CCNA 思科网络章节考试题及答案《数据链路层》
思科网院考试题库
思科网院考试题库CCNA1 - Module 2CCNA1 - Module 21Which two layers of the OSI model have the same functions as the TCP/IP model Network Access Layer? (Choose two.)NetworkTransportPhysical**Data Link**Session2What is a primary function of the trailer information added by the data link layer encapsulation?supports error detection**ensures ordered arrival of dataprovides delivery to correct destinationidentifies the devices on the local networkassists intermediary devices with processing and path selection3During the encapsulation process, what occurs at the data link layer? No address is added.The logical address is added.The physical address is added.**The process port number is added.4What device is considered an intermediary device?file serverIP phonelaptopprinterswitch**5Which layer encapsulates the segment into packets?physicaldata link**networktransport6Which statements correctly identify the role of intermediary devices in the network? (Choose three.)determine pathways for data**initiate data communicationsretime and retransmit data signals**originate the flow of datamanage data flows**final termination point for data flow7What can be identified by examining the network layer header?the destination device on the local mediathe path to use to reach the destination host**the bits that will be transferred over the mediathe source application or process creating the data8What is the proper order of the layers of the OSI model from the highest layer to the lowest layer?physical, network, application, data link, presentation, session, transportapplication, physical, session, transport, network, data link, presentationapplication, presentation, physical, session, data link, transport, networkapplication, presentation, session, transport, network, data link, physical**presentation, data link, session, transport, network, physical, application9Refer to the exhibit. Which three labels correctly identify the network types for the network segments that are shown? (Choose three.) Network A -- WANNetwork B -- WAN**Network C -- LAN**Network B -- MANNetwork C -- WANNetwork A -- LAN**10What are the key functions of encapsulation? (Choose three.)allows modification of the original data before transmissionidentifies pieces of data as part of the same communication**enables consistent network paths for communicationensures that data pieces can be directed to the correct receiving end device**enables the reassembly of complete messages**tracks delay between end devices11Refer to the exhibit. Which networking term describes the data interleaving process represented in the graphic?pipingPDUstreamingmultiplexing**encapsulation12What is a PDU?corruption of a frame during transmissiondata reassembled at the destinationretransmitted packets due to lost communication**a layer specific encapsulation13Refer to the exhibit. "Cell A" at IP address has established an IP session with "IP Phone 1" at IP address Based upon the graphic, which device type best describes the function of wireless device "Cell A?"the destination device**an end devicean intermediate devicea media device14Refer to the exhibit. Which set of devices contains only end devices? A, C, DB, E, G, HC, D, G, H, I, JD, E, F, H, I, J**E, F, H, I, J15Refer to the exhibit. Which term correctly identifies the device type thatis included in the green area?sourceendtransfer**intermediary16Which three statements best describe a Local Area Network (LAN)? (Choose three.)**A LAN is usually in a single geographical area.**The network is administered by a single organization.The connection between segments in the LAN is usually through a leased connection.The security and access control of the network are controlled by a service provider.**A LAN provides network services and access to applications for users within a common organization.Each end of the network is generally connected to a Telecommunication Service Provider (TSP).17Refer to the exhibit. What type of network is shown?WANMAN**LANWLAN18What is the purpose of the TCP/IP Network Access layer?path determination and packet switching**data representation, encoding, and controlreliability, flow control, and error detectiondetailing the components that make up the physical link and how to access itthe division of segments into packets19Which characteristic correctly refers to end devices in a network? manage data flowsoriginate data flow**retime and retransmit data signalsdetermine pathways for data20What is the primary purpose of Layer 4 port assignment?to identify devices on the local mediato identify the hops between source and destinationto identify to the intermediary devices the best path through the network to identify the source and destination end devices that are communicating **to identify the processes or services that are communicating within the end devices21Select the statements that are correct concerning network protocols.(Choose three.)**define the structure of layer specific PDU'sdictate how to accomplish layer functions**outline the functions necessary for communications between layers limit hardware compatibility**require layer dependent encapsulationseliminate standardization among vendorsCCNA1 - Module 3CCNA1 - Module 31. What is the purpose of resource records in DNS?used by the server to resolve names2. What are two forms of application layer software?applicationssyntax3. What application layer protocol is commonly used to support for file transfers between a client and a server?FTP4. What are two characteristics of peer-to-peer networks? decentralized resourcesresource sharing without a dedicated server5. Which layer of the OSI model supplies services that allow user to interface with the network?application6. What are three properties of peer-to-peer applications?acts as both a client and server within the same communicationhybrid mode includes a centralized directory of filesdoes not require specialized software7. What is the role of the OSI application layer?provides the interface between the applications on either end of the network8. What three protocols operate at the Application layer of the OSI model? DNS, SMTP, POP9. Which email components are used to forward mail between servers? MDA, MTA10. Which two protocols are used to control the transfer of web resources from a web server to a client browser?HTTPSHTTP11. Which statements are correct concerning the role of the MTA in handling email?receives email from the client's MUApasses email to the MDA for final deliveryuses SMTP to route email between servers12. As compared to SSH, what is the primary disadvantage of telnet?does not support encryption13. Which application layer protocols correctly match a corresponding function?DNS dynamically allocates IP addresses to hostsTelnet provides a virtual connection for remote access14. What is the automated service that matches resource names with the required IP address?DNS15. Refer to the exhibit. What is the destination port for the communication that is represented on line 5?8016. What are two characteristics of clients in data networks?initiate data exchangesmay upload data to servers17. What application layer protocol describes the services that are used for file sharing in Microsoft networks?SMB18. A network administrator is designing a network for a new branch office of twenty-five users. What are the advantages of using a client-server model?centralized administrationsecurity is easier to enforce19. A small home network has been installed to interconnect three computers together for gaming and file sharing. What two properties represent this network type?User accounts are centralized.Security is difficult to enforce.20. How does the application layer on a server usually process multiple client request for services?uses support from lower layer functions to distinguish between connections to the serviceCCNA1 - Module 4CCNA1 - Module 41Refer to the exhibit. What two pieces of information can be determined from the output that is shown? (Choose two.)The local host is using well-known port numbers to identify the source ports.**A termination request has been sent toCommunication with is using HTTP Secure.**The local computer is accepting HTTP requests.is performing the three-way handshake with2After a web browser makes a request to a web server that is listening tothe standard port, what will be the source port number in the TCP header of the response from the server?1353**80102417283Which information is found in both the TCP and UDP header information? sequencingflow control**acknowledgmentssource and destination4Which is an important characteristic of UDP?acknowledgement of data delivery**minimal delays in data deliveryhigh reliability of data deliverysame order data delivery5Refer to the exhibit. Host A is using FTP to download a large file from Server 1. During the download process, Server 1 does not receive an acknowledgment from Host A for several bytes of transferred data. Whataction will Server 1 take as a result?create a Layer 1 jam signal**reach a timeout and resend the data that needs to be acknowledged send a RESET bit to the hostchange the window size in the Layer 4 header6Refer to the exhibit. In line 7 of this Wireshark capture, what TCP operation is being performed?**session establishmentsegment retransmitdata transfersession disconnect7Refer to the exhibit. The initial TCP exchange of data between two hosts is shown in the exhibit. Assuming an initial sequence number of 0, what sequence number will be included in Acknowledgment 2 if Segment 6 is lost? 236**1850343134758Why is flow control used for TCP data transfer?to synchronize equipment speed for sent datato synchronize and order sequence numbers so data is sent in complete numerical order**to prevent the receiver from being overwhelmed by incoming datato synchronize window size on the serverto simplify data transfer to multiple hosts9During a TCP communication session, if the packets arrive to the destination out of order, what will happen to the original message? The packets will not be delivered.The packets will be retransmitted from the source.**The packets will be delivered and reassembled at the destination. The packets will be delivered and not reassembled at the destination.10With TCP/IP data encapsulation, which range of port numbers identifies all well-known applications?0 to 255256 to 1022**0 to 10231024 to 204749153 to 6553511Which transport layer protocol provides low overhead and would be used for applications which do not require reliable data delivery?TCPIP**UDPHTTPDNS12What are two features of the User Datagram Protocol (UDP)? (Choose two.) **flow control**low overheadconnectionlessconnection-orientedsequence and acknowledgements13What mechanism is used by TCP to provide flow control as segments travel from source to destination?sequence numberssession establishment**window sizeacknowledgments14What is dynamically selected by the source host when forwarding data? destination logical addresssource physical addressdefault gateway address**source port15Why are port numbers included in the TCP header of a segment?to indicate the correct router interface that should be used to forward a segmentto identify which switch ports should receive or forward the segment to determine which Layer 3 protocol should be used to encapsulate the data **to enable a receiving host to forward the data to the appropriate applicationto allow the receiving host to assemble the packet in the proper order16Which two options represent Layer 4 addressing? (Choose two.) identifies the destination network**identifies source and destination hostsidentifies the communicating applications**identifies multiple conversations between the hostsidentifies the devices communicating over the local media17Which three features allow TCP to reliably and accurately track the transmission of data from source to destination?**encapsulationflow controlconnectionless services**session establishment**numbering and sequencingbest effort delivery18Which OSI model layer is responsible for regulating the flow of information from source to destination, reliably and accurately? applicationpresentationsession**transportnetwork19Based on the transport layer header shown in the diagram, which of the following statements describe the established session? (Choose two.) This is a UDP header.**This contains a Telnet request.This contains a TFTP data transfer.The return packet from this remote host will have an Acknowledgement Number of 43693.**This is a TCP header.20Which event occurs during the transport layer three-way handshake? The two applications exchange data.TCP initializes the sequence numbers for the sessions.**UDP establishes the maximum number of bytes to be sent.The server acknowledges the bytes of data received from the client. CCNA1 - Module 5CCNA1 - Module 51In an IPv4 environment, what information is used by the router to forward data packets from one interface of a router to another?**destination network addresssource network addresssource MAC addresswell known port destination address2What information is added during encapsulation at OSI Layer 3?source and destination MACsource and destination application protocolsource and destination port number**source and destination IP address3In a connectionless system, which of the following is correct?The destination is contacted before a packet is sent.**The destination is not contacted before a packet is sent.The destination sends an acknowledgement to the source that indicates the packet was received.The destination sends an acknowledgement to the source that requests the next packet to be sent.4Which IP packet field will prevent endless loops?type-of-serviceidentificationflags**time-to-liveheader checksum5Which portion of the network layer address does a router use to forward packets?host portionbroadcast address**network portiongateway address6Refer to the exhibit. Using the network in the exhibit, what would be the default gateway address for host A in the network?**7If the default gateway is configured incorrectly on the host, what is the impact on communications?The host is unable to communicate on the local network.**The host can communicate with other hosts on the local network, but is unable to communicate with hosts on remote networks.The host can communicate with other hosts on remote networks, but is unable to communicate with hosts on the local network.There is no impact on communications.8What is the purpose of a default gateway?physically connects a computer to a networkprovides a permanent address to a computeridentifies the network to which a computer is connectedidentifies the logical address of a networked computer and uniquely identifies it to the rest of the network**identifies the device that allows local network computers to communicate with devices on other networks9What type of routing uses information that is manually entered into the routing table?dynamicinterior**staticstandard10When the destination network is not listed in the routing table of a Cisco router, what are two possible actions that the router might take? (Choose two.)**The router sends an ARP request to determine the required next hop address.The router discards the packet.The router forwards the packet toward the next hop indicated in the ARP table.**The router forwards the packet to the interface indicated by the source address.The router forwards the packet out the interface indicated by the default route entry.11What are the key factors to consider when grouping hosts into a common network? (Choose three.)**gatewayspurposephysical addressingsoftware version**geographic location**ownership12What is a component of a routing table entry?the MAC address of the interface of the routerthe destination Layer 4 port numberthe destination host address**the next-hop address13Which intermediary devices could be used to implement security between networks? (Choose two.)**routerhubswitch**firewallaccess pointbridge14What are three common problems with a large network? (Choose three.) too few broadcasts**performance degradation**security issues**limited management responsibilityhost identificationprotocol compatibility15Refer to the exhibit. All devices shown in the exhibit have factory default settings. How many broadcast domains are represented in the topology that is shown?3**45781116Which three statements are true about routes and their use? (Choose three.) If no route to the destination network is found, the packet is returned to the previous router.If the destination network is directly connected, the router forwards the packet to the destination host.**If multiple network entries exist for the destination network, the most general route is used to forward the packet.**If no route exists for the destination network and a default route is present, the packet is forwarded to the next-hop router.**If the originating host has a default gateway configured, the packet for a remote network can be forwarded using that route.If a host does not have a route manually configured for the destination network, the host will drop the packet.17Refer to the exhibit. A network administrator is troubleshooting a connectivity problem and needs to determine the address that is used to forward network packets out the network. Using the netstat -r command, the administrator would identify which address as the address to whichall hosts send packets that are destined for an outside network?**18Refer to the exhibit. A network administrator notices that there are too many broadcasts on the network. What two steps can the network administrator take to resolve this problem? (Choose two.)**Replace S2 with a router.Place all servers on S1.Disable TCP/IP broadcasts.**Subnet the /24 network.Disable all unused interfaces on the switches.19Refer to the exhibit. The network in the exhibit is fully operational. What two statements correctly describe the routing for the topology that is shown? (Choose two.)** is the next-hop address that is used by R3 to route a packet from the network to the network.is the next-hop address that is used by R1 to route a packet from thenetwork to the network.** is the next-hop address that is used by R1 to route a packet from the network to the network.is the next-hop address that is used by R3 to route a packet from the to the network.is the next-hop address that is used by R2 to route a packet from the network to the network.is the next-hop address that is used by R2 to route a packet from the network to the network.20What two characteristics are commonly associated with dynamic routing protocols? (Choose two.)require no device configuration**provide routers with up-to-date routing tablesrequire less processing power than static routes requireconsume bandwidth to exchange route information**prevent manual configuration and maintenance of the routing table21What statement describes the purpose of a default route?A host uses a default route to transfer data to another host on the same network segment.A host uses a default route to forward data to the local switch as the next hop to all destinations.A host uses a default route to identify the Layer 2 address of an end device on the local network.**A host uses a default route to transfer data to a host outside the local network when no other route to the destination exists.CCNA1 - Module 6CCNA1 - Module 61How many bits make up an IPv4 address?128644832 **2Refer to the exhibit. A network administrator has to develop an IP addressing scheme that uses the /24 address space. The network that contains the serial link has already been addressed out of a separate range. Each network will be allocated the same number of host addresses. Which network mask will be appropriate to address the remaining networks?**3Refer to the exhibit. The network administrator has assigned the internetwork of LBMISS an address range of This address range has been subnetted using a /29 mask. In order to accommodate a new building, the technician has decided to use the fifth subnet for configuring the new network (subnet zero is the first subnet). By company policies, the router interface is always assigned the first usable host address and the workgroup server is given the last usable host address. Which configuration should be entered into the workgroup server's properties to allow connectivity to the network?IP address: subnet mask: default gateway:IP address: subnet mask: default gateway:IP address: subnet mask: default gateway: **IP address: subnet mask: default gateway:IP address: subnet mask: default gateway:4Refer to the exhibit. Which network prefix will work with the IP addressing scheme shown in the graphic./24/16/20/27 **/25/285Refer to the exhibit. A network administrator discovers that host A is having trouble with Internet connectivity, but the server farm has full connectivity. In addition, host A has full connectivity to the server farm. What is a possible cause of this problem?The router has an incorrect gateway.Host A has an overlapping network address.Host A has an incorrect default gateway configured.Host A has an incorrect subnet mask.NAT is required for the host A network. **6What subnet mask would a network administrator assign to a network address of if it were possible to have up to 254 hosts?**7Given the IP address and subnet mask of , which of the following would describe this address?This is a useable host address.This is a broadcast address.This is a network address. **This is not a valid address.8What three facts are true about the network portion of an IPv4 address? (Choose three.)identifies an individual deviceis identical for all hosts in a broadcast domainis altered as packet is forwarded **varies in length **is used to forward packets **uses flat addressing9What is the network address of the host /23 in binary?... **.. 00010001.01000011. 01100010.10A router interface has been assigned an IP address of with a mask of To which subnet does the IP address belong?**11Refer to the exhibit. Why would the response shown be displayed after issuing the command ping on a PC?The IP settings are not properly configured on the host. **Internet Protocol is not properly installed on the host.There is a problem at the physical or data link layer.The default gateway device is not operating.A router on the path to the destination host has gone down.12What two things will happen if a router receives an ICMP packet which hasa TTL value of 1 and the destination host is several hops away? (Choose two.)The router will discard the packet.The router will decrement the TTL value and forward the packet to the next router on the path to the destination host.The router will send a time exceeded message to the source host. **The router will increment the TTL value and forward the packet to the next router on the path to the destination host.The router will send an ICMP Redirect Message to the source host. ** 13Refer to the exhibit. An administrator is designing security rules for the /24 network. Each security rule requires an address and mask pair to represent the machines that will be affected by the rule. Which two address and mask pairs will be the most precise way to reference the servers and hosts separately. (Choose two.)****14Which of the following are features of IPv6? (Choose three.)larger address space **faster routing protocolsdata types and classes of service **authentication and encryption **improved host naming conventionssame addressing scheme as IPv415Which process do routers use to determine the subnet network address basedupon a given IP address and subnet mask?binary addinghexadecimal andingbinary divisionbinary multiplicationbinary ANDing **16What is the primary reason for development of IPv6? securityheader format simplificationexpanded addressing capabilities **addressing simplification17Which three IP addresses are private? (Choose three.)******18Which statements are true regarding IP addressing? (Choose two.)NAT translates public addresses to private addresses destined for the Internet.Only one company is allowed to use a specific private network address space.Private addresses are blocked from public Internet by router. **Network is part of the private address space.IP address can be used for a host to direct traffic to itself. **Which IPv4 subnetted addresses represent valid host addresses? (Choose three.)/26/26 **/26 **/27/27/27 **20What is a group of hosts called that have identical bit patterns in the high order bits of their addresses?an interneta network **an octeta radi **21Refer to the exhibit. Host A is connected to the LAN, but it cannot get access to any resources on the Internet. The configuration of the host is shown in the exhibit. What could be the cause of the problem?The host subnet mask is incorrect.The default gateway is a network address.The default gateway is a broadcast address.The default gateway is on a different subnet from the host. **22Which of the following network devices are recommended to be assigned static IP addresses? (Choose three.)LAN workstationsservers **network printers **routers **remote workstationslaptopsCCNA1 - Module 7CCNA1 - Module 71Which options are properties of contention-based media access for a shared media? (Choose three.)**non-deterministic**less overheadone station transmits at a time**collisions existdevices must wait their turntoken passing2What is a primary purpose of encapsulating packets into frames? provide routes across the internetworkformat the data for presentation to the user**facilitate the entry and exit of data on mediaidentify the services to which transported data is associated3。
思科题目
CCNACCNA11章节考试题之01《生活在以网络为中心的世界》1、在主要使用文本相互通信的两人或多人之间，他们使用的哪种通信形式属于基于文本的实时通信？A.网络日志B.维基C.即时消息D.播客E.协作工具2、哪种网络为客户提供对企业数据（如库存、部件列表和订单）的有限访问？A.内部网B.外联网C.网际网络D.Internet3、出于管理数据的目的，需要使用什么来权衡通信的重要性及其特征？A.网络管理B.网络流量C.QoS策略D.网络评估4、对网络通信采取哪些处理后才能使服务质量策略正常发挥作用？（选择两项）A.根据服务质量要求对通信分类。
B.对应用程序数据的每个分类分配优先级。
C.始终对Web通信分配高优先级处理队列。
D.始终对数字电影分配高优先级处理队列。
E.始终对电子邮件通信分配低优先级队列。
5、网络体系结构有哪两个部分？（选择两项）A.构成以人为本网络的人B.通过网络传输消息的编程服务和协议C.通过网络传输的数据D.支持网络通信的技术E.运营和维护数据网络的企业6、在当初开发Internet时，放弃面向连接的电路交换技术出于哪三个原因？（选三项）A.电路交换技术要求将单个消息划分为包含编址信息的多个消息。
B.早期的电路交换网络在电路出现故障时不能自动建立备用链路。
C.电路交换技术要求即使两个位置之间当前并未传输数据，也必须在网络端点之间建立开放电路。
D.通过面向连接的电路交换网络传输消息无法保证质量和一致性。
E.建立多路并发开放电路获得容错能力成本高昂。
7、开发Internet时使用数据包交换无连接数据通信技术出于哪三个原因？（选三项）A.它能快速适应数据传输设施的丢失。
B.它能有效利用网络基础架构传输数据。
C.数据包可同时通过网络采取多条路径传输。
D.支持按建立连接的时间收取网络使用费用。
E.传输数据之前需要在源设备和目的设备之间建立数据电路。
8、QoS在融合网络中的作用是什么?A.确保丢弃高于可用带宽水平的所有通信B.确定网络中不同通信的传输优先级C.针对所有网络通信确定精确的优先级D.允许网络中的其它组织共享未使用的带宽9、将左侧的选项和右侧的对象连线，使网络体系结构的特征与其定义相匹配。
思科练习题2(带参考答案)
1第 3 层头部包含的哪一项信息可帮助数据传输？端口号设备物理地址目的主机逻辑地址虚拟连接标识符标题描述最高分值1 correctness of response2 points for Option 30 points for any other option2此试题参考以下领域的内容：CCNA Exploration: 网络基础知识∙ 2.5.3 数据通过网际网络2IP 依靠 OSI 哪一层的协议来确定数据包是否已丢失并请求重传？应用层表示层会话层传输层标题描述最高分值1 correctness of response2 points for Option 40 points for any other option2此试题参考以下领域的内容：CCNA Exploration: 网络基础知识∙ 5.1.4 IPv4 协议 - 尽力3请参见图示。
图中所示为在各层添加的头部。
哪一层会添加目的进程号和源进程号以确保将数据传递到正确的应用程物理层数据链路层网络层传输层标题描述最高分值1 correctness of response2 points for Option 4 20 points for any other option此试题参考以下领域的内容：CCNA Exploration: 网络基础知识∙ 2.5.1 网络中的编址4下列哪一个 OSI 层使用头部信息将数据段重组为数据流？应用层网络层表示层会话层传输层标题描述最高分值1 correctness of response2 points for Option 50 points for any other option2此试题参考以下领域的内容：CCNA Exploration: 网络基础知识∙ 4.1.2 控制会话5请参见图示。
图中所示为客户端之间发送电子邮件的过程。
从下列选项中选择正确标识图中各编号阶段使用的组件或1.MUA2.MDA3.MTA4.SMTP5.MTA6.POP7.MDA8.MUA1.MUA2.POP3.MDA4.SMTP5.MTA6.MDA7.SMTP8.MUA1.MUA2.POP3.SMTP4.MDA5.MTA6.SMTP7.POP8.MUA1.MDA2.SMTP3.MTA4.SMTP5.MTA6.MUA7.POP8.MDA1.MUA2.SMTP3.MTA4.SMTP5.MTA6.MDA7.POP8.MUA标题描述最高分值1 correctness of response2 points for Option 50 points for any other option2此试题参考以下领域的内容： CCNA Exploration: 网络基础知识∙3.3.3 电子邮件服务及 SMTP/POP 协议6某主机正在网络上传输视频。
CCNA-6.0第一学期第3章答案
1 两台计算机可以使用什么方法来确保数据包不会因为过多数据发送过快而被丢弃？•封装•流量控制•访问方法•响应超时Option 22 哪种类型的通信会向局域网上的所有设备发送消息？•广播•组播•单播•全播Option 13 哪个过程用于将一个消息放入另一消息内以从源传输到目的地？•访问控制•解码•封装•流量控制Option 34 Web 客户端向 Web 服务器发送一个网页请求。
从客户端的角度来讲，用于准备传输请求的协议栈正确顺序是什么？•HTTP、IP、TCP、以太网•HTTP、TCP、IP、以太网•以太网、TCP、IP、HTTP•以太网、IP、TCP、HTTPOption 25 下列有关网络协议的陈述哪项是正确的？•网络协议定义了所用硬件类型及其如何在机架中安装。
•网络协议定义了消息在源地址和目的地址之间如何交换。
•网络协议都是在 TCP/IP 的网络接入层发挥作用。
•只有在远程网络中的设备之间交换消息时才需要使用网络协议。
Option 26 下列有关 TCP/IP 和 OSI 模型的说法，哪一项是正确的？•TCP/IP 传输层与 OSI 第 4 层提供类似的服务和功能。
•TCP/IP 网络接入层与 OSI 网络层具有类似的功能。
•OSI 第 7 层和 TCP/IP 应用层提供相同的功能。
•前三个 OSI 层描述 TCP/IP 网络层提供的相同常规服务Option 17 使用标准开发和实施协议的优点是什么？•某一特定协议只能由一个制造商实施。
•来自不同制造商的产品可以成功进行互操作。
•在实施协议时，不同制造商可以自由应用不同要求。
•标准使制造商能够灵活创建符合特殊要求的设备。
Option 28 以下哪三种应用层协议是 TCP/IP 协议簇的一部分？（选择三项。
）•ARP•DHCP•DNS•FTP•NAT•PPPOption 2, Option 3, and Option 4 are correct.9 什么是专有协议？•由私人组织开发且能在所有供应商硬件上运行的协议•可供所有组织或供应商自由使用的协议•由控制协议定义和操作的组织开发的协议•称为 TCP/IP 协议簇的协议集合Option 310 网络设备使用开放标准协议有什么好处？•网络通信局限于来自相同供应商的设备之间的数据传输。
思科CCNA第一学期第9章答案
将二进制数字10111010 转换为等值的十六进制数字。
请从下面选择正确的答案。
8590BAA1B31C以下哪些选项描述的是帧间隙？（选择两项）任何站点在发送另一帧前必须等待的最短时间间隔，以比特时间为测量单位任何站点在发送另一帧前必须等待的最长时间间隔，以比特时间为测量单位插入帧中的96 位负载填充位，用于使其达到合法的帧大小帧之间传输的96 位帧填充位，用于实现正确同步可以让速度较慢的站点处理帧并准备下一帧的时间站点在发送另一帧前不得超过的最长时间间隔，否则将视其为无法到达采用CSMA/CD 的网络中发生冲突时，需要传输数据的主机在回退时间到期后做何反应？主机恢复传输前侦听模式。
造成冲突的主机优先发送数据。
造成冲突的主机重新传输最后16 个帧。
主机延长其延迟时间以便快速传输。
发生以太网冲突之后调用回退算法时，哪种设备优先传输数据？涉入冲突的设备中MAC 地址最小的设备涉入冲突的设备中IP 地址最小的设备冲突域中回退计时器首先过期的任何设备同时开始传输的设备以下哪项是CSMA/CD 访问方法的缺点？冲突会降低网络性能。
比非确定性协议复杂。
确定性介质访问协议会减慢网络速度。
CSMA/CD LAN 技术只能以低于其它LAN 技术的速度提供。
请参见图示。
交换机和工作站已针对全双工操作进行了管理配置。
下列哪项陈述准确反映了此链路的运行？此链路不会发生冲突。
每次只有一台设备能够传输。
交换机将优先传输数据。
如果发生过多冲突，设备将默认恢复半双工操作。
以太网网段中的主机发生冲突时，为何要在尝试传输帧之前随机延迟？随机延迟旨在确保无冲突链路。
每台设备的随机延迟值由制造商指定。
网络设备厂商之间无法就标准的延迟值达成一致。
随机延迟有助于防止站点在传输期间再次发生冲突。
在图示中，当主机 B 希望向主机 C 传输帧时，主机 A 向主机 D 发送1 KB 以太网帧的过程已完成了50%。
主机B 必须执行什么操作？主机 B 可以立即传输，因为它连接到自己的电缆部分中。
思科CCNA考试答案(全)
CCNA思科考试答案（全）第 1 章考试1一家拥有10 名员工的小型公司使用单个LAN 在计算机之间共享信息。
哪种类型连接适合此公司？由当地电话服务提供商提供的拨号连接能够使公司方便且安全地连接员工的虚拟专用网络通过当地服务提供商建立的私有专用线路通过当地服务提供商提供的宽带服务（如DSL）答案：4解析：对于这种小型办公室，比较适合通过被称为数字用户线路(DSL) 的常见宽带服务实现Internet 连接，这种服务由当地的电话服务提供商提供。
由于员工人数很少，带宽的问题并不突出。
如果公司较大，在远程站点有分支机构，则专用线路会更加适合。
如果公司员工需要通过Internet 与公司联系，则采用虚拟专用网。
2哪种网络情况需要使用WAN？员工工作站需要获取动态分配的IP 地址。
员工在出差时需要通过VPN 连接到公司电子邮件服务器。
分支机构的员工需要与同一园区网络上的另一座建筑物内的公司总部共享文件。
员工需要访问托管在其建筑物内DMZ 中的公司Web 服务器上的网页。
答案：2解析：当出差的员工需要通过WAN 连接到公司电子邮件服务器时，VPN 将通过WAN 连接在员工笔记本电脑与公司网络之间创建一个安全隧道。
通过DHCP 获取动态IP 地址是LAN 通信的功能。
在企业园区的不同建筑物之间共享文件可通过LAN 基础设施来实现。
DMZ 是企业LAN 基础设施内一个受保护的网络。
3以下哪项描述了WAN 的特征？WAN 和LAN 在同一地理范围内运行，但有串行链路。
WAN 网络归运营商所有。
所有串行链路均被视为WAN 连接。
WAN 可提供到园区主干网的终端用户网络连接。
答案：2解析：WAN 可用于将企业LAN 互连到远程分支机构站点LAN 和远程工作人员站点。
WAN 归运营商所有。
虽然WAN 连接一般通过串行接口实现，但并不是所有串行链路均连接至WAN。
LAN（而非WAN）可在组织中提供终端用户网络连接。
4电路交换WAN 技术的两个常见类型是什么？（请选择两项。
(完整版)ccna1章节与期末答案
第一章：正确答案：2.4.5•解析：由于不需要使用网络设备和专用服务器，对等网络易于创建，复杂性更低，且成本更少。
而且对等网络也没有集中管理。
这种网络安全性更低，不可扩展，而且那些同时充当客户端和服务器的设备可能性能更差正确答案：1解析：正确答案： 3.5解析：选择网络介质的条件包括：所选介质可以成功传送信号的距离、要安装所选介质的环境、必须传输的数据量和速度以及介质和安装的成本。
正确答案：3和4解析：终端设备上的应用程序可以生成数据，更改数据内容并且负责启动封装过程。
正确答案：1和4解析：终端设备会发出通过网络传输的数据。
中间设备会在链路发生故障时通过备用路径传输数据，并且会过滤数据传输以增强安全性。
网络介质提供网络消息的传输通道。
正确答案：4解析：外联网是公司外部的人或企业合作伙伴访问数据的网络区域。
内部网只描述通常仅供内部人员访问的网络区域。
当设备连接到有线网络时，有线LAN 会受BYOD（自带设备）影响。
使用大学无线LAN 的设备多为平板电脑和智能手机。
大学生主要使用无线WAN 来访问他们的手机运营商网络。
.正确答案：2解析：由于通过Internet 可以联系在线供应商，所以家庭用户通过Internet 进行网上购物。
内联网基本上是仅供内部使用的局域网。
外联网是外部合作伙伴访问组织内部特定资源的网络。
家庭用户并不一定使用LAN 来访问Internet。
例如，PC 可以通过调制解调器直接连接到ISP。
正确答案：1解析：内部网这个术语用于表示一个组织的私有局域网和广域网连接。
内部网的设计旨在仅允许该组织的成员、员工或其他获得授权的人员进行访问。
正确答案：2和4解析：电缆和DSL 均能实现高带宽、始终联网，并提供到主机计算机或LAN 的以太网连接。
10正确答案：2和3解析：移动电话连接需要使用移动电话网络。
卫星连接通常用于家庭或企业外部不便使用物理布线的位置。
11正确答案：2解析：当对网络资源的请求超出了可用容量时，网络就会变得拥堵。
CCNA中文试题
一、为了提高（加强）企业网的安全性，网络管理员使用ACL（访问控制列表）。
下列哪两个原因将使网络管理员使用访问控制列表？1.控制vty访问路由器时To control vty access into a router2.当数据包流过路由器时，对数据包进行过滤的时候。
To filter traffic as it passes through a router.二、当你是某网站的管理员时，为了提高交换网络的安全性，请参考下面意见，哪两个方法可以在思科交换机上的第二层协议上安全实现？1.禁止交换机建立协商通路。
disable trunk negotation on the switch2.为交换机连接主机的接口进行适当的配置。
configure a switch port host where appropriate三、一个802.11g的AP已经被配置并且安装在一个正方形的办公室中央，一些无线用户有丢包和性能下降现象，而大多使用户工作正常。
从下面列表中找出哪三个是可能的原因？1.无线电话（手机）cordlee phones;2.金属文件橱柜metal file cabinets;3.无线类型或天线指向antenna type or direction;四、参考图示，连接在交换机上的两个接口没有变黄或者变绿，下面哪些方法是最有效的调试物理层问题的方法？（选3个）1.确保电缆A,B是直通线Ensure that cables A and B are straight-through cables2.重做所有电缆Reseat all cables3.确保交换机有电工作正常Ensure the P4S-S has power五、一个网络管理员正在配置一个路由器，使他成为一个帧中继中星型的布局中的集线器。
下面那个是在路由器上使用点到点子接口代替多点接口的优点？1.它可以避免距离矢量路由协议中的负载平衡问题It avoids split-horizon issues with distance vector routing protocols六、如图所示，图中无线局域网运行了哪两个设备管理系统？（选2）1、网络图中显示的一个长期运行的一套系统是ESS（主管支持系统）The network diagram represents an extended service set(ESS)2、两个APS（辅助推进系统）应该被配置在不同的通道起作用。
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《数据链路层》
在网络中实现第 2 层协议时应该考虑哪三个因素？（选择三项）
所选的第 3 层协议
网络的地址范围
传输层定义的PDU
物理层实现
要连接的主机数量
请参见图示。
假设图示中的网络已收敛，即路由表和ARP 表均完整，主机
A 将在发往www.server 的以太网帧目的地址字段中放入以下哪个MAC
地址？
00-1c-41-ab-c0-00
00-0c-85-cf-65-c0
00-0c-85-cf-65-c1
00-12-3f-32-05-af
下列哪些选项是共享介质以竞争为原则的介质访问属性？（选择三项）
非确定性
开销较低
每次只有一个站点能够传输
存在冲突
设备必须等待轮到自己
令牌传递
有关物理拓扑和逻辑拓扑的陈述，下列哪一项正确？
逻辑拓扑始终与物理拓扑相同。
物理拓扑与网络传输帧的方法有关。
物理信号路径是按数据链路层协议定义的。
逻辑拓扑由节点之间的虚拟连接组成。
决定介质访问控制方法的因素是什么？（选择两项）
网络层编址？
介质共享
应用进程
逻辑拓扑
中间设备的功能
下列哪些有关介质访问控制的陈述是正确的？（选择三项）
以太网采用CSMA/CD
定义为帧在介质中的放置方法
以竞争为原则的访问亦称确定性访问
802.11 采用CSMA/CD
数据链路层协议定义了访问不同介质的规则
受控访问存在数据冲突
下列哪些陈述描述的是令牌传递逻辑拓扑？（选择两项）
按照先到先得原则使用网络。
只有当计算机拥有令牌时才能传输数据。
所有主机都将接收其它主机发送的数据。
相互之间依次传递电子令牌。
令牌传递网络存在冲突率高的问题。
网络管理员有责任以图形精确表示公司网络线路和设备在建筑内的位置。
这种图是什么？
逻辑拓扑
物理拓扑
电缆路径
线路网
接入拓扑
以太网帧中的前导码有何作用？
作为数据的填充位
用于同步计时
用于标识源地址。
用于标识目的地址。
下列哪些关于OSI 模型各层地址的陈述是正确的？（选择两项）
第 2 层通过烧录到网卡的物理地址来标识设备
第 2 层地址标识正在通信的应用程序
第 3 层地址代表分层编址方案
第 4 层地址将通信转发到正确的目的网络
第 4 层地址由中间设备用于转发数据
请参见图示。
下列哪项陈述描述了图示网络使用的介质访问控制方法？
三个网络全部采用CSMA/CA。
所有网络都不需要介质访问控制。
网络 1 采用CSMA/CD 而网络 3 采用CSMA/CA。
网络 1 采用CSMA/CA 而网络 2 采用CSMA/CD。
网络 2 采用CSMA/CA 而网络 3 采用CSMA/CD。
请参见图示。
流量从PC 路由到笔记本电脑时，会进行多少次CRC 计算？
1
2
4
6
8
16
请参见图示。
PC 正在向笔记本电脑发送帧。
离开RouterB 时，帧中包括的源MAC 地址和源IP 地址分别是什么？（选择两项）
源MAC - PC
源MAC - RouterA 的S0/0
源MAC - RouterB 的Fa0/1
源IP - PC
源IP - RouterA 的S0/0
源IP - RouterB 的Fa0/1
数据链路层的哪个子层负责准备供物理层传输的信号？
LLC
MAC
HDLC
网卡
当设备从一个网络或子网移至另一个网络或子网时，下列哪两项陈述是正确的？（选择两项）
必须重新分配第 2 层地址。
不应改变默认网关地址。
设备使用同一个第 2 层地址仍可正常工作。
需要将其它端口号分配给应用程序和服务。
必须重新分配第 3 层地址才能与新的网络通信。
数据链路层有何功能？
提供数据格式化
在两台主机之间提供端到端数据传送
在两个应用程序之间提供数据传送
通过公共本地介质提供数据交换
逻辑点对点拓扑的特征是什么？
对节点进行物理连接。
节点的物理布局受到限制。
介质访问控制协议可以非常简单。
链路上使用的数据链路层协议需要较大的帧头。
将数据包封装成帧的主要作用是什么？
提供网间路由
格式化数据以便向用户显示
有助于数据进出介质
标识与传输的数据相关联的服务
数据链路层帧尾有何主要作用？
定义逻辑拓扑
提供介质访问控制
支持帧错误检测
传送帧的路由信息
有效的以太网第 2 层地址有哪三项特征？（选择三项）其长度为48 个二进制位。
被视为物理地址。
通常以十六进制格式表示。
由四个二进制八位数组成。
用于确定数据的网络通路。
当网络中添加或删除以太网设备时必须更改。