计网作业1

2

Q. A system has an 7-layer protocol hierarchy. Applications generate messages of length 1000 bytes. At each of the layers , an 20 byte header is added. What fraction of the network bandwidth is filled with headers?
A.（11） % (round to integer)

3

Q. How long was a bit on the original 802.3 standard in meters? Use a transmission speed of 10 Mbps and assume the propagation speed in coax is 2/3 the speed of light in vacuum.
A. （20） meters.

4

Q.A client-server system uses a satellite network, with the satellite at a height of 40000 km. What is the best-case delay in response to a request?
A.
267 msec

5

Q. An image is 1024 x 768 pixels with 3 bytes/pixel. Assume the image is uncompressed. How long does it take to transmit it over a 56-kbps modem channel? Over a 1-Mbps cable modem? Over a 10-Mbps Ethernet? Over 100-Mbps Ethernet? (round to three decimal place)
A. for 56kbps: （337.042） sec
A. for 1Mbps: （18.874） sec
A. for 10Mbps: （1.887） sec
A. for 100Mbps: （0.189） sec

6

Q. A collection of five routers is to be connected in a point-to-point subnet. Between each pair of routers, the designers may put a high-speed line, a medium-speed line, a low-speed line, or no line. If it takes 100 ms of computer time to generate and inspect each topology, how long will it take to inspect all of them? (give your answer as xxx.xx)
A. （） seconds ？？？140857.60

7

Which of the following description about OSI layers is incorrect?

The physical layer is concerned with transmitting raw bits over a communication channel
The data link layer is a true end-to-end layer, all the way from the source to the destination
The network layer controls the operation of the subnet and determines how packets are routed from source to destination
The application layer contains a variety of protocols that are commonly needed by users
B

8

Which service model is connection-oriented service?

virtual circuit service
acknowledged datagram service
client-server service
datagram service
Box 1: Select the best answer
A

9

What is the name of PDU at the network layer of the OSI reference model?

message
frame
packet
segment
Box 1: Select the best answer
C

10

Some network systems support transmission to a subset of the machines. This mode of operation is called:

flow control
congestion control
multicasting
broadcasting
C
Box 1: Select the best answer

操作系统作业1

Which of the following instructions should be privileged(in kernel mode)?

a. Set value of timer.

b. Read the clock.

c. Clear memory.

d. Issue a trap instruction.

e. Turn off interrupts.

f. Modify entries in device-status table.

g. Switch from user to kernel mode.

h. Access I/O device.

简答题 (10 分)
附件上传最多可上传6张图片
2.
Name three ways in which the processor can transition from user mode to kernel mode?

简答题 (10 分)
附件上传最多可上传6张图片
3.
Describe three general methods for passing parameters to the operating system

简答题 (10 分)
附件上传最多可上传6张图片
4.
What is the difference between kernel mode and user mode? Why is the difference important to an operating system?

简答题 (10 分)
附件上传最多可上传6张图片
5.
What are exceptions? Name two different types of exceptions and give an example of each type.

简答题 (10 分)
附件上传最多可上传6张图片
6.
What is the purpose of interrupts? What are the differences between a trap and an interrupt? Can traps be generaged intentionally by a user program? If so, for what purpose?

Which of the following instructions should be privileged(in kernel mode)?   a.  Set value of timer.   b.  Read the clock.   c.  Clear memory.   d.  Issue a trap instruction.   e.  Turn off interrupts.   f.  Modify entries in device-status table.   g.  Switch from user to kernel mode.   h.  Access I/O device.简答题                     (10             分)             a, c, f, g, h             附件                              上传             最多可上传6张图片         2.     Name three ways in which the processor can transition from user mode to kernel mode?

简答题 (10 分) System calls; exceptions; I/O device interrpts 附件上传最多可上传6张图片 3. Describe three general methods for passing parameters to the operating system
简答题 (10 分) passing parameters through register;
passing parameters through stack;
passing parameters through kernel message queue. 附件上传最多可上传6张图片 4. What is the difference between kernel mode and user mode? Why is the difference important to an operating system?
简答题 (10 分) The kernel mode has all the top privilege to the software/hareware operation,such as accessing memory, handling I/O devices or setting the timer,Wrong operations in which could lead to computer system crash or damage,address space could be shared with all the process with the right privilege;
The user mode can` t directly access memory or control I/O devices, they must use system calls to use the interfaces provided by the kernel mode to do the job indirectly.
This difference is important because kernel mode is like an encapsulation of the important operations, it ensures most not-well-designed code could only generate software exception/error/crash, rather than computer system crash.,which protects the system in a great mean. 附件上传最多可上传6张图片

What are exceptions? Name two different types of exceptions and give an example of each type.简答题                     (10             分)             Exception is a kind of sofeware-generated intterupt caused by an error or by a specific request from auser program that an operating-system service be performed by executing a special operation called a system call.

Former : some number divided by 0 could generate ArithmeticException .
Latter : When a program needs to use the printer, it`ll generate a system call to ask the kernel to handle the printer`s driver to do the work. 附件上传最多可上传6张图片

What is the purpose of interrupts? What are the differences between a trap and an interrupt? Can traps be generaged intentionally by a user program? If so, for what purpose?

简答题 (10 分) Interrupts are used to help the kernel communicate with the user programs or all kinds of I/O devices.
Trap is the sub-concept of interrupt,the former only refers to the interrupts generated by error or system call.
Yes. The user program may need to access memory or use I/O devices, yet they can not do such things directly, so they generate traps to ask the kernel api to do such things without the posibility of causing frequent system crash.

计网与操作系统作业(1)相关推荐

计网与操作系统作业（3）
计网 1. ans:使用多项式除法,可以得到商.余,用bit string表示多项式即可 2. A channel has a bit rate of 4 kbps and a propagation ...
计算机专业面试知识点整理（计网与操作系统）
计算机网络与网络安全 1.TCP/IP 五层网络架构物理层:接收识别比特流,透明地传送比特流,数据单位是比特.规定了机械特性.电气特性.功能特性.过程特性. 数据链路层:在两个相邻结点间的链路上传送 ...
计算机基础类面试（计网，操作系统，数据库，数据结构等）
计算机网络基础 Q:五层协议的体系结构分别是什么?每一层都有哪些协议? https://blog.csdn.net/cainv89/article/details/46885197 应用层,应用层确 ...
Shopee C++ / 计网 / OS / DS / DB / 算法部分题目解析
Shopee 是东南亚发展最快的电商平台,2015年于新加坡成立并设立总部,社群媒体粉丝数量超3000万,拥有700万活跃卖家,员工超8000人遍布东南亚及中国. Shopee 在中国的总部位于广东深 ...
大二学科不挂科速冲方法推荐（数据结构+计组+操作系统+算法+数据库+计网）
文章目录前引学科速成总结 1.数据结构 2.计算机组成原理 3.操作系统 4.数据库系统概论 5.算法设计与分析结束语前引这段时间本来是紧锣密鼓的在准备面试原本以为自己已经学过的科目考试 ...
Linux大作业任务书,《Linux系统管理》期末大作业任务书(计网14级).doc
<Linux系统管理>期末大作业任务书(计网14级) 软件学院大作业任务书课程名称: Linux系统管理题目: Linux系统管理期末大作业专业: 班级: 学号: 学生姓名: ...
2020计算机网络原理（计网第七版）作业
2020计算机网络原理(计网第七版) 第一次作业 1-17收发两端之间的传输距离为1000 km,信号在媒体上的传播速率为2x108 m/s.试计算以下两种情况的发送时延和传播时延: (1) 数据长度 ...
前端面试计网、HTTP协议，操作系统（自留，持续更新）
参考: https://juejin.cn/post/6844903590058786824 https://space.bilibili.com/327247876 https://blog.csd ...
计网第2周作业（2022.9.5-2022.9.11）
一.单项选择题 1. 计算机网络可被理解为(B) A. 执行计算机数据处理的软件模块 B. 由自治的计算机互联起来的集合体 C. 多个处理器通过共享内存实现的紧耦合系统 D. 用于共同完成一项任务的分 ...
java 柱状图jar_GitHub - mafulong/NetworkExper: 计网实验，抓包，java,jigloo界面开发，柱状图，文件自定义保存...
jiWangShiYanByJava 计网实验,抓包,java,jigloo界面开发,柱状图,文件自定义保存基于Winpcap的网络流量统计分析系统的设计与实现一.实验内容描述本实验是用java ...

计网与操作系统作业(1)

计网作业1

2

3

4

5

6

7

8

9

10

操作系统作业1

计网与操作系统作业(1)相关推荐

最新文章

热门文章