I'IHITIIBIFI UI'IIVERSITY

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1 I I'IHITIIBIFI UI'IIVERSITY 0F SCIEITCE FII'ID TECHI IOLOGY FACULTY OF COMPUTING AND INFORMATICS DEPARTMENT OF COMPUTER SCIENCE QUALIFICATION: BACHELOR OF COMPUTER SCIENCE, BACHELOR OF INFORMATICS, BACHELOR OF ENGINEERING QUALIFICATION CODE: 07BACS, 07BCCS, 07BAIF, 3SBEE,3SBEET LEVEL' I 7 COURSE: INTRODUCTION TO COMPUTER NETWORKING COURSE CODE: ICN511$ DATE: JUNE 2017 PAPER: THEORY DURATION: 2H30 MARKS: 80 FIRST OPPORTUNITY EXAMINATION QUESTION PAPER EXAMINER(S) MRS LOINI IIYAMBO, MRS EEPERI HONGONEKUA, MR PETER GALLERT, MR SHADRECK CHITAURO,MS ALBERTINA SHILONGO MODERATOR: MRS MERCY CHITAURO THIS QUESTION PAPER CONSISTS OF 4 PAGES (Excluding this front page) INSTRUCTIONS Answer ALL the questions on the answer scripts Write clearly and neatly 3 Number the answers clearly 1 Calculator PERMISSIBLE MATERIALS

2 (1 (1 Question 1 (10 Fill in the missing words No abbreviations are allowed 11 The default port number for TELNET protocol is 12 With, the waves are guided along a solid medium 13 Every operating system use which temporarily stores segments meant to be send through the TCP link 14 In a topology, devices are connected to one central switch 15 In a LAN, all devices connecting to the Internet are configured with the same the network which serves as an exit point for all the packets they send out of 16 A is a hardware device that acts as a central transmitter and receiver of wireless radio signals 17 The umbrella term used to define the addition of layer specific headers to packets on the sending device is called 18 Sending s to selected students in NUST is an example of delivery method 19 A web user came across a page notfound error after trying to access a certain web page This error is retrieved by an application layer protocol called 110 A is a group of one or more routers in the provider s network where customers ISPs can connect into the providers ISP Question 2 (20 You recently got a position as a Network Support Technician at Vector Technologies Part of your job description is as follows: connecting end-user devices to the company s wired/ wireless network, making sure that the network is up and running and managing the company s servers Vector Technologies have 200 employees 21 A new employee recently joined the company and you are tasked to connect his laptop to the network Name the three (3) key network addresses required to access the Internet? (3 22 Identify any three (3) types of network servers that your company might have What are the functions of these servers? (6

3 23 Sockets are crucial in the client-server architecture How do clients connecting to wwwnustna obtain the NUST server s socket information? 24 All the users connecting to the wireless/wired network share the communicating medium with other users Explain how access to the wired LAN is controlled allowing all users to equally share the medium (3 25 Network components such as laptops, servers and smartphones systems Motivate that statement are referred to as end (2 26 Incoming packets in your network can find the router buffer full What are the consequences that a full buffer have on: i) Incoming packets ii) Packets in the buffer Question 3 (20 The diagram below shows a TCP connection between two communicating devices DATA ACK DATA ACK // a)\ b)? < "/ 31 Fill in the missing information 32 What will happen if segment DATA did not arrive at the receiver? (2 33 TCP is said to be a reliable protocol What is the benefit of this attribute to the segments sent using TCP? 34 In your opinion, is it a good design practice for each of the above devices to each have their own independent sequence numbering as seen above? (2 35 User Datagram Protocol (UDP) is another transport layer protocol from TCP? How does it differ

4 , a [Destination, " gment, ' ' 36 Once the two devices above are done communicating, connection needs to be terminated Use a diagram to depict how this connection is terminated (Ignore the sequence numbers and use flags as labels only) Question 4 (20 Use the following figure to answer the questions below All the questions refer to the selected packet [A I 'Wireless Network Connection [Wireshark 203 (v eed34f0 from master-20)) 3' *dm' E_il_e Edit View 60 Capture Analyze Statistics Telephony loals internals Help earn-to :zégfteoema-qqq am "a a FIIter:,E E Expression Clear f pply Sea/e No TIme Source Destination Protocol Length Info TCP [ACK] Seq: 1 Ack=1 Win=17520 Len= HTTP 251 GET /igddesc xml HTTP/1 1 r ; ACK- '19" of a reassemblequdujnlnfl TCP 1514 [TCP segment of a reassembled PDU] S1 TCP [ACK] seq=198 Ack=1742 Win=17520 Len=0 1'! 1I nr1n11 «n1 1: «cu 17D 1'1 Trn EA rfi rn -n-_nno- a; L1nd nni'li Frame 18: 54 bytes on wdre (432 bits), 54 bytes captured (432 bits) on interface 0 Ethernet II src: Avaudio_cd:83:97 (5c:49:79:cd:83:97) Dst: IntelCor_67:11:b9 (4c:80:93:67:11:b9) Internet Protocol Version 4, Src: Dst: = version: 4 Header Length: = 20 bytes a Differentiated Services Field: 0x00 (DSCP: cso ECN: Not ECT) Totai Length: 40 Identification: 0xb374 (45940) I Flags: 0x02 (Don't Fragment) Fragment offset: 0 Time to live: 64 Protocol: TCP (6) I Header checksum: 0xa1f2 [validation disabled] source: Destination: [Source GeoIP: Unknown] GeoIP: Unknown] 1 E Transmission Control Protocol, src Port: (49000), Dst Port: (61754), seq: 1, Ack: 198, Len: O 41 Write down the physical layer information (2 42 State the data-link layer standard used 43 Name any two communication links that use the standard above? (2 44 Observing the MAC address above, what is the maximum number of MAC addresses possible? (2 45 Routers are responsible for ensuring that packets in the network arrive at their destinations Explain how routers process/forward packets to their destinations 46 Which of the routers components are responsible for performing the following tasks:

5 (3 i) Executing the routing protocols ii) Storing packets that will be send to the outgoing link iii) Connecting the routers incoming ports to its outgoing ports 47 Using the source IP address and its default subnet mask, determine the following and show all your work i) Network Number (2 ii) Broadcast address iii) To which device is the network number assigned to? (2 iv) How many bits represent the host portion of the address? (1 Question 5 (10 Consider sending a file of bits from a source host to a destination host The path from the source host to the destination host has three links of rates R1 = 500 Mbps, R2 = 200 Mbps, and R3: 200 Mbps The lengths are as follows: Source to Router 1 is 4,5Km, Router 1 to Router 2 is 600 Km and Router 2 to destination host is 3Km The propagation speed for all the three links are 25 *10"8 This file makes use of the TCP/IP protocol stack which is designed in layers 51 What is the benefit of protocol layering? (3 52 Calculate the total end to end delay for the file? Assume no queueing delay and processing delay Show all your calculations and give your delay in seconds (7 END