Chapter 2: Data Communication and Networking
Basic elements of communication
Sender
(source) which creates the message to be transferred.
Medium
which carry message.
Receiver
(sink) which receives the message
Data:
The information or message to be carried.
Protocol:
Rules to carry the data.
Communication
System
Modes of
communication
1.
Simplex: It
is unidirectional mode of communication on which sender always sends the data
and receiver receives it. In this mode receiver never sends the data. For
example, radio, television
2.
Half
duplex: It is the bidirectional mode of communication in which sender can
send the data and receives the data as well and vice versa but only one at a
time that means sender is not allowed to receive data while it is sending data.
For eg, walkie talkie
3.
Full
duplex: It is the bidirectional mode of communication in which both sender
and receiver can send and receives data simultaneously. For eg, mobile
phones, telephone etc
Computer Network
From
the very beginning there is an emerging trend of making communication. People
use computer to share different data and information at different location.
Thus, the group of computer Interconnected with each other through any type of
transportation media that may be either wired on wireless in order to share
different hardware software and other resources is known as computer network.
The concept of connected computer sharing resources is called Networking. We
use different bounded media like twisted pair cable , coaxial cable and fibre
optics cable or unbounded media like microwave, radio wave, infrared ,
satellites to establish connection between different computers at different
location
Advantages of
computer network
·
Hardware
sharing: Using computer network expensive hardware devices can be shared
among multiple number of computers. For example, in cyber one printer can be
shared among multiple number of computers which help to save money as well
time.
·
Software
sharing: Similarly, software also can be shared among computer n a network
which helps to access application program from any remote location.
·
Centralized
control and management: Network provides the centralized control and
management that means every other computer in a network are centrally connected
with server which controls and monitor all the activities within the network.
This helps to ensure security
·
Speedy
and fast effective communication: Since all the computer in a Network are
interconnected with each other, one can sends and receives messages within the
computer in just few seconds.
·
Backup
and Recovery: Since all the computer are connected with server, it helps
to maintain backup at periodic interval. that means keeping extra copy so that
data and the formation can be recover when lost accidentally or intentionally.
·
Flexible
Access: In a network a computer can easily access files from other
computer he/she has authority or privilege to access/use.
·
Work
group computing: Network allows different user to work in group that
means; different user can work on o single task by dividing work load.
Disadvantage of
computer network
·
Virus
Transfer: Since computer Network allows data and information to be
transferred , still there remains the possibility of virus transfer and other
malicious program.
·
Less
reliable: Since computer in a network are inter connected with each other
performance of one computer may affect performance of another computer. That
means if one computer start malfunctioning in a network than it may affect
another computers in a network.
·
Security: Computer
network is a group of computer interconnected with each other. That means, one
computer in a network can access data and information from other computer.
Since there may be also possibility of unauthorized access there exist security
issue in a network.
·
Expensive: Creating
a network among different computer is itself a complex task or job. We may need
different inter networking devices and others special devices and other to
establish a network. Buying all the devices, cables and equipment may be
expensive.
·
Need
Technical Manpower: Since establishing a network is a Technical job we
need a technical manpower in order to establish and trouble shoot a network.
Hiring technical manpower may be expensive.
Type of Network
On
the basis of geographical area covered
LAN
MAN
WAN
On
the basis of network architecture
Peer-to-
peer
Client
server
On
the basis of geographical area covered
|
|
LAN |
MAN |
WAN |
|
Area
Covered |
Room,
building |
City,
village |
Across
the cities, country |
|
Transmission
media |
Guided/wired |
Wired/wireless |
Often
Wireless |
|
Transmission
speed |
Fastest |
Faster |
Fast |
|
Reliable |
Highly |
Reliable |
Less
reliable |
1)
LAN: LAN stands for Local Area Network. It is the type of Network which
covers small geographical area such as room, building, school, university etc.
Since it covers small area, are interconnected with guided or wired media such
as twisted pair cable, coaxial cable or fibre optic cable. It is one of the
fastest network in term of transmission speed among all other. Since, they are
connected with wires they have higher reliability. Some of the implementation of
LAN can be in computer lab, cyber, network between different department.
Advantages
of LAN
·
It
is cheaper to establish.
·
Data
transmission is faster than MAN and WAN.
·
It
has higher security to resources of the network
·
It
is eager to establish, manages of the network and operate
Disadvantages
of LAN
·
It
is limited only to a small area.
·
It
can connect less number of computers comparatively.
·
Cannot
be used as distributed network.
2)
MAN: MAN stands for Metropolitan Area Network. It covers an entire city, district
or village. MAN connects two or more than two LAN together. Big companies like
banks, and many organization have their branches or sub offices in a city or in
neighboring city use MAN to connect with each other. The communication media in
MAN can be guided as well as unguided. This network use bridge, repeater,
router, switch etc to establish a connection. The data transmission speed of
MAN is faster compared to LAN and slower to thot of LAN. Media like microwave,
radio wave, infrared etc are used to connect devices in a MAN.
Advantages of MAN
·
It
covers larger geographical area than LAN.
·
It
can connect large number of computer than LAN.
·
We
can use guided as well as unguided type of transmission media.
Disadvantages
of MAN
·
It
is expensIve to set up then LAN.
·
Transmission
speed slower compared to LAN.
·
It
is complex to establish, manage and provides security.
3)
WAN: It stands for Wide Area Network, which can be extended to the whole
world. It is also known as the network of networks. They are used to connect
LANs together so that users and computers in one location can communicate with
users and computer in another location. WAN is unlimited. It is the slowest
data communication among all of three as it covers entire country, continents
or even a whole world. These type of network use unguided media such as
microwave, radio wave, satellites and even fibre optics some times to
communicate in larger distance. The best example of WAN is Internet which is a
public network whereas Intranet is a private network earn by an organizations
Advantage of WAN
·
It
covers larger geographical area than LAN and MAN.
·
It
can connect large number of computer compared to LAN and MAN.
·
Using
WAN communication can be done over a large distance.
Disadvantage
of WAN
·
It
is expensive to establiSh, manage and operate.
·
It
is the slowest type of network compared to that of LAN and MAN.
·
Highly
qualified manpower are required to establish and run these type of network.
On
the basis of Network architecture.
1)
Peer-to-peer: These type of network architecture in which all the
computers in a network are connected with each other having equal access
and responsibility are known as peer -to-peer network. In this type of network
architecture there is no presence of main computer that is server which
provides services to the network. All the jobs and task are carried out
by themselves without having authority from other computer. Hence, they are
known as peers. Each computer in a network behave itself as a client as well as
server. This type of architecture can be used to small work group where
security may not be of greater issue.
Peer
to Peer Network Architecture
Advantages
·
It
is simple cheap and easier to set up.
·
Since
there is no dedicated server, user can manage their own server.
·
Failure
of a computer in a network doesn't effect the other computer in a network.
Disadvantages
·
Data
security is very poor in this type of architecture.
·
Data
recovery and backup is difficult.
·
It
is not appropriate for large scale organization.
·
Network
administration is difficult it without dedicated Server.
2)
Client server: Unlike peer to peer Network, client server architecture has
the main computer called server which control and monitors all the computers or
client in a network. The server always provides services to the client. In this
type of architecture client cannot carry out any operation without the
authority of server. Server act as a central computer in a network. Due to
presence of server this type of architecture is much more secure. The data and
application program are stored on powerful centrally located server. Each
workstation or client on the network shares the resources of the server
computer. The server computer is high capacity, high speed and large memory
capacity. In this architecture user having client computer can access server
only when he/she has right to do so. That means , unauthorized person cannot
access the server. On this network the client have to request the server for
the the data instead of carrying out by themselves.
Client
Server Network Architecture
Advantages
·
Centralized
administration is possible through this network.
·
High
security can be provided by suing appropriate server.
·
It
is appropriate for large organization.
·
Data
recovery and backup process is easier.
Disadvantages
·
If
server fails whole network is affected.
·
It
is expensive due to use of dedicated server.
·
It
is complex to establish and manage.
·
Experienced
administrator is required to operate.
Transmission
Media
·
Wired
/ guided / bounded
·
Twisted
pair cable
·
Co-axial
cable
·
Fiber optic cable
Wireless
/ unguided / unbounded
·
Microwave
·
Radiowave
·
Infrared
·
Satellites
Transmission
media / communication media
Transmission
media are means through which data travel form source to destination.
Transmission media are from often called communication media or communication
channel. As we know the basic component of communication are sender (source),
communication media and receiver (sink / destination) which means communication
media are used to transmit data. In other word, the physical channel or pathway
through which data travel from one place to another or from one computer to
another is called transmission media or communication channel.
Depending
upon the cost, requirement and reliability, communication media are classified
into:
A)
Guided / bounded / wired media
Those
type of transmission media in which data are restricted to travel inside a
physical wire are known as guided media. In the type of transmission media data
have to travel in a closed path. There are different types of guided media
1)
Twisted pair cable: As a name suggest in this type of transmission media
the pair of cable are twisted around each other. They are twisted in order to
reduce the electro magnetic interference (EMI). This type of cable have greater
transmission and fewer chance of error in transmission. It is the most common
type of transmission media used in telephone system and in most of the LAN.
Twisted pair offers some significant benefits. It is cheaper, lighter, thinner,
more flexible and easy to install than coaxial cable or fibre optics. Twisted
pair cable are found in one pair, two pair and four pair. The media connector
used for 4 pair cable is RJ45. Similarly RJ11 are used for two pair twisted
pair. There are 2 types of twisted pair cable.
i)
UTP (Unshielded Twisted Pair) It is the type of twisted pair cable in
which inner pair of conducting wire are not shielded. Since the pair of wire
are not shielded they are immune to EMI (Electro Magnetic Interference). It is
cheaper and cannot transfer data for longer distance compared to STP. It is the
most common twisted pair cable. Eg CAT5
ii)
STP (Shielded Twisted Pair) It is the rare type of twisted pair of cable
in which inner pair of conducting wire are shielded. In order to reduce EMI.
They are expensive and can be used for longer distance of transmission. Eg, lBM
type 1
Advantages
·
It
is cheaper than other cables.
·
It
is light and thin. So, it is flexible for LAN.
·
It
can travel data in short distance with higher bandwidth.
Disadvantage
·
It
is only used for short distance transmission.
·
It
can be affected by electrical and magnetic field.
·
It
is slower type of transmission media compared to other cables.
2)
Co-axial cable: It is one of the most common television broadcasting
transmission media that carries data signal of higher frequency and at higher
speed than twisted pair cable. Co-axial cable has large bandwidth and better
reliability which means it can handle large volume of data at high speed. The
other advantages includes that it can carry signal over significant speed.
Co-axial cable has inner layer of conducting wire covered with an insulator
which is surrounded by a conducting mesh and finally covered with a jacket.
Co-axial cable used BNC connector.
Advantages:
·
It
is faster and reliable than twisted pair cable.
·
It
can transfer data over medium range of distance.
Disadvantages
·
It
is not appropriate for relatively larger distance.
·
It
is expensive than twisted pair cable.
·
It
is rarely used in computer network.
3)
Fiber Optics: A fibre optics cable is made up of glass or plastic material
in order to transmit data in the form of light. This cable are different than
other cables as it plays different set of rules that means data are transferred
in the form of photons (light) instead of electricity (electron). Since there
is no electricity it is completely immune to Electromagnetic Interference
(EMI). Hence data are transferred in a very high speed with better reliability
& less error. It has enormous bandwidth and can carry signal for long
distance. It is also more source than other cable.
Advantages:
·
It
has higher bandwidth that means it can handle large volume of data.
·
This
medium can be used for long distance transmission.
·
It
is the most secured and error free transmission medium.
Disadvantages
·
It
is one of the expensive type of transmission media.
·
It
is not used for short distance transmission.
·
Highly
qualified and technical manpower are required to operate on fibre optics.
B)
Unguided media / Unbounded / wireless media
Those
types of transmission media in which data doesn't have to travel in a close
path. Data are not restricted to travel inside physical wire instead they
travel through air medium which are known as unbounded media. For eg;
microwave, radiowave, satellite communication, infrared etc
1)
Microwave: It is the type of transmission media which are used for longer
distance. This type of wave have higher frequency than radio wave hence it can
handle large amount of a data. Microwave signal cannot pass obstacles like
hills, buildings and others. So, it is necessary that microwave transmission
(sender and receiver) must be in line of sight (LOS). The transmitting station
must be in visible contact with receiving station.
2)
Satellite: They are the microwave transmission system in space. It is used
as amplifier or repeater that is used to receive information from one location
on the earth, repeats the data and send it to one or more receiving location on
the earth. The communication is carried out through uplink and downlink. To
make communication possible in even longer distance multiple satellites are
used. Satellites are set in geo-stationary orbit directly over the equator
which notates in synchronization to the earth hence it looks stationary from
any point on the earth.
3)
Radio wave: It is the type of wireless transmission medium that con
operate on single as well as multiple frequency band. In this type of
transmission medium sender and receiver station must not be in the line of
sight.
4)
Infrared: It is wireless transmission technology that use red-light
(below the visibility of human eye) to transmit information. Like fibre
optics,information infrared use light for communication. They are commonly used
for TV remote. They are used for closed area using line of sight communication.
That means it cannot penetrate the wall or any obstacle. It cannot be used in
open area or outside the building because sun ray also contain infrared in it
which may interfere the communication.
Network
Topology / LAN Topology
The
physical layout or a geographical orientation of the computer in a network is
known as a network topology. There are many different way for setting up LAN.
Therefore, topology is a physical arrangement in which computers or devices in
a network are interconnected with each other. People may choose different
topologies due to different requirement of the user. This requirements may be
high speed of data transfer, data security, cost etc.
Types
of Network Topology.
1)
Bus Topology: In this type of topology every computers or devices in a
network are directly connected to a single cable called back-bone or trunk in a
linear way. The linear cable is connected with terminator at its end so that,
data will not be able to escape. The position of the server is not fixed in
this type of topology. The signal pass through the bus in both direction and
can be received by all other nodes. All the nodes, In this type of topology has
equal access to the bus and there is no discrimination.
Bus
Topolgy
Advantages
·
It
is easy setup.
·
It
is not expensive as it requires least amount of cable.
·
It
is easy to implement and extent.
·
Terminator
doesn't allow data to escape
·
Each
computer in a network has equal access and priority to communicate on the
network.
Disadvantages:
·
Since
every computer in a network are connected to the bus, if the cable fails to
work then whole network is affected.
·
As
the number of computer increases, performance decreases.
·
It
cannot cover large geographical area.
2)
Ring topology: In this type of topology every computer or devices are
connected to a single cable or trunk in a circular way. In this topology, first
and last computer are connected with each other. Here, each computer act as a
repeater which accepts the incoming signal and regenerate it before pass it to
next one. One data may flow either in clockwise or in anti-clockwise direction.
If any break through occur the whole network is collapsed. Guided media like
twisted pair cable co-axial cable are used for data transmission.
Ring
Topology
Advantages
·
All
station (nodes) have equal access.
·
As
data travels in only one direction, speed is high.
·
Since
each computer act as a repeater it can be extended to a greater distance.
·
Increase
in number of computer will have minimal impact to overall network performance.
Disadvantages
·
Since
every computer are connected with the single cable, if that single cable fails
to work whole network is affected.
·
Adding
computer in this type of network is difficult as we need to rewrite the
program.
3)
Star Topology: In this type of network every computer and networking
devices are connected with centrally located device called hub. It is not
always necessary to form a star in this type of topology. Here, client and
server both are connected with the hub. So that adding and removing extra
computer is fairly easy. Moreover it provides excellent platform for
troubleshooting and reconfiguration. In this type of topology breakdown
in any medium won’t effect the entire network. The commonly used transmission
media in this type of topology is twisted pair cable. It is one of the most
popular and practical type of network topology.
Star
Topology
Advantages
·
Adding
and removing computers and devices is very easy.
·
If
one computer fails to works its doesn’t affect the entire network.
·
It
is one of the most reliable and practical network topology.
Disadvantage
·
It
depends upon a central device so if it fails to work it affect the whole
network.
·
It
maybe expensive as we require maximum number of cables and devices.
4)
Mesh Topology: As a name suggest computer and devices in a network are
randomly connected with each other. It is only true point to point design. This
design is one of the most impractical type as it is difficult to install and
reconfigure. It require maximum amount of cable. As the number of cable
increases, difficulty of the installation increases simultaneously.
Mesh
Topology
Advantages
·
Data
transmission is faster in this type of topology.
·
Since
devices are connected point to point , it is one of the reliable network topology.
·
Identifying
faults and isolating them is easier.
Disadvantages
·
It
is expensive as it use maximum number of cables.
·
This
type of network topology is difficult and complex in structure
5)
Tree topology (Hybrid topology): This type of topology is the combination
of two or more than two type of topology. In this topology both star and bus
topology are connected with each other.
OSI
model
(Open Systems Interconnection model)
The
OSI model is a conceptual framework used to understand and standardize
how different networking protocols interact in a telecommunication or computing
system. It divides network communication into 7 layers, from the
physical transmission of data to the application that uses the data.
The 7 OSI Layers (from bottom to top):
|
Layer |
Name |
Description |
|
7 |
Application |
User-facing layer. Provides network services to
applications (e.g., web browsers, email). |
|
6 |
Presentation |
Translates data between application and network
formats. Handles encryption, compression, etc. |
|
5 |
Session |
Manages sessions or connections between
applications (start, maintain, end). |
|
4 |
Transport |
Ensures complete data transfer with error checking
(e.g., TCP, UDP). |
|
3 |
Network |
Determines how data is sent to the receiving
device. Handles addressing and routing (e.g., IP). |
|
2 |
Data Link |
Manages node-to-node data transfer. Detects and
corrects errors in the physical layer (e.g., Ethernet, MAC). |
|
1 |
Physical |
Transmits raw bitstreams over a physical medium
(e.g., cables, switches). |
Example:
Sending an Email (Alice → Bob)
7.
Application Layer
Alice
opens her email app (e.g., Outlook or Gmail).
She
composes a message to Bob and clicks Send.
The
app uses SMTP (Simple Mail Transfer Protocol) to prepare the email for
delivery.
6.
Presentation Layer
The
email text is converted into a standard format (e.g., ASCII or UTF-8).
If
encryption (e.g., TLS) or compression is used, it's applied here.
5.
Session Layer
A
session is established between Alice’s device and the mail server.
Handles
authentication and session setup.
4.
Transport Layer
Breaks
the email into smaller packets.
Ensures
delivery using a reliable protocol like TCP (Transmission Control Protocol).
Adds
port numbers (e.g., port 25 for SMTP).
3.
Network Layer
Adds
IP addresses to the packets (Alice’s IP → Bob’s mail server IP).
Determines
the routing path for delivery across the internet.
2.
Data Link Layer
Converts
each packet into frames.
Adds
MAC (Media Access Control) addresses.
Handles
error detection for each hop across local networks.
1.
Physical Layer
Bits
(1s and 0s) are transmitted physically over cables, fiber optics, or wirelessly
via routers, switches, etc.
Data
travels through multiple networks (ISPs, routers) to Bob’s mail server.
Analog
vs Digital Signals
|
Feature |
Analog
Signal |
Digital
Signal |
|
Definition |
A continuous signal that varies smoothly over
time. |
A discrete signal that changes in steps (usually
0s and 1s). |
|
Nature |
Continuous (infinite values) |
Discrete (limited values, typically binary) |
|
Waveform |
Sine waves (smooth and continuous) |
Square waves (abrupt transitions) |
|
Examples |
Human voice, radio waves, analog clocks |
Computers, digital clocks, binary data |
|
Data Representation |
Amplitude/frequency varies continuously |
Represented in binary (0s and 1s) |
|
Noise Resistance |
Sensitive to noise and distortion |
More resistant to noise |
|
Quality over distance |
Degrades over long distances (static, hiss) |
Maintains quality (error correction possible) |
|
Transmission |
Requires amplifiers to boost signal |
Uses repeaters and error detection |
What is a MAC Address?
A MAC address (Media Access Control address) is a unique identifier
assigned to a network interface card (NIC) for
communication on a physical network segment. It operates at the Data Link Layer (Layer 2) of the OSI model.
MAC Address Basics
|
Property |
Description |
|
Full Name |
Media Access Control address |
|
Used In |
Local network communication (Ethernet, Wi-Fi) |
|
Length |
48 bits (6 bytes) |
|
Format |
Usually written in hexadecimal, e.g., |
|
Uniqueness |
Intended to be globally unique |
|
Set By |
Manufacturer (can sometimes be changed manually) |
Book's Activity Page number 82
Multiple choice
questions
i.Which is not a
communication media?
a.Wire
b.satellite
c.microwave
d. NIC
ii.A hub is connected in
a.Ring Topology
b.Bus Topology
c.Star Topology
d.Nowe of above
iii. A ….is two or more
LANs connected together, generally across large geographic area.
a.CAN
b.MAN
c.WAN
d.SAN
iv. A term relating to
sending data to a satellite is...
a.downlink
b.modulate
c.uplink
d.download
v.Which communication
media is the fastest?
a. Twisted pair
b. Co-axial cable
c.Fiber optics
d. Microwave
vi.Which is bounded
media?
a.fiber optic
b.microwave
c.infrared
d.laser
vii.Which is the service
of remote login?
a. Video Conference
b. FTP
c.Telnet
d.TCP/IP
viii. The connection
pattern of computers in the network is.......
a.protocol
b. topology
c. twisted pair
d. all of them
ix. Which layer of the
OSI model is responsible for logical addressing and routing?
a Data Link Layer
b. Network Layer
c.Transport Layer
d. Application Layer
x.Which network topology
requires the most cabling?
a. Bus
b. Ring
c.Star
d. Mesh
xi. Which protocol is
used to send and receive email over the Internet?
a HTTP
b. FTP
c.SMTP
d.SNMP
xii.Which device
connects multiple network segments and operates at the Data Link Layer of the
OSI model?
a Switch
b Router
c.Hub
d. Bridge
xiii. In IPv4, how many
bits are used for the subnet mask in a Class C address?
a.8 bits
b. 16 bits
c.24 bits
d. 32 bits
2. Short Answer
Questions
i. What is a computer network? How is it
useful?
A computer network is a system in
which multiple computers are connected together to share resources, data, and
applications.
Uses/Importance:
·
Resource sharing (printers, files,
internet)
·
Centralized data management
·
Cost-effective communication (email,
chat)
·
Remote access to information
·
Better collaboration
ii. Differences between Client/Server and
Peer-to-Peer Architecture
|
Client/Server
Architecture |
Peer-to-Peer
Architecture |
|
Central server controls data and
resources. |
No central server, all computers
are equal. |
|
More secure and scalable. |
Less secure, suitable for small
networks. |
|
Expensive to set up and
maintain. |
Cost-effective and simple to set
up. |
|
Example: Banking system. |
Example: File sharing at
home. |
iii. Define bandwidth. How is it measured?
Bandwidth is the maximum data
transfer rate of a network or internet connection.
Measurement:
Digital: Bits per second (bps), Kbps, Mbps,
Gbps
Analog: Hertz (Hz)
iv. Difference between LAN and WAN
|
LAN
(Local Area Network) |
WAN
(Wide Area Network) |
|
Covers small area (e.g., a
building). |
Covers large area (e.g.,
countries). |
|
High data transfer speed. |
Slower
than LAN. |
|
Easy to maintain. |
Complex and costly
maintenance. |
|
Example: School computer lab network. |
Example: Internet. |
v. Justify: "Internet is called network
of networks"
The Internet connects multiple
smaller networks (LANs, WANs, MANs) from different organizations, countries,
and users worldwide. These interconnected networks share information using
standard protocols like TCP/IP. Hence, it is called a "network of
networks."
vi. What is communication media? Difference
between bounded and unbounded media
Communication media is the physical
or wireless channel through which data is transmitted from one device to
another.
|
Feature |
Guided Media |
Unguided Media |
|
Definition |
Data travels through physical wires or cables |
Data travels through air (wireless) |
|
Examples |
Twisted pair cable, coaxial cable, fiber optic |
Radio waves, microwaves, infrared |
|
Medium |
Has a physical path |
No physical path |
|
Speed |
Usually faster |
Usually slower |
|
Cost |
Can be cheaper for short distances |
Can be cost-effective for wide areas |
|
Security |
More secure |
Less secure (signals can be intercepted) |
|
Installation |
Needs physical setup |
Easier to set up (no wires) |
vii. Why do computer networks reduce the cost
of operation?
·
Shared resources (printers, storage)
·
Centralized software reduces license
cost
·
Reduced data duplication
·
Enables remote work, saving office
costs
·
Minimizes communication cost via
email/chat
viii. What is bandwidth? How is it measured in
analog and digital devices?
Bandwidth is the amount of data that
can be transferred over a network in a given time.
Measurement:
|
Device Type |
Unit of Measurement |
|
Analog Devices |
Hertz (Hz) |
|
Digital Devices |
Bits per second (bps) |
ix. List the types of communication channels
·
Twisted Pair Cable
·
Co-axial Cable
·
Fiber Optic Cable
·
Microwave
·
Infrared
·
Satellite
x. Arrange the computer networks on the basis
of their size:
LAN < MAN < WAN
xi. Define LAN with its characteristics
LAN (Local Area Network) connects
computers within a small area like a room or building.
Characteristics:
·
High data transfer rate
·
Low latency
·
Private ownership
·
Easy to set up and maintain
xii. What is MAN? Mention any 3 characteristics
MAN (Metropolitan Area Network)
connects networks in a city or large campus.
Characteristics:
·
Covers larger area than LAN
·
Uses high-speed media like fiber
optics
·
Owned by governments or large
institutions
xiii. What is network topology? List its types
Topology is the physical or logical
layout of a network.
Types:
·
Bus
·
Star
·
Ring
·
Mesh
·
Tree
·
Hybrid
xiv. Star Topology Diagram +
Advantages/Disadvantages
Advantages:
·
Easy to add/remove devices
·
Easy to detect faults
Disadvantages:
·
Failure of hub affects whole network
·
More cable required
xv. Define Ring Topology + Token Ring
Advantages/Disadvantages
Ring topology connects each device
in a circular loop. Data passes in one direction using tokens.
Advantages:
·
No data collision
·
Predictable data flow
Disadvantages:
·
Failure in one device affects the
whole network
·
Difficult to troubleshoot
xvi. Define network architecture. Sketch and
describe Peer-to-Peer
Network architecture defines how
computers are organized and how resources are shared.
Peer-to-Peer:
Each computer acts as both client
and server. No central authority exists.
xvii. What is OSI reference model? List the
layers
OSI (Open System Interconnection) is
a standard model for network communication.
7 Layers (Bottom to Top):
1. Physical
2. Data Link
3. Network
4. Transport
5. Session
6. Presentation
7. Application
xviii. Which layer is responsible for
encryption and decryption?
Presentation Layer
xix. What is the function of Network Layer?
·
Responsible for logical addressing
(IP)
·
Determines routing path
·
Transfers packets from source to
destination
xx. Describe the function of Presentation
Layer
·
Data encryption and decryption
·
Data compression
·
Data translation (syntax and format
conversion)
xxi. Difference between IPv4 and IPv6
|
IPv4 |
IPv6 |
|
32-bit address |
128-bit address |
|
Supports \~4.3 billion
devices |
Supports trillions of devices |
|
Dotted decimal (e.g., 192.168.0.1) |
Hexadecimal (e.g., 2001:0db8::1) |
|
Limited security |
Improved security features |
3. Long Answer Questions
i. What is a computer
network? List advantages and disadvantages of computer network
A computer network is a
collection of two or more interconnected computers that share resources, data,
and applications through communication channels.
Advantages:
·
Resource Sharing:
Printers, files, internet access.
·
Cost Reduction:
Centralized software and hardware usage.
·
Data Sharing: Quick and
efficient file transfer.
·
Remote Access: Access
files/applications from different locations.
·
Improved Communication:
Email, instant messaging, VoIP.
Disadvantages:
·
Security Risks: Data
breaches, hacking.
·
Viruses/Malware Spread:
Can affect multiple computers quickly.
·
Initial Setup Cost:
Infrastructure cost is high.
·
Maintenance Required:
Needs technical expertise.
·
Dependency on Network:
Failure can affect all users.
ii. What are the components of a computer
network? Illustrate them.
Main Components:
|
Component |
Function |
|
Nodes |
Devices like
computers, printers, etc. |
|
Network Interface Card
(NIC) |
Hardware to connect to
the network. |
|
Transmission Media |
Cables or wireless
signals for communication. |
|
Switch/Hub |
Connects multiple
devices in a LAN. |
|
Router |
Connects different
networks (e.g., LAN to WAN). |
|
Protocols |
Set of rules for
communication (e.g., TCP/IP). |
iii. How server differs from client computers?
Explain
|
Feature |
Server |
Client |
|
Role |
Provides
services/resources |
Requests services from
server |
|
Hardware Power |
High-performance
hardware |
Standard or low-end
hardware |
|
Usage |
Runs 24/7 for
continuous access |
Used only when
needed |
|
Example |
File server, web
server |
User desktop accessing
web pages |
Servers are specialized
computers that manage network resources and respond to requests from client
computers. Clients use applications and request data from servers.
iv. Explain LAN, MAN, and WAN with figures
|
Features |
LAN |
MAN |
WAN |
|
Area Covered |
Room, building |
City, village |
Across the cities,
country |
|
Transmission media |
Wired |
Wired/wireless |
Often Wireless |
|
Transmission speed |
Fastest |
Faster |
Fast |
|
Reliable |
Highly |
Reliable |
Less reliable |
vi. What is topology?
Explain bus topology with figure
Definition:
Topology is the physical
or logical layout of network connections between devices.
Bus Topology:
All devices are connected to a single central
cable (the bus).
Data travels in both directions.
Advantages:
·
Easy to install.
·
Requires less cable.
·
Cost-effective.
Disadvantages:
·
Failure in main cable
affects the whole network.
·
Difficult to
troubleshoot.
·
Slow performance with
high traffic.
vii. Draw the diagram of client-server network
architecture and explain in detail
Server: Manages and provides resources (files,
printers, applications).
Clients: Request services/resources from the
server.
Centralized Control: Server maintains
security, data, and user management.
Scalable: Easy to add new clients.
Features:
·
Centralized security and
backup.
·
Efficient resource
management.
·
Used in organizations
and enterprises.
viii. Describe all the layers of OSI reference
model
|
Layer |
Name |
Description |
|
7 |
Application |
User-facing layer. Provides network services to
applications (e.g., web browsers, email). |
|
6 |
Presentation |
Translates data between application and network
formats. Handles encryption, compression, etc. |
|
5 |
Session |
Manages sessions or connections between
applications (start, maintain, end). |
|
4 |
Transport |
Ensures complete data transfer with error checking
(e.g., TCP, UDP). |
|
3 |
Network |
Determines how data is sent to the receiving
device. Handles addressing and routing (e.g., IP). |
|
2 |
Data Link |
Manages node-to-node data transfer. Detects and
corrects errors in the physical layer (e.g., Ethernet, MAC). |
|
1 |
Physical |
Transmits raw bitstreams over a physical medium
(e.g., cables, switches). |