2022 SP3 WGIT127 Final exam paper.docxWGIT127 Networks and CommunicationsFinal Assessment (SP3...

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2022 SP3 WGIT127 Final exam paper.docxWGIT127 Networks and CommunicationsFinal Assessment (SP3 2022)WGIT127 Networks and CommunicationsFinal Assessment (SP3 2022)Please read all the instructions given in each question carefully.Your submission must be completely your own work. If it is suspected that you have accessed or received assistance, e.g, from an electronic source or another person, the matter can be investigated as an alleged each of the  College Academic Integrity and Student Conduct Policy, in accordance with the Procedure for Managing Alleged Student Misconduct. Please note, as part of this investigation, you may be required to undergo an oral examination to verify your understanding of the assessment content.PART A: Short Answer Questions (5 x 8 = 40 Marks)1. Explain the similarity and differences between a switch and a hub? Please justify your answer with appropriate visuals and diagrams. (8 marks)2. Draw in chart form the voltage representation of the following bit sequence XXXXXXXXXXusing different digital encoding schemes; NRZ-L, NRZI, Manchester, differentialManchester, and Bipolar AMI. (8 marks)(Note: Please clearly identify the voltage levels for each scheme)3. What are the main characteristics of a circuit-switched and packet-switched? Explain the advantages and disadvantages for each network? Justify your answer with an appropriate diagram. (8 marks)4. Explain different types of substitution-based ciphers used for data encryption with the help of diagrams. (8 marks)5. Part A and B (8 Marks)A. Code division multiplexing allows multiple users to share a common set of frequencies by assigning a unique digital code to each user. Let us consider an example of two (2) mobile users A and B who use code division multiplexing. Mobile user A has been assigned a binary code of XXXXXXXXXX, and Mobile user B has been assigned a binary code XXXXXXXXXXThe mobile user A transmits a 1, while Mobile user B transmits a 0. Show the sum ofproducts that results and your calculations. (4 marks)B. To protect data from catastrophic disk failure, disk drivers support one of the redundant aays of independent disks (RAID) techniques. What are some of the more common RAID techniques used to store this information across multiple disks? (4 marks)PART B: Long Answer Questions (5 x 12 = 60 Marks)1. A company has 245 workstations in their head office and the IT manager would like to assign a subnetwork address for each department. She wants to create 8 subnets using the XXXXXXXXXX/24 block. How will she compute the subnetwork requirement? Clearly identify the network ID, oadcast ID and host IDs for each subnet. (12 marks)2. In an internet networking environment, the TCP/IP protocol suite performs different networking functions using the Open Systems Interconnections (OSI) reference model comprising of 7 different layers. Please explain the functionality of each OSI layer and identifies how the OSI model and the TCP/IP Protocol suite are mapped with each other. (12 marks)3. Using the flooding technique on the network graph shown in the figure, how many packets will be created if a packet originates at node A and the network hop limit is set to three? The cost of each path in the network is shown in the figure below. Similarly, what if the packets originate from node B and the hop limit is set to 3? (12 Marks)4. When designing or updating a computer network, the selection of one type of media over another is an important issue to justify the time, effort and cost invested. Please explain these different media selection criteria. Provide two examples for each typeof (wireless/wired) media, using figures to justify your reason of choice. (12 marks)5. Medium access control protocols allow devices to “take turns” at transmitting data. Two major types of medium access control protocols are contention-based and round-robin protocols. Use a diagram/flowchart or otherwise explain how the caier sense multiple access with collision detection (CSMA/CD) and (CSMA/CA) work and how they differentiate from each other. (12 marks)END OF EXAMPage 1 of 7Page 1 of 7Page 1 of 7

Baljit · Accepted Answer

TCP/IP PROTOCOL SUITE PERFORMS
PART A:
1. A switch and a hub are devices which are used to connect different devices in the network. A hub works in the physical layer which  transmits signal to the port on the other hand switch works in data link layer which  send information on the network.
Similarities in the Switch and Hub are:-
a. Both are used to connect one or more computer with the other computers in the network.
b. Each  of them  used in local area network.
c. Both are available with USB,wireless,Ethernet and firewire connections. 
d. Each of them have one broadcast domain.
e. computer connected through hub or switch can communicate with each other.
          Difference in the switch or Hub are:-
a. Switch operate at data link layer of the OSI model on the other hand hub  operate at  physical layer of the OSI model.
b. Switch is active device with software on the other hand Hub is passive device without software.
c. In switch data is transferred in the form of  Frame and packets on the other hand in hub data is transferred in the form of electrical signal or bits.
d. In switch data is transferred in Full duplex mode on the other  hand in hub data transferred in half duplex mode.
e. In switch multiple devices can send data on same time on the other hand in hub only one device can send data at same time.
f. switch stores media access control(MAC) addresses in look up table on the other hand hub cannot deal with MAC addresses.
g. Switch is expensive than Hub.
Figure 1 Hub and Switch
2. Voltage representation of given bit sequence using different schemes:-
3. Circuit Switching:-It is network switching technique in which physical connection is established between source and destination device for the dedicated duration of time.Landline telephone system uses circuit switching.There are three phases of circuit switching circuit establishment, data transfer and circuit Disconnect. 
Advantages of circuit switching are:-
a. It utilizes fixed Bandwidth.
b. It is good for long and continues transmission.
c. Data is transferred with steady Data rate.
d. Once connection is established no delay in transmission.
e. Since it provides continues transmission so it give high quality service.
Disadvantages of circuit switching:_
a. Once connection is established other data cannot be transferred even channel is free so resources are not utilized well.
b. Time taken for making connection with two devices is long.
c. Each connection requires more bandwidth.
d. Link will continue until terminated by user.
Figure 2 Circuit Switching
Packet Switching:- In this data is divided into small pieces called  packet  than send across the  different networks. There is virtual  connection established between source and receiver. Each packet contains address of sender and receiver, number of pieces and sequence number used for reassembly. Message of  acknowdgment  is sent by receiver to sender if packets are received in case of missing packet receiver send message to sender to resend it.
Advantages of Packet Switching:-
a. It uses resource in efficient manners no wastage of  bandwidth.
b. Less waiting for the connection establishment.
c. Since there is no physical connection so it can even works in disaster or crises.
d. It utilize small disk space.
             Disadvantages of Packet switching:-
a. Packets of data can lost.
b. Specific protocols are required for transfer.
c. It is inefficient in heavy  use.
d. It ineeficient in real time stream of data.
Figure 3 Packet switching
4. Different type of substitution cipher techniques are:
a. Caeser cipher:-In this set of  texts are replaced by other character,symbol and numbers.Each alphabet in message is replaced by alphabet which comes after 3 place after. Example  if message text is ABC then A in the message replace by D,B by Eand C by F so encrypted text is DBE
.
Figure 4 Caeser cipher
b. Monoalphabatic cipher:- In this each alphabet in text is replaced by any of the other alphabet except itself. Example in message text ABC ,A can be replaced by any other alphabe from B to Z except A.Similar for B and C.
c. Homophonic Subsitution  cipher:In this each alphabet in text is replaced by fixed set of alphabet. Example in message text ABC , each alphabet  have fixed set of alphabet for replacement.
d. Polygram substitution cipher:-In this block of alphabet is replaced by another block of alphabet,Example ABCDE can be replaced by QGTHS.
e. Polyalphabetic substitution cipher:-Uses multiple substitution alphabets for encryption. The table contains 26 alphabets written in different lines; each alphabet is cyclically shifted to the left according to the previous alphabet, corresponding to 26 possible Caesar ciphers. The cipher uses a different alphabet from one of the lines at different points in the encryption process.
f. Playfair Cipher:-Playfair cipher technique can be used to encrypt or encode a message. It works exactly like typical encryption. The only difference is that it encode a digraph, or a pair of two alphabet, as opposed to a single alphabet. An initial 5x5 matrix key table is created. The plaintext encryption key consists of the alphabetic characters of the matrix. Keep in mind that you should not repeat letters.

2022 SP3 WGIT127 Final exam paper.docx WGIT127 Networks and Communications Final Assessment (SP3 2022) WGIT127 Networks and Communications Final Assessment (SP3 2022) Please read all the instructions...

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