.)Partitions are necessary in multi-boot installations.A hard drive can be divided into an operating system partition and a data partition.User data is never overwritten when a drive is partitioned.A disk partition is a defined section of an operating system.Each partition requires a different file system type.Which Windows file system is more likely to be used in a business environment?ext2ext3NTFSFAT16FAT32What occurs when computers are configured to receive their network configurations dynamically?Each computer receives a permanent IP address.A network administrator enters information on each computer.Each computer requests configuration information from a server.An NIC automatically provides configuration information to the computer and stores that configuration information.Which three pieces of information must be specified on a computer to allow that computer to send and receive information across networks? (Choose three.)IP addresssubnet maskclosest serverdefault gatewayoperating systemnetwork card manufacturerWhat is the purpose of a default gateway?physically connects a computer to a networkprovides a permanent address to a computeridentifies the network to which a computer is connectedidentifies the logical address of a networked computer and uniquely identifies it to the rest of the networkidentifies the device that allows local network computers to communicate with devices on other networksWhich statement is true about installing an operating system on computers in a networked environment?The computer name must be unique for all computers on the same network.The operating system must be the same on all computers on the same network.The amount of installed RAM must be the same on all computers on the same network.The operating system must have the latest patch applied during the installation or it will not participate in the network.Which two items must be unique to each computer and cannot be duplicated on a network? (Choose two.)partitionfile systemcomputer nameIP addressoperating systemWhich Windows XP Automatic Update option allows you to select the time when a Windows update is executed?Automatic (recommended).Install updates from the Windows Update web site.Notify me but don’t automatica lly download or install them.Download updates for me, but let me choose when to install them.Which operating system patch installation method is used when a user is notified of a security update for remotely accessing a computer, but wishes not to install this patch?manualautomaticsemi-automaticprompt for permissionThe Lesson TaskMaster application from ChalkBoard has a problem. Every time the software isinstalled and loaded on a Windows XP-based Dell computer, and the moment something is typed followed by a tab, two tabs are inserted instead of one. What would be the best solution to this problem?Uninstall and then reinstall Lesson TaskMaster.Download, install, and apply a patch from Dell.Download, install, and apply a patch from Microsoft.Download, install, and apply a patch from ChalkBoard.What two items are available from the About Windows option through the Windows Explorer Help menu? (Choose two.)a list of troubleshooting linksthe end-user license agreementa list of installed hardware devicesthe date of the last Windows updatethe operating system version numbera list of terms with links to definitionsWhat Explorer menu option is used to determine the Windows XP version installed on a computer?EditHelpViewToolsFavoritesWindows XP has a known problem with specific Intel processors. What is the best course of action to take in this situation?Power off the computer and reinstall the CPU.Delete Windows XP and perform a clean install.Reinstall Windows XP to the same hard drive partition.Reinstall Windows XP to a different hard drive partition.Download and install the Windows patch that fixes this problem.Replace the Intel processor with one that is approved by Microsoft.A computer in the Advanced Technology Center computer room on the second floor, room number 217, has the computer name ATC_217_7. What fact is true about the computer name?The name is dynamically assigned by the DNS server.The name is required to allow connectivity to the DHCP server.The name must include the floor number to support the SLA agreement.The names of all devices in a workgroup must be the same to allow LAN connectivity.The name makes it easier for users to reference the device when connecting to it to share resources.。

ccna第2章考试题

ccna第2章考试题

1以下哪个事件发生于传输层三次握手期间?两个应用程序交换数据。

TCP 初始化会话的序列号。

UDP 确定要发送的最大字节数。

服务器确认从客户端接收的数据字节数。

2采用 TCP/IP 数据封装时,以下哪个端口号范围标识了所有常用应用程序?0 到255256 到 10220 到10231024 到204749153 到655353请参见图示。

主机 A 正在使用FTP 从服务器1 下载大型文件。

在下载期间,服务器1 没有收到主机 A 对若干字节传输数据的确认。

服执行什么操作?创建第1 层堵塞信号到达超时时间后重新发送需要确认的数据向主机发送 RESET 位更改第4 层报头中的窗口大小4下列哪项是UDP 的重要特征?确认数据送达数据传输的延迟最短数据传输的高可靠性同序数据传输5下列哪三项功能使 TCP 得以准确可靠地跟踪从源设备到目的设备的数据传输?封装流量控制无连接服务会话创建编号和定序尽力传输6下列哪两项是用户数据报协议(UDP) 的功能?(选择两项)流量控制系统开销低无连接面向连接序列和确认7OSI 模型哪一层负责规范信息从源设备到目的设备准确可靠地流动?应用层表示层会话层传输层网络层8以下哪两个选项代表第4 层编址?(选择两项)标识目的网络标识源主机和目的主机标识正在通信的应用程序标识主机之间的多个会话标识通过本地介质通信的设备9下列哪个传输层协议提供低开销传输因而可用于不需要可靠数据传输的应用场合?TCPIPUDPHTTPDNS10请参见图示。

图中显示的是两台主机之间的TCP 初始数据交换。

假设初始序列号为0,如果数据段6 丢失,确认2 中将包含哪个序列23618503431347511TCP 报头信息和UDP 报头信息中都包含下列哪项信息?定序流量控制确认源和目的12下列哪项由源主机在转发数据时动态选择?目的逻辑地址源物理地址默认网关地址13请参见图示。

从显示的输出中可以确定以下哪两项信息?(选择两项)本地主机使用公认端口号标识源端口。

CCNA第二学期答案

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。

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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。

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