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400L Pqs

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Ahmad Bello
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DEPARTMENT OF MATHEMATICS AHMADU BELLO UNIVERSITY, ZARIA COSC TITLE: Professional and Social Aspects of Computing COSC CODE: COSC409 Continuous Assessment ANSWER ALL QUESTIONS Time: 40mins Registration Number: Signature Qn is a set of beliefs about right and wrong behavior. Q2) An Estimated 85 percent of all fraud is committed by Employee. TRUE or FALSE. Q3) IT workers are not liable for malpractice because they do not meet the legal definition of a professional. TRUE or FALSE Q4) List three characieristics that distinguish a gift from a bribe. and a process that one undertake voluntarily to prove competency in a set of es skills (a) licensing (b) Certification (c) Registering (d) all of the above QA provide the would-be hackers with fake information. (a) Firewall (b) intrusion prevention system (c) honey pot (d) none of the above Q7) An attack on information system that takes advantage of vulnerability is called (a) exploit (b) firewalls(c) honey pot. Q8) which of the following identifies the numbers of dialed outgoing call (a) Wiretap b) pen register(c) trap and trace (d) phishing . (Q9) which of the following is nota technique employed by identity thieves. (a) Spyware (b) hacking database (c) trap and trace (d) phishing QU0) The is the most basic legal guarantee to the right of freedom of expression (a) Bill of right (b) Fourth Amendment (c) First Amendment (d) Constitution QI1) A written statement that is false and that harms another person is called Q12) True or False Under U.S.law, a bribe is not a crime if it was paid as part of doing business im eforeign-countey- Q13) Information that describe individual employees is called , and information that describe a company and its operations is called QA) Risk is the product of an event’s multiplied by its, QU5) A device that serves as a barrier between company and outside world is called is a program a hacker secretly installs on a computer act provide the public with the means to gain access to QI6) QI7) The certain government records. QI8) Judges frequently deny government request for Title III wiretap. TRUE or FALSE Qs) is the science of encoding messages so that only the sender and intended receiver can understand them. Q20) A lawsuit in which the true identity of the defendant is temporarily unknown is called Q21) Anonymous expiession which allows people to state opinions without revealing their identity has been found unconstitutional. TRUE or FALSE Q22) The Communication Decency Act which was passed in 1996 and was aimed at protecting children from pornography was found unconstitutional. TRUE or FALSE Q23) is software that can be installed with a web browser to block access to certain website that contains offensive material. Q24) CAN-SPAM legalizes the sending of unsolicited emails. TRUE or FALSE Q25) number of people. Q26) The public key encryption algorithm that uses 128 bits encryption that represents 2'2° is the transmission of the same e-mail messages to large possible keys is called @27) Implementation of a strong firewall provides adequate security for any network. TRUE or FALSE Q28) Executive 12333 is legal authority for electronic surveillance inside the U.S, TRUE or FALSE 29) Computer crime is rapidly increasing in the United States but not in the rest of the world. TRUE or FALSE Q30) The types of data collected while surfing the web are. 2 ; i ocean and 7 DEPARTMENT OF MATHEMATICS AHMADU BELLO UNIVERSITY, ZARIA COSC 409 TEST ANSWER ALL QUESTIONS Signature Time: 40mins ‘ation Number:_ Regi QI) Habits that incline people to do what is unacceptable are called .ccepted social norms. Q2) A person who act with integrity acts accordance with generally a TRUE or FALSE. Q3) IT workers are not liable for malpractice because they do not meet the legal definition of a professional. TRUE or FALSE Q4) List three characteristics that distinguish a gift from a bribe ; and Q5) is a process that one undertake voluntarily to prove competency in a set of skills (a) licensing (b) Certification (c) Registering (4) all of the above QA provide the would-be hackers with fake information. (a) Firewall (b) intrusion prevention system (c) honeypot (4) none of the above 7) Anattack on information system that takes advantage of vulnerability is called (2) exploit (b) firewalls(c) honey pot. Q8) which of the following identifies the numbers dialed for outgoing call (a) Wiretap b) pen register (c) trap and trace (d) phishing Q9) which of the following is not a technique employed by identity thieves. (a) Spyware (b) hacking database (c) trap and trace (d) phishing Q10) The is founded in 1947 and sponsor special interest group on IT related issues (a) ACM (b) AITP (c) PMI (d) COPA QI1) Executive Order 12333 is legal authority for electronic surveillance inside U.S.TRUE or FALSE Q12) True or False Under U.S.law, a bribe is not a crime if it was paid as part of doing business in a foreign country. Q13) Information that describe individual employces is and information that describe a accompany and its operations is QI4) Risk is the product of an event’s. multiplied by its QI5) The Check Clearing Act Requires Banks to Accept paper document in lieu of Original Paper checks. TRUE or FALSE Q16)____—__ isa harmful code that can propagate without human intervention QI7) The act provide the public with the means to gain access to certain government records. QI8) Judges frequently deny government request for Title III wiretap. TRUE or FALSE is the science of encoding messages so that only the ais) sender and intended receiver ean understand them. 0) act allows wiretapping of aliens and citizens in the United States liated website and keep Q21) Click stream data monitor consumer surfing through any affi track of information. TRUE or FALSE 22) The Electronic Communication Act of 1986 Prosecutors must justify their request. TRUE or FALSE Q23) undesirable character. Q2) Ingress filtering means ensuring spoofed packet doesn’t leave a network. TRUE or is software that identifies criminal’s suspects and their FALSE Q25) is the transmission of the same e-mail messages to large number of people. Q26) An encryption system that uses a single key to both encodes and decodes messages. Q27) Implementation of a strong firewall provides adequate security for any network. TRUE or FALSE Q28) and are nonprofit organization that regulate approach to data privacy Q29) Computer crime is rapidly increasing in the United States but not in the rest of the world. TRUE or FALSE Q30) A person who tests the limitations of computer systems out of intellectual curiosity is called (a) Crackers (b) Hackers (c) Insiders (d) Industrial Spies Ahmadu Bello University, Zaria t of Computer Science tion Technology st Semester Examination 2017/2018 F Instruction: Answer any four questions Time: 2 hours Question 1 a) What is Ethics? And why is it important to foster good business ethics? (7 marks) b) Why are public concerns about the ethical use of information technology? Discuss. (6 marks) c) What is the difference between opt-in policy and opt-out policy? (2 marks) Question 2 a) Discuss the five (5) Issues that apply to intellectual property and information technology (10 marks) b) What is an affiliated website’ while surfing the web. (5 marks) .2 List and explain the types of data collected Question 3 a) What is Cryptography? (2 marks) b) With the aid of a diagram explain a public key encryption system. (5 marks) c) List and explain the four (4) most frequent attacks on network computer and their characteristics (8 marks) Question 4 n the following Nontraditional workers. (9 marks) a) Write short notes o1 (i) Contingent, (ii) H-IB (iii) Outsourced offshore b) List the five (5) steps used to combat student plagiarism? (5 marks) c) What is Internet Filter? (1 mark) Question 5 a) Discuss any four b) List the four ways to limit or stop (4 marks) c) What is a corporate ethics officer? (1 mark) (4) software testing methods? (10 marks) deposit of cookies on hard drives. Question 6 a) List and explain the four (4) use of Information Technology (IT) in Healthcare industry. (8 marks) b) List 3 differences between a gift and a bribe (6 marks) ¢c) What is an anonymous remailer service? (1 mark) Department of Computer Science Ahmadu Bello University, Zaria crnenter Hxamination 2016/2017 Session = Fitst COSCA0S: Webs Application Engineering HE Ol Finns Allowed: 2.5 Nowe Date: Ap Instructions: Answer ANY four questions, ‘Question (1) is Compulsory Write your answers in the space provided! on this quest 1 3 paper Student's Matric Nor — nature Students Sivy lator’s Signatures ajhane simple CRUD application , i evelop J been asked by yur projet supervisor to develop a simpli CAN Te 1. Youh a containing two (2) fields (Full name and Gender). The table that fe he PHP and database schema you must adhere to, Also you are expected to write the a MySQL codes for the filenames highlighted next. udent [Field name [Data type | Primary Ke: Auto Inc iE [nt [Yes Yes Fullname | Varchar (50) [No No. [Gender | Varchar (10) [No No a. student sql (SQL codes only) fomnection-php (Use connection parameters of your choice) c. listphp 4. create.html (This should contain plain HTML) x ©. ereate_exec.php ; not to trust user input In public interfaces of web applications, a developer is Se several approaches. and this has resulted in ensuring input validation of form fil form using PHP's Write the complete PHP codes to validate all user inputs on a fo the following native functions or regular expressions. Assume the form contains S fields i. Name in full. ii, Matric number (Adhere to the format of A.B.U). Password (This must contain exactly 10 alphanumeric character and must begin with the string phpmysql). iv. Mobile phone number (This ent as +2348090909090), v. Email Address, 6. Write the PHP function definition that tr ity must adhere to international format such ‘ansfers an uploaded file to a new location 405 lecturer has Successfully dew race in which he sets session ¥ shboard. He has also a. Write the ccloped a web application containing user ariables on successful login and redirects the annie ee ‘ded a user logoutaction without implementation. ocssTons arid Techs hee ere ese a wil tere all be Wate tc matte te user to the login page (losn-php). P function that will convert an associative array to a JSON object. 4. Study carefully the table below and answer the questions that follows: | Grade Remark [A Excellent iD Very Good | tc Merit Create an associative array using entries in Table 1. Entries in grade column should be captured as keys while entries in remark column should captured as values. b. Write a simple PHP function that accepts the associative array in (a) above as parameter. Inside the function body, write the codes to iterate the array and set cookies using the key value pairs. All cookies must expire in one month time SI — ronous Javascript And XMLis a group of interrelated client-side to create interactive web applicatioy ‘d web, t to load the content of HTML file (cose fas h 405.htm, x an acronym for Asynch development methods used on the a. Wrie the complete AJAX scrip! inte a div element. Assume the div b Meation three (3) Data Manipulation Staten tents (DML) in SQL you kno you know element hus its id set to “loadme’ n example for each, writ its simplest, the client/server architecture is about dividing up application processing into two or more logically distinet pieces. a. Using a diagram describe the dynam of web applications. b. Mention three (3) simple data types in PHP you know, 6 ic client / server request / response sequence Department of Computer Science Ahmadu Bello University, Zaria 2017/2018 Session - First Semester Examination COSC405: Web Application Engineering Il Date: May 22, 2018 Time Allowed: 2 Hours Instructions: 1. Answer Question 1 « 2. Write your answers in the d any other three (3). ¢ provided on this question paper Registration Number: _ Student's Signature: Invigilator's Signature: Date/Ti { Question — “Max Score Score Obtained | H 7 | 15 | Ke le | 2 15 ince {3 15 | L = \4 15 I | . LL | | 2 | 15 Cosca05-2017/2018. sressions and Control(Compulsory) —— (15mis) 3.0 and $e=5 Question I = (3mks) (3mks) b) Write the output (rom browser) of the following PHP script? "; } _ “ cc) Mention three (3) simple data types in PHP you know (3mks) ‘ANS: . | i) ii) iti) ~ Junction getGrade() that returns a grade for any given score. The function elie ore (assume integer ranging from 0 to 100 inclusive) and returns i : corresponding grade (A, B, C, D, E or F). Complete the implementation of the function te ow. Use the following ‘ation for the range of scores for each grade: -39 is F, 40-44 is 45-49 ig D, 50-59 is C, 60-69 is B, 70-100 is A 4) Below is aceepls one parame — COSC405-2017/2018 rade (gscore) { function 3} sgrade return sgrade; } Snudy the PHP seript given ext and write any possible output. (mks) fase ee ™ COSC405-2017/2018 5 7 7 Question 2— Forms and Database Interaction s 15, i clement: “onsider the following form elemen . spar" » See confections “handler .php* method ="POsT an Username: i. Is there anything wrong with the above form element? If yes what is the error? (3.5mky) [' NS: When the form is filled and submitted, which of the following variables) will be available in handler.php? S_POST, SGLOBALS, S_REQUEST, S_FILES, S_GBT (4.5mky) [ANs: ) Consider the HTML for
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“Save” /> Write a PHP seri name, (Sinks) )_Declare an array ($2eudents) with the follow mks) Fuvecs 1001 | Aliy 26 | mal Tool, [4.31 Hose Stoo | Tatu [30 th ~ [3000 [3.05 j YOECS 1003 } Sikivat 22 Accounting 200L_| 2.87 [W0oCS 1004 | Chinedu | 39 Pharmac S00L [3.56 kirat to Bukola Gris) . print all the elements in the array declared in (a) (mks) d) Study the PHP script given next and write the output (Gmks) $value) { if (function_exists ($value) ) echo 1; else echo 0; Page 5 (1Smks) pup onject Oriented Program Question +> should contain the followin, student. T 2) formal os AN : : constructor with two string trom $id and $ ay Using: PEDO jos aN) mo) pay se anal eanettio that eeTueTsS parametel s and invoke a method viaobject reference. 2mky) stance of the ela ¢) Mention two (2) advantages and two disadvantages of server sideform validation (4mks mks) d) Briefly describe the tollowi Brietly des Je Hollow rds for defini in PHP OOP(6nkyy ing Xeywords for detining the scope of properties and method ethods i. Public Protected Whe Private munications anu +- 4. 190 Minutes tion 3— Cookies and ons Question 5 — Cookies and (1Smks) Write the PIPScript to embed 1 cookie in a client’s machine, The cookie is character A vih the following: Cookie name is user, Cookie value is uOleslO01 and Coure actly ong hour [rom now okie a) expiration is e: (7.8inks) by Your COSC 05 lecture! successfully developed a web application containing user login interface in which he sets session variables on successful login and redirects the user to a dashboard. He has also provided a user logout action without implementation. Write the complete implementation of logout.php script that will terminate all sions and redireet the user to the login page (login.php). (7.Smks) sion and Web Technologies (sms) Question 6 - Type Conve sion tae with the appropriate values, The Hest done as ay a) Fill in the follow: conversion ti example:(5 ky) CONTEXT Fiat | Bootes 7 String |false “ov 0 0 ° } cosca 05” | | Bee eee : false jo | - | “7 points” , — b) What is the output of the following code: Qmks) $x = "10 minus " + "5 equals “ + 10; echo $x; [ans: ~ | ©) Match each item in the lefi to the item in the right that best describes/exemplifies it, An example has been done for you. (7mks) Browser Interaction Protocol MySQL Server Side Technology Apache Client Software JavaScript WSDL PHP Interpreter Client Side Technology HTTP Storage Engine CG I CGI Program Web Service Web Server a E COSC405-2017/2018 Page 8 Ahmadu Bello University, Zaria Department of Computer Science 2018/2019 First Semester Examination COSC407: Data Communications and Networking Date: June 7, 2019 Time Allowed: 120 Minutes Instructions: 1. Attempt ANY FIVE questions. 2. Write your answers in the spaces provided on this Question Paper. Student’s Registration Numb Date of Examination. Scores: Question | Question Attempted Scores Scores . Obtainable Obtained (Please Tick) 1 ; 15 15 15 15 15 15 60 airment. emission IMP: stlon. typos of transm parts of ths ae the three (3) as) answer al ineach ks), fuetly expel i wuestions below . (4 marks). Use the following frequency-domain graph to answer the q\ , Amplitude —— 4 2|— 11 SEE Frequency (1 mark). What is the frequency spectrum? i (1. mark). What is the bandwidth? ii (2 marks). Is this an analog or digital Signal? Why? M. Adar 858. nady Page 2of 13 pr, 2 __y wewtERSITYs ZARA g c. (5 marks). What is the maximum capacity of a medium with a bandwidth of 750KHz and @ signal-to-noise ratio of 30dB? J ahis question. 15 marke) A sme aan “Pmt De block co ing echemes. Whic esieraming. The” frees is most ¢ ing 2 not these sc riefly & costly? szplain polar why? unipolar and bipo lar cow VF RSITYS .gram for the following cases. Find the peak amplitude value ‘of modulation (ASK, FSK, PSK, or QAM).The numbers in ly. b. (8 marks). Draw the constellation dias for each case and define the type Parentheses define the values of | and Q respec i. (2 marks), Two points at (2, 0) and (3, 0) ji, (2 marks). Two points at (3, 0) and (-3, 0) iii, (2 marks). Four points at (2, 2), (-2, 2), (-2, -2), and (2, -2) iv. (2 marks). Two points at (0, 2) and (0, -2) i h gst appropriate option for each question ap, and write the MOSEAT 4 4.5 marks. an internetwork, how many interconnecting in ender toa receiver I twork? om as here in the interne! ifthere are n nodes fr devices (routers) are t aon b. nd ce m2 — ned ink-layer address nn " ast or a router needs to find the link-layer network, it sends_____—" a. an IP request packet b. an ARP request packet can ICMP request packet d, an IGMP request packet ili, An ARP request is 2 2. unicast, broadcast b. broadcast, unicast ¢. multicast, broadcast d. broadcast, multicast iv. Which of the following is not a service pro} a. Framing b. Flow control c. Error control d. Congestion control e. Routing ¥ _The hamming distance between two codewords of the same size is a. the number of differences between the corresponding bits ». the number of bits that are corrupted during transmiscion €. the number of 1s in the EXCLUSIVE. acces ‘OR of the two codewords Wi Ifa system is to detect up to s errors, another host or router in its while its reply is a . led at the data-link layer? Stem the minimum distance between the valid codes must be bos cst d s42 Wi The number of redundant bits in 2 parlyechone is always one bit b. linear block codes © cyclic codes 4. none of the aby ove ‘Which of the followin 1B codes h; ; 2 (3,2) She highest numberof redundant g rT ‘Odewords? vill, y ix, Which of i the following is an advantage of cyclic codes? a. They havea b. They can ete good performance in detecting some classes of errors eitinestessiene implemented in hardware and software specially fast when implemented in hardware d. They area good candi Seung ieee ane for many networks x — Ifa system is isto correct up to s errors, the minimum distance between the valid codes must be a ds-1 b. 2s ce. 2st gd. 2s+10 4. (15 marks) Answer all parts of this question. . es marks). In a block code, a dataword is 20 bits and th at are the values of kr, and n according to the definitions in our rereferenc many redundant bits are added to each dataword? e corresponding codeword is 25 bits. e textbook? How codeword, we add two redundant bits to each 8-bit data word. Find the b. (2.5 marks). In ac number of valid codewords and invalid codewords. NC providas MI. Fv or 10111, © (10 mar rks), Given the dataword 1010011110 and the divis the sender site using polynomials i (S mark s). Show the generation of the codeword at ii, (5 marks). Show the checking of the codeword at the receiver site using polynomials. {15 marks). ANs\ ans (9 marks). Select th: ause wasted becaus 5 A are ny organization Clas for almost any izations for most og0ni23t0r§ common idresses in 7 Most one ae too irae too sma a They define multicast addresses W! None of the above ih Most of the addresses in Class C are wasted ce a. They are too large for almost any ore b. They re too smalfor most organizations c. They define multicast addresses which a! d. None of the above iii, Multicast addresses in IPv4 start with the pattern a. 11111112 b. 1110 c 1010 d. 11111110 €. None of the above Multicast addresses in IPv6 start with the pattern a 11122111 b. 1110 © 1010 d. 11111110 e. None of the above v. The checksum is because iv. in IPV6 because it i a. Provided, not Provided by lower-layer = Protocols b. Provided, not provided by upper-layer © Eliminated, provided by lower-layer 4. Eliminated, provided by upp oe ne er-layer i. Ww many addresses i pee are there in 197.135.1.0/247 b. 232 « 28 d. 255 b. (6 marks). An IPv4 data; hexadecimal): can rae 00 00 54 00 03 58 50 20 06 00 00 7¢ 4E 03 02 BA OE OF 02 e value of header fields below to answer the questions that follow. VER = 0x4 = 4; HLEN <0x: Time to live = 0x20 = 32 Total Lengt! Checksum 5850; Source Address: Ox7C4E0302 = 124.78.3.2; Destination Address: OxB40EOFO2 = 180.14.15.; Flags and Fragmentation = 0x0000 -> Is the packet corrupted? 'gram has arrived with the following information in the header (in ii, Are there any options? ili, Is the packet fragmented? iv. Whatis the size of the data? y. How many more routers can the packet travel to? What is the identification number of the packet? nee WHLVOISILY, Lua! cession « Binet © , jestions be! ), study the a See umber in the fol the question 1 ation, noni (orp areses 07 Port numbers only © WP addresses and por fe swiped jieved using i ee ec communication I ache For process-t0 proc a. Transport layer protocols Network layer protocols c. Dataslink layer protocols , ication layer protocols cee a cain eco port numbers are those ir According t0 a. 0101023 b. 10240 49,151 ¢. 49,152 to 65,535 d. 1024 to 65,535 oo ue layer at the source performs wi performs: a. Transport, multiplexing, demultiplexing . Application, multiplexing, demultiplexing ¢. Transport, demultiplexing, multiplexing d. Application, demultiplexing, multiplexing ¥. Which of the following statements is correct? a. Inflow control, the receiving transport layer manages flow control 'b. In flow control, the sending transport layer manages flow control ‘¢._Inerror control, the receiving transport layer manages error control 4. In error control, the ‘sending transport layer manages error control @. Only (a) and (c) are correct f. Only (b) and (4) are correct &. Allare correct vi. Cie i oe {coving 's used to know that a duplicate packet is received? b. Port number IP address and port number 4. Sequence number e “ congesion mayo aber 2. lessthan the capac otee Hed a Of packets sent to the network is b. equal to the capacity of the mann § Beater than the capacity of the 4. none of the above pe Which of the followir t number Apri7, 2019 Cc. At the transport layer, connectioniess service means independency between packets d. At the transport layer, a connection-oriented service means dependency between PACKERS e. Allof the above ix. Which of the following services can be i transport layer? a. Flow control b. Error control c. Congestion control 4. None of the above x. Which of the following protocols supports pipelining? a. Stop-and-Wait b. Go-Back-N c. Selective-Repeat d. Both (a) and (c) e. f. tionless protocol at the plemented using a con’ Both (a) and (b) Both (b) and (c) AHMADU Lar Le COMPUTE Dera TMENT ata Commun on/Networks oscso © RSE TITLE pas ‘Academ| ‘Session: 20 17/2018 hours COURSE COD! Time allowed: er any four questions Instruction: Answer its types. nthe aid of a diagram briefly explain each of ach type of the topoloBy an advantage for € rwvork consisting of eleven de of ports for each device. L Define transmission mode and wit network topologies and give ly connected mesh ne s. Calculate the .d the number a, b. List the ABC Corporation has @ full 1 of cable links needed an cework and briefly explain the three ——rr—= = yer to the last layer. < efficient network. b. Define OSI model and list the respons! yy ofeach layer from the first 18 a ‘The highest frequency is 60 Hz, What is the lowest c. A periodic frequency? Draw * total number Define Computer N contains all frequencies of the same amplitude. the spectrum if the signal percent chance of arriving frames, each of which has an 80 the data link protocol, how many times must the message slayer packet is split into 10 a, An upper! ed. If no error control is done by undamag be sent on average to get the entire thing through? b. i, What is bit stuffing? ‘Abit string, O11 11011111011 11110, needs to be transmitted at the data link layer. What is the string actually transmitted after bit stuffing? iii, Why do data link protocols almost always put the CRC ina trailer rather than in a header? Use the binary division in a CRC generator technique to divide 100100 by 1101 and use the binary division ina CRC checker to check the result of the ‘computation for accuracy. 4 ‘a. Convert 192.168.99.1 to IPv6 b. Convert 2002:C0A8:6301::1/64 to IPv4 « uuter sends a packet at the network layer to another computer somewhere in the pens to the i, Suppose a comp: Internet. The logical destinatior packet? How can the source computer be informed of I n address of the packet is corrupted. What hap| the situation? 6 itching networks each contain n nodes, The first network has a packets Three P : _ ii «i the second is a (bidirectional) ring, and the th : ha contral sw itch, the second is a (bidirectional) ring, and the third is fully intercon, will node to every other node, What are the best-, ave syith a wire from every 7 sransission paths i hops \ | (7-4) Hamming code is received as 1010111, Determine the correct code with even parity, Using the same (7, 4) ham i ii ming code, construct message for (1000) using even parity What is the polynomial representation of: i, 101110? ji, 101110? iii, 1011102 i, What is the result of shifting (ii) three bits to the left? ji, What is the result of shifting (iii) four bits to the right ie reliable connection-oriented service. One of them offers a reliable Two networks each provid yese identical? If so, why is byte stream and the other offers a reliable message stream. Are th the distinction made? If not, give an example of how they differ. How many frequencies does a full-duplex QAM-64 modem use? What is the essential difference between message switching and packet switching? How is HTTP related to WWW? What is the difference between an active document and a dynamic document? i ii Define the following: i. Distortion i, Thermal noise ‘Throughput Propagation speed v. Line coding i. A host with IPv4 address 114.45.7.9 receives an IGMP query. When it checks its group table, . it finds no entries. What action should the host take? Should it send any messages? ii, A router receives an IPv4 packet with source IP address 130.45.3.3 and destination IP address 201.23.4.6. The router cannot find the destination IP address in its routing table. Which ICMPv4 message should be sent? AHMADUBELLOUNIVERSITY, ZARIA DEPARTMENT OF COMPUTER SCIENCE COURSE CODE: COSC407 COURSE TITLE: Data Communication/Networks First Semester Examination Questions Academic Session: 2016/2017 ‘Time allowed: 2hours Instruction: Answer any four questions i a i, A client-server system uses a satellite network, with the satellite at a height of 40,000 km. What is the best-case delay in response to a request? Which signal has a wider bandwidth, a sine wave with a frequency of 100 Hz or a sine wave with a frequency of 200 Hz? iii, The attenuation of a signal is -10 dB. What is the final signal power if it was originally 5 W? b. A group of 2"- 1 routers are interconnected in a centralized binary tree, with a router at each tree node. Router i communicates with router j by sending a message to the root of the tree. The root then sends the message back down to j. Derive an approximate expression for the mean number of hops per message for large n, assuming that all router pairs are equally likely c. Describe three internal factors affecting communication. d. List six network supported technologies that impact on how people learn, work and play, a. A system has an n-layer protocol hierarchy. Applications generate messages of length M bytes. At each of the layers, an h-byte header is added. What fraction of the network bandwidth is filled with headers? Performance is inversely related to delay. When you use the Internet, which of the following applications are more sensitive to delay? i, Sending an e-mail ii, Copying a file iii, Surfing the Internet &. For each ofthe following four networks, discuss the consequences iffa connection fails. i. Five devices arranged in a mesh topology Five devices arranged in a star topology (not counting the hub) ili, Five devices arranged in a bus topology iv. Five devices arranged in a ring topology wi ifr hat isthe difference between internet and Internet? For n devices in network, what and number of port per device required for a mesh, ring is the number of cable bus and star topology? ise ratio is 20 4B, Ifa binary signal is sent over a 3-KHz channel whose signalto-n0 What is the maximum achievable data rate? Compare and contrast telephone network and the Internet jods, calculate the corresponding frequencies Given the following per i 5s ii, 12ps iii, 220ns Identify and illustrate the fi on system. ive components of data communicat Sueeinetly explain the thre criteria necessary for an effective and efficient network. ibuted processing. List the advantages of di i. What is bit stuffing? ii, A bit string, 0111101111101111110, needs to be transmitted at the data link layer. What did the string actually transmitted after bit stuffing? Convert IPv4 address: 192.168.99.1 to IPv6 and vice versa. Which signal has a wider bandwidth, 2 sine wave with a frequency’ of 100 Hz or a sine wave with a frequency of 200 Hz? ‘A device is sending out data at the rate of 1000 bps. How long does it take to send out 10 bits? a single character (8 bits)? 0 characters ii, How long does it take to send out ji, How long does it take to send a file of 100,00 Illustrate the functions of the TCP/IP model. (0 frames, each of which has an 80 percent a. An upper-layer packet is split into 1 1 is done by the data link chance of arriving undamaged. If no error control how many times must the message be sent on average to get the entire protocol, thing through? ‘ATV channel has a bandwidth of 6 MHz. If we send a digital signal using one channel, what are the data rates if we use one harmonic, three harmonics, and five harmonics? c. Use the bir iv mae he binary division in a CRC generator technique to divide 100100 by 1101 n in a CRC checker to check the result of the and use the binary divis computation for accuracy d. Why do data link protocols almost always put the CRC in a trailer rather than in a header? Assume that a voice channel occupies a bandwidth of 4 kHz. We need to multiplex 10 voice channels with guard bands of 500 Hz using FDM. Calculate the required bandwidth a. A large number of consecutive IP address are available starting at 198.16.0.0. Suppose that four organizations, A, B, C, and D, request 4000, 2000, 4000, and 8000 addresses, respectively, and in that order. For each of these, give the first IP address assigned, the last IP address assigned, and the mask in the w.x.y.2/s notation. b. What do you understand by physical addressing? In a Stop-and-Wait ARQ system, the bandwidth of the line is 1 Mbps, and 1 bit takes 20 ms to make a round trip. What is the bandwidth-delay product? Ifthe system data frames are 1000 bits in length, what is the imagine thata signal travels through a utilization percentage of the link? Now, P2= 1/2 Pl. transmission medium and its power is reduced to half. This means that Calculate the attenuation (loss of power). c. Answer the following questions: i. What is the polynomial representation of 101110? ii, What is the result of shifting 101110 three bits to the left? iii, Repeat part b using polynomials iv. What is the result of shifting 101110 four bits to the right? v. Repeat part d using polynomials Ahmadu Bello University, Zaria Department of Com 2016/2017 First COSC 401: Algorithms and Complexit\ Date: March, 2017 Instructions: puter Science Semester Examination 1. Attempt ANY FOUR questions. 2. Write all your answers in the spaces Invigilator's Signature: Registration Number: Date: Scores: M.A. Kufena y Analysis Time Allowed: 120 Minutes provided on this Question Paper. Scores Obtained Question | Maximum Scores 1 20 2 ~ 20 3 20 4 20 5 20 6 20 80 Page 1 aw urrence of a key value in an array 1. a. Write an Algorithm that returns the index of the last occ ‘and if not found it returns -1. For example: [6 Marks] ieKeyis: |. ‘Array ~_[ Returns 3 31813111312 | 4 2 | 2[5[7 [10] 1] 2 5 iL 32 [41] 7] 11] 13 | 12 3 b. Using bubble sort algorithm sort the list below: {8 Marks} 978]2/4/3/115|6 ¢. Using Master's Theorem solve T(n)= 4T(n/3) +1 and vajza [6 Marks} 2. 2. Astudent went to a business center to buy some softcopy reading materials for 400 Level B.Sc Computer Science programme with related course materials saved in the same folder. Each of the folders has a size and cost att [item 1D~ | item Folder Size | Prize (N) 1 | coscao1 36B 200 2 ‘coscao3 5GB 300 3 COsC405 10GB 500 4 | coscaos 5GB 100 tached to it as shown in the table below: Generate all possible item combinations and choose the most expensive that can be convey in a 16GB flash drive of the student? [10 Marks} b. what will be the basic operation in solving this problem? Ans: ¢. Using Insertion Sort algorithm, sort the list below: aifii} © (2][7[el4 [el2i Jo [309 I [4 Marks] [6 Marks] ‘a. Considering the Algorithm below ‘Algorithm doJob(A{0,..,n=1)) ke 0 for j + 1 toni ag(atiler") AU) = ALK) return True; i, Ifthe Array Al] below is passed to the dogob algorithm, what will be its new content? - [10 Marks} Initial Array content (AL | Resulting Array content (AL | ) (Bislels [4 2 [ez la TT it) ji. Does it have best and worst cases? If yes, give sample inputs for both cases. [4 Marks] b. How many times the basic operation will be visited using the array below as an input? {6 Marks} 3[9]6[8 [4[3|9 2] No, of times: 4. a, Study the algorithm below and answer the questions that follow: Algorithm produceResult (A(O..n-1]) for i — 0 to n-1 do Count(i] ~ 0 for i - 0 to n-2 do for j — itl to n-1 do Tf Ali) < Ali) Count [j] - Count{j] +1 else Count [i] + Count{i} + 1 for i — 0 to n-1 do S{Count[i]] ~ Afi] return S ¢, thm produceResult in da). etsy ory rithm Pr the the algo" ta the complesity class of" iv ‘ work should be show” ll, What is the basic operation.of the Algorithm? [2 Marks] 6. Using Mergesort, how many comparisons would be made to merge and sort these arrays? [5 Marks} [3477 [a2 [a3 Tia Number of Comparisons: When is an algorithm said to have a Worst, Average and Best case scenario? [6 Marks} orithm below to answer the qui 4. use the al i ‘ . Lions that follow algorithm compute (n) //Input: A positive integer n //Output: if return 1 else return n *n *n + compute(n-1) i, What does the Algorithm accomplish? {6 Marks}, ii, What is the Algorithm’s basic operation? {3 Marks} elation for the number of times the algorithm’s basic b. Setup and solve a recurrence r {11 Marks} operation is executed {Use backward substitution}. ven: 6. a.ina Brute-Force String Matching the details below were 6! 101111620 Text: 10010101. 401001160: Pattern: 001011 (7 Marks} 2 i. How many character comparison(s) would be made? Ans: {7 Marks} ii, How many pattern alignment{s) would be made? Ans: b. Derive the complexity class of the segment code below. [Show detail of your work] [6 Marks] for i~ 0 ton-mdo jo while j

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