[计算机类试卷]思科认证640-802模拟试卷11及答案与解析.doc

1、思科认证 640-802模拟试卷 11及答案与解析 1 After connecting a PC to an available port on a switch, you find that the PC can not access any of the resources on the LAN. No other PCs connected to the switch appear to be having any issues. What is the most likely cause for this problem? （ A） The router lacks a routin

2、g table entry for the new host （ B） The host switch port is assigned to the incorrect VLAN （ C） The host MAC address is incorrectly configured （ D） A STP instance for the new host has not been initialized （ E） The switch does not have the MAC address hard coded in the CAM table. 2 You need to config

3、ure a default route on a Ezonexam router. Which command will configure a default route on a router? （ A） VE1(config)# ip route 0.0.0.0 10.1.1.0 10.1.1.1 （ B） VE1(config)# ip default-route 10.1.1.0 （ C） VE1(config)# ip default-gateway 10.1.1.0 （ D） VE1(config)# ip route 0.0.0.0 0.0.0.0 10.1.1.1 3 You

4、 have set up an Internet based FTP server, where people can upload and download files. In terms of the OSI model, what is the highest layer used during the FTP sessions. A. Application B. Presentation C. Session D. Transport E. Internet F. Data Link G. Physical 4 What value is primarily used to dete

5、rmine which port becomes the root port on each nonroot switch in a spanning-tree topology? A. path cost B. lowest port MAC address C. VTP revision number D. highest port priority number E. port priority number and MAC address F. None of the above 5 You are logged into a router and wish to view the l

6、ayer 3 information about your neighboring Cisco routers. What IOS command gives layer 3 information for of the directly connected router interfaces? A. show ip links B. show cdp neighbor C. show cdp neighbor detail D. show ip clients E. show ip route F. None of the above 6 The 213.115.77.0 network w

7、as subnetted using a /28 subnet mask. How many usable subnets and host addresses per subnet were created as a result of this? A. 2 networks with 62 hosts B. 6 networks with 30 hosts C. 16 networks and 16 hosts D. 62 networks and 2 hosts E. 14 networks and 14 hosts F. None of the above 7 Which of the

8、 following are types of flow control? (Choose three) （ A） Buffering （ B） Cut-through （ C） Windowing （ D） Congestion avoidance （ E） Load balancing 8 The network security policy for Ezonexam requires that only one host be permitted to attach dynamically to each switch interface. If that policy is viol

9、ated, the interface should be automatically disabled. Which two commands must the Ezonexam network administrator configure on the 2950 Catalyst switch to meet this policy? (Choose two) （ A） SWEzonexam1(config-if)# switchport port-security maximum 1 （ B） SWEzonexam1(config)# mac-address-table secure

10、（ C） SWEzonexam1(config)# access-list 10 permit ip host （ D） SWEzonexam1(config-if)# switchport port-security violation shutdown （ E） SWEzonexam1(config-if)# ip access-group 10 9 The network 172.25.0.0 has been divided into eight equal subnets. Which of the following IP addresses can be assigned to

11、hosts in the third subnet if the ip subnet-zero command is configured on the router? (Choose three) A. 172.25.78.243 B. 172.25.98.16 C. 172.25.72.0 D. 172.25.94.255 E. 172.25.96.17 F. 172.25.100.16 10 What will cause a Ezonexam router to enter setup mode? (Choose two) A. The configuration file is mi

12、ssing in NVRAM. B. The configuration register is set to 0x2100. C. Boot system commands are misconfigured in the running-configuration. D. The setup command was issued from the privileged mode prompt. E. The IOS is missing. F. The IOS is corrupt. 11 You need to configure an 802.1Q link on a Ezonexam

13、 switch. Which commands, when used together, would do this? (Select two answer choices) A. Switch(vlan)# mode trunk B. Switch(config)# switchport access mode trunk C. Switch(config-if)# switchport mode trunk D. Switch(config-if)# switchport trunk encapsulation dot1q E. Switch(config)# switchport acc

14、ess mode 1 F. Switch(vlan)# trunk encapsulation dot1q 思科认证 640-802模拟试卷 11答案与解析 1 【正确答案】 B 【试题解析】 Explanation: Virtual LANs break up broadcast domains in a layer-two switched internetwork. If a host is in a different VLAN then the network services it needs to use, the packets must go through a router

15、. If routing does not take place, the PC will be unable to communicate with any other devices not in the same VLAN. Answer B is the best answer for this question. Incorrect Answers: A. The PC is unable to communicate with other LAN users. No router needs to even be installed for this to work. C, E.

16、The MAC address of the PC does not need to be entered manually into the switch. The switch will dynamically learn of the MAC address of the PC. D. The STP algorithm does not need to have any end host information added in order for it to work. 2 【正确答案】 D 【试题解析】 Explanation: The command “IP route 0.0.

17、0.0 0.0.0.0 “ command is used to configure a default route on a router. In this case, a default route with a next hop IP address of 10.1.1.1 was configured. Incorrect Answers: A. This will be an invalid route, since the “10.1.1.0“ value will specify the network mask, which in this case is invalid. B

18、, C. These commands are invalid. The command “ip default-network“ could be used, but not “ip default-route“ or “ip default-gateway“. IP default-gateway is used on switches, not routers. 3 【正确答案】 A 【试题解析】 Explanation: The application layer is the highest layer (layer 7) of the OSI model, and is reser

19、ved for end user applications. Since FTP is itself an application, layer 7 is the highest layer used. Incorrect Answers: B, C, D, E, F, G. In any given FTP session, all of these layers will be used at some point but they are incorrect because the question asked for the highest layer used by FTP. 4 【

20、正确答案】 A 【试题解析】 Explanation: At the conclusion of the root bridge election process, the switches move on to selecting Root Ports. The Root Port of a bridge is the port that is closest to the Root Bridge in terms of Path Cost. Every non-Root Bridge must select one Root Port. Again, bridges use the con

21、cept of cost to measure closeness. As with some routing metrics, the measure of closeness using STP is not necessarily reflected by hop count. Specifically, bridges track what is referred to as Root Path Cost, which is the cumulative cost of all links to the Root Bridge. 5 【正确答案】 C 【试题解析】 Explanatio

22、n: To display detailed information about neighboring devices discovered using Cisco Discovery Protocol (CDP), use the show cdp neighbors privileged EXEC command. Detail - (Optional) Displays detailed information about a neighbor (or neighbors) including network address, enabled protocols, hold time,

23、 and software version. Incorrect Answers: A, D. These are invalid commands. B. The “show cdp neighbor“ command, without the “detail“ keyword will not display the additional layer 3 protocol information. E. This will show all routes from all other routers within the domain. We wish to see information

24、 from just the direct interface neighbors. 6 【正确答案】 F 【试题解析】 Explanation: A class C subnet with a 28 bit mask requires 4 bits for the network address, leaving 4 bits for host addresses. Using the 2n-2 formula (24-2 in this case) we have 14 host addresses and 16 network addresses. Incorrect Answers:

25、A. This would be the result of a /26 network mask B. This would be the result of a /27 network mask C. Remember we need to always subtract two for the network and broadcast addresses, so this answer is incorrect. D. This would be the result of a /30 network mask. 7 【正确答案】 A,C,D 【试题解析】 Explanation: D

26、ata transmission flow control occurs at layer 4 with the help of buffering, windowing and congestion avoidance. 8 【正确答案】 A,D 【试题解析】 Explanation Catalyst switches offer the port security feature to control port access based on MAC addresses. To configure port security on an access layer switch port,

27、begin by enabling it with the following interface configuration command: Switch(config-if)# switchport port-security Next, you must identify a set of allowed MAC addresses so that the port can grant them access. You can explicitly configure addresses or they can be dynamically learned from port traf

28、fic. On each interface that uses port security, specify the maximum number of MAC addresses that will be allowed access using the following interface configuration command: Switch(config-if)# switchport port-security maximum max-addr Finally, you must define how each interface using port security sh

29、ould react if a MAC address is in violation by using the following interface configuration command: Switch(config-if)# switchport port-security violation shutdown | restrict | protect A violation occurs if more than the maximum number of MAC addresses are learned, or if an unknown (not statically de

30、fined) MAC address attempts to transmit on the port. The switch port takes one of the following configured actions when a violation is detected: shutdown-The port is immediately put into the errdisable state, which effectively shuts it down. It must be re-enabled manually or through errdisable recov

31、ery to be used again. restrict-The port is allowed to stay up, but all packets from violating MAC addresses are dropped. The switch keeps a running count of the number of violating packets and can send an SNMP trap and a syslog message as an alert of the violation. protect-The port is allowed to sta

32、y up, as in the restrict mode. Although packets from violating addresses are dropped, no record of the violation is kept. 9 【正确答案】 A,C,D 【试题解析】 Explanation: If we divide the address 172.25.0.0 in 8 subnets, the resulting subnets will be: 1. 172.25.0.0 2. 172.25.32.0 3. 172.25.64.0 This is the third

33、subnet 4. 172.25.96.0 5. 172.25.128.0 6. 172.25.160.0 7. 172.25.192.0 8. 172.25.224.0 Addresses that fall in the 3rd subnet will be from 172.25.64.0 - 172.25.95.255 Choices A, C and D lie in this network range. 10 【正确答案】 A,D 【试题解析】 Explanation: When router boots up, it checks the valid configuration

34、 into NVRAM and tries to load the configuration. If there is not configuration router automatically goes into setup dialog. From setup dialog, you able to configuration the basic configuration. As well you can run the setup command manually from privileged mode using the setup command. 11 【正确答案】 C,D

35、 【试题解析】 Explanation: Creating this trunk link is a two step process. First you have to set the switchport mode to trunk, and then you configure the encapsulation. The giveaway on this question is the fact that to create a trunk on an interface, you have to be in interface configuration mode. So switchport mode trunk sets the trunk, and switchport trunk encapsulation dot1q sets the encapsulation.