计算机网络思科英文版第四章
2019年思科ITE3,4,5,6章考试原题及答案
清洁计算机内部可以减少以下哪种负面环境因素？灰尘在清洁计算机机箱内部时，直接喷射压缩空气容易损坏下列哪种组件？风扇在生产车间，一个家具工厂用笔记本电脑来实现进程监控和报告。
生产车间的环境温度大约为27 摄氏度（80 华氏度）。
湿度相当高，大约为70% 。
风扇安装在通风口顶部。
这里的木屑灰尘非常多。
以下哪个条件最可能对在这一环境中使用的笔记本电脑产生不利影响？灰尘蔬菜罐头工厂使用笔记本电脑来监控生产线。
生产环境的环境温度大约是24 摄氏度（75 华氏度）。
湿度约为30% 。
由于装罐设备的使用，因此噪音很高。
笔记本电脑放在一个木箱中，木箱三面距离笔记本电脑较近。
以下哪个因素最可能对在这一环境中使用的笔记本电脑产生不利影响？放置笔记本电脑的木箱科考队正在用笔记本电脑工作。
科学家们工作地点的温度范围为-13 华氏度（-25 摄氏度）到80 华氏度（27 摄氏度）。
湿度约为40% 。
噪声水平较低，但地形崎岖，风速可达每小时45 英里（每小时72 公里）。
在需要时，科学家们会停下脚步，用笔记本电脑输入数据。
下列哪一项条件最有可能对于在此环境下使用的笔记本电脑造成负面影响？温度以下哪一项是制定预防性维护计划的一部分？记录每项维护任务的详细信息和频率技术人员正在施工现场执行PC 硬件维护。
作为预防性维护计划的一部分，技术人员应该执行什么任务？进气风扇除尘。
以下哪项任务应作为硬件维护例行程序的一部分？检查并固定任何松动的电缆。
在测试导致某个问题的若干可能原因时，应该首先测试哪类原因？最容易最明显的原因在解决计算机问题时可以使用下列哪两项物品来帮助制定行动计划？（选择两项。
）计算机手册计算机维修历史记录日志为客户排除计算机故障之前应该备份哪两类数据？（选择两项。
）Internet Explorer 收藏夹文件客户创建的文档一位客户反映最近有几个文件无法访问。
维修技术人员决定检查硬盘状态和文件系统结构。
技术人员问客户是否对磁盘执行了备份，客户回答一个星期之前对磁盘上的另一个逻辑分区进行过备份。
unit4 计算机专业英语
Notes
[5]Routing tables are the means by which a router selects the fastest or nearest path to the next “hop” on the way to a data packet’s final destination. 本句中， by which a router selects the fastest or nearest path to the next “hop” on the way to a data packet’s final destination 是一个介词前置的定语从句，修饰和限定the means。on the way to“在……途中”。
学生课下活动设计
阅读Unit4的Reading。完成作业
作业： 我的梦想是成为一家电脑公司的销售经理。 老师告诉同学们别触摸电脑屏幕。 他停下来喝了杯茶。 他努力学习为了通过期末考试。 学校是孩子们学习的好地方。 这些学生经常帮助老师打扫实验室。 昨天我忘了邮信了。 他足够大了可以自己做决定。
教学参考资料推荐
Notes
[3] The MAU does actively regenerate signals as it transmits data around the ring. 本句中，does起强调作用。 [4]Routers contain internal tables of information called routing tables that keep track of all known network addresses and possible paths throughout the internetwork,along with cost of reaching each network. 本句中，called routing tables是过去分词短语，做定语，修饰 和限定internal tables of information。that keep track of all known network addresses and possible paths throughout the internetwork,along with cost of reaching each network是一 个定语从句，修饰和限定routing tables。keep track of是“ 跟踪”。
计算机网络(第四版)英文原版1.1 Uses of Computer Networks
1.1.1 Business Applications
Many companies have a substantial number of computers. For example, a company may have separate computers to monitor production, keep track of inventories, and do the payroll. Initially, each of these computers may have worked in isolation from the others, but at some point, management may have decided to connect them to be able to extract and correlate information about the entire company.
计算机网络 Chapter1_4e
<file>
Introduction
1-9
Chapter 1: roadmap
1.1 What is the Internet? 1.2 Network edge
end systems, access networks, links
1.3 Network core
circuit switching, packet switching, network structure
flow control:
sender won’t overwhelm receiver
TCP - Transmission Control Protocol
Internet’s reliable data transfer service
congestion control:
senders “slow down sending rate” when network congested
client/server model
client host requests, receives service from always-on server client/server e.g. Web browser/server; email client/server minimal (or no) use of dedicated servers e.g. Skype, BitTorrenth
a human protocol and a computer network protocol:
Hi Hi
Got the time?
TCP connection request TCP connection response
计算机网络第4版(自顶向下方法)英文版ppt
connect adjacent nodes along communication path are links
wired links wireless links LANs
layer-2 packet is a frame,
encapsulates datagram
data-link layer has responsibility of transferring datagram from one node to adjacent node over a link
services:
error detection, correction sharing a broadcast channel: multiple access link layer addressing reliable data transfer, flow control: done!
each link protocol
tourist = datagram
provides different services
transport segment =
e.g., may or may not provide rdt over link
communication link transportation mode = link layer protocol travel agent = routing algorithm
5-11
Parity Checking
Single Bit Parity:
Detect single bit errors
Two Dimensional Bit Parity:
计算机网络基础知识课件英文版
Discover the world of computer networks, from their definition and significance to their classification and protocols. Explore the fascinating concepts of OSI and TCP/IP models, network topologies, devices, security, performance optimization, applications, and management.
Network Performance Optimization
Data Transmission Rate
Learn about factors that influence transmission speeds, such as bandwidth, latency, and throughput.
Star
A network topology where devices are connected to a central hub or switch.
Ring
A network topology where devices are connected in a circular manner, forming a
Reducing Latency
Discover techniques to minimize latency, ensuring faster response times and smoother network performance.
Increasing Bandwidth
计算机网络(第四版)英文原版1.9 Summary
A factor in the delay of a store-and-forward packet-switching system is how long it takes to store and forward a packet through a switch. If switching time is 10 μsec, is this likely to be a major factor in the response of a client-server system where the client is in New York and the server is in California? Assume the propagation speed in copper and fiber to be 2/3 the speed of light in vacuum.
Well-known networks include the Internet, ATM networks, Ethernet, and the IEEE 802.11 wireless LAN. The Internet evolved from the ARPANET, to which other networks were added to form an internetwork. The present Internet is actually a collection of many thousands of networks, rather than a single network. What characterizes it is the use of the TCP/IP protocol stack throughout. ATM is widely used inside the telephone system for long-haul data traffic. Ethernet is the most popular LAN and is present in most large companies and universities. Finally, wireless LANs at surprisingly high speeds (up to 54 Mbps) are beginning to be widely deployed.
思科网络学院第二期第四章
1 下列哪两项是路由器的功能？（选择两项。
）正确响应您的响应确定发送数据包的最佳路径。
连接多个 IP 网络。
扩大广播域。
通过使用第 2 层地址控制数据流。
管理 VLAN 数据库。
此试题参考以下领域的内容：Routing and Switching Essentials∙ 4.1.1 路由器的功能2 为了将数据包发送到远程目的地，必须对主机上的哪三条信息进行配置？（正确响应您的响应IP 地址DNS 服务器地址默认网关hostnameDHCP 服务器地址子网掩码主机可以使用其 IP 地址和子网掩码来确定目的主机位于相同网络还是远程网络。
如果位于远程网络，主机需将数据包发送到远程目标。
DNS 服务器将名称转换为 IP 地址，并且 DHCP 服务器用于将 IP 寻址信息自动分都不必配置为基本远程连接。
此试题参考以下领域的内容：Routing and Switching Essentials∙ 4.1.2 连接设备3请参见图示。
如图所示，网络管理员已配置了 R1。
当管理员检查串行接口的状态时，接口显示为管理性关闭。
要打开 R1 的串行接口，必须在其中额外输入什么命令？正确响应您的 响应end no shutdownipv6 enableclockrate 128000 默认情况下所有路由器接口关闭。
要打开接口，管理员必须在接口模式发出 noshutdown 命令。
此试题参考以下领域的内容：Routing and Switching Essentials∙ 4.1.3 路由器上的基本设置4 哪一项功能可以将路由器与第 2 层交换机区别开来？正确响应您的响应路由器支持多种类型的接口。
交换机通常支持以太网接口。
交换机使用信息表确定如何处理数据流量。
路由器不是这样。
交换机将数据包从一个物理接口转发到另一个物理接口。
路由器不是这样。
路由器可以配置 IP 地址。
交换机不能。
路由器支持多种接口连接 WAN，例如串行接口、DSL 和无线接口。
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1、Based on the transport layer header shown in the diagram, which of the following statements describe the established sess 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.2、With TCP/IP data encapsulation, which range of port numbers identifies all well-known applications?0 to 255256 to 10220 to 10231024 to 204749153 to 655353、Why 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 segmentto determine which Layer 3 protocol should be used to encapsulate the datato enable a receiving host to forward the data to the appropriate applicationto allow the receiving host to assemble the packet in the proper order4、Which OSI model layer is responsible for regulating the flow of information from source to destination, reliably and accurateapplicationpresentationsessiontransportnetwork5、Refer to the exhibit. Host A is using FTP to download a large file from Server 1. During the downloadprocess, Server 1 does not receive an acknowledgment from Host A for several bytes of transferred data.What action will Server 1 take as a result?create a Layer 1 jam signalreach a timeout and resend the data that needs to be acknowledgedsend a RESET bit to the hostchange the window size in the Layer 4 header6、Why 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 orderto prevent the receiver from being overwhelmed by incoming datato synchronize window size on the serverto simplify data transfer to multiple hosts7、Which two options represent Layer 4 addressing? (Choose two.)identifies the destination networkidentifies source and destination hostsidentifies the communicating applicationsidentifies multiple conversations between the hostsidentifies the devices communicating over the local media8、Refer to the exhibit. In line 7 of this Wireshark capture, what TCP operation is being performed?session establishmentsegment retransmitdata transfersession disconnect9、Refer to the exhibit. What two pieces of information can be determined from the output that is shown? (Choose two.)The local host is using three client sess ions.The local host is using web sessions to a remote server.The local host is listening for TCP connections using public addresses.The local host is using well-known port numbers to identify the source ports.The local host is performing the three-way handshake with 192.168.1.101:1037.10、What is dynamically selected by the source host when forwarding data?destination logical addresssource physical addressdefault gateway addresssource port11、What are two features of the User Datagram Protocol (UDP)? (Choose two.)flow controllow overheadconnectionlessconnection-orientedsequence and acknowledgements12、What mechanism is used by TCP to provide flow control as segments travel from source to destination?sequence numberssession establishmentwindow sizeacknowledgments13、Which transport layer protocol provides low overhead and would be used for applications which do not require reliable dataTCPIPUDPHTTPDNS14、Which information is found in both the TCP and UDP header information?sequencingflow controlacknowledgmentssource and destination port15、Which three features allow TCP to reliably and accurately track the transmission of data from source todestination? (Choose three.)flow controlurgent pointerbest effort deliverysession establishmentconnectionless servicesnumbering and sequencing16、During a TCP communication session, if the packets arrive to the destination out of order, what willhappen 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.17、Which is an important characteristic of UDP?acknowledgement of data deliveryminimal delays in data deliveryhigh reliability of data deliverysame order data delivery18、After a web browser makes a request to a web server that is listening to the standard port, what will be the source port numb header of the response from the server?1353801024172819、Which 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.20、Refer to the exhibit. Host1 is in the process of setting up a TCP session with Host2. Host1 has sent a SYN message to begin session establishment. What happens next?Host1 sends a segment with the ACK flag = 0, SYN flag = 0 to Host2.Host1 sends a segment with the ACK flag = 1, SYN flag = 0 to Host2.Host1 sends a segment with the ACK flag = 1, SYN flag = 1 to Host2.Host2 sends a segment with the ACK flag = 0, SYN flag = 1 to Host1.Host2 sends a segment with the ACK flag = 1, SYN flag = 0 to Host1.Host2 sends a segment with the ACK flag = 1, SYN flag = 1 to Host1.。