ccna第2学期第2章答案

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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。

CCNA2

CCNA中文笔记第2章:Internet Protocols作者：红头发Chapter2 Internet ProtocolsTCP/IP and the DoD ModelDoD模型被认为是OSI参考模型的浓缩品,分为4层,从上到下是:1.Process/Application layer2.Host-to-Host layer3.Internet layerwork Access layer其中,如果在功能上和OSI参考模型互相对应的话,那么:1.DoD模型的Process/Application层对应OSI参考模型的最高3层2.DoD模型的Host-to-Host层对应OSI参考模型的Transport层3.DoD模型的Internet层对应OSI参考模型的Network层4.DoD模型的Network Access层对应OSI参考模型的最底2层The Process/Application Layer ProtocolsProcess/Application层包含的协议和应用程序有：Telnet,FTP,X Windows,TFTP,SMTP,SNMP,NFS和LPD等等Dynamic Host Configuration Protocol(DHCP)/BootP(Bootstrap Protocol)动态主机配置协议(DHCP)服务器可以提供的信息有:1.IP地址2.子网掩码(subnet mask)3.域名(domain name)4.默认网关(default gateway)5.DNS6.WINS信息The Host-to-Host Layer ProtocolsHost-to-Host层描述了2种协议:1.传输控制协议(Transmission Control Protocol,TCP)2.用户数据报协议(User Datagram Protocol,UDP)Transmission Control Protocol(TCP)当1个主机开始发送数据段(segment)的时候,发送方的TCP协议要与接受方的TCP协议进行协商并连接,连接后即所谓的虚电路(virtual circuit),这样的通信方式就叫做面向连接(connection-oriented).面向连接的最大优点是可靠,但是它却增加了额外的网络负担(overhead)User Datagram Protocol(UDP)UDP协议的最他特点是无连接(connectionless),即不可靠,因为它不与对方进行协商并连接,它也不会给数据段标号,也不关心数据段是否到达接受方Key Concepts of Host-to-Host Protocols现在把TCP协议和UDP协议的一些特性做个比较:1.TCP.协议在传送数据段的时候要给段标号;UDP协议不2.TCP协议可靠;UDP协议不可靠3.TCP协议是面向连接;UDP协议采用无连接4.TCP协议负载较高;UDP协议低负载5.TCP协议的发送方要确认接受方是否收到数据段;UDP反之6.TCP协议采用窗口技术和流控制;UDP协议反之Port NumbersTCP和UDP协议必须使用端口号(port number)来与上层进行通信,因为不同的端口号代表了不同的服务或应用程序.1到1023号端口叫做知名端口号(well-known port numbers).源端口一般是1024号以上随机分配The Internet Layer Protocols在DoD模型中,Internet层负责：路由,以及给上层提供单独的网络接口Internet Protocol(IP)IP协议查找每个数据包(packets)的地址,然后,根据路由表决定该数据包下1段路径该如何走,寻找最佳路径Internet Control Message Protocol(ICMP)ICMP协议一样是工作在DoD模型的Internet层,IP协议使用ICMP协议来提供某些不同的服务,ICMP协议是一种管理协议一些ICMP协议相关信息和事件:1.目标不可达(destination unreachable):假如1个routers不能把IP协议数据报发送到更远的地方去,于是router将发送ICMP协议信息给数据报的发送方,告诉它说目标网络不可达2.缓冲区已满(buffer full):假如router的缓冲区已经存满发送方发来的IP协议数据报了,它将发送ICMP协议信息给发送方并告诉它缓冲区已满,如果再继续接受的话将导致缓冲区溢出,造成数据丢失3.跳(hops):IP协议数据报经过1个router,称为经过1跳4.Ping(Packet Internet Groper):采用ICMP协议信息来检查网络的物理连接和逻辑连接是否完好5.Traceroute:根据ICMP协议信息来跟踪数据在网络上的路径,经过哪些跳Address Resolution Protocol(ARP)地址解析协议(ARP)用于根据1个已知的IP地址查找硬件地址.它把IP地址翻译成硬件地址Reverse Address Resolution Protocol(RARP)RARP协议用于把MAC地址翻译成IP地址IP AddressingIP地址是软件地址,MAC地址是硬件地址,MAC地址是烧录在NIC里的,MAC地址用于在本地网络查找主机地址.IP地址是唯一的,也叫做网络地址(network address);硬件地址也叫节点地址(node address)Network Address网络地址分为5类:1.A类地址:4个8位位组(octets).第一个octet代表网络号,剩下的3个代表主机位.范围是0xxxxxxx,即0到1272.B类地址: 前2个octets代表网络号,剩下的2个代表主机位. 范围是10xxxxxx,即128到1913.C类地址: 前3个octets代表网络号,剩下的1个代表主机位. 范围是110xxxxx,即192到2234.D类地址:多播地址,范围是224到2395.E类地址:保留,实验用,范围是240到255Network Address:Special Purpose一些特殊的IP地址:1.IP地址127.0.0.1:本地回环(loopback)测试地址2.广播地址:255.255.255.2553.IP地址0.0.0.0:代表任何网络4.网络号全为0:代表本网络或本网段5.网络号全为1:代表所有的网络6.节点号全为0:代表某个网段的任何主机地址7.节点号全为1:代表该网段的所有主机广播地址TCP/IP协议规定,主机号部分各位全为1的IP地址用于广播.所谓广播地址指同时向网上所有的主机发送报文,也就是说,不管物理网络特性如何,Internet网支持广播传输.如136.78.255.255就是B类地址中的一个广播地址,你将信息送到此地址,就是将信息送给网络号为136.78的所有主机.有时需要在本网内广播,但又不知道本网的网络号时,TCP/IP协议规定32比特全为1的IP地址用于本网广播,即255.255.255.255Private IP Address私有IP地址(private IP address):节约了IP地址是空间,增加了安全性.处于私有IP地址的网络称为内网,与外部进行通信就必须靠网络地址翻(network address translation,NA T)一些私有地址的范围:1.A类地址中:10.0.0.0到10.255.255.255.2552.B类地址中:172.16.0.0到172.31.255.2553.C类地址中:192.168.0.0到192.168.255.255Broadcast Address广播地址:1.层2广播:FF.FF.FF.FF.FF.FF,发送给LAN内所有节点2.层3广播:发送给网络上所有节点3.单播(unicast):发送给单独某个目标主机4.多播:由1台主机发出,发送给不同网络的许多节点Introduction to Network Address T ranslation(NAT)NA T一般都操作在Cisco router上,用于连接2个网络,同时把私有地址翻译公有地址一些NA T的种类以及特点:1.静态NA T(static NA T):本地地址和全局地址一一对应.这样的方式需要你拥有真正的Internet上的IP地址2.动态NA T(dynamic NA T):把未注册的IP地址对应到已注册IP地址池中的某个IP地址上.你不必需要静态配置你的router使内外地址对应3.超载(overloading):采用的最广泛的NA T配置类型.类似动态NA T,但是它是把1组未注册的IP地址根据不同的端口(ports)对应到1个已注册的IP地址上.因此,它又叫做端口地址翻译(port address translation,PA T)。

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 2 Chapter 2 V4.0 Answers

1. A static route that points to the next hop IP will have what administrative distance and metric in the routing table?administrative distance of 0 and metric of 0administrative distance of 0 and metric of 1administrative distance of 1 and metric of 0administrative distance of 1 and metric of 12. What address can be used to summarize networks 172.16.1.0/24, 172.16.2.0/24, 172.16.3.0/24, and 172.16.4.0/24?172.16.0.0/21172.16.1.0/22172.16.0.0 255.255.255.248172.16.0.0 255.255.252.03.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?192.1.1.0/26 and 192.1.1.64/27192.1.1.128/25192.1.1.0/23 and 192.1.1.64/23192.1.1.0/24192.1.1.0/25192.1.1.0/24 and 192.1.1.64/244.Refer to the exhibit. What is the significance of the /8 in the route to the 10.0.0.0 network?It indicates that there are 8 hops between this router and the 10.0.0.0 network.It represents the time, in milliseconds, it takes for a ping to reply when sent to the 10.0.0.0 network.It indicates that there are 8 subnets in the destination network to which the router can forward packets.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.5.Refer 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.Router1 will perform recursive lookup and packet will exit S0/1.There is no matching interface associated with network 172.16.0.0 so packets will be dropped.There is no matching interface associated with network 172.16.0.0 so packets will take gateway of last resort and exit out S0/2.6. A 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 for 192.168.0.22/24. After finding the recently configured static route in the routing table, what does Router1 do next to process the packet?drops the packet because the destination host is not listed in the routing table looks up the MAC address of the S0/1/0 interface to determine the destination MAC address of the new frameperforms a recursive lookup for the IP address of the S0/1/0 interface before forwarding the packetencapsulates the packet into a frame for the WAN link and forwards the packet out the S0/1/0 interface7.Refer to the exhibit. Given the output in the exhibit, how would a clock rate be determined for this link?The rate would be negotiated by both routers.A rate would not be selected due to the DCE/DTE connection mismatch.The rate configured on the DTE determines the clock rate.The rate configured on the DCE determines the clock rate.8.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 0.0.0.0 192.168.146.1 Altamonte(config)# ip route 10.0.234.0 255.255.255.0 192.168.146.2 Altamonte(config)# ip route 0.0.0.0 0.0.0.0 s0/1WinterPark(config)# ip route 0.0.0.0 0.0.0.0 192.168.146.1 Altamonte(config)# ip route 10.0.234.0 255.255.255.0 192.168.146.2 Altamonte(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 0.0.0.0 192.168.146.1 Altamonte(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 10.0.234.0 255.255.255.0 192.168.146.2 Altamonte(config)# ip route 0.0.0.0 0.0.0.0 s0/09. 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.)pingshow arptracerouteshow ip routeshow interfaceshow cdp neighbor detail10.Refer 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 10.1.2.0 255.255.255.0 192.168.0.1 R2(config)#ip route 10.1.1.0 255.255.255.0 192.168.0.2R1(config)# ip route 10.1.2.0 255.255.255.0 192.168.0.2 R2(config)# ip route 10.1.1.0 255.255.255.0 192.168.0.1R1(config)# ip route 10.1.1.0 255.255.255.0 192.168.0.2 R2(config)# ip route 10.1.2.0 255.255.255.0 192.168.0.1R1(config)# ip route 10.1.1.0 255.255.255.0 192.168.0.1 R2(config)#ip route 10.1.2.0 255.255.255.0 192.168.0.2R1(config)# ip route 0.0.0.0 0.0.0.0 10.1.2.1 R2(config)# ip route 0.0.0.0 0.0.0.010.1.1.111. Which of the following are displayed by the Router# show cdp neighbors command? (Choose three.)loadplatformreliabilityholdtimelocal interface12.Refer to the exhibit. What two commands are required to provide connectivity between 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 0/1/0A(config)# 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 s 0/0/0B(config)# ip route 192.168.1.0 255.255.255.0 s 0/0/0B (config)# ip route 192.168.1.0 255.255.255.0 172.16.40.1B(config)# ip route 192.168.1.0 255.255.255.0 s 0/1/013.Refer 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 network 10.0.0.0 255.0.0.0 172.16.40.2A(config)# no ip address 10.0.0.1 255.0.0.0 172.16.40.2A(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 s0/0/0A(config)# ip route 10.0.0.0 255.0.0.0 192.168.1.214. What 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 router polls neighbors for a replacement route.The route remains in the table because it was defined as static.The router redirects the static route to compensate for the loss of the next hop device.15. A router has one static route 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.The destination network is moved to a different interface on the same router.The path between the source and destination is upgraded with a higher bandwidth link.A topology change occurs where the existing next-hop address or exit interface is notaccessible.The remote destination network interface has to be down for 15 minutes of maintenance.16. Why is it advisable to enter a next-hop IP address when creating a static route whose exit interface is an Ethernet network?Adding the next-hop address eliminates the need for the router to do any lookups in the routing table before forwarding a packet.In a multi-access network, the router cannot determine the next-hop MAC address for the Ethernet frame without a next-hop address.Using a next-hop address in a static route provides a route with a lower metric.In multi-access networks, using a next-hop address in a static route makes that routea candidate default route.17. 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?Serial0/1 is shutdown.There is no cable connecting the routers.The remote router is using serial 0/0.No clock rate has been set.18.Refer to the exhibit. Which static route should be configured on Router1 so that host A will be able to reach host B on the 172.16.0.0 network?ip route 192.168.0.0 172.16.0.0 255.255.0.0ip route 172.16.0.0 255.255.0.0 192.168.0.1ip route 172.16.0.0 255.255.0.0 S0/0/1ip route 172.16.0.0 255.255.0.0 S0/0/019. What two devices are responsible for converting the data from the WAN service provider into a form acceptable by the router? (Choose two).the serial port of the routera modema switchthe ethernet port of the routera CSU/DSU devicea DTE device20.Which of the following is true regarding CDP and the graphic shown?CDP running on Router D will gather information about routers A, B, C, and E.By default, Router A will receive CDP advertisements from routers B and C.If routers D and E are running different routing protocols, they will not exchange CDP information.Router E can use CDP to identify the IOS running on Router B.21. 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 operates at the network layer and allows two systems to learn about each other. It creates a topology map of the entire network.It allows systems to learn about each other even if different network layer protocols are configured.It forwards advertisements about routes for faster convergence.22. Which piece of information is available from examining the output of the command show ip interface brief?Interface speed and duplexInterface MTUErrorsInterface MAC addressInterface IP address。

CCNA第二学期第二章考试答案

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哪个接口是包含用于管理24 个端口以太网交换机的IP 地址的默认位置？正确响应您的响应VLAN 1Fa0/0Fa0/1连接到默认网关的接口VLAN 99此试题参考以下领域的内容：Routing and Switching Essentials• 2.1.1 使用初始设置配置交换机2下列关于使用全双工快速以太网的陈述中，哪三项是正确的？（请选择三项。

）正确响应您的响应通过双向数据流改善了性能。

由于禁用了设备上的冲突检测功能，因此性能得到了改善。

节点以全双工单向数据流运行。

由于网卡可以检测到冲突，因此性能得到了改善。

全双工快速以太网在两个方向上提供100% 的效率。

由于网卡能更快速地处理帧，因此延迟减少了。

此试题参考以下领域的内容：Routing and Switching Essentials• 2.1.2 配置交换机端口3使用mdix auto 配置命令会对交换机上的以太网接口产生什么影响？正确响应您的响应自动检测双工设置自动检测接口速度自动检测铜电缆类型自动将第一个检测到的MAC 地址分配给接口此试题参考以下领域的内容：Routing and Switching Essentials• 2.1.2 配置交换机端口4在Cisco IOS 软件无法加载的情况下，网络管理员需要哪种类型的电缆将PC 与交换机连接才能恢复它？正确响应您的响应同轴电缆控制台电缆交叉电缆直通电缆因为交换机上没有运行Cisco IOS 软件，所以管理员需要使用控制台电缆将PC 连接到交换机控制台端口，比便将来自PC 的软件转移到交换机。

此试题参考以下领域的内容：Routing and Switching Essentials• 2.1.1 使用初始设置配置交换机5在对连接问题进行故障排除时，网络管理员发现交换机端口状态LED 在绿色和琥珀色之间跳转。

CCNA2. 2014 Chapter 2 (Form A).Answer

CCNA2.Chapter 2 (Form A)1What are two advantages of static routing over dynamic routing? (Choose two.)Static routing is more secure because it does not advertise over the network.Static routing scales well with expanding networks.Static routing requires very little knowledge of the network for correct implementation.Static routing uses fewer router resources than dynamic routing.Static routing is relatively easy to configure for large networks.Static routing requires a thorough understanding of the entire network for proper implementation. It can be prone to errors and does not scale well for large networks. Static routing uses fewer router resources, because no computing is required for updating routes. Static routing can also be more secure because it does not advertise over the network.This item references content from the following areas: Routing Protocols2.1.1 Static Routing2Refer to the exhibit.Which is the best way for PC A and PC B to successfully communicate with sites on theInternet?Configure a static route from R1 to ISP and a dynamic route from ISP to R1.Configure a default route from R1 to ISP and a static route from ISP to R1.Configure a dynamic route from R1 to ISP and a static route from ISP to R1.Configure a routing protocol between R1 and ISP and advertise all the routes.Two routes have to be created: a default route in R1 to reach ISP and a static route in ISP to reach R1 for the return traffic. This is abest solution once PC A and PC B belong to stub networks. Moreover, static routing consumes less bandwidth than dynamic routing.This item references content from the following areas:Routing Protocols∙ 2.1.1 Static Routing3 What type of route allows a router to forward packets even though its routing table containsno specific route to the destination network?dynamic routedefault routedestination routegeneric routeThis item references content from the following areas:Routing Protocols∙ 2.1.2 Types of Static Routes4 Why would a floating static route be configured with an administrative distance that is higherthan the administrative distance of a dynamic routing protocol that is running on the same router?to be used as a backup routeto load-balance the trafficto act as a gateway of last resortto be the priority route in the routing tableBy default, dynamic routing protocols have a higher administrative distance than static routes. Configuring a static route with a higher administrative distance than that of the dynamic routing protocol will result in the dynamic route being used instead of the static route. However, should the dynamically learned route fail, then the static route will be used as a backup.This item references content from the following areas:Routing Protocols∙ 2.1.2 Types of Static Routes5 Which type of static route that is configured on a router uses only the exit interface?recursive static routedirectly connected static routefully specified static routedefault static routeWhen only the exit interface is used, the route is a directly connected static route. When the next-hop IP address is used, the route is a recursive static route. When both are used, it is a fully specified static route.This item references content from the following areas:Routing Protocols∙ 2.2.1 Configure IPv4 Static Routes6Refer to the graphic. Whichcommand would be used on router A to configure a static route to direct traffic from LAN A that is destined for LAN C?A(config)# ip route 192.168.4.0 255.255.255.0 192.168.5.2A(config)# ip route 192.168.4.0 255.255.255.0 192.168.3.2A(config)# ip route 192.168.5.0 255.255.255.0 192.168.3.2A(config)# ip route 192.168.3.0 255.255.255.0 192.168.3.1A(config)# ip route 192.168.3.2 255.255.255.0 192.168.4.0The destination network on LAN C is 192.168.4.0 and the next-hop address from the perspective of router A is 192.168.3.2.This item references content from the following areas:Routing Protocols∙ 2.2.1 Configure IPv4 Static Routes7 The network administrator configures the router with the ip route 172.16.1.0 255.255.255.0172.16.2.2 command. How will this route appear in the routing table?C 172.16.1.0 is directly connected, Serial0/0S 172.16.1.0 is directly connected, Serial0/0C 172.16.1.0 [1/0] via 172.16.2.2S 172.16.1.0 [1/0] via 172.16.2.2This item references content from the following areas:Routing Protocols∙ 2.2.1 Configure IPv4 Static Routes8Refer to the exhibit. What two commands willchange 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 network 10.0.0.0 255.0.0.0 172.16.40.2A(config)# no ip address 10.0.0.1 255.0.0.0 172.16.40.2A(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 s0/0/0A(config)# ip route 10.0.0.0 255.0.0.0 192.168.1.2This item references content from the following areas: Routing Protocols2.2.1 Configure IPv4 Static Routes9 The output of the show ip routecommand contains the following entry:S 10.2.0.0 [1/0] via 172.16.2.2.What value is indicated by the 1 in the [1/0] portion of the output?metricnumber of hopsadministrative distanceinterface ID through which the network can be reachedIn the routing table entry, S 10.2.0.0 [1/0] via 172.16.2.2, the numbers inside the bracket indicate the administrative distance and metric respectively.This item references content from the following areas:Routing Protocols∙ 2.2.1 Configure IPv4 Static Routes10Refer to the exhibit. The network administrator needs to configure a default route on the Border router. Whichcommand would the administrator use to configure a default route that will require the least amount of router processing when forwarding packets?Border(config)# ip route 0.0.0.0 0.0.0.0 198.133.219.5Border(config)# ip route 0.0.0.0 0.0.0.0 198.133.219.6Border(config)# ip route 0.0.0.0 0.0.0.0 s0/0/1Border(config)# ip route 0.0.0.0 0.0.0.0 s0/0/0The default route configured with the next-hop option requires a recursive lookup.This item references content from the following areas:Routing Protocols∙ 2.2.2 Configure IPv4 Default Routes11Refer to the exhibit. What command would be used to configure a static route on R1 so that traffic from both LANs can reach the 2001:db8:1:4::/64 remote network?ipv6 route ::/0 serial0/0/0ipv6 route 2001:db8:1:4::/64 2001:db8:1:3::1ipv6 route 2001:db8:1:4::/64 2001:db8:1:3::2ipv6 route 2001:db8:1::/65 2001:db8:1:3::1To configure an IPv6 static route, use the ipv6 route command followed by the destination network. Then add either the IP address ofthe adjacent router or the interface R1 will use to transmit a packet to the 2001:db8:1:4::/64 network.This item references content from the following areas:Routing Protocols2.2.3 Configure IPv6 Static Routes12Refer to the exhibit. Whichdefault static route command would allow R1 to potentially reach all unknown networks onthe Internet?R1(config)# ipv6 route 2001:db8:32::/64 G0/0R1(config)# ipv6 route ::/0 G0/0 fe80::2R1(config)# ipv6 route ::/0 G0/1 fe80::2R1(config)# ipv6 route 2001:db8:32::/64 G0/1 fe80::2To route packets to unknown IPv6 networks a router will need an IPv6 default route. The static route ipv6 route ::/0 G0/1 fe80::2 will match all networks and send packets out the specified exit interface G0/1 toward R2.This item references content from the following areas: Routing Protocols∙ 2.2.4 Configure IPv6 Default Routes13 Which two statements describe classful IP addresses? (Choose two.)It is possible to determine which class an address belongs to by reading the first bit.The number of bits used to identify the hosts is fixed by the class of the network.Only Class A addresses can be represented by high-order bits 100.Up to 24 bits can make up the host portion of a Class C address.All subnets in a network are the same size.Three of the five classes of addresses are reserved for multicasts and experimental use.This item references content from the following areas: Routing Protocols∙ 2.3.1 Classful Addressing14 A company has several networks with the following IP address requirements: IP phones - 50 PCs - 70IP cameras - 10wireless access points - 10 network printers - 10network scanners - 2Which block of addresses would be the minimum to accommodate all of these devices if each type of device was on its own network?172.16.0.0/25172.16.0.0/24172.16.0.0/23172.16.0.0/22The network for the PCs would require a subnet mask of /25 in order to accommodate 70 devices. That network could use IP addresses 0 through 127. Phones require a subnet mask of /26 for 50 devices (addresses 128-191). Three /28 networks are needed in order to accommodate cameras, APs, and printers. The network scanner network can use a /30. A block of addresses with a mask of/24 will accommodate this site as the minimum amount needed.This item references content from the following areas:Routing Protocols∙ 2.3.3 VLSM15 What does VLSM allow a network administrator to do?utilize one subnet mask throughout a hierarchical networkutilize multiple routing protocols within an autonomous systemutilize one dynamic routing protocol throughout the entire networkutilize multiple different subnet masks in the same IP address spaceutilize one public IP address to translate multiple private addressesThis item references content from the following areas:Routing Protocols∙ 2.3.3 VLSM16 What would be the best summary route for the following networks?10.50.168.0/2310.50.170.0/2310.50.172.0/2310.50.174.0/2410.50.160.0/2210.50.164.0/2310.50.168.0/1610.50.168.0/2110.50.168.0/2210.50.168.0/23Write 168, 170, 172, and 174 (the third octet where things start changing) in binary. Look at the 1s and 0s pattern. Notice the digits on the right where the change occurs. Draw a line after the column of 1s or 0s that is the last column that remains constant (exactly the same) to the left of that line. This would be immediately after the "8s" column, meaning that the 128, 64, 32, 16, and 8 columns all have the same pattern of 1s and 0s. Because this is in the third octet and the mask is /16 for the first two octets, add 5 more to the mask for the columns that are consistently the same in the third octet (/21).This item references content from the following areas:Routing Protocols2.4.1 Configure IPv4 Summary Routes17 What is a valid summary route for IPv6 networks 2001:0DB8:ACAD:4::/64,2001:0DB8:ACAD:5::/64, 2001:0DB8:ACAD:6::/64, and 2001:0DB8:ACAD:7::/64?2001:0DB8:ACAD:0000::/632001:0DB8:ACAD:0000::/642001:0DB8:ACAD:0004::/622001:0DB8:ACAD:0004::/63The IPv6 networks with the fourth octet of hex characters converted to binary are:2001:0DB8:ACAD:0000000000000100::/642001:0DB8:ACAD:0000000000000101::/642001:0DB8:ACAD:0000000000000110::/642001:0DB8:ACAD:0000000000000111::/64The common bits are 2001:0DB8:ACAD:00000000000001. Then add zeros to determine the network summarized address, giving 2001:0DB8:ACAD:0000000000000100. Convert this to hexadecimal and count the number of left-most matching bits. The summarized address will be 2001:0DB8:ACAD:0004::/62.This item references content from the following areas:Routing Protocols∙ 2.4.2 Configure IPv6 Summary Routes18Refer to the exhibit. The network engineer for the company that is shown wants to use the primary ISP connection for all external connectivity. The backup ISP connection is used only if the primary ISP connection fails. Which set of commands would accomplish this goal?ip route 198.133.219.24 255.255.255.252ip route 64.100.210.80 255.255.255.252ip route 198.133.219.24 255.255.255.252ip route 64.100.210.80 255.255.255.252 10ip route 0.0.0.0 0.0.0.0 s0/0/0ip route 0.0.0.0 0.0.0.0 s0/1/0ip route 0.0.0.0 0.0.0.0 s0/0/0ip route 0.0.0.0 0.0.0.0 s0/1/0 10A static route that has no administrative distance added as part of the command has a default administrative distance of 1. The backuplink should have a number higher than 1. The correct answer has an administrative distance of 10. The other quad zero route wouldload balance packets across both links and both links would appear in the routing table. The remaining answers are simply static routes (either a default route or a floating static default route).This item references content from the following areas:Routing Protocols∙ 2.4.3 Configure Floating Static Routes19 Which three IOS troubleshooting commands can help to isolate problems with a static route?(Choose three.)show versionpingtracertshow ip routeshow ip interface briefshow arpThe ping, show ip route, and show ip interface brief commands provide information to help troubleshoot static routes. Showversion does not provide any routing information. The tracert command is used at the Windows command prompt and is not an IOS command. The show arp command displays learned IP address to MAC address mappings contained in the Address ResolutionProtocol (ARP) table.This item references content from the following areas:Routing Protocols2.5.2 Troubleshoot IPv4 Static and Default Route Configuration20Refer to the exhibit. The small company shown uses static routing. Users on the R2 LAN have reported a problem with connectivity. What is the issue?R2 needs a static route to the R1 LANs.R1 and R2 must use a dynamic routing protocol.R1 needs a default route to R2.R1 needs a static route to the R2 LAN.R2 needs a static route to the Internet.R1 has a default route to the Internet. R2 has a default route to R1. R1 is missing a static route for the 10.0.60.0 network. Any trafficthat reached R1 and is destined for 10.0.60.0/24 will be routed to the ISP.This item references content from the following areas:Routing Protocols∙ 2.5.2 Troubleshoot IPv4 Static and Default Route Configuration21 What happens to a static route entry in a routing table when the outgoing interface is notavailable?The route is removed from the table.The router polls neighbors for a replacement route.The route remains in the table because it was defined as static.The router redirects the static route to compensate for the loss of the next hop device.This item references content from the following areas:Routing Protocols∙ 2.5.2 Troubleshoot IPv4 Static and Default Route Configuration22 The PT initialization was skipped. You will not be able to view the PT activity.Open the PT activity. Perform the tasks in the activity instructions and then answer the question. What is the name of the web server that is displayed in the webpage?Main-WebserverWWW-ServerWebserver10MNSRVStatic routes can be configured by using the syntax router(config)# ip route prefix mask {ip-address | exit-intf}. In this case, the command to be issued would be router(config)# ip route 192.168.3.0 255.255.255.0 192.168.2.2.This item references content from the following areas:Routing Protocols∙ 2.2.1 Configure IPv4 Static Routes23 The PT initialization was skipped. You will not be able to view the PT activity.Open the PT Activity. Perform the tasks in the activity instructions and then answer the question.What IPv6 static route can be configured on router R1 to make a fully converged network?ipv6 route 2001:db8:10:12::/64 S0/0/1ipv6 route 2001:db8:10:12::/64 S0/0/0ipv6 route 2001:db8:10:12::/64 2001:db8:10:12::1ipv6 route 2001:db8:10:12::/64 2001:db8:32:77::1To reach the remote network, R1 will need a static route with a destination IPv6 address of 2001:db8:10:12::/64 and an exit interface ofS0/0/1. The correct static route configuration will be as follows:ipv6 route 2001:db8:10:12::/64 S0/0/1.This item references content from the following areas:Routing Protocols∙ 2.2.3 Configure IPv6 Static Routes。

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.。

CCNA2期末测试题

1请参见图示。

对于发往192.168.2.0 的数据包，R2 会采取什么操作？它会丢弃数据包。

它会通过S0/0/0 接口转发数据包。

它会通过Fa0/0 接口转发数据包。

它会将数据包转发给R1。

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 .0 0.0.0.0 Fa0/0ip route .0 0.0.0.0 Fa0/1ip routeip routeip route 209.165.202.0 255.255.255.0 .14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 172.16.1.1 时失败。

造成此问题的原因可能是什么？R1 上的串行接口配置有误。

默认路由配置有误。

必须在R1 上发出default-information originate命令。

必须在R1 上禁用自动总结。

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。

）主机A 缺少网关或配置不正确。

主机B 缺少网关或配置不正确。

R1 的路由表中缺少192.168.1.0/24 的条目。

R2 的路由表中缺少192.168.1.0/24 的条目。

R1 的路由表中缺少192.168.2.0/24 的条目。

R2 的路由表中缺少192.168.2.0/24 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？R1 的快速以太网接口被禁用。

其中一条默认路由配置有误。

未在这两台路由器上配置路由协议。

主机A 上尚未配置默认网关。

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。

计算机网络课后题答案第二章

第二章物理层2-01 物理层要解决什么问题？物理层的主要特点是什么？（1）物理层要解决的主要问题：①.物理层要尽可能屏蔽掉物理设备、传输媒体和通信手段的不同，使上面的数据链路层感觉不到这些差异的存在，而专注于完成本曾的协议与服务。

②.给其服务用户（数据链路层）在一条物理的传输媒体上传送和接收比特流（一般为串行按顺序传输的比特流）的能力。

为此，物理层应解决物理连接的建立、维持和释放问题。

③.在两个相邻系统之间唯一地标识数据电路。

（2）物理层的主要特点：①.由于在OSI 之前，许多物理规程或协议已经制定出来了，而且在数据通信领域中，这些物理规程已被许多商品化的设备锁采用。

加之，物理层协议涉及的范围广泛，所以至今没有按OSI 的抽象模型制定一套心的物理层协议，而是沿用已存在的物理规程，将物理层确定为描述与传输媒体接口的机械、电气、功能和规程特性。

②.由于物理连接的方式很多，传输媒体的种类也很多，因此，具体的物理协议相当复杂。

2-02 规程与协议有什么区别？答：在数据通信的早期，对通信所使用的各种规则都称为“规程”（procedure），后来具有体系结构的计算机网络开始使用“协议”（protocol）这一名词，以前的“规程”其实就是“协议”，但由于习惯，对以前制定好的规程有时仍常用旧的名称“规程”。

2-03 试给出数据通信系统的模型并说明其主要组成构件的作用。

答：一个数据通信系统可划分为三大部分：源系统（或发送端）、传输系统（或传输网络）、和目的系统（或接收端）。

源系统一般包括以下两个部分：源点：源点设备产生要传输的数据。

例如正文输入到PC 机，产生输出的数字比特流。

发送器：通常源点生成的数据要通过发送器编码后才能在传输系统中进行传输。

例如，调制解调器将PC 机输出的数字比特流转换成能够在用户的电话线上传输的模拟信号。

接收器：接收传输系统传送过来的信号，并将其转换为能够被目的设备处理的信息。

例如，调制解调器接收来自传输线路上的模拟信号，并将其转换成数字比特流。

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。

计算机网络第二版习题答案

计算机网络第二版习题答案计算机网络第二版习题答案计算机网络是现代社会中不可或缺的一部分。

它连接了世界各地的计算机，使得信息的传递和共享变得更加便捷和高效。

而对于学习计算机网络的人来说，习题是检验自己理解和掌握程度的重要途径。

本文将为大家提供《计算机网络第二版》中一些习题的答案，希望能够帮助读者更好地学习和理解计算机网络。

第一章：计算机网络和因特网1. 什么是计算机网络？计算机网络是指将分布在不同地理位置的计算机和其他设备通过通信链路互相连接起来，以实现信息的传递和共享的系统。

2. 什么是因特网？因特网是全球最大的计算机网络，它由无数的网络设备和计算机组成，通过TCP/IP协议族进行通信。

3. 描述因特网的组成部分。

因特网由边缘部分和核心部分组成。

边缘部分包括所有连接到因特网的主机和终端设备，核心部分则由大量的路由器和链路组成。

4. 什么是协议？协议是计算机网络中用于规定通信双方之间交换信息的规则和约定。

常见的协议有TCP/IP、HTTP、FTP等。

第二章：应用层1. 什么是应用层？应用层是计算机网络中最高层的一层，它为应用程序提供了访问网络的接口。

2. HTTP协议是什么？HTTP（Hypertext Transfer Protocol）是一种用于在Web浏览器和Web服务器之间传输超文本的协议。

3. 描述HTTP请求和响应的过程。

HTTP请求由客户端发出，包括请求行、请求头和请求体。

服务器接收到请求后，返回一个HTTP响应，包括响应行、响应头和响应体。

4. 什么是DNS？DNS（Domain Name System）是一种用于将域名转换为IP地址的系统。

它提供了域名和IP地址之间的映射关系。

第三章：运输层1. 什么是运输层？运输层是计算机网络中负责提供可靠的数据传输服务的一层。

2. TCP和UDP的区别是什么？TCP（Transmission Control Protocol）是一种面向连接的、可靠的传输协议，它提供了数据的可靠传输和流量控制等功能。

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。

（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），即时信息代理，P2P文件共享代理。

如Real Networks player），即时信息代理，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，吞吐量，TCP和UDP均为提供此服务。

定时，TCP和UDP均为提供此服务。

3.定时，安全性，TCP在应用层可以很容易地通过SSL来提供安全服 4.安全性，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。

信息论与编码第二版第2章习题答案

(4) 参考上面的两个点数的排列，可以得出两个点数求和的概率分布如下：
2 3 4 5 6 7 8 9 10 11 12 X 1 1 1 1 5 1 5 1 1 1 1 = P ( X ) 36 18 12 9 36 6 36 9 12 18 36 H ( X ) = −∑ p ( xi ) log p ( xi )
画出状态图，并计算各状态的稳态概率。解： p (0 | 00) = p (00 | 00) = 0.8
p (0 | 01) = p (10 | 01) = 0.5 p (0 |10) = p (00 |10) = 0.5 p (1| 01) = p (11| 01) = 0.5 p (1|10) = p (01|10) = 0.5
15 25 35 45 55 65
16 26 36 46 56 66
1 1 1 × = 6 6 36
1 1 1 × = 6 6 18
1 1 1 1 H ( X ) = −∑ p ( xi ) log p ( xi ) = − 6 × log + 15 × log = 4.337 bit / symbol 36 18 18 36 i
2.2 由符号集{0，1}组成的二阶马尔可夫链，其转移概率为： p (0 | 00) =0.8， p (0 |11) =0.2，
p (1| 00) =0.2， p (1|11) =0.8， p (0 | 01) =0.5， p (0 |10) =0.5， p (1| 01) =0.5， p (1|10) =0.5。
87.81 = 1.95 bit/符号 45
2-14 (1)
P(ij)=
P(i/j)=
(2) 方法 1:

计算机网络第二章课后答案

第二章2-01 物理层要解决哪些问题？物理层的主要特点是什么？答：物理层要解决的主要问题：首部应用层数据首部首部尾部TCP 数据报IP 数据报MAC桢网络层及以上使用IP 地址链路层及以下使用硬件地址（1）物理层要尽可能地屏蔽掉物理设备和传输媒体，通信手段的不同，使数据链路层感觉不到这些差异，只考虑完成本层的协议和服务。

（2）给其服务用户（数据链路层）在一条物理的传输媒体上传送和接收比特流（一般为串行按顺序传输的比特流）的能力，为此，物理层应该解决物理连接的建立、维持和释放问题。

（3）在两个相邻系统之间唯一地标识数据电路物理层的主要特点：（1）由于在 OSI 之前，许多物理规程或协议已经制定出来了，而且在数据通信领域中，这些物理规程已被许多商品化的设备所采用，加之，物理层协议涉及的范围广泛，所以至今没有按OSI 的抽象模型制定一套新的物理层协议，而是沿用已存在的物理规程，将物理层确定为描述与传输媒体接口的机械，电气，功能和规程特性。

（2）由于物理连接的方式很多，传输媒体的种类也很多，因此，具体的物理协议相当复杂。

2-02 规程与协议有什么区别？答：规程专指物理层协议2-03 试给出数据通信系统的模型并说明其主要组成构建的作用。

答：源点：源点设备产生要传输的数据。

源点又称为源站。

发送器：通常源点生成的数据要通过发送器编码后才能在传输系统中进行传输。

接收器：接收传输系统传送过来的信号，并将其转换为能够被目的设备处理的信息。

终点：终点设备从接收器获取传送过来的信息。

终点又称为目的站传输系统：信号物理通道2-04 试解释以下名词：数据，信号，模拟数据，模拟信号，基带信号，带通信号，数字数据，数字信号，码元，单工通信，半双工通信，全双工通信，串行传输，并行传输。

答：数据：是运送信息的实体。

信号：则是数据的电气的或电磁的表现。

模拟数据：运送信息的模拟信号。

模拟信号：连续变化的信号。

数字信号：取值为有限的几个离散值的信号。

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。