[计算机类试卷]思科认证640-802模拟试卷6及答案与解析.doc

1、思科认证 640-802模拟试卷 6及答案与解析 1 The network administrator has configured port security on a Ezonexam switch. Why would a network administrator configure port security on this Ezonexam device? （ A） To prevent unauthorized hosts from getting access to the LAN （ B） To limit the number of Layer 2 broadcasts

2、on a particular switch port （ C） To prevent unauthorized Telnet or SSH access to a switch port （ D） To prevent the IP and MAC address of the switch and associated ports （ E） None of the above 2 You are a senior network administrator at Ezonexam, and while performing the password recovery procedure o

3、n your 2500 series Cisco router, you type in the following command: o/r 0x2142 What is the purpose of this command? （ A） 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. （ E）

4、It is used to save the changes to the configuration. 3 Why might the Ezonexam network administrator set the configuration register to 0x2142 on a 2600 series Cisco router? （ A） To boot the IOS from ROM （ B） To reset the console password （ C） To upload a new version of the configuration file （ D） To

5、upload a new version of the IOS （ E） To allow a new memory upgrade to be recognized by the router 4 While troubleshooting an issue in the Ezonexam LAN you notice that a network interface port has collision detection and carrier sensing enabled on a shared twisted pair network. From this statement, w

6、hat is known about the network interface port? A. This is an Ethernet port operating at half duplex B. This is an Ethernet port operating at full duplex C. This is a port on a network interface card in a PC D. This is 10 MB/s switch port E. This is a 100 MB/s switch port F. None of the above 5 Why w

7、ould the Ezonexam administrator change the value of the spanning-tree priority of a switch? A. in order to optimize the path that frames take from source to destination B. to increase the priority so a designated port will become a root port C. to increase the BID, so the switch is more likely to be

8、come root bridge D. in order to allow VLANs to be sent from one switch to another across a single link E. to force a given switch to become an STP server F. None of the above 6 After working on a router, some problems arise and you wish to view the commands that you recently entered. Which IOS comma

9、nd opens the history buffer and displays the most recently entered commands? A. Show history B. Show buffers C. Show typed commands D. Show terminal buffer E. Show command F. None of the above 7 A network administrator wants to control which user hosts can access the network based on their MAC addre

10、ss. What will prevent workstations with unauthorized MAC addresses from connecting to the network through a switch? A. BPDU B. Port security C. RSTP D. STP E. VTP F. Blocking mode 8 Which OSI layer is associated with the following: The acknowledgement of transmissions, sequencing, and flow control a

11、cross a network? A. Layer 2 B. Layer 3 C. Layer 4 D. Layer 5 E. Layer 6 F. Layer 7 9 You need to configure two Ezonexam switches to exchange VLAN information. Which protocol provides a method of sharing VLAN configuration information between these two switches? A. STP B. 802.1Q C. VLSM D. ISL E. VTP

12、 F. HSRP G. None of the above 10 Which Layer 4 protocol is used for a Telnet connection between two Ezonexam routers? A. IP B. ICMP C. DNS D. TCP E. UDP F. RTP 11 You are trying to connect directly into the LAN prot of a Ezonexam router. You want to telnet to the local Cisco router using TCP/IP but

13、cannot create a session. What should you do to resolve the problem? A. Use a straight-through cable to connect your computers COM port to the routers console port. B. Use a crossover cable to connect your computers COM port to the routers console port. C. Use a straight-through cable to connect your

14、 computers COM port to the routers Ethernet port. D. Use a crossover cable to connect your computers Ethernet port to the routers Ethernet port. E. Use a rollover cable to connect your computers Ethernet port to the routers Ethernet port. F. Use a straight-through cable to connect your computers Eth

15、ernet port to the routers Ethernet port. G. None of the above 12 You are unable to telnet to a router at address 203.125.12.1 from a workstation with the IP address 203.125.12.23. You suspect that there is a problem with the IP protocol stack in your PC. Which of the following actions is most likely

16、 to confirm your diagnosis? A. ping 127.0.0.0 B. ping 203.125.12.1 C. telnet 127.0.0.1 D. ping 127.0.0.1 E. tracert 203.125.12.1 F. None of the above 13 How could the Ezonexam corporation benefit from using VLANs on their network? (Select three answer choices.) A. VLANs allow access to network servi

17、ces based on department, not physical location. B. VLANs utilize packet filtering to enhance network security. C. VLANs provide a low-latency, high bandwidth internetworking alternative. D. VLANs provide a method of communication between IP addresses in large networks. E. VLANs establish segmented b

18、roadcast domains in switched networks. F. VLANs can greatly simplify adding, moving, or changing hosts on the network. 14 An administrator would like to configure a switch over a virtual terminal connection from locations outside of the local LAN. Which of the following are required in order for the

19、 switch to be configured from a remote location? (Choose two) A. The switch must be reachable through a port connected to its management VLAN. B. The switch console port must be connected to the Ethernet LAN. C. The switch must be fully configured as an SNMP agent. D. The switch must be configured w

20、ith an IP address, subnet mask, and default gateway. E. The switch management VLAN must be created and have a membership of at least one switch port. F. The switch must be connected to a router over a VLAN trunk. 15 Ezonexam has implemented the use of VLANs in their network. Which of the following a

21、re considered to be a benefit of VLANs? (Choose three) A. They increase the size of collision domains. B. They allow logical grouping of users by function. C. They can enhance network security, D. The increase the size of broadcast domains while decreasing the number of the broadcast domains. E. The

22、 increase the number of broadcast domains while decreasing the size of the broadcast domains. F. They simplify switch administration. 16 Which encapsulation types are configurable on a Cisco switch for a trunk? (Select two answer choices) A. VTP B. ISL C. CDP D. 802.1Q E. 802.1p F. LLC G. IETF 17 A

23、new switch is installed in the Ezonexam network. This switch is to be configured so that VLAN information will be automatically distributed to all the other Cisco Catalyst switches in the network. Which of the conditions below have to be met in order for this to occur? (Choose all that apply). A. Th

24、e switch that will share the VLAN information must be in the VTP Server mode. B. The switches must be in the same VTP domain. C. The switch that will share the VLAN information must be configured as the root bridge. D. The switches must be configured to use the same VTP version. E. The switches must

25、 be configured to use the same STP version. F. The switches must be configured to use the same type of ID tagging. G. The switches must be connected over VLAN trunks. 18 Which of the following correctly describe the various functions and virtues of a router? (Select all valid answer choices) A. Pack

26、et switching B. Collision prevention on a LAN segment. C. Packet filtering D. Broadcast domain enlargement E. Broadcast forwarding F. Internetwork communication G. None of the above 19 You have a class B network with a 255.255.255.0 mask. Which of the statements below are true of this network? (Sele

27、ct all valid answers) A. There are 254 usable subnets. B. There are 256 usable hosts per subnet. C. There are 50 usable subnets. D. There are 254 usable hosts per subnet. E. There are 24 usable hosts per subnet. F. There is one usable network. 20 When a switch port is used as a VLAN trunk, which of

28、the following trunk modes are valid? (Select all that apply.) A. Blocking B. Auto C. Desirable D. On E. Transparent F. Learning 思科认证 640-802模拟试卷 6答案与解析 1 【正确答案】 A 【试题解析】 Explanation: You can use the port security feature to restrict input to an interface by limiting and identifying MAC addresses of

29、the stations allowed to access the port. When you assign secure MAC addresses to a secure port, the port does not forward packets with source addresses outside the group of defined addresses. If you limit the number of secure MAC addresses to one and assign a single secure MAC address, the workstati

30、on attached to that port is assured the full bandwidth of the port. If a port is configured as a secure port and the maximum number of secure MAC addresses is reached, when the MAC address of a station attempting to access the port is different from any of the identified secure MAC addresses, a secu

31、rity violation occurs. Also, if a station with a secure MAC address configured or learned on one secure port attempts to access another secure port, a violation is flagged. 2 【正确答案】 B 【试题解析】 Explanation: Theo/r 0x2142 command changes the value of config-register to 2142 in a Cisco 2500 series router

32、, so that the Router ignores the NVRAM contents and reverts to the initial setup configuration mode when it boots. 3 【正确答案 】 B 【试题解析】 Explanation: About 99 percent of the time someone uses a config-register, its more than likely because of a lost router password. The two config-registers for recover

33、ing passwords are 0x2102 and 0x2142. The first config-register, 0x2102, is the normal config-register if you boot the router from internal Flash. You can see this config-register by using the show version command. In this output, youll notice the last line says, “Configuration register is 0x2102.“ T

34、his is normal. But lets say you forgot the routers password. To recover this password (as long as its unencrypted), boot the router and bypass the startup-config using config-register 0x2142; you should then be able to see the password in the startup-config. You can use the same method for encrypted

35、 passwords, but youll need to overwrite the original password with a new one. To change the configuration register, enter the following: Router(config)# config-register 0x2142 This will instruct the router to bypass the configuration and boot up as if it were a brand new router using factory default

36、 settings. 4 【正确答案】 A 5 【正确答案】 A 【试题解析】 Explanation: The Bridge Priority is used to measure the preference of a bridge in the spanning-tree Algorithm. The possible values range between 0 and 65,535. The default setting is 32,768. By adjusting the priority, the root bridge can be manually assigned to

37、 meet the needs of the network administrator. 6 【正确答案】 A 【试题解析】 Explanation: The router will buffer previously entered commands. By default, the “show history“ command will display the previous ten commands that were entered. To see the contents of the buffer you enter the show history command. Inco

38、rrect Answers: B. This command will show the memory buffer information C, D. These are invalid commands. 7 【正确答案】 B 【试题解析】 Explanation: Understanding How Port Security Works: You can use port security to block input to an Ethernet, Fast Ethernet, or Gigabit Ethernet port when the MAC address of the

39、station attempting to access the port is different from any of the MAC addresses specified for that port. Alternatively, you can use port security to filter traffic destined to or received from a specific host based on the host MAC address. When a secure port receives a packet, the source MAC addres

40、s of the packet is compared to the list of secure source addresses that were manually configured or autoconfigured (learned) on the port. If a MAC address of a device attached to the port differs from the list of secure addresses, the port either shuts down permanently (default mode), shuts down for

41、 the time you have specified, or drops incoming packets from the insecure host. The ports behavior depends on how you configure it to respond to a security violation. If a security violation occurs, the Link LED for that port turns orange, and a link-down trap is sent to the Simple Network Managemen

42、t Protocol (SNMP) manager. An SNMP trap is not sent if you configure the port for restrictive violation mode. A trap is sent only if you configure the port to shut down during a security violation. 8 【正确答案】 C 【试题解析】 Explanation: The Transport layer (Layer 4) defines several functions, including the

43、choice of protocols. The most important Layer 4 functions are error recovery and flow control. The transport layer may provide for retransmission, i.e., error recovery, and may use flow control to prevent unnecessary congestion by attempting to send data at a rate that the network can accommodate, o

44、r it might not, depending on the choice of protocols. Multiplexing of incoming data for different flows to applications on the same host is also performed. Reordering of the incoming data stream when packets arrive out of order is included. Examples include: TCP, UDP, and SPX. 9 【正确答案】 E 【试题解析】 Expl

45、anation: VLAN Trunking Protocol (VTP) is a Cisco proprietary Layer 2 messaging protocol that manages the addition, deletion, and renaming of VLANs on a network-wide basis. Virtual Local Area Network (VLAN) Trunk Protocol (VTP) reduces administration in a switched network. When you configure a new VL

46、AN on one VTP server, the VLAN is distributed through all switches in the domain. This reduces the need to configure the same VLAN everywhere. To do this VTP carries VLAN information to all the switches in a VTP domain. VTP advertisements can be sent over ISL, 802.1q, IEEE 802.10 and LANE trunks. VT

47、P traffic is sent over the management VLAN (VLAN1), so all VLAN trunks must be configured to pass VLAN1. VTP is available on most of the Cisco Catalyst Family products. 10 【正确答案】 D 【试题解析】 Explanation: TCP is a reliable connection-oriented protocol. TCP uses acknowledgments, sequencing, and flow cont

48、rol to ensure reliability. Telnet uses TCP port 23. 11 【正确答案】 D 【试题解析】 Explanation: In order to connect directly to a router via telnet, you must connect to the router via one of the LAN ports. When connecting directly to the Ethernet port with a PC without the use of a switch or hub, a crossover ca

49、ble must be used. Incorrect Answers: A, B, C. In order to telnet directly into the router via a TCP/IP connection, the COM port of the PC can not be used. The COM port is used for direct terminal emulation programs such as HyperTerminal. E. Rollover cables are used for console connections into the router, not for TCP/IP connections. F. Straight through cables are used for connections into a switch or hub from the PC. It will not work for direct Ethernet connections into the router. 12 【正确答案】 D 【试题解析】 Explanation: Every Windows based PC uses the 127.0.0.1 as the local loopbac