CISCO模拟试题CCNA考试自测题1
完整版CCNA测试题库及答案
完整版CCNA测试题库及答案描述载波侦听多路由访问/冲突检测（CSMA/CD）的工作原理。
CSMA/CD是一种帮助设备均衡共享带宽的协议，可避免两台设备同时在网络介质上传输数据。
虽然他不能消除冲突，但有助于极大的减少冲突，进而避免重传，从而提高所的设备的数据传输效率。
区分半双工和全双工通信。
并指出两种方法的需求。
与半双工以太网使用一对导线不同，全双工以太网使用两队导线，全双工使用不同的导线来消除冲突，从而允许同时发送和接收数据，而半双工可接收或发送数据，但不能同时接收和发送数据，且仍会出现冲突。
要使用全双工，电缆两端的设备都必须支持全双工，并配置成一全双模式运行。
描述MAC地址的组成部分以及各部分包含的信息。
MAC（硬件）地址时一种使用十六进制表示的地址，长48位（6B）。
其中前24位（3B）称为OUI（Organizationally Unique Idebtifier,组织唯一表示符），有IEEE分配给NIC制造商；余下的部分呢唯一地标识了NIC识别十进制数对应的二进制值和十六进制值。
用这三种格式之一表示的任何数字都可以转换为其他两种格式，能够执行这种转换对理解IP地址和子网划分至关重要。
识别以太网帧中与数据链路层相关的字段。
在以太网中，与数据链路层相关的字段包括前导码，帧其实位置分隔符，目标MAC地址，源MAC地址，长度或者类型以及帧校验序列。
识别以太网布线相关的IEEE标准。
这些标准描述了各种电缆类型的功能和物理特征，包括（但不限于）10Base2、10Base5和10BaseT。
区分以太网电缆类型及其用途。
以太网电缆分3种：直通电缆，用于将PC或路由器的以太网接口连接到集线器或交换机；交叉电缆。
用于将集线器连接到集线器，集线器连接到交换机，交换机连接到交换机以及PC连接到PC；反转电缆，用于PC和路由器或交换机之间建立控制台连接。
描述数据封装过程及其在分组创建中的作用。
数据封装指的是在OSI模型各层给数据添加信息的过程，也成为分组创建。
CISCO模拟试题-CCNA考试自测题1
CISCO模拟试题:CCNA考试自测题1CISCO模拟试题:CCNA考试自测题1CISCO模拟试题:CCNA考试自测题11) match the following application layer services to their corresponding transport layer protocol port. (匹配下列的应用层服务和它们对应的传输层协议端口)：a. smtp 1. tcp/23b. ftp 2. tcp/25c. tftp 3. tcp/80d. te l n e t 4. tcp/21e. http 5. udp/69f. dns 6. tcp/532) which osi reference model layer does telnet function at (te l n e t在哪一个o s i参考模型层运作)？a. transport 下载b. networkc. sessiond. application3) how many layers does the tcp/ip protocol suite have, compared to the osi reference model (和o s i参考模型相比，t c p / i p协议具有几层)？a. tcp model has 4, osi model has 6b. tcp model has 7, osi model has 8c. tcp model has 4, osi model has 7d. tcp model has 7, osi model has 44) the tcp/ip protocol suite has a formal session layer that includes netbios、rpcs and tli functions (tcp/ip协议套件具有包含n e t b i o s、r p c和t l i功能的一个正式的会话层)。
思科模拟试题及答案
思科模拟试题及答案一、选择题1. 以下哪个命令用于查看路由器的接口状态？A. show interfaceB. show ip interfaceC. show running-configD. show ip route答案：A2. 在思科路由器上配置默认网关的命令是什么？A. ip default-gatewayB. default gatewayC. ip route 0.0.0.0D. route 0.0.0.0答案：C3. 以下哪个协议用于在大型网络中自动发现路由？A. RIPB. OSPFC. BGPD. EIGRP答案：B4. 以下哪个命令用于查看当前路由器的配置？A. show running-configB. show startup-configC. show interfaceD. show ip route答案：A5. 以下哪个命令用于在路由器上配置静态路由？A. ip routeB. routeC. static routeD. configure static route答案：A二、填空题6. 思科的网络操作系统称为________。
答案：IOS7. 在思科设备上，使用________命令可以进入特权模式。
答案：enable8. 配置VLAN的命令是________。
答案：VLAN configuration mode9. 动态主机配置协议的缩写是________。
答案：DHCP10. 用于测试网络连通性的命令是________。
答案：ping三、简答题11. 简述什么是子网掩码，并说明其作用。
答案：子网掩码是一种用于区分IP地址中网络部分和主机部分的位模式。
它的作用是告诉路由器或交换机，IP地址的哪部分是网络地址，哪部分是主机地址，以便正确地进行路由和数据传输。
12. 描述什么是VLAN，以及它在网络中的作用。
答案：VLAN（虚拟局域网）是一种将局域网划分为多个虚拟网络的技术。
思科考试CCNA
CCNA(1)适用班级：CCNA注意事项：1.在试卷的标封处填写姓名和班级2.考试时间共120分钟3.答案写在答题卡上1. What is the maximum number of IP addresses that can be assigned to hosts on a local subnetthat uses the subnet maskA. 14B. 15C. 16D. 30E. 31F. 622. You have a network that needs 29 subnets while maximizing the number of host addressesavailable on each subnet. How many bits must you borrow from the host field to provide thecorrect subnet maskA. 2B. 3C. 4D. 5E. 6F. 73. What is the subnetwork address for a host with the IP address The network address of provides how many subnets and hostsA. 7 subnets, 30 hosts eachB. 7 subnets, 2,046 hosts eachC. 7 subnets, 8,190 hosts eachD. 8 subnets, 30 hosts eachE. 8 subnets, 2,046 hosts eachF. 8 subnets, 8,190 hosts each5. Which two statements describe the IP address 10.16.3.65/23 (Choose two.)A. The subnet address is 10.16.3.0 The lowest host address in the subnet is 10.16.2.1 The last valid host address in the subnet is 10.16.2.254 The broadcast address of the subnet is 10.16.3.255 The network is not subnetted.6. If a host on a network has the address what is the subnetwork this hostbelongs toA. On a VLSM network, which mask should you use on point-to-point WAN links in order toreduce the waste of IP addressesA. /27B. /28C. /29D. /30E. /318. What is the subnetwork number of a host with an IP address of You have an interface on a router with the IP address of Including the routerinterface, how many hosts can have IP addresses on the LAN attached to the router interfaceA. 6B. 8C. 30D. 62E. 12610. You need to configure a server that is on the subnet The router has the firstavailable host address. Which of the following should you assign to the serverA. You have an interface on a router with the IP address of What is thebroadcast address the hosts will use on this LANA. You need to subnet a network that has 5 subnets, each with at least 16 hosts. Which classfulsubnet mask would you useA. A network administrator is connecting hosts A and B directly through their Ethernet interfaces,as shown in the illustration. Ping attempts between the hosts are unsuccessful. What can bedone to provide connectivity between the hosts (Choose two.)A. A crossover cable should be used in place of the straight-through cable.B. A rollover cable should be used in place of the straight-through cable.C. The subnet masks should be set to A default gateway needs to be set on each host.E. The subnet masks should be set to Address: Address: Cable164 Chapter 3 Subnetting, VLSMs, and Troubleshooting TCP/IP14. If an Ethernet port on a router were assigned an IP address of what wouldbe the valid subnet address of this hostA. Using the following illustration, what would be the IP address of E0 if you were using theeighth subnet The network ID is and you need to use the last available IPaddress in the range. The zero subnet should not be considered valid for this question.A. Using the illustration from the previous question, what would be the IP address of S0 if you wereusing the first subnet The network ID is and you need to use the last availableIP address in the range. Again, the zero subnet should not be considered valid for this question.A. Which configuration command must be in effect to allow the use of 8 subnets if the Class C subnet mask is Router(config)#ip classlessB. Router(config)#ip version 6C. Router(config)#no ip classfulD. Router(config)#ip unnumberedE. Router(config)#ip subnet-zeroF. Router(config)#ip all-nets18. You have a network with a subnet of Which is the valid host addressA. Your router has the following IP address on Ethernet0: Which of the following can be valid host IDs on the LAN interface attached to the router (Choose two.)A. To test the IP stack on your local host, which IP address would you pingA. 1.0.0.127C. You type show running-config and get this output:[output cut]Line console 0Exec-timeout 1 44Password 7098C0BQRLogin[output cut]What do the two numbers following the exec-timeout command meanA. If no command has been typed in 44 seconds, the console connection will be closed.B. If no router activity has been detected in 1 hour and 44 minutes, the console will be locked out.C. If no commands have been typed in 1 minute and 44 seconds, the console connection willbe closed.D. If you’re connected to the router by a Telnet connection, input must be detected within 1 minute and 44 seconds or the connection will be closed.22. You need to find the broadcast address used on a LAN on your router. What command willyou type into the router from user mode to find the broadcast addressA. show running-configB. show startup-configC. show interfacesD. show protocols23. You want to totally reinitialize the router and replace the current running-config with the current startup-config. What command will you useA. replace run startB. copy run startC. copy start runD. reloadReview Questions 24324. Which command will show you whether a DTE or a DCE cable is plugged into serial 0A. sh int s0B. sh int serial 0C. show controllers s 0D. show serial 0 controllers25. What keystroke will terminate setup modeA. Ctrl+ZB. Ctrl+^C. Ctrl+CD. Ctrl+Shift+^26. You set the console password, but when you display the configuration, the password doesn’t show up; it looks like this:[output cut]Line console 0Exec-timeout 1 44Password 7098C0BQRLogin[output cut]What cause the password to be stored like thisA. encrypt passwordB. service password-encryptionC. service-password-encryptionD. exec-timeout 1 4427. Which of the following commands will configure all the default VTY ports on a routerA. Router#line vty 0 4B. Router(config)#line vty 0 4C. Router(config-if)#line console 0D. Router(config)#line vty all28. Which of the following commands sets the secret password to CiscoA. enable secret password CiscoB. enable secret ciscoC. enable secret CiscoD. enable password Cisco244 Chapter 4 Cisco’s IOS and Security Device Manager29. If you wanted administrators to see a message when logging into the router, which command would you useA. message banner motdB. banner message motdC. banner motdD. message motd30. How many simultaneous Telnet sessions does a Cisco router support by defaultA. 1B. 2C. 3D. 4E. 5F. 631. What command do you type to save the configuration stored in RAM to NVRAMA. Router(config)#copy current to startingB. Router#copy starting to runningC. Router(config)#copy running-config startup-configD. Router#copy run startup32. You try to telnet into SFRouter from router Corp and receive this message:Corp#telnet SFRouterTrying SFRouter (10.0.0.1)…OpenPassword required, but none set[Connection to SFRouter closed by foreign host]Corp#Which of the following sequences will address this problem correctlyA. Corp(config)#line console 0B. SFRemote(config)#line console 0C. Corp(config)#line vty 0 4D. SFRemote(config)#line vty 0 433. Which command will delete the contents of NVRAM on a routerA. delete NVRAMB. delete startup-configC. erase NVRAMD. erase startReview Questions 24534. What is the problem with an interface if you type show interface serial 0 and receive the following messageSerial0 is administratively down, line protocol is downA. The keepalives are different times.B. The administrator has the interface shut down.C. The administrator is pinging from the interface.D. No cable is attached.35. Which of the following commands displays the configurable parameters and statistics of all interfaces on a routerA. show running-configB. show startup-configC. show interfacesD. show versions36. If you delete the contents of NVRAM and reboot the router, what mode will you be inA. Privileged modeB. Global modeC. Setup modeD. NVRAM loaded mode37. You type the following command into the router and receive the following output: Router#show serial 0/0^% Invalid input detected at ‘^’marker.Why was this error message displayedA. You need to be in privileged mode.B. You cannot have a space between serial and 0/0.C. The router does not have a serial0/0 interface.D. Part of the command is missing.38. You type Router#sh ru and receive an % ambiguous command error. Why did you receivethis messageA. The command requires additional options or parameters.B. There is more than one show command that starts with the letters ru.C. There is no show command that starts with ru.D. The command is being executed from the wrong router mode.246 Chapter 4 Cisco’s IOS and Security Device Manager39. Which of the following commands will display the current IP addressing and the layer 1 and2 status of an interface (Choose three.)A. show versionB. show protocolsC. show interfacesD. show controllersE. show ip interfaceF. show running-config40. What layer of the OSI model would you assume the problem is in if you type show interface serial 1 and receive the following messageSerial1 is down, line protocol is downA. Physical layerB. Data Link layerC. Network layerD. None; it is a router problem.41. What does the command o/r 0x2142 provideA. It is used to restart the router.B. It is used to bypass the configuration in NVRAM.C. It is used to enter ROM Monitor mode.D. It is used to view the lost password.42. Which command will copy the IOS to a backup host on your networkA. transfer IOS to copy run startC. copy tftp flashD. copy start tftpE. copy flash tftp43. You are troubleshooting a connectivity problem in your corporate network and want to isolate the problem. You suspect that a router on the route to an unreachable network is at fault.What IOS user exec command should you issueA. Router>pingB. Router>traceC. Router>show ip routeD. Router>show interfaceE. Router>show cdp neighbors44. You copy a configuration from a network host to a router’s RAM. The configuration looks correct, yet it is not working at all. What could the problem beA. You copied the wrong configuration into RAM.B. You copied the configuration into flash memory instead.C. The copy did not override the shutdown command in running-config.D. The IOS became corrupted after the copy command was initiated.45. A network administrator wants to upgrade the IOS of a router without removing the image currently installed. What command will display the amount of memory consumed by the currentIOS image and indicate whether there is enough room available to hold both the currentand new imagesA. show versionB. show flashC. show memoryD. show buffersE. show running-config46. The corporate office sends you a new router to connect, but upon connecting the console cable,you see that there is already a configuration on the router. What should be done before a new configuration is entered in the routerA. RAM should be erased and the router restarted.B. Flash should be erased and the router restarted.C. NVRAM should be erased and the router restarted.D. The new configuration should be entered and saved.47. Which command loads a new version of the Cisco IOS into a routerA. copy flash ftpB. copy ftp flashC. copy flash tftpD. copy tftp flash48. Which command will show you the IOS version running on your routerA. sh IOSB. sh flashC. sh versionD. sh running-config49. What should the configuration register value be after you successfully complete the password recovery procedure and return the router to normal operationA. 0x2100B. 0x2101C. 0x2102D. 0x214250. You save the configuration on a router with the copy running-config startup-configcommand and reboot the router. The router, however, comes up with a blank configuration.What can the problem beA. You didn’t boot the router with the correct command.B. NVRAM is corrupted.C. The configuration register setting is incorrect.D. The newly upgraded IOS is not compatible with the hardware of the router.E. The configuration you save is not compatible with the hardware.51. If you want to have more than one Telnet session open at the same time, what keystroke combination would you useA. Tab+spacebarB. Ctrl+X, then 6C. Ctrl+Shift+X, then 6D. Ctrl+Shift+6, then X52. You are unsuccessful in telnetting into a remote device. What could the problem be (Choose two.)A. IP addresses are incorrect.B. Access control list is filtering Telnet.C. There is a defective serial cable.D. The VTY password is missing.53. What information is displayed by the show hosts command (Choose two.)A. Temporary DNS entriesB. The names of the routers created using the hostname commandC. The IP addresses of workstations allowed to access the routerD. Permanent name-to-address mappings created using the ip host commandE. The length of time a host has been connected to the router via Telnet54. Which three commands can be used to check LAN connectivity problems on a router(Choose three.)A. show interfacesB. show ip routeC. tracertD. pingE. dns lookups55. You telnet to a router and make your necessary changes; now you want to end the Telnet session. What command do you type inA. closeB. disableC. disconnectD. exit56. You telnet into a remote device and type debug ip rip, but no output from the debug command is seen. What could the problem beA. You must type the show ip rip command first.B. IP addressing on the network is incorrect.C. You must use the terminal monitor command.D. Debug output is sent only to the console.57. Which command displays the configuration register settingA. show ip routeB. show boot versionC. show versionD. show flash58. You need to gather the IP address of a remote switch that is located in Hawaii. What can youdo to find the addressA. Fly to Hawaii, console into the switch, then relax and have a drink with an umbrella in it.B. Issue the show ip route command on the router connected to the switch.C. Issue the show cdp neighbor command on the router connected to the switch.D. Issue the show ip arp command on the router connected to the switch.E. Issue the show cdp neighbors detail command on the router connected to the switch.59. You have your laptop directly connected into a router’s Ethernet port. Which of the following are among the requirements for the copy flash tftp command to be successful (Choose three.)A. TFTP server software must be running on the router.B. TFTP server software must be running on your laptop.C. The Ethernet cable connecting the laptop directly into the router’s Ethernet port mu st bea straight-through cable.D. The laptop must be on the same subnet as the router’s Ethernet interface.E. The copy flash tftp command must be supplied the IP address of the laptop.F. There must be enough room in the flash memory of the router to accommodate the file tobe copied.60. The configuration register setting of 0x2102 provides what function to a routerA. Tells the router to boot into ROM monitor modeB. Provides password recoveryC. Tells the router to look in NVRAM for the boot sequenceD. Boots the IOS from a TFTP serverE. Boots an IOS image stored in ROM61. A receiving host has failed to receive all of the segments that it should acknowledge. What can the host do to improve the reliability of this communication sessionA. Send a different source port number.B. Restart the virtual circuit.C. Decrease the sequence number.D. Decrease the window size.62. Which fields are contained within an IEEE Ethernet frame header (Choose two.)A. Source and destination MAC addressB. Source and destination network addressC. Source and destination MAC address and source and destination network addressD. FCS field63. Which layer 1 devices can be used to enlarge the area covered by a single LAN segment (Choose two.)A. SwitchB. NICC. HubD. RepeaterE. RJ45 transceiver64. Segmentation of a data stream happens at which layer of the OSI modelA. PhysicalB. Data LinkC. NetworkD. Transport65. Which of the following describe router functions (Choose four.)A. Packet switchingB. Collision preventionC. Packet filteringD. Broadcast domain enlargementE. Internetwork communicationF. Broadcast forwardingG. Path selection66. Routers operate at layer __. LAN switches operate at layer __. Ethernet hubs operate at layer __. Word processing operates at layer __.A. 3, 3, 1, 7B. 3, 2, 1, noneC. 3, 2, 1, 7D. 2, 3, 1, 7E. 3, 3, 2, none67. When data is encapsulated, which is the correct orderA. Data, frame, packet, segment, bitB. Segment, data, packet, frame, bitC. Data, segment, packet, frame, bitD. Data, segment, frame, packet, bit68. Why does the data communication industry use the layered OSI reference model (Choose two.)A. It divides the network communication process into smaller and simpler components, thus aiding component development, design, and troubleshooting.B. It enables equipment from different vendors to use the same electronic components, thus saving research and development funds.C. It supports the evolution of multiple competing standards and thus provides business opportunities for equipment manufacturers.D. It encourages industry standardization by defining what functions occur at each layer ofthe model.E. It provides a framework by which changes in functionality in one layer require changes inother layers.69. What are two purposes for segmentation with a bridgeA. To add more broadcast domainsB. To create more collision domainsC. To add more bandwidth for usersD. To allow more broadcasts for users70. Which of the following are unique characteristics of half-duplex Ethernet when compared tofull-duplex Ethernet (Choose two.)A. Half-duplex Ethernet operates in a shared collision domain.B. Half-duplex Ethernet operates in a private collision domain.C. Half-duplex Ethernet has higher effective throughput.D. Half-duplex Ethernet has lower effective throughput.E. Half-duplex Ethernet operates in a private broadcast domain.58 Chapter 1 Internetworking71. You want to implement a network medium that is not susceptible to EMI. Which type of cabling should you useA. Thicknet coaxB. Thinnet coaxC. Category 5 UTP cableD. Fiber-optic cable72. Acknowledgments, sequencing, and flow control are characteristics of which OSI layerA. Layer 2B. Layer 3C. Layer 4D. Layer 773. Which of the following are types of flow control (Choose all that apply.)A. BufferingB. Cut-throughC. WindowingD. Congestion avoidanceE. VLANs74. Which of the following types of connections can use full duplex (Choose three.)A. Hub to hubB. Switch to switchC. Host to hostD. Switch to hubE. Switch to host75. What is the purpose of flow controlA. To ensure that data is retransmitted if an acknowledgment is not receivedB. To reassemble segments in the correct order at the destination deviceC. To provide a means for the receiver to govern the amount of data sent by the senderD. To regulate the size of each segment76. Which three statements are true about the operation of a full-duplex Ethernet networkA. There are no collisions in full-duplex mode.B. A dedicated switch port is required for each full-duplex node.C. Ethernet hub ports are preconfigured for full-duplex mode.D. In a full-duplex environment, the host network card must check for the availability of the network media before transmitting.E. The host network card and the switch port must be capable of operating in full-duplex mode. Review Questions 5977. What type of RJ45 UTP cable is used between switchesA. Straight-throughB. Crossover cableC. Crossover with a CSU/DSUD. Crossover with a router in between the two switches78. How does a host on an Ethernet LAN know when to transmit after a collision has occurred (Choose two.)A. In a CSMA/CD collision domain, multiple stations can successfully transmit data simultaneously.B. In a CSMA/CD collision domain, stations must wait until the media is not in use before transmitting.C. You can improve the CSMA/CD network by adding more hubs.D. After a collision, the station that detected the collision has first priority to resend thelost data.E. After a collision, all stations run a random backoff algorithm. When the backoff delay period has expired, all stations have equal priority to transmit data.F. After a collision, all stations involved run an identical backoff algorithm and then synchronize with each other prior to transmitting data.79. What type of RJ45 UTP cable do you use to connect a PC’s COM port to a router or switch console portA. Straight-throughB. Crossover cableC. Crossover with a CSU/DSUD. Rolled80. You have the following binary number:What are the decimal and hexadecimal equivalentsA. 69/0x2102B. 183/B7C. 173/A6D. 83/0xC581. What are the decimal and hexadecimal equivalents of the binary number(Choose two.)A. 159B. 157C. 185D. 0x9DE. 0xD9F. 0x15982. Which of the following allows a router to respond to an ARP request that is intended for a remote hostA. Gateway DPB. Reverse ARP (RARP)C. Proxy ARPD. Inverse ARP (IARP)E. Address Resolution Protocol (ARP)83. 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 useto accomplish thisA. SMTPB. SNMPC. DHCPD. ARP84. What protocol is used to find the hardware address of a local deviceA. RARPB. ARPC. IPD. ICMPE. BootP85. Which of the following are layers in the TCP/IP model (Choose three.)A. ApplicationB. SessionC. TransportD. InternetE. Data LinkF. Physical86. Which class of IP address provides a maximum of only 254 host addresses per network IDA. Class AB. Class BC. Class CD. Class DE. Class E87. Which of the following describe the DHCP Discover message (Choose two.)A. It uses FF:FF:FF:FF:FF:FF as a layer 2 broadcast.B. It uses UDP as the Transport layer protocol.C. It uses TCP as the Transport layer protocol.D. It does not use a layer 2 destination address.8. Which layer 4 protocol is used for a Telnet connectionA. IPB. TCPC. TCP/IPD. UDPE. ICMP89. Which statements are true regarding ICMP packets (Choose two.)A. They acknowledge receipt of a TCP segment.B. They guarantee datagram delivery.C. They can provide hosts with information about network problems.D. They are encapsulated within IP datagrams.E. They are encapsulated within UDP datagrams.90. Which of the following services use TCP (Choose three.)A. DHCPB. SMTPC. SNMPD. FTPE. HTTPF. TFTP91. Which of the following services use UDP (Choose three.)A. DHCPB. SMTPC. SNMPD. FTPE. HTTPF. TFTP92. Which of the following are TCP/IP protocols used at the Application layer of the OSI model (Choose three.)A. IPB. TCPC. TelnetD. FTPE. TFTP93. The following illustration shows a data structure header. What protocol is this header fromA. IPB. ICMPC. TCPD. UDPE. ARPF. RARP94. If you use either Telnet or FTP, which is the highest layer you are using to transmit dataA. ApplicationB. PresentationC. SessionD. Transport95. The DoD model (also called the TCP/IP stack) has four layers. Which layer of the DoD model is equivalent to the Network layer of the OSI modelA. ApplicationB. Host-to-HostC. InternetD. Network Access96. Which two of the following are private IP addressesA. 12.0.0.1B. What layer in the TCP/IP stack is equivalent to the Transport layer of the OSI model A. ApplicationB. Host-to-HostC. InternetD. Network Access98. Which statements are true regarding ICMP packets (Choose two)A. ICMP guarantees datagram delivery.B. ICMP can provide hosts with information about network problems.C. ICMP is encapsulated within IP datagrams.D. ICMP is encapsulated within UDP datagrams.99. What is the address range of a Class B network address in binaryA. 01xxxxxxB. 0xxxxxxxC. 10xxxxxxD. 110xxxxx100. Which of the following protocols uses both TCP and UDPA. FTPB. SMTPC. TelnetD. DNS答题卡。
ccna考试题库最新版
ccna考试题库最新版CCNA（Cisco Certified Network Associate）认证是全球范围内最受欢迎的网络工程师认证之一，具备CCNA认证可以证明一个人在建立、规划、运行、安装和配置中等规模的局域网和广域网方面的专业知识。
为了帮助广大考生顺利通过CCNA考试，不断更新的CCNA考试题库至关重要。
以下是最新版本的CCNA考试题库，希望对考生们有所帮助。
第一部分：网络基础知识1. 什么是OSI七层模型？简要介绍每一层的功能。
2. TCP和UDP之间有哪些区别？请分别举例说明。
3. 什么是IP地址？IP地址的类型有哪些？请列举并简要介绍各自的特点。
4. 什么是子网掩码？为什么在网络中使用子网掩码？5. 简述常见的网络设备有哪些，以及各自的功能与作用。
第二部分：路由和交换技术1. 路由器和交换机之间有何区别？请进行比较并指出各自的优势和劣势。
2. 什么是VLAN？VLAN的作用及在网络中的应用场景是什么？3. OSPF和EIGRP是两种常见的路由协议，请比较它们的特点并举例说明。
4. 请解释静态路由和动态路由的概念以及在网络中的应用。
5. 交换机在网络中扮演什么角色？交换机的MAC地址表是如何工作的？第三部分：网络安全和管理1. 网络安全的重要性是什么？请列举几种常见的网络安全威胁并介绍应对策略。
2. 什么是ACL（访问控制列表）？ACL的作用是什么？请给出一个ACL的配置示例。
3. VPN是什么？VPN的工作原理及在企业网络中的应用。
4. SNMP是网络管理中常用的协议，它的作用是什么？请解释SNMP中的几个重要概念。
5. 如何保护无线网络的安全？请列举几种方法。
第四部分：WAN技术1. 什么是WAN？WAN的主要特点是什么？2. PPP协议和HDLC协议分别是什么？请比较它们的异同。
3. 什么是Frame Relay？Frame Relay的工作原理及在WAN中的应用。
4. 请解释T1和E1的概念，以及它们在传输速率和应用方面的差异。
思科CCNA考试答案(全)
CCNA思科考试答案（全）第 1 章考试1一家拥有10 名员工的小型公司使用单个LAN 在计算机之间共享信息。
哪种类型连接适合此公司？由当地电话服务提供商提供的拨号连接能够使公司方便且安全地连接员工的虚拟专用网络通过当地服务提供商建立的私有专用线路通过当地服务提供商提供的宽带服务（如DSL）答案：4解析：对于这种小型办公室，比较适合通过被称为数字用户线路(DSL) 的常见宽带服务实现Internet 连接，这种服务由当地的电话服务提供商提供。
由于员工人数很少，带宽的问题并不突出。
如果公司较大，在远程站点有分支机构，则专用线路会更加适合。
如果公司员工需要通过Internet 与公司联系，则采用虚拟专用网。
2哪种网络情况需要使用WAN？员工工作站需要获取动态分配的IP 地址。
员工在出差时需要通过VPN 连接到公司电子邮件服务器。
分支机构的员工需要与同一园区网络上的另一座建筑物内的公司总部共享文件。
员工需要访问托管在其建筑物内DMZ 中的公司Web 服务器上的网页。
答案：2解析：当出差的员工需要通过WAN 连接到公司电子邮件服务器时，VPN 将通过WAN 连接在员工笔记本电脑与公司网络之间创建一个安全隧道。
通过DHCP 获取动态IP 地址是LAN 通信的功能。
在企业园区的不同建筑物之间共享文件可通过LAN 基础设施来实现。
DMZ 是企业LAN 基础设施内一个受保护的网络。
3以下哪项描述了WAN 的特征？WAN 和LAN 在同一地理范围内运行，但有串行链路。
WAN 网络归运营商所有。
所有串行链路均被视为WAN 连接。
WAN 可提供到园区主干网的终端用户网络连接。
答案：2解析：WAN 可用于将企业LAN 互连到远程分支机构站点LAN 和远程工作人员站点。
WAN 归运营商所有。
虽然WAN 连接一般通过串行接口实现，但并不是所有串行链路均连接至WAN。
LAN（而非WAN）可在组织中提供终端用户网络连接。
4电路交换WAN 技术的两个常见类型是什么？（请选择两项。
思科认证考试(CCNA)考试模拟题集锦(1-71题)及答案
思科认证考试（ＣＣＮＡ）考试模拟题集锦(1-71题)及答案19及答案1. [OxNx] During a TFTP transfer using Cisco Routers what is the numeric value, in decimal, of the destination port field of the User Datagram Protocol (UDP) header? a) 96b) 47c) a random number above 1024d) 69e) none of the above2. [CxNx] What is the standard encapsulation method used by Cisco routers for the Internet Protocol (IP) on it’s Ethernet interfaces?a) SNAPb) ARPAc) NOVELL-ETHERd) DARPAe) Ethernet_802.33. [CxNx] What will be the correct command on a Cisco router to set the IP address of an interface assuming you are at the "router(config-if)#" prompt?a) ip address 1.1.1.1 255.255.255.0b) ip address 1.1.1.1c) ip 1.1.1.1d) ip 1.1.1.1 255.255.255.0e) none of the above4. [CxNx] Which commands will display the IP addresses of all interfaces on a Cisco Router? (Choose all that apply)a) show ip routeb) show ip addressc) show ip interfaced) show interfacee) display ip addresses5. [CxNx] Which of the following commands will display the contents of the ARP cache of your Cisco router?a) show ip arp cacheb) show ip routec) show ip arpd) show arpe) there is no way to display the ARP cache6. [CxNx] Reverse Address Resolution Protocol (RARP) is the process:a) Where an I P host resolves it’s IP address by broadcasting it’s MAC address to the network and a BOOTP server assigns it an IP address.b) Where an IP host resolves it’s MAC address by broadcasting to the local network it’s IP address.c) Where an IP host tries to resolve the MAC address of a destination by sending a network broadcast. The destination responds to the broadcast with it’s MAC address.d) Where an IP host resolves a destination IP address by sending a broadcast on the local network and the destination host responds with it’s IP address.e)There is no such process.7. [OxNx] Which of the following applications requires the connection-oriented layer four protocol, TCP? (Choose all that apply)a) Telnetb) FTPc) TFTPd) SNMPe) none of the above8. [RxNx] Which of the following are link state Routing Protocols.(Choose all that apply.)a) IPb) OSPFc) RIPd) EIGRPe) IS-IS9. [CxNx] Of the following commands, identify the correct one for clearing the IP arp table in memory of the router.a) clear ip arp-cacheb) clear ip arp-tablec) clear arp-cached) clear arp-tablee) clear arp-ram10. [CxNx] Which of the following explains the correct definition of administrative distance as it pertains to Cisco’s IOS?a) The process by which routers select an administrator for an autonomous system.b) The process where a router will select the best path to a destination network.c) The process where a router will distance itself from other routers due to it’s lack of administrative experience.d) The process where a router will prioritize routing protocols so that in the event two routing protocols have conflicting next hop addresses, the routing protocol with the lowest administrative distance will take priority.e) The process where a router will prioritize routing protocols so that in the event two routing protocols have conflicting next hop addresses, the routing protocol with the highest administrative distance will take priority.11. [ExNx] Collisions occur whena) multiple packets are placed on a serial linkb) multiple stations listen for traffic and transmit at the same timec) when multiple tokens are on a ring simultaneouslyd) beaconing process takes place12. [RINx] How many subnets are possible with a Class C address and a subnet mask of 255.255.255.252?a) 32b) 30c) 60d) 62e) 413. [RxNx] What commands will list all protocols that are currently being routed? (Choose all that apply.)a) show ip protocolb) show protocolc) show rund) show starte) All of the above14. [xxNx] Which of the following are true of access lists?a) Access list should have at least one permit statement.b) The last configured line should always be a permit statement.c) Every access-list will implicitly deny all traffic.d) Access-lists are processed top down.e) All of the above.15. [xxNx] If the access-group command is configured on an interface and there is no access-list created which of the following is most correct?a) An error message will appear.b) The command will be executed and deny all traffic out.c) The command will be executed and permit all traffic out.d) The command will be executed and permit all traffic in and out.e) The command will be executed and deny all traffic in and out.16. [xxNx] What is the result of the command?" access-list 101 permit tcp any 172.16.0.0 0.0.255.255 established"a) telnet sessions will be permitted regardless of the source addressb) telnet sessions will be denied regardless of the source addressc) telnet sessions will be denied if initiated from any address other than 172.16.0.0 networkd) telnet sessions will be permitted to the 172.16.0.0 network onlye) telnet sessions will be denied to the 172.16.0.0 network only17. [xxNx] Which is generally true of the location of access-lists? (Choose all that apply.)a) Standard lists will most likely be placed close to the destination.b) Standard lists will most likely be placed close to the source.c) Extended lists will most likely be placed close to the destination.d) Extended lists will most likely be placed close to the source.e) It does not matter.18. [RxNx] Which of the following is most correct?a) IP is to TCP. as IPX is to SPX.b) RTMP is to Appletalk as IP RIP is to IP.c) NLSP is to IPX as OSPF is to IP.d) a is true.e) b is true.f) a & b are true.g) c is true.h) b & c are true.i) a, b and c are true.19. [ExNx] If Host A sends a packet to Host B over ethernet and Host B is not active:a) The packet will time out.b) The packet will be removed by Host A.c) The NVRAM of Host B will remove the packet.d) The packet will "die" when it reaches the terminator.e) The packet will be removed by the token monitor.Coding Key and InformationThe first character represents the category of question.A - ATMB - BridgingC - Cisco specificE - EthernetF - Frame relayH - HDLCI - FDDIN - ISDNO - OSI modelP - PPPR - RoutingS - SwitchingT - Token ringX - X.25x - Not applicableThe second character represents protocol.A - AppletalkB - Banyan VinesD - DecnetI - IPL - Dial on DemandN - NLSPO - OSPFX - IPXx - Not ApplicableThe third character represents the certification that the question will help you prepare for.N - CCNA Exam #640-407P - CCNPAdvanced Cisco Router Configuration (ACRC) Exam 640-403Cisco LAN Switch Configuration (CLSC) Exam #640-404Cisco Monitoring and Troubleshooting Dial-up Services Exam #640-405Cisco Internetworking Troubleshooting ( CIT) Exam #640-406D - CCDA & CCDPCisco Design Specialist Exam #9E0-004Cisco Internetwork Design#640-025We will reserve the fourth character for future use.As an example, when you come across a question coded "BXDx", it signifies a question that will help you gain the CCDA or CCDP certification.CCNA试题1-19答案1. [OxNx] During a TFTP transfer using Cisco Routers what is the numeric value, in decimal, of the destination port field of the User Datagram Protocol (UDP) header?a) 96b) 47c) a random number above 1024d) 69e) none of the aboveAnswerd) 69Here is a sampling of other port numbers and the application they are associated with. The first 8 of these protocols are automatically forwarded through the router by using the helper-address commandTrivial File Transfer (TFTP) (port 69)Domain Name System (port 53)IEN-116 Name Server (port 42)Time service (port 37)NetBIOS Name Server (port 137)NetBIOS Datagram Server (port 138)Boot Protocol (BootP) client and server datagrams (port 67)TACACS service (port 49)Simple Mail Transfer Protocol (25)File Transfer Protocol (21)Simple Network Management Protocol (161)2. [CxNx] What is the standard encapsulation method used by Cisco routers for the Internet Protocol (IP) on it’s Ethernet interfaces?a) SNAPb) ARPAc) NOVELL-ETHERd) DARPAe) Ethernet_802.3Answerb) ARPASNAP is the default encapsulation for a token ring interface NOVELL-ETHER is the default encapsulation for a ipx interface.3. [CxNx] What will be the correct command on a Cisco router to set the IP address of an interface assuming you are at the "router(config-if)#" prompt?a) ip address 1.1.1.1 255.255.255.0b) ip address 1.1.1.1c) ip 1.1.1.1d) ip 1.1.1.1 255.255.255.0e) none of the aboveAnswera) ip address 1.1.1.1 255.255.255.0If you are not in the configuration mode, the ip address can be set by using the setup mode.Configuring interface Ethernet0/0:Is this interface in use? [yes]:Configure IP on this interface? [yes]:IP address for this interface [10.10.10.1]: 10.10.10.1Number of bits in subnet field [16]: 16Class A network is 10.0.0.0, 16 subnet bits; mask is /24Take note when using the setup mode the mask is configured using the number of subnet bits.4. [CxNx] Which commands will display the IP addresses of all interfaces on a Cisco Router? (Choose all that apply)a) show ip routeb) show ip addressc) show ip interfaced) show interfacee) display ip addressesAnswerc) show ip interfaced) show interfaceExamples of each of these commands are shown below: Router_A#sh int e0/0Ethernet0/0 is up, line protocol is upHardware is AmdP2, address is0010.7b15.bd41(bia 0010.7b15.bd41)Internet address is 10.10.10.1/24MTU 1500 bytes, BW 10000 Kbit,DLY 1000 usec,rely 255/255, load 1/255Encapsulation ARPA, loopback not set,keepalive set (10 sec)ARP type: ARPA, ARP Timeout 04:00:00Last input never, output 00:00:06,output hang neverLast clearing of "show interface"counters neverQueueing strategy: fifoOutput queue 0/40, 0 drops;input queue 0/75,0 drops5 minute input rate 0 bits/sec,0 packets/sec5 minute output rate 0 bits/sec,0 packets/sec0 packets input, 0 bytes,0 no bufferReceived 0 broadcasts, 0 runts,0 giants,0 throttles, 0 input errors, 0 CRC,0 frame, 0 overrun, 0 ignored,0 abort0 input packets with dribblecondition detected127 packets output, 11802 bytes,0 underruns0 output errors, 0 collisions,2 interface resets0 babbles, 0 late collision,0 deferred0 lost carrier, 0 no carrier0 output buffer failures, 0 outputbuffers swapped outRouter_A#sh ip int e0/0Ethernet0/0 is up, line protocol is upInternet address is 10.10.10.1/24Broadcast address is 255.255.255.255Address determined bynon-volatile memoryMTU is 1500 bytesHelper address is not setDirected broadcast forwarding is enabledOutgoing access list is not setInbound access list is not setProxy ARP is enabledSecurity level is defaultSplit horizon is enabledICMP redirects are always sentICMP unreachables are always sentICMP mask replies are never sentIP fast switching is enabledIP fast switching on the sameinterface is disabledIP multicast fast switching is enabledRouter Discovery is disabledIP output packet accounting is disabledIP access violation accounting isdisabledTCP/IP header compression is disabledProbe proxy name replies are disabledGateway Discovery is disabledPolicy routing is disabledNetwork address translation is disabled5. [CxNx] Which of the following commands will display the contents of the ARP cache of your Cisco router?a) show ip arp cacheb) show ip routec) show ip arpd) show arpe) there is no way to display the ARP cacheAnswerc) show ip arpExample:Router_A#sh ip arpProtocol Address Age(min) Hardware Address Type InterfaceInternet 1.1.1.2 - 0010.7b15.bd50 ARPA FastEthernet1/0Internet 10.10.10.1 - 0010.7b15.bd41 ARPA Ethernet0/06. [CxNx] Reverse Address Resolution Protocol (RARP) is the process:a) Where an IP host resolves it’s IP address by broadcasting it’s MAC address to the network a nd a BOOTP server assigns it an IP address.b) Where an IP host resolves it’s MAC address by broadcasting to the local network it’s IP address.c) Where an IP host tries to resolve the MAC address of a destination by sending a network broadcast. The dest ination responds to the broadcast with it’s MAC address.d) Where an IP host resolves a destination IP address by sending a broadcast on the local network and the destination host responds with it’s IP address.e)There is no such process.Answera) Whe re an IP host resolves it’s IP address by broadcasting it’s MAC address to the network and a BOOTP server assigns it an IP address.Choice C describes Address Resolution Protocol (ARP). A host never has to resolve it’s own MAC address. The MAC address is burned into the Network Interface card. When the host is booted the MAC address will be loaded into memory.7. [OxNx] Which of the following applications requires the connection-oriented layer four protocol, TCP? (Choose all that apply)a) Telnetb) FTPc) TFTPd) SNMPe) none of the aboveAnswera) Telnetb) FTPTFTP and SNMP use layer 4 UDP.8. [RxNx] Which of the following are link state Routing Protocols.(Choose all that apply.)a) IPb) OSPFc) RIPd) EIGRPe) IS-ISAnswerb) OSPFe) IS-ISA link state routing protocol advertises, to it’s neighbors, the state of the link when the state of the link changes.A distance vector routing protocol advertises its routing table periodically.9. [CxNx] Of the following commands, identify the correct one for clearing the IP arp table in memory of the router.a) clear ip arp-cacheb) clear ip arp-tablec) clear arp-cached) clear arp-tablee) clear arp-ramAnswerc) clear arp-cacheIf you have changed an ip address or a NIC card on a host you might use this command to reset the cache.10. [CxNx] Which of the following explains the correct definition of administrative distance as it pertains to Cisco’s IOS?a) The process by which routers select an administrator for an autonomous system.b) The process where a router will select the best path to a destination network.c) The process where a router will distance itself from other routers due to it’s lack of administrative experience.d) The process where a router will prioritize routing protocols so that in the event two routing protocols have conflicting next hop addresses, the routing protocol with the lowest administrative distance will take priority.e) The process where a router will prioritize routing protocols so that in the event two routing protocols have conflicting next hop addresses, the routing protocol with the highest administrative distance will take priority.Answerd) The process where a router will prioritize routing protocols so that in the event two routing protocols have conflicting next hop addresses, the routing protocol with the lowest administrative distance will take priority.Cisco uses administrative distances (AD) to measure the reliability of the routing protocol. The lower the (AD) the more reliable the protocol.Router_C#sh ip routeCodes: C - connected, S - static,I - IGRP, R - RIP,M - mobile, B - BGPD - EIGRP, EX - EIGRP external, O - OSPF,IA - OSPF inter areaN1 - OSPF NSSA external type 1, N2 - OSPFNSSA external type 2E1 - OSPF external type 1,E2 - OSPF external type 2,E - EGPi - IS-IS, L1 - IS-IS level-1,L2 - IS-IS level-2, * -candidate defaultU - per-user static route, o - ODRGateway of last resort is not set172.16.0.0/24 is subnetted, 2 subnetsC 172.16.1.0 is directly connected,Serial1C 172.16.2.0 is directly connected,Serial0I 10.0.0.0/8 [100/8576] via 172.16.1.1,00:00:09, Serial1[100/8576] via 172.16.2.1, 00:00:19,Serial0The 100 in bold is the administrativedistance for IGRP.A partial list of administrative distances is included below:Protocol ADEIGRP 90IGRP 100OSPF 110RIP 120BGP 180If a router hears a IP RIP and a IGRP update for the same network the router will discard the rip information. IP RIP uses hop count as it’s metric, while IGRP uses a composite metric including bandwidth and load, speed is the primary consideration.11. [ExNx] Collisions occur whena) multiple packets are placed on a serial linkb) multiple stations listen for traffic and transmit at the same timec) when multiple tokens are on a ring simultaneouslyd) beaconing process takes placeAnswerb) multiple stations listen for traffic and transmit at the same timeCollisions is a term that is used in an ethernet environment. Ethernet can be described as a listen then transmit scenario. First a station will listen for traffic if no traffic is sensed then a transmission will take place. If two stations transmit at the same time collisions will occur. The first station to detect the collision sends out a jamming signal to alert all stations a collision has occurred. At this point these stations set up a random interval timer when the timer expires re-transmission will occur.Token ring is a token passing process a station can transmit only when he has the token. There never can be multiple tokens on the ring. Early token release allows up to two data frames to be transmitted on a token ring LAN at the same time. Collisions do not occur on a token ring.Because of the point to point nature of serial links collisions do not occur.Beaconing is a term used in a token passing environment.12. [RINx] How many subnets are possible with a Class C address and a subnet mask of 255.255.255.252?a) 32b) 30c) 60d) 62e) 4Answerd) 62The above mask is using 6 bits to describe subnets. The formula used to determine the number of subnets (not including the all 0’s or all 1’s subnet) is 2n - 2 were n is the number of subnet bits. This is the number to use when configuring a ip address with the setup dialog.13. [RxNx] What commands will list all protocols that are currently being routed? (Choose all that apply.)a) show ip protocolb) show protocolc) show rund) show starte) All of the aboveAnswerb) show protocolc) show runShow ip protocol will show just the ip routing protocols that are currently configured. Show start may or may not show the current routed protocols.Below is the output of show protocolRouter_B#show protocolGlobal values:Internet Protocol routing is enabledAppletalk routing is enabledBRI0 is administratively down, line protocol is downBRI0:1 is administratively down, line protocol is downBRI0:2 is administratively down, line protocol is downSerial0 is administratively down, line protocol is downSerial1 is administratively down, line protocol is downSerial2 is administratively down, line protocol is downSerial3 is administratively down, line protocol is downTokenRing0 is administratively down, line protocol is down14. [xxNx] Which of the following are true of access lists?a) Access list should have at least one permit statement.b) The last configured line should always be a permit statement.c) Every access-list will implicitly deny all traffic.d) Access-lists are processed top down.e) All of the above.Answere) All of the above.Every access list has an implicit deny all at the end. What would the need be to create a access list with just deny statements. Access-list are processed from the top down therefore the order of each statement could be critical, for instance suppose you created an access list and the first line was a permit any and the next line was a deny. Since it’s top down processing a packet would be permitted to pass on the first line and the second line would never be executed. An extended list will give you a "match count" that will help in determining what the most efficient order should be.15. [xxNx] If the access-group command is configured on an interface and there is no access-list created which of the following is most correct?a) An error message will appear.b) The command will be executed and deny all traffic out.c) The command will be executed and permit all traffic out.d) The command will be executed and permit all traffic in and out.e) The command will be executed and deny all traffic in and out.d) The command will be executed and permit all traffic in and out.There are two steps to use an access list .1. Create the list2. Place the access list on a interfaceThe analogy I use in class is:Suppose you reside in a gated community. The community is not protected until you hire the guard and then place him at the gate. If you hire the guard and never place him at the gate all traffic will be permitted. When there is no access list on an interface it is implicit permit anyWhen an access list is placed on a interface it is implicit deny any16. [xxNx] What is the result of the command?" access-list 101 permit tcp any 172.16.0.0 0.0.255.255 established"a) telnet sessions will be permitted regardless of the source addressb) telnet sessions will be denied regardless of the source addressc) telnet sessions will be denied if initiated from any address other than 172.16.0.0 networkd) telnet sessions will be permitted to the 172.16.0.0 network onlye) telnet sessions will be denied to the 172.16.0.0 network onlyAnswerc) telnet sessions will be denied if initiated from any address other than 172.16.0.0 networkThe secret to this question is the key word "established." Established means that the packet will be permitted unless it is the first part of the three way handshake. Recall that when we initiate a TCP connection we have no ACK. How can we acknowledge a sequence number from the other side when we have not established a session with him?17. [xxNx] Which is generally true of the location of access-lists? (Choose all that apply.)a) Standard lists will most likely be placed close to the destination.b) Standard lists will most likely be placed close to the source.c) Extended lists will most likely be placed close to the destination.d) Extended lists will most likely be placed close to the source.e) It does not matter.Answera) Standard lists will most likely be placed close to the destination.d) Extended lists will most likely be placed close to the source.A standard list will only check the source address. It makes no difference where the packet is going. If you place a standard list close to the source you could very well be denying that traffic to go to other destinations. An extended list can be placed close to the source because we can permit or deny traffic based upon the source and destination address. This insures that only traffic we wish to have denied is denied.18. [RxNx] Which of the following is most correct?a) IP is to TCP. as IPX is to SPX.b) RTMP is to Appletalk as IP RIP is to IP.c) NLSP is to IPX as OSPF is to IP.d) a is true.e) b is true.f) a & b are true.g) c is true.h) b & c are true.i) a, b and c are true.i) a, b and c are true.19. [ExNx] If Host A sends a packet to Host B over ethernet and Host B is not active:a) The packet will time out.b) The packet will be removed by Host A.c) The NVRAM of Host B will remove the packet.d) The packet will "die" when it reaches the terminator.e) The packet will be removed by the token monitor.Answerd) The packet will "die" when it reaches the terminator.２０—３９及答案20. [TxNx] If Host A sends a packet to Host B over token ring, and Host B is not active: a) The packet will time out.b) The packet will be removed by Host A.c) The NVRAM of Host B will remove the packet.d) The packet will "die" when it reaches the terminator.e) The packet will be removed by the token monitor.21. [TxNx] If Host A sends a packet to Host B over token ring: Host A dies after transmitting, and Host B is not active:a) The packet will time out.b) The packet will be removed by Host A.c) The NVRAM of Host B will remove the packet.d) The packet will "die" when it reaches the terminator.e) The packet will be removed by the Active monitor.22. [FxNx] BECN and FECN are:a) Used to provide keepalives in a Frame Relay environmentb) Used to provide error checking in a Frame Relay environmentc) Used to provide congestion information in a Frame Relay environmentd) Used to provide flow control parameters in a Frame Relay environmente) BECN and FECN are not used in a Frame Relay environment.23. [RxNx] Which of the following are benefits of a Link-State routing protocol? (Choose all that apply.)a) Allows the use of a more robust addressing scheme.b) Allows for a larger scalable networkc) Reduces convergence timed) Allows "supernetting"e) All of the above.24. [OxNx] Which of the following are reasons for the OSI model?a) Standardizes interfacesb) Allows modular engineeringc) Facilitates learning and teachingd) All of the above.25. [RxNx] Which of the following is NOT a ROUTING protocol:a) OSPFb) RIPc) IPXd) EIGRP26. [RxNx] Which statement is NOT true about link state protocols:a) Link state advertisements are sent to all routers in an area.b) Each router executes the SPF algorithm.c) Link state routers keep a topological database of the network.d) Link state routers include the originating router s routing table.e) Link state routers know of possible alternate paths to a particular network.27. [RxNx] Which of the following would NOT appear in a routing table?a) Next hop addressb) Interface Port referencesc) MAC addressd) Network addresse) Metrics28. [OxNx] Which statement is true of the Datalink OSI layer ?a) 802.3 is the MAC sub layer.b) No such thingc) MAC sublayer provides the connection to the network layer.d) MAC sublayer uses SAPS to access the network layer.e) SAP sublayer uses the MAC layer to access the LAN medium.29. [RINx] Given the IP address of 193.243.12.43 and a subnet mask of 255.255.255.128, what is the subnet address?a) 194.243.12.32b) 193.243.0.0c) 194.243.12.43d) 193.243.12.128e) None of the above.30. [CxNx] Cisco uses a naming convention to identify frame types. Which four of the following mappings are correct?Cisco_name = Common_namea) cisco_II = Ethernet_IIb) arpa = Ethernet_IIc) sap = Ethernet_802.3d) sap = Ethernet_802.2 LLCe) Novell Ether = Ethernet_802.2 LLCf) cisco_802 = Ethernet_802.2 LLCg) snap = Token Ring Snaph) snap = Ethernet_SNAP31. [RxNx] In order to communicate throughout an internetwork, which of the following are required. Choose Two.a) The use of a routable protocol such as NetBEUI or LATb) A hierarchical naming scheme server such as DNSc) A host file at each communicating deviced) A two part network addressing scheme such as Network/Hoste) The use of a routable protocol such as IP or IPXf) The use of a routable protocol such as TCP or IPX32. [CxNx] What is the default route on an IP network? Choose one.a) This is the route that will be chosen first by IP for delivery of a datagram.。
ccna考试试题库
ccna考试试题库CCNA（Cisco Certified Network Associate）考试是思科认证网络专家的初级认证，主要测试考生在网络基础、路由、交换、无线和安全等方面的知识。
以下是一些模拟CCNA考试的试题和答案：1. 什么是子网掩码，它有什么作用？答案：子网掩码是一种IP地址的附加信息，用于指定IP地址中网络部分和主机部分的界限。
它的作用是允许路由器区分IP地址中的网络地址和主机地址，从而实现不同网络之间的路由。
2. 描述静态路由和动态路由的区别。
答案：- 静态路由：由网络管理员手动配置的路由信息，不随网络结构的变化而自动调整。
- 动态路由：由路由器根据网络拓扑的变化自动生成和更新的路由信息。
3. 什么是VLAN，它有什么好处？答案： VLAN（虚拟局域网）是一种在交换机上划分不同网络的技术，即使物理上连接在同一交换机上，也可以属于不同的VLAN。
VLAN的好处包括提高安全性、减少广播域、提高网络管理的灵活性等。
4. 简述TCP和UDP的区别。
答案：- TCP（传输控制协议）：提供可靠的、面向连接的传输服务，有流量控制和拥塞控制机制。
- UDP（用户数据报协议）：提供不可靠的、无连接的传输服务，适用于对实时性要求高的应用。
5. 什么是DHCP，它的作用是什么？答案： DHCP（动态主机配置协议）是一种网络管理协议，用于自动分配IP地址和其他网络配置信息给网络中的设备。
它的作用是简化网络配置，避免IP地址冲突。
6. 什么是NAT，它在网络中扮演什么角色？答案： NAT（网络地址转换）是一种技术，允许多个设备共享一个公共IP地址与互联网通信。
它在网络中扮演的角色是节省IP地址资源，隐藏内部网络结构。
7. 什么是STP（生成树协议）？答案： STP（生成树协议）是一种网络协议，用于在局域网中防止网络环路的产生。
通过创建一个无环的逻辑拓扑，STP确保网络的稳定性和可靠性。
8. 描述OSPF（开放最短路径优先）协议的工作原理。
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1) Match the following application layer services to their corresponding transport layer protocol port. (匹配下列的应用层服务和它们对应的传输层协议端口)：A. SMTP 1. TCP/23B. FTP 2. TCP/25C. TFTP 3. TCP/80D. Te l n e t 4. TCP/21E. HTTP 5. UDP/69F. DNS 6. TCP/532) Which OSI reference model layer does Telnet function at (Te l ne t在哪一个O S I参考模型层运作)？A. Transport 下载B. NetworkC. SessionD. Application3) How many layers does the TCP/IP protocol suite have, compared to the OSI reference model (和O S I参考模型相比，T C P / I P协议具有几层)？A. TCP model has 4, OSI model has 6B. TCP model has 7, OSI model has 8C. TCP model has 4, OSI model has 7D. TCP model has 7, OSI model has 44) The TCP/IP protocol suite has a formal session layer that includes NetBIOS、RPCs and TLI functions (TCP/IP协议套件具有包含N e t B I O S、R P C和T L I功能的一个正式的会话层)。
A. TrueB. False5) What is the function of RPCs (RPC的功能是什么)？A. To move files from remote PCs to a local PCB. To make remote function calls transparent, so they appear to be loca lC. To initialize a program on a remote PCD. To send a procedure that is local to a remote node for processing elsewhere6) What does RPC stand for (RPC代表什么)？A. Remote personal computerB. Reserved-programming callC. Routed-procedure callD. Remote-procedure call7) What OSI reference model layer do sockets function at (套接字在O S I参考模型的哪层运作)？A. ApplicationB. PresentationC. SessionD. TransportE. NetworkF. Data linkG. Physical8) What function do sockets perform (套接字的功能是什么)？A. They make remote functions appear local, transparent to the userB. They transfer files to and from remote nodesC. They make the transport layer independentD. They allow multiple applications to share the same connection to the network9) What is WinSock (什么是Wi n S o c k )？A. A version of sockets for the Microsoft Windows platformB. Sockets on BSD UNIXC. A session layer API commonly considered to be its own protocolD. A network layer service for Microsoft Wi n d o w s10) What does TLI do (TLI的作用是什么)？A. It makes remote functions appear local, transparent to the userB. It transfers files to and from remote nodesC. It makes the transport layer independentD. It allows multiple applications to share the same connection to the network11) What OSI layer does NetBIOS function at (NetBIOS在O S I哪一层运作)？A. ApplicationB. PresentationC. SessionD. TransportE. NetworkF. Data LinkG. Physical12) Which protocols can NetBIOS bind to? (Select all that are applic able.) (NETBIOS可以绑定在哪个协议上，选择所有可能的协议)？A. AppletalkB. IPXC. IPD. NetBEUI13) What layers do not exist in the TCP/IP model that are in the OSI model (哪层不在T C P / I P模型中，但它在O S I模型中)？A. Application, presentation, and networkB. Presentation, session, and data linkC. Session, network, and physicalD. Presentation, data link, and physical14) What is a socket in the transport layer (传输层中的套接字是什么)？A. The socket is an IP address plus a portB. An API that makes the transport layer independentC. An API that allows multiple applications to share a network connectio nD. A function that makes remote procedures appear to be local15) What is a port (什么是端口)？A. An API that makes the transport layer independentB. An API that allows multiple applications to share a network connectio nC. A function that makes remote procedures appear to be localD. The point where upper-layer processes access transport layer services16) Which of the following services uses a process called windowing (下面的哪一个服务使用了所谓的窗口机制)？A. Reliable data transferB. Connection-oriented virtual circuitC. Buffered transferD. ResequencingE. MultiplexingF. Efficient, full-duplex transmissionG. Flow control17) What is UDP (什么是U D P )？A. An API that makes the transport layer independentB. A connectionless, unreliable transport protocolC. An API that allows multiple applications to share a network connectio nD. A function that makes remote procedures appear to be local18) What is IP (什么是I P )？A. It is the transport mechanism for upper layer servicesB. It is the session layer API for making the transport layer independe ntC. It is the network layer protocol that moves data from one node to anotherD. It is the physical layer protocol for Internet connections19) What is ICMP (什么是I C M P )？A. It is a network layer protocol that handles control messagesB. It is a network layer protocol that resolves addressesC. It is a session layer API that makes remote procedures transparent t o a userD. It is a transport layer function for unreliable transport20) Ping sends an ICMP echo command to an IP address in order to determine whether anetwork connection exists to that node (Ping向一个I P 地址发送了一个I C M P回送命令，目的是确定是否存在到那个节点的网络连接)？A. TrueB. False21) Which of the following best describes TCP/IP (下面的哪句话最准确地说明了T C P / I P )？A. A static protocolB. A proprietary protocolC. A collection of internetworking protocols22) UDP and TCP represent mechanisms used by which layer of the TCP /IP (UDP和T C P表示了T C P / I P的哪层使用的机制)？A. Data link layerB. Physical layerC. Presentation layerD. Transport layer23) RPCs provide which of the following (RPC提供了下面的哪个功能)？A. Connection-oriented sessionB. Transparency to make remote calls look localC. Portability of applications between heterogeneous systemsD. A and C onlyE. B and C onlyF. A, B, and C24) Distributed Computing Environment (DCE) is an example of (分布式计算环境( D E C )是下面的哪一项的一个例子)？A. OSI modelB. RPC implementationC. Extreme Data RepresentationD. A and B。