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...

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. There are 26...