[计算机类试卷]思科认证640-802模拟试卷8及答案与解析.doc

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1、思科认证 640-802模拟试卷 8及答案与解析 1 Which of the following are true of Ethernet technology? （ A） Hosts use a logical ring topology. （ B） Hosts use a logical bus topology （ C） Hosts must wait for an electronic signal to transfer data. （ D） Hosts are directly connected to a wiring concentrator called a MSAU. （

2、 E） None of the above 2 What is the purpose of the spanning-tree algorithm in a switched LAN? （ A） To provide a monitoring mechanism for networks in switched environments. （ B） To manage VLANs across multiple switches. （ C） To prevent switching loops in networks with redundant switched paths. （ D） T

3、o segment a network into multiple collision domains. （ E） To prevent routing loops in networks. 3 Ezonexam has a Class C network and you need ten subnets. You wish to have as many addresses available for hosts as possible. Which one of the following subnet masks should you use? （ A） 255.255.255.192

4、（ B） 255.255.255.224 （ C） 255.255.255.240 （ D） 255.255.255.248 （ E） None of the above 4 What will a new Ezonexam router do during startup if a configuration file is not located in NVRAM? （ A） It will search for the configuration file in the locations specified by boot system commands. （ B） It will s

5、earch for the configuration file in flash and if no configuration file is found there, it will enter the setup dialog. （ C） It will search for the configuration file on a TFTP server and if no configuration file is found there, it will enter the setup dialog. （ D） It will search for the configuratio

6、n file in flash and if no configuration file is found there, it will load a limited configuration file from ROM. （ E） It will search for the configuration file on a TFTP server and if no configuration file is found there, it will load a limited configuration file from ROM. 5 Which type of cable shou

7、ld be used to make a connection between the Fa0/0 port on a router and the Fa0/0 port switch? （ A） Rollover cable （ B） Console cable （ C） Crossover cable （ D） Straight-through cable （ E） Serial cable 6 Which command on router EzonexamA will assign the last usable IP address from the 192.168.32.128/2

8、8 subnetwork to a router interface? A. EzonexamA(config-if)# ip address 192.168.32.142 255.255.255.240 B. EzonexamA(config-if)# ip address 192.168.32.143 255.255.255.240 C. EzonexamA(config-if)# ip address 192.168.32.158 255.255.255.240 D. EzonexamA(config-if)# ip address 192.168.32.145 255.255.255.

9、240 E. EzonexamA(config-if)# ip address 192.168.32.144 255.255.255.240 F. EzonexamA(config-if)# ip address 192.168.32.158 255.255.255.240 G. None of the above 7 Youve been assigned a single Class C address. From this, you need 8 subnets, and your subnet mask is 255.255.255.224. Which one of the foll

10、owing configuration commands would you have to use before you begin? A. Router(config)# ip classless B. Router(config)# ip subnet-zero C. Router(config)# ip version 6 D. Router(config)# no ip classful E. Router(config)# ip unnumbered F. Router(config)# ip all-nets 8 You are given a PC, a router, and

11、 a cable. Select the correct combination that will allow you to log into router VE1 locally using a terminal emulation program such as HyperTerminal. A. Connect the PCs COM port to the routers console port using a straight-through cable. B. Connect the PCs COM port to the routers console port using

12、a rollover cable. C. Connect the PCs COM port to the routers Ethernet port using a straight-through cable. D. Connect the PCs Ethernet port to the routers Ethernet port using a rollover cable. E. Connect the PCs Ethernet port to the routers Ethernet port using a straight- through cable. F. None of t

13、he above 9 You are an administrator of the Ezonexam switched network and your goal is to reduce some of the administrative overhead on your network. You plan on achieving this by configuring a new VLAN for each department in the Ezonexam network. However, you need to share the VLAN information acros

14、s numerous switches. Which of the following would allow you accomplish this? A. STP B. GVRP C. SNMP D. VTP E. DHCP F. None of the above 10 You wish to segment your LAN into multiple broadcast domains. Which technology method should you implement in order to do this? A. Transparent bridging B. Cut-th

15、rough switching C. Fragment-free switches D. Virtual LANs E. Store-and-forward switching F. None of the above 11 Which sequence of actions will allow telnet traffic from a Ezonexam users PC to a router using TCP/IP? A. Connect the PCs COM port to the routers console port using a straight-through cab

16、le. B. Connect the PCs COM port to the routers console port using a crossover cable. C. Connect the PCs COM port to the routers Ethernet port using a straight-through cable. D. Connect the PCs Ethernet port to the routers Ethernet port using a crossover cable. E. Connect the PCs Ethernet port to the

17、 routers Ethernet port using a rollover cable. F. Connect the PCs Ethernet port to the routers Ethernet port using a straight-through cable. G. None of the above 12 Regarding DHCP (dynamic host configuration protocol), which two of the following choices below are true? (Select two answer choices) A.

18、 The DHCP Discover message uses FF-FF-FF-FF-FF as the Layer 2 destination address. B. The DHCP Discover message uses UDP as the transport layer protocol. C. The DHCP Discover message uses a special Layer 2 multicast address as the destination address. D. The DHCP Discover message uses TCP as the tra

19、nsport layer protocol. E. The DHCP Discover message does not use a Layer 2 destination address. F. The DHCP Discover message does not require a transport layer protocol. 13 You need to describe the various types of flow control to your co-workers. Which of the following are types of flow control tha

20、t can be used in a network? (Choose three) A. Congestion avoidance B. Windowing C. Cut-through D. Buffering E. Load Balacing F. Fast Forward 14 CDP is being used throughout the Ezonexam network. What are two reasons why the Ezonexam network administrator would use CDP? (Choose two) A. To determine t

21、he status of network services on a remote device B. To obtain the IP Address of a connected device in order to telnet to the device C. To verify the type of cable interconnecting two devices D. To verify Layer 2 connectivity between two devices when Layer 3 fails E. To obtain VLAN information from d

22、irectly connected swticehs F. To determine the status of the routing protocols between directly connected routers G. To support automatic network failover during outages 15 The Ezonexam network Topology is displayed in the exhibit below: A switch has been configured for three different VLANs: VLAN 2

23、, VLAN 3, and VLAN 4. For the purposes of communication between VLANs a router is to be added. Host from one VLAN should be able to reach the hosts in the other VLANs.Based on this requirement, what type of connection is acceptable between the router and switch?(Select all valid answers) （ A） 10 Mbp

24、s Ethernet （ B） 56 kbps serial （ C） 100 Mbps Ethernet （ D） 1,544 Mbps serial （ E） 1000 Mbps Ethernet 16 Using a subnet mask of 255.255.255.224, which of the IP addresses below can you assign to the hosts on this subnet? (Select all that apply) A. 16.23.118.63 B. 87.45.16.159 C. 92.11.178.93 D. 134.1

25、78.18.56 E. 192.168.16.87 F. 217.168.166.192 17 On a half-duplex Ethernet LAN, two hosts attempt to send data simultaneously, resulting in a collision. Following this collision, what will the hosts do? (Select all valid answers) A. The destination host sends a request to the source for retransmissio

26、n. B. The jam signal indicates that the collision has been cleared. C. The hosts will attempt to resume transmission after a time delay has expired. D. An electrical pulse indicates that the collision has cleared. E. The router on the segment will signal that the collision has cleared. F. The hosts

27、will do nothing, as the higher layers are responsible for data error correction and re-transmission. 思科认证 640-802模拟试卷 8答案与解析 1 【正确答案】 B 【试题解析】 Explanation:LAN topologies define the manner in which network devices are organized. Four common LAN topologies exist: bus, ring, star, and tree. These topol

28、ogies are logical architectures, but the actual devices need not be physically organized in these configurations. Logical bus and ring topologies, for example, are commonly organized physically as a star. A bus topology is a linear LAN architecture in which transmissions from network stations propag

29、ate the length of the medium and are received by all other stations. Of the three most widely used LAN implementations, Ethernet/IEEE 802.3 networks, including 100BaseT, implement a bus topology, which is illustrated in Figure 2-3.Some networks implement a local bus topology. 2 【正确答案】 C 【试题解析】 Expla

30、nation: STP is used in LANs with redundant paths or routes to prevent loops in a layer 2 switched or bridged LAN. Incorrect Answers: A, B: The primary purpose of STP is to prevent loops, not for monitoring or management of switches or VLANs. D. VLANs are used to segment a LAN into multiple collision

31、 domains, but the STP process alone does not do this. E. Routers are used to prevent routing loops at layer 3 of the OSI model. STP operates at layer 2. 3 【正确答案】 C 【试题解析】 Explanation: Using the 2n-2 formula, we will need to use 4 bits for subnetting, as this will provide for 24-2 = 14 subnets. The s

32、ubnet mask for 4 bits is then 255.255.255.240. Incorrect Answers: A. This will give us only 2 bits for the network mask, which will provide only 2 networks. B. This will give us 3 bits for the network mask, which will provide for only 6 networks. D. This will use 5 bits for the network mask, providi

33、ng 30 networks. However, it will provide for only for 6 host addresses in each network, so C is a better choice. 4 【正确答案】 C 【试题解析】 Explanation: When a router boots and is able to locate the IOS it begins to load the configuration file. The configuration file, saved in NVRAM, is loaded into main memo

34、ry and executed one line at a time. These configuration commands start routing processes, supply addresses for interfaces, and set media characteristics. If no configuration file exists in NVRAM, the router attempts a network boot and sends a broadcast request for the file on a TFTP server. If this

35、is also not found, the operating system executes a question-driven initial configuration routine called the system configuration dialog. 5 【正确答案】 D 【试题解析】 Explanation:Straight-through cables are used to connect host to switch (or hub) and router to switch (or hub). 6 【正确答案】 A 【试题解析】 Explanation: The

36、 last usable IP address would be 128 + (16-2) = 142 because only the last 4 bits of the last octet are used for host addressing. 7 【正确答案】 B 【试题解析】 Explanation: To get 8 subnets from a class C address, and a mask of 255.255.255.224 use the reserved subnet space. To do this, you need the command ip su

37、bnet-zero. This will allow the router to use the very first subnet, which is normally reserved and unused as the network address. Prior to Cisco IOS? Software Release 12.0, Cisco routers, by default, did not allow an IP address belonging to subnet zero to be configured on an interface. However, if a

38、 network engineer working with a Cisco IOS software release older than 12.0 finds it safe to use subnet zero, the ip subnet-zero command in the global configuration mode can be used to overcome this restriction. As of Cisco IOS Software Release 12.0, Cisco routers now have ip subnet-zero enabled by

39、default, but if the network engineer feels that it is unsafe to use subnet zero, the no ip subnet-zero command can be used to restrict the use of subnet zero addresses. In versions prior to Cisco IOS Software Release 8.3, the service subnet-zero command was used. It should be noted that even though

40、it was discouraged, the entire address space including subnet zero and the all-ones subnet have always been usable. The use of the all-ones subnet was explicitly allowed and the use of subnet zero is explicitly allowed since Cisco IOS Software Release 12.0. Even prior to Cisco IOS Software Release 1

41、2.0, subnet zero could be used by entering the ip subnet-zero global configuration command. On the issue of using subnet zero and the all-ones subnet, RFC 1878 states, “This practice (of excluding all-zeros and all-ones subnets) is obsolete. Modern software will be able to utilize all definable netw

42、orks.“ Today, the use of subnet zero and the all-ones subnet is generally accepted and most vendors support their use. However, on certain networks, particularly the ones using legacy software, the use of subnet zero and the all-ones subnet can lead to problems. 8 【正确答案】 B 【试题解析】 Explanation: To con

43、nect the Router in Console port to configure using HyperTerminal, you required the Rollover Cable, which connects the PCs COM port to the routers Console port. Incorrect Answers: A, C, E: Straight Cables are used for: Host to switch, Switch to Router. D: Rollover cables are used for Console/COM conn

44、ections, not for IP traffic over the Ethernet ports. 9 【正确答案】 D 【试题解析】 Explanation: The VTP (VLAN Trunking Protocol) is a Cisco Layer 2 messaging protocol that manages the addition, deletion, and renaming of VLANs on a network-wide basis. It allows for VLAN information to span multiple switches with

45、in the switch domain. Incorrect Answers: A. STP is a switching protocol but it is used for preventing network loops. B. GVARP is an actual protocol used in switch administration, but it beyond the scope of what a CCNA is expected to know. C. SNMP is a protocol used for managing and monitoring networ

46、ks E. DHCP is the Dynamic Host Configuration Protocol, which allows for PCs to obtain their IP address dynamically upon booting up, along with their DNS and default gateway information. 10 【正确答案】 D 【试题解析】 Explanation: The creation of VLANs in a switch will provide separate Broadcast domains. By defa

47、ult, all ports in a Catalyst switch belong to VLAN 1. By creating additional VLANs, the LAN will be logically segmented into separate broadcast domains. Incorrect Answers A. Transparent bridging is called Transparent because the endpoints devices do not need to know that the bridges exists. It will

48、not play any role for creating separate broadcast domain B, E. Both of these are switching methods. C. This has nothing to do with the creation of multiple broadcast domains. 11 【正确答案】 D 【试题解析】 Explanation: A crossover cable is used to directly connect a switch to a switch, a hub to a hub, a host to

49、 a host, or a hosts Ethernet port to a routers Ethernet interface. If your Routers interface is configured with IP addressing and telnet service is enabled you can log through the telnet program into your router. Incorrect Answers: A, B, C: The COM port is used for direct terminal connections to a router, via the use of terminal emulation programs such as hyperterminal. E: A rollover cable is used to connect via a console connection. F: A straight through cable would be used if there was a LAN switch or a hub in place, but when connecting to the router directly