[计算机类试卷]思科认证640-802模拟试卷12及答案与解析.doc

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1、思科认证 640-802模拟试卷 12及答案与解析 1 When you use the ping command to send ICMP messages across a network, whats the most common request/reply pair youll see? (Select one answer choice) （ A） Echo request and Echo reply （ B） ICMP hold and ICMP send （ C） ICMP request and ICMP reply （ D） Echo off and Echo on （

2、E） None of the above 2 You need to perform some initial configuration tasks on a new Ezonexam switch. What is the purpose of assigning an IP address to a switch? （ A） To provide local hosts with a default gateway address （ B） To allow remote management of the switch. （ C） To allow the switch to resp

3、ond to ARP requests between two hosts （ D） To ensure that hosts on the same LAN can communicate with each other. （ E） None of the above 3 Which VTP mode should a Cisco switch be set to if this switch is to add or delete VLANs to a management domain? （ A） Transparent （ B） Server （ C） Auto （ D） Client

4、 （ E） User 4 Your network uses the172.12.0.0 class B address. You need to support 459 hosts per subnet, while accommodating the maximum number of subnets. Which mask would you use? （ A） 255.255.0.0. （ B） 255.255.128.0. （ C） 255.255.224.0. （ D） 255.255.254.0. （ E） None of the above 5 You download a f

5、ile from an FTP site on the Internet. What is the highest layer in the OSI model used in this FTP operation? A. Application B. Presentation C. Session D. Transport E. Internet F. Data Link G. Physical 6 The Ezonexam network administrator needs to verify that switch interface 0/5 has been assigned to

6、 the Marketing VLA.N. Which command will accomplish this task? A. Show vlan B. Show mac-address-table C. Show vtp status D. show spanning-tree root E. show ip interface brief F. None of the above 7 You have a network that supports VLSM and you need to reduce IP address waste in your point to point W

7、AN links. Which of the masks below would you use? A. /38 B. /30 C. /27 D. /23 E. /18 F. /32 8 The Ezonexam network administrator issues the ping 192.168.2.5 command and successfully tests connectivity to a host that has been newly connected to the network. Which protocols were used during the test?

8、(Choose two) （ A） ARP （ B） CDP （ C） DHCP （ D） DNS （ E） ICMP 思科认证 640-802模拟试卷 12答案与解析 1 【正确答案】 A 【试题解析】 Explanation: The ICMP protocol uses Echo request and Echo reply with the Ping command. The PING utility is the most commonly used message to verify connectivity to a remote device within the networ

9、k. 2 【正确答案】 B 【试题解析】 Explanation: Switch is a layer 2 device and doesnt use network layer for packet forwarding. The IP address may be used only for administrative purposes such as Telnet access or for network management purposes. 3 【正确答案】 B 【试题解析】 Explanation: VTP Modes: If you intend to make a swi

10、tch part of a VTP management domain, each switch must be configured in one of three possible VTP modes. The VTP mode assigned to a switch will determine how the switch interacts with other VTP switches in the management domain. The three VTP modes that can be assigned to a Cisco switch include serve

11、r mode, client mode, and transparent mode. Each of these roles is outlined below: Server Mode: Once VTP is configured on a Cisco switch, the default mode used is Server Mode. In any given VTP management domain, at least one switch must be in Server Mode. When in Server Mode, a switch can be used to

12、add, delete, and modify VLANs, and this information will be passed to all other switches in the VTP management domain. Client Mode: When a switch is configured to use VTP Client Mode, it is simply the recipient of any VLANs added, deleted, or modified by a switch in Server Mode within the same manag

13、ement domain. A switch in VTP client mode cannot make any changes to VLAN information. Transparent Mode: A switch in VTP Transparent Mode will pass VTP updates received by switches in Server Mode to other switches in the VTP management domain, but will not actually process the contents of these mess

14、ages. When individual VLANs are added, deleted, or modified on a switch running in transparent mode, the changes are local to that particular switch only, and are not passed to other switches in the VTP management domain. Based on the roles of each VTP mode, the use of each should be more or less ob

15、vious. For example, if you had 15 Cisco switches on your network, you could configure each of them to be in the same VTP management domain. Although each could theoretically be left in the default Server Mode, it would probably be easier to leave only one switch in this configuration, and then confi

16、gure all remaining switches for VTP Client Mode. Then, when you need to add, delete, or modify a VLAN, that change can be carried out on the VTP Server Mode switch and passed to all Client Mode switches automatically. In cases where you need a switch to act in a relatively standalone manner, or do n

17、ot want it to propagate information about its configured VLANs, use Transparent Mode. Incorrect Answers: A. A switch in VTP Transparent Mode will pass VTP updates received by switches in Server Mode to other switches in the VTP management domain, but will not actually process the contents of these m

18、essages. C, E. These are not valid VTP modes. D. Client mode merely accepts changes made by the switch that is connected and in SERVER mode. 4 【正确答案】 D 【试题解析】 Explanation: To obtain 459 hosts the number of host bits will be 9. This can support a maximum of 510 hosts. To keep 9 bits for hosts means t

19、he last bit in the 3rd octet will be 0. This gives 255.255.254.0 as the subnet mask. 5 【正确答案】 A 【试题解析】 Explanation: Layer 7 is the application layer, which is the highest layer in the OSI model. This layer describes the use of end user applications, such as opening movie files (avi, mpeg, etc) used

20、Microsoft Office applications, using WWW browsers, using Telnet, and using FTP. 6 【正确答案】 A 【试题解析】 Explanation: The “show vlan“ command displays the configured vlan name and ID as well as the ports that belong to each VLAN, etc. By default all ports belongs to VLAN 1 Note: You can also use: show vlan

21、 brief, show vlan ID where ID is the VLAN ID. 7 【正确答案】 B 【试题解析】 Explanation: For a single point to point link, only 2 IP addresses are required, one for the serial interface of the router at each end. Therefore, the 255.255.255.252 subnet mask is often used for these types of links because no IP add

22、resses are wasted. The subnet mask 255.255.255.252 is a /30, so answer B is correct. Incorrect Answers: A. The largest mask that can be used is the single IP host mask, which is /32. It is not possible to use a /38 mask, unless of course IPv6 is being used. C, D, E. These masks will provide for a la

23、rger number of host addresses, and since only 2 IP addresses are needed for a point to point link, these extra addresses are wasted. F: No available host addresses with a /32 mask 8 【正确答案】 A,E 【试题解析】 Explanation: ARP finds the hardware address of a host from a known IP address. Heres how it works: w

24、hen IP has a datagram to send, it must inform a Network Access protocol, such as Ethernet or Token Ring, of the destinations hardware address on the local network. (It has already been informed by upper-layer protocols of the destinations IP address.) If IP doesnt find the destination hosts hardware

25、 address in the ARP cache, it uses ARP to find this information. ICMP works at the Network layer and is used by IP for many different services. ICMP is a management protocol and messaging service provider for IP. Its messages are carried as IP datagrams. RFC 1256 is an annex to ICMP, which affords h

26、osts extended capability in discovering routes to gateways. Periodically, router advertisements are announced over the network, reporting IP addresses for the routers network interfaces. Hosts listen for these network infomercials to acquire route information. A router solicitation is a request for immediate advertisements and may be sent by a host when it starts up.