[计算机类试卷]思科认证640-802模拟试卷10及答案与解析.doc

1、思科认证 640-802模拟试卷 10及答案与解析 1 When files are transferred between a host and an FTP server, the data is divided into smaller pieces for transmission. As these pieces arrive at the destination host, they must be reassembled to reconstruct the original file. What provides for the reassembly of these piec

2、es into the correct order? （ A） The sequence number in the TCP header （ B） The Start Frame Delimiter in the 802.3 Preamble （ C） The TTL in the IP header （ D） The acknowledgement number in the segment header （ E） The frame check sequence in the Ethernet frame trailer 2 The IP network 210.106.14.0 is

3、subnetted using a /24 mask. How many usable networks and host addresses can be obtained from this? （ A） 1 network with 254 hosts （ B） 4 networks with 128 hosts （ C） 2 networks with 24 hosts （ D） 6 networks with 64 hosts （ E） 8 networks with 36 hosts 3 A Ezonexam technician is troubleshooting connect

4、ivity problems between two routers that are directly connected through the serial line. The technician notices that the serial line is up but cannot see any neighbors displayed in the output of the show cdp neighbors command. In which OSI layer is the problem most likely occurring? （ A） Physical （ B

5、） Data link （ C） Network layer （ D） Transport layer （ E） Application layer 4 By default, which of the following factors determines the spanning-tree path cost? （ A） It is the individual link cost based on latency （ B） It is the sum of the costs based on bandwidth （ C） It is the total hop count （ D）

6、It is dynamically determined based on load （ E） None of the above 5 You are a systems administrator and you are about to assign static IP addresses to various servers on your network. For the network 192.168.20.24/29 the router is assigned to the first usable host address, while the last usable host

7、 address goes to your Sales server. Which one of the following commands would you enter into the IP properties box of the sales server? （ A） IP address: 192.168.20.14 Subnet Mask: 255.255.255.248 Default Gateway: 192.168.20.9 （ B） IP address: 192.168.20.254 Subnet Mask: 255.255.255.0 Default Gateway

8、: 192.168.20.1 （ C） IP address: 192.168.20.30 Subnet Mask 255.255.255.248 Default Gateway: 192.168.20.25 （ D） IP address: 192.168.20.30 Subnet Mask 255.255.255.240 Default Gateway: 192.168.20.17 （ E） IP address: 192.168.20.30 Subnet Mask 255.255.255.240 Default Gateway: 192.168.20.25 6 Which one of

9、the following protocols uses both UDP and TCP ports for the transport layer operation? （ A） FTP （ B） TFTP （ C） SMTP （ D） Telnet （ E） DNS 7 The Ezonexam network administrator needs to a switch named VE1 to become the root bridge for a redundant path switched network. What can be done to ensure that V

10、E1 will always assume the role as the root bridge? （ A） Assign the switch a higher MAC address than the other switches in the network have （ B） Establish a direct link from the switch to all other switches in the network （ C） Configure the switch full-duplex operation and configure the other switche

11、s for half-duplex operation （ D） Configure the switch so that it has lower priority than other switches in the network （ E） None of the above 8 The Ezonexam network administrator has issued the “VTP password ezonexam“ command on a Cisco device. What is the purpose of this command? （ A） It allows two

12、 VTP servers to exists in the same domain, each configured with different passwords （ B） It is the password required when promoting a switch from VTP client mode to VTP server mode （ C） It is used to access the VTP server to make changes to the VTP configuration （ D） It is used to validate the sourc

13、es of VTP advertisements sent between switches （ E） None of the above 9 The Ezonexam network was assigned the Class C network 199.166.131.0 from the ISP. If the administrator at Ezonexam were to subnet this class C network using the 255.255.255.224 subnet mask, how may hosts will they be able to sup

14、port on each subnet? A. 14 B. 16 C. 30 D. 32 E. 62 F. 64 10 You need subnet a Ezonexam network segment. How many subnetworks and hosts are available per subnet if you apply a /28 mask to the 210.10.2.0 class C network? A. 30 networks and 6 hosts. B. 6 networks and 30 hosts. C. 8 networks and 32 host

15、s. D. 32 networks and 18 hosts. E. 16 networks and 14 hosts. F. None of the above 11 While troubleshooting a network connectivity problem, a Ezonexam technician observes steady link lights on both the workstation NIC and the switch port to which the workstation is connected. However, when the ping c

16、ommand is issued from the workstation, the output message “Request timed out.“ is displayed. At which layer of the 7-layer OSI model does the problem most likely exist? A. The data link layer B. The application layer C. The protocol layer D. The access layer E. The session layer F. The network layer

17、 G. None of the above 12 You have configured a Ezonexam switch as shown below: Ezonexam3(config-if)# switchport port-security Ezonexam3(config-if)# switchport port-security mac-address sticky Select the action below that results from executing these commands. A. A dynamically learned MAC address is

18、saved in the VLAN database. B. A dynamically learned MAC address is saved in the startup-configuration file. C. Statically configured MAC addresses are saved in the startup-configuration file if frames from that address are received. D. A dynamically learned MAC address is saved in the running-confi

19、guration file. E. Statically configured MAC addresses are saved in the running-configuration file if frames from that address are received. F. None of the above 13 What is the default configuration register setting on most Cisco routers? A. 0x2104 B. 0x2012 C. 0x2210 D. 0x2102 E. 0x2142 F. None of t

20、he above 14 The Ezonexam network administrator needs to determine what LAN devices to install on the Ezonexam network. What are two advantages of using Layer 2 Ethernet switches over hubs? (Choose two) （ A） Allowing simultaneous frame transmissions （ B） Increasing the size of broadcast domains （ C）

21、Increasing the maximum length of UTP cabling between devices （ D） Filtering frames based on MAC addresses （ E） Decreasing the number of collision domains 15 What are two results of entering the VESwitch(config)# vtp mode client command on a Catalyst switch in the Ezonexam LAN? (Choose two.) （ A） The

22、 switch will ignore VTP summary advertisements （ B） The switch will forward VTP summary advertisements （ C） The switch will process VTP summary advertisements （ D） The switch will originate VTP summary advertisements （ E） The switch will create, modify and delete VLANs for the entire VTP domain 16 W

23、hich of the following are spanning tree port states? (Select three answer choices) A. Learning B. Spanning C. Listening D. Forwarding E. Initializing F. Filtering G. Permitting 17 As a CCNA candidate, you will be expected to know the OSI model very well. Which of the following are associated with th

24、e application layer (layer 7) of the OSI model? (Choose two) A. TCP B. Telnet C. FTP D. Ping E. IP F. UDP 18 Which two statements describe the operation of the CSMA/CD access method, which is in use on the Ezonexam network? (Choose two) A. After a collision, the station that detected the collision h

25、as first priority to resend the lost data. B. In a CSMA/CD collision domain, stations must wait until the media is not in use before transmitting. C. In a CSMA/CD collision domain, multiple stations can successfully transmit data simultaneously. D. The use of hubs to enlarge the size of collision do

26、mains is one way to improve the operation of the CSMA/CD access method. 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 backof

27、f algorithm and then synchronize with each other prior to transmitting data. 19 What must the Ezonexam network administrator do in order to successfully configure a VLAN trunk between two switches named VE1 and VE2? (Select two answer choices) A. Set each end of the trunk line to IEEE 802.1Q encapsu

28、lation. B. Set the same VTP management domain name on both switches. C. Set all ports on the two switched as access ports. D. Configure one of the two switches as a VTP server. E. Connect the two switches using a rollover cable. F. Use a router to forward VTP traffic between the VLANs. 20 You want t

29、o influence the root bridge selection within the Ezonexam LAN. Which two values are used by spanning tree protocol to elect a root bridge? (Choose two.) A. Amount of RAM B. Speed of the links C. IOS Version D. MAC Address E. Bridge Priority F. IP Address G. Router ID 思科认证 640-802模拟试卷 10答案与解析 1 【正确答案

30、】 A 【试题解析】 Explanation: The Transport layer can provide reliable networking via acknowledgments, sequencing, and flow control. Acknowledgments Delivered segments are acknowledged to the sender. If they are not acknowledged, the sender will retransmit. Sequencing Data segments are sequenced into thei

31、r original order when they arrive at the destination. Flow Control Provides buffer controls that prevent packet flooding to the destination host. Buffers store bursts of data for processing when the transmission is complete. Layer 4 protocols include the following: Transmission Control Protocol (TCP

32、) User Datagram Protocol (UDP) Sequenced Packet Exchange (SPX)A reliable communications protocol created by Novell NetWare 2 【正确答案】 A 【试题解析】 Explanation: A subnet with 24 bits on would be 255.255.255.0. Since this is a class C network, this subnet can have only 1 network and 254 usable hosts. 3 【正确答

33、案】 B 【试题解析】 Explanation: As the question states that serial line is up, it means the problem is not on the Network layer. The administrator cannot see any output by issuing the show cdp neighbors command. It means that CDP is disabled and CDP is a protocol that runs over Layer2 (the data link layer)

34、 on all Cisco routers, bridges, access servers, and switches. 4 【正确答案】 B 【试题解析】 Explanation:“The STP cost is an accumulated total path cost based on the available bandwidth of each of the links.“Note: A path cost value is given to each port. The cost is typically based on a guideline established as

35、part of 802.1d. According to the original specification, cost is 1,000 Mbps (1 gigabit per second) divided by the bandwidth of the segment connected to the port.Therefore, a 10 Mbps connection would have a cost of (1,000/10) 100.To compensate for the speed of networks increasing beyond the gigabit r

36、ange, the standard cost has been slightly modified. The new cost values are: You should also note that the path cost can be an arbitrary value assigned by the network administrator, instead of one of the standard cost values.Incorrect Answers:A, D: The STP process does not take into account the late

37、ncy or load of a link. STP does not recalculate the link costs dynamically.C. Hop counts are used by RIP routers to calculate the cost of a route to a destination. The STP process resides at layer 2 of the OSI model, where hop counts are not considered. 5 【正确答案】 C 【试题解析】 Explanation A subnet mask us

38、es 29 bits. This means that it uses 5 bits in the 4th octet. This equates to 255.255.255.248. This network has 3 bits for hosts. Using the 2n-2 formula (23-2) in this case), we are left with 6 (2*2*2 - 2 = 6) host addresses. 192.168.20.24 is the network address. Therefore the next address (192.168.2

39、0.25) would be the first host address. This address must be assigned to the router, which serves as the gateway for the network. The last available host address would be 192.168.20.30 (192.168.20.24+6). This address is assigned to the server. The broadcast address is 192.168.20.31. 6 【正确答案】 E 【试题解析】

40、 Explanation: TCP and UDP must use port numbers to communicate with the upper layers. Port numbers keep track of different conversations crossing the network simultaneously. Originating-source port numbers are dynamically assigned by the source host, which will be some number starting at 1024. 1023

41、and below are defined in RFC 1700, which discusses what is called well-known port numbers. Virtual circuits that do not use an application with a well-known port number are assigned port numbers randomly chosen from within a specific range instead. These port numbers identify the source and destinat

42、ion host in the TCP segment. Only DNS uses both UDP and TCP port 53. 7 【正确答案】 D 8 【正确答案】 D 9 【正确答案】 C 【试题解析】 Explanation: The subnet mask 255.255.255.224 is a 27 bit mask (11111111.11111111.11111111.11100000). It uses 3 bits from the last octet for the network ID, leaving 5 bits for host addresses.

43、We can calculate the number of hosts supported by this subnet by using the 2n-2 formula where n represents the number of host bits. In this case it will be 5. 25-2 gives us 30. Incorrect Answers: A. Subnet mask 255.255.255.240 will give us 14 host addresses. B. Subnet mask 255.255.255.240 will give

44、us a total of 16 addresses. However, we must still subtract two addresses (the network address and the broadcast address) to determine the maximum number of hosts the subnet will support. D. Subnet mask 255.255.255.224 will give us a total of 32 addresses. However, we must still subtract two address

45、es (the network address and the broadcast address) to determine the maximum number of hosts the subnet will support. E. Subnet mask 255.255.255.192 will give us 62 host addresses. F. Subnet mask 255.255.255.192 will give us a total of 64 addresses. However, we must still subtract two addresses (the

46、network address and the broadcast address) to determine the maximum number of hosts the subnet will support. 10 【正确答案】 E 【试题解析】 Explanation: A 28 bit subnet mask (11111111.11111111.11111111.11110000) applied to a class C network uses a 4 bits for networks, and leaves 4 bits for hosts. Using the 2n-2

47、 formula, we have 24-2 (or 2x2x2x2-2) which gives us 14 for the number of hosts, and the number of networks is 24 = 16. Incorrect Answers: A. This would be the result of a /29 (255.255.255.248) network. B. This would be the result of a /27 (255.255.255.224) network. C. This is not possible, as we mu

48、st subtract two from the subnets and hosts for the network and broadcast addresses. D. This is not a possible combination of networks and hosts. 11 【正确答案】 F 12 【正确答案】 D 【试题解析】 Explanation: With port security, the switch supports these types of secure MAC addresses: Static secure MAC addresses-These

49、are manually configured by using the switchport port-security mac-address mac-address interface configuration command, stored in the address table, and added to the switch running configuration. Dynamic secure MAC addresses-These are dynamically configured, stored only in the address table, and remo

50、ved when the switch restarts. Sticky secure MAC addresses-These are dynamically configured, stored in the address table, and added to the running configuration. If these addresses are saved in the configuration file, when the switch restarts, the interface does not need to dynamically reconfigure th