[计算机类试卷]思科认证640-802模拟试卷1及答案与解析.doc

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1、思科认证 640-802模拟试卷 1及答案与解析 1 As a Ezonexam trainee you are required to set the default gateway on a Cisco switch to the IP address of 192.168.1.115. Which IOS command should you use? （ A） TestKSwitch(config)# ip route-default 192.168.1.115 （ B） TestKSwitch(config)# ip default-gateway 192.168.1.115 （ C

2、） TestKSwitch(config)# ip route 192.168.1.115 0.0.0.0 （ D） TestKSwitch(config)# ip default-network 192.168.1.115 （ E） None of the above 2 You have just purchased a brand new router and wish to have the router prompt you through the initial configuration commands. Which router mode does this describe

3、? （ A） ROM Monitor mode （ B） SETUP mode （ C） Autoflash mode （ D） RXBOOT mode （ E） None of the above 3 While troubleshooting a connectivity problem on the network, you issue the ping command from your PC command prompt, but the output shows “request times out.“ At which OSI layer is this problem asso

4、ciated with? （ A） The data link layer （ B） The application layer （ C） The access layer （ D） The session layer （ E） The network layer 4 The Ezonexam corporate LAN consists of one large flat network. You decide to segment this LAN into two separate networks with a router. What will be the affect of th

5、is change? （ A） The number of broadcast domains will be decreased. （ B） It will make the broadcasting of traffic between domains more efficient between segments. （ C） It will increase the number of collisions. （ D） It will prevent segment 1s broadcasts from getting to segment 2. （ E） It will connect

6、 segment 1s broadcasts to segment 2. 5 In the Ezonexam switched LAN environment, what does the IEEE 802.1Q standard describe? A. VLAN pruning B. A method of VLAN trunking C. An approach to wireless LAN communication D. The operation of VTP E. The process for root bridge selection F. None of the abov

7、e 6 Which one of the following protocols allows the information about the configuration of a new VLAN to be distributed across entire switched network? A. STP B. VTP C. EIGRP D. SNMP E. CDP F. None of the above 7 A host computer has been correctly configured with a static IP address, but the default

8、 gateway is incorrectly set. Which layer of the OSI model will be first affected by this configuration error? A. Layer 1 B. Layer 2 C. Layer 3 D. Layer 4 E. Layer 5 F. Layer 6 E. Layer 7 8 Which OSI layer header contains the address of a destination host that is on another network? A. Application B.

9、 Presentation C. Session D. Transport E. Network F. Data link G. Physical 9 As the Ezonexam network administrator, you are required to have a firm understanding of the OSI model. Why does the data communication industry use the layered OSI reference model? (Choose two) （ A） It enables equipment from

10、 different vendors to use the same electronic components, thus saving research and development funds （ B） It encourages industry standardization by defining what functions occur at each layer of the model （ C） It divides the network communication process into smaller and simpler components; thus aid

11、ing component development, design and troubleshooting （ D） It provides a means by which changes in functionality in one layer require changes in other layers （ E） It supports the evolution of multiple competing standards and thus provides business opportunities for equipment manufacturers 10 Why is

12、full-duplex Ethernet superior to its single-duplex counterpart? (Select two answer choices.) （ A） It uses inexpensive hubs （ B） It operates without collisions （ C） It operates on switches （ D） It provides faster data transfer （ E） It utilizes fewer wiring pairs 11 Which of the following are VLAN fra

13、me encapsulation types that may be configured on a Catalyst switch? (Choose two.) A. VTP B. ISL C. CDP D. 802.1Q E. 802.1p F. LLC 12 Which of the following services use TCP? (Choose three) A. DHCP B. SMTP C. SNMP D. FTP E. HTTP F. TFTP 13 Which of the following addresses can be assigned to a host wh

14、en using a subnet mask of 255.255.254.0? (Select three) A. 113.10.4.0 B. 186.54.3.0 C. 175.33.3.255 D. 26.35.2.255 E. 152.135.7.0 F. 17.35.36.0 14 Which of the following steps are necessary in order to add a new VLAN to the Ezonexam switched network? (Select all that apply) （ A） Create the VLAN. （ B

15、） Name the VLAN. （ C） Configure an IP address for the VLAN. （ D） Add the desired ports to the new VLAN. （ E） Add the VLAN to the VTP domain. 15 Regarding the extended ping command; which of the statements below are true? (Select all valid answer choices) （ A） The extended ping command is supported f

16、rom user EXEC mode. （ B） The extended ping command is available from privileged EXEC mode. （ C） With the extended ping command you can specify the TCP and UDP port to be pinged. （ D） With the extended ping command you can specify the timeout value. （ E） With the extended ping command you can specify

17、 the datagram size. 16 Ezonexam is using IP addressing according to RFC 1918. Which three address ranges are used for internal private address blocks as defined by RFC 1918? (Choose all that apply) A. 0.0.0.0 to 255.255.255 B. 10.0.0.0 to 10.255.255.255 C. 172.16.0.0 to 172.16.255.255 D. 172.16.0.0

18、to 172.31.255.255 E. 127.0.0.0. to 127.255.255.255 F. 192.168.0.0 to 192.168.255.255 G. 224.0.0.0 to 239.255.255.255 思科认证 640-802模拟试卷 1答案与解析 1 【正确答案】 B 【试题解析】 Explanation: Use the “ip default-gateway“ command to enter the IP address of the next-hop router interface that is directly connected to the

19、switch where a default gateway is being configured. The default gateway receives IP packets with unresolved destination IP addresses from the switch. Once the default gateway is configured, the switch has connectivity to the remote networks with which a host needs to communicate. 2 【正确答案】 B 【试题解析】 E

20、xplanation: Setup mode is a convenient mode that walks you through the setup procedure by prompting you with specific questions and options one by one. 3 【正确答案】 E 【试题解析】 Explanation: TCP/IP includes ICMP, a protocol designed to help manage and control the operation of a TCP/IP network. The ICMP prot

21、ocol provides a wide variety of information about a networks health and operational status. Control message is the most descriptive part of a name. ICMP helps control and manage IPs work and therefore is considered part of TCP/IPs network layer. 4 【正确答案】 D 【试题解析】 Explanation A router does not forwar

22、d broadcast traffic. It therefore breaks up a broadcast domain, reducing unnecessary network traffic. Broadcasts from one segment will not be seen on the other segment. Incorrect Answers: A. This will actually increase the number of broadcast domains from one to two. B. All link level traffic from s

23、egment one to segment two will now need to be routed between the two interfaces of the router. Although this will reduce the traffic on the LAN links, it does also provide a less efficient transport between the segments. C. Since the network size is effectively cut into half, the number of collision

24、s should decrease dramatically. E. Broadcasts from one segment will be completely hidden from the other segment. 5 【正确答案】 B 【试题解析】 Explanation: A broadcast domain must sometimes exist on more than one switch in the network. To accomplish this, one switch must send frames to another switch and indica

25、te which VLAN a particular frame belongs to. On Cisco switches, a trunk link is created to accomplish this VLAN identification. ISL and IEEE 802.1Q are different methods of putting a VLAN identifier in a Layer 2 frame. The IEEE 802.1Q protocol interconnects VLANs between multiple switches, routers,

26、and servers. With 802.1Q, a network administrator can define a VLAN topology to span multiple physical devices. Cisco switches support IEEE 802.1Q for FastEthernet and Gigabit Ethernet interfaces. An 802.1Q trunk link provides VLAN identification by adding a 4-byte tag to an Ethernet Frame as it lea

27、ves a trunk port. 6 【正确答案】 B 【试题解析】 Explanation: Sybex CCNA Study Guide 4th Edition states on page 359: “The basic goals of VLAN Trunking Protocol (VTP) are to manage all configured VLANs across a switched internetwork and to maintain consistency throughout that network. VTP allows an administrator

28、to add, delete, and rename VLANs-information that is then propagated to all other switches in the VTP domain.“ Incorrect Answers: A. STP is the Spanning Tree Protocol, used to prevent bridging loops in a LAN. C. EIGRP is a routing protocol used to exchange routing information, not VLAN information.

29、D. SNMP is the Simple Network Management Protocol, used to provide information to remote network management stations. E. CDP is the Cisco Discovery Protocol, which is used to exchange information between Cisco devices. It can only be used between Cisco routers and switches. 7 【正确答案】 C 【试题解析】 Explana

30、tion: IP Addressing and IP routing resides on the OSI Network layer, which is layer 3. 8 【正确答案】 E 【试题解析】 Explanation: Only network address contains this information. To transmit the packets the sender uses network address and datalink address. But the layer 2 address represents just the address of t

31、he next hop device on the way to the sender. It is changed on each hop. Network address remains the same. 9 【正确答案】 B,C 【试题解析】 Explanation: The OSI (Open System Interconnection) reference model was created as a reference point for communications devices. A layered approach is used to segment the enti

32、re telecommunications process into a series of smaller steps. A is correct because it encourages a level of standardization by encouraging that functions be compared to known layers. D is also correct because it allows engineers to focus on the development, refining, and perfection of simpler compon

33、ents. 10 【正确答案】 B,D 【试题解析】 Explanation: Full duplex Ethernet allows concurrent sending and receiving, which allows the full bandwidth to be used for both sending and receiving. The result is a collision free network with increased throughput. Incorrect Answers: A, C. These are incorrect because full

34、 duplex doesnt require hubs or switches. Full duplex operation can be used on switch and router ports, as well as PC hosts. E. This is incorrect because full duplex actually uses more wiring pairs. In full duplex, both wire pairs are used. Half duplex uses only a single pair. 11 【正确答案】 B,D 【试题解析】 Ex

35、planation: The two VLAN trunking encapsulation types are: Inter-Switch Link (ISL): This is proprietary to Cisco switches, and its used for Fast Ethernet and Gigabit Ethernet links only. ISL routing can be used on a switch port, router interfaces, and server interface cards to trunk a server. ISL let

36、s you explicitly tag VLAN information onto an Ethernet frame. This tagging information allows VLANs to be multiplexed over a trunk link through an external encapsulation method, which allows the switch to identify the VLAN membership of a frame over the trunked link. IEEE 802.1Q: Created by the IEEE

37、 as a standard method of frame tagging, this actually inserts a field into the frame to identify the VLAN. If youre trunking between a Cisco switched link and a different brand of switch, you have to use 802.1Q for the trunk to work. 12 【正确答案】 B,D,E 【试题解析】 Explanation: TCP (Transmission Control Prot

38、ocol) is a reliable mechanism for data delivery. SMTP, FTP and HTTP services use TCP via ports 25, 20/21, and 80, respectively. 13 【正确答案】 B,D,E 【试题解析】 Explanation: These are all valid host IP addresses within the /23 subnet. Incorrect Answers: A. This is the network address for the 113.10.4.0/23 sub

39、net. C. This is the broadcast address for the 175.33.2.0/23 subnet. F. This is the network address for the 17.35.36.0/23 subnet. 14 【 正确答案】 A,B,D 【试题解析】 Explanation: The following are the basic requirements for creating VLANs: * Creating the VLAN numbers and names * Configuring each ports assigned V

40、LAN Incorrect Answers: C. This is an optional feature, but not a necessary step for creating a VLAN. E. Adding any VLAN to a Virtual Trunking Protocol (VTP) domain may be desired in a complex multi-switch and multi-VLAN network. However, it is not a necessary step for creating stand-alone VLANs on a

41、 single switch. 15 【正确答案】 B,D,E 【试 题解析】 Explanation: The extended ping command works only at the privileged EXEC command line. Some of the extended ping command values include the datagram size and timeout value as shown: Datagram size 100: Size of the ping packet (in bytes). Default: 100 bytes. Tim

42、eout in seconds 2: Timeout interval. Default: 2 (seconds). The ping is declared successful only if the ECHO REPLY packet is received before this time interval. Incorrect Answers: A. Regular pings are available in both user and privileged mode, but not extended pings. C. Ports can not be specified. 1

43、6 【正确答案】 B,D,F 【试题解析】 Explanation: RFC 1918 defines three different IP address ranges as private, meaning that they can be used by any private network for internal use, and these ranges are not to be used in the Internet. The class A private range is 10.0.0.0 to 10.255.255.255. The class B address r

44、ange is 172.16.0.0 to 172.31.255.255. The class C private IP address range is 192.168.0.0 to 192.168.255.255. Incorrect Answers: A. The 0.0.0.0 network address is invalid and can not be used. C. The correct address range is 172.16.X.X through 172.31.X.X E. The 127.0.0.1 address is reserved for the internal loopback IP address, but the entire 127.X.X.X range is not defined in RFC 1918 as a private address range for networks. G. This address range describes the class D multicast address range.