关书 (close book) 请带学生证考试 1. (12%) Describe the mechanism of CSMA/CD 2. (12%) DoD model of TCP/IP a. Write down the four layers b. Relate the four layers with "chops message into packets", "assign intermediate address to each packet", "prepares message and attaches destination address", and "transfers packet into its intermediate address". c. TCP, HTTP, RIP, FTP 各属那一层(layer)? 3. (10%) acronyms: 请写出缩写的原文 如: LAN = Local Area Network GUI, ISP, DHCP, DNS, HTTP, SMTP, POP3, TCP, IP, FTP, WWW 4. Programming: 学写电脑程式最有效的方法之一是参考他人的电脑程式， 了解、更改然後学起来变成自己的电脑程式知识。 a.下列程式码(蓝色的部分)是列印 Hello! 三次。 请问如果要列印 Happy New Year! 五 次，程式要作何修改? #include <stdio.h> void main() { int count=3; // 设定 初始值 count=3 while (count>0) // 当 count>0 时 执行 括号内的指令 { ….} { printf("Hello!\n"); // 列印Hello! count=count-1; // 每列印一次 count 自动减一 } } b. 下列程式码(蓝色的部分)是计算 1+2+…+10，并将结果印出来。 请问如果要计算1+2+ …+100，并将结果印出来，程式要作何修改? #include <stdio.h> void main() { int number, sum=0; // 使用两个变数 并设加总sum=0 for (number=1;number<=10;number++) // number从一到十并执行下一行指令 sum=sum+number; // sum+number 并存入新的 sum printf("sum=%d\n",sum); // 把 sum 的大小列印出来 } 5. Algorithm: 请问如果有212笔由小到大有序(ordered)的资料， a. 如果用sequential search 平均要比对多少次才可以找到所要的那笔资料? Ans: 2^12/2=? b. 如果用 binary search最差情况要比对多少次才可以找到所要的那笔资料? Ans: log2(2^12)=? 6. Programming: 请写出一种低阶(low level)程式语言，两种高阶(high level) 程式语言，以及一种跨平台(cross platform)的程式语言。 7. OS: 请写出作业系统(Operating System)的四大功能(functions) Ans: a. CPU - Process management b. RAM - Memory management c. File system - Storage management d. Device drivers - I/O management 8. 针对a. single-user, single-tasking, b. single-user, multi-tasking, 及 c. multi-user, multi-tasking, 请各举出一种作业系统。 (e.g. DOS is a single-user and single-tasking OS). 9. 请写出两种multi-tasking or multi-programming的作业系统(Operating System) CPU在不同的processes间切换的方式 并说明之。又当硬碟读取完毕发出 讯号向CPU要求处理，属哪一种? a. Event-driven Switch from one process to another by triggering events b. Time-sharing Switch from one process to another based on the share of CPU time Which one? 10. 请比较fixed size partition, variable size partition 及page 三种记忆体管理方式的可管理性(manageability)及记忆体的运用效率。 Ans: 11. 把硬碟当做RAM(physical memory)的延伸，使得电脑上的可使用记忆体得以 扩充，这样的记忆体管理方式称之为 virtual memory。 12. a. 请写出四种网路的结构 (topologies) b. 早期的Ethernet是哪一种? c. Ethernet现在最常见的是哪一种? a. bus ……. b. 13. Comparison: the transmission media 　 Twisted pairs Coaxial Cable Optical fiber Wireless signals electrical electrical light(光) microwave cost cheap inexpensive expensive expensive noise noise little noise least noise lots of noise 14. Comparison : dialup, ADSL, cable modem 　 Dialup ADSL Cable modem medium twisted pair twisted pair coaxial cable bandwidth (bps) up to 56K 128K to 8.45M 128K to 10M always on N Y Y sharing bandwidth N N Y digital-analog conversion Y Y Y 15. Differences: repeater, bridge, hub, router 　 Repeater Bridge Switch Router Hub same segment Y N N N Y same network Y Y Y N Y shared bandwidth Y Y N Not in the same network　 Y 16. Subnet defined by gateway and netmask: e.g. 140.112.1.1 netmask=255.255.0.0 => from 140.112.0.0 to 140.112.255.255, what is the subnet if netmask = 255.255.128.0 ? 17. Comparison: TCP and UDP 　 TCP UDP Flow/Congestion Control Y N Retransmission/acknowledgement Y N reliable Y N efficient N Y establishing connection b4 sending message Y N DNS 　 V E-mail V 　 18. What is the MAC address? 19. In P2P file sharing, what is the major difference between Napster and Gnutella? Napster was ordered to shut down by the court. Why? Gnutella is itself legal(合法). Do you think that it is legal to use Gnutella to distribute(散布) copyrighted(有版权的) music and films? 20. Please explain the difference(s) between half duplex and full duplex. Is switched Ethernet half or full duplex? --

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