The document provides an overview of computer networks, including their architecture, types, and protocols such as the OSI and TCP/IP models. It discusses key components like transmission media, sender, and receiver, as well as various network topologies and the functionalities of different layers within the OSI model. Additionally, it outlines the concept of the internet, its governance, Internet Service Providers (ISPs), and applications like email.

1. Basics concept of Network and Internet
Submitted To:-
Dr. Ankit Srivastava
Submitted By:-
Mansi Gupta
M.sc. 2nd sem.
Dr. APJ Abdul Kalam Institute of Forensic Science &
Criminology

2. • Overview of network.
• Architecture of Computer Network.
• Topology of Computer network.
• Types of Computer Network.
• OSI Model.
• TCP/IP Model.
• Concept of Internet.
• Internet Service Provider.
• Electronic Mail
CONTENT:

3. • A network is a collection of computers, servers, mainframes, network devices, peripherals, or other
devices connected to one another to allow the sharing of data.
• An excellent example of a network is the internet, which connects millions of people all over the world.
• Let’s take a Simple example, the picture given below shows that the sender and receiver are connected to
one another through a transmission media to share the data.
Network

4. Five basic components
of networkTransmissi
on
Media
Sender
Message
Receiver
Protocol
Message is the
data or
information which
needs to be
transferred from
one device to
another over a
computer network
A protocol is a
set of rules
that are
agreed by
both sender
& receiver.
Transmission
media help
to transfer
data from
one device
to another
such as
wires,cables,
radiowave.
Sender is a
device that had
the data and
needs to send
the data to other
device
connected to the
network.
A receiver is the
device which is
expecting the
data from other
device on the
network.

5. 1 Performance
2.Data Sharing
3. Backup
4.Reliability
5. Scalability
6. Security
Performance of a
computer network
is measured in
terms of response
time. The response
time of sending
data from one node
to another should
be minimal.
Computer
network is use to
share the data
between systems
connected with
each other
through a
transmission
media.
It have a
central
server that
keeps the
backup of all
the data.
There should
not be any
failure in the
network or if
it occurs the
recovery from
a failure.
A computer
network should
be scalable
means it should
always allow to
add new nodes
to the already
existing
network.
A computer
network should be
secure so that the
data transmitting
over a network
should be safe
from unauthorized
access.
Feature of Computer
Network

6. Peer to peer
Computer Network
Architecture
A Computer Architecture is a design in which all the computers are connected in a computer network are
organized. Two most popular computer architecture are peer to peer and client- server architecture.
Peer to peer architecture: Client-Server architecture:
In which nodes are interconnected with
each other and share resources with each
other without the central controlling
server.
A central computer acts as hub and serves all
the requests from client computer. All the
shared data is stored in the server computer
shared with client computer when a request
is made.
Client
Server

7. Hardware Components
for the Networks
1. Cables: A wire that is used to connect more than
one computer or other devices such as printers and
scanner to each other.
2. Network Interface Card: NIC is used to format the
data, send the data and receive the data at the receiving
node.
3. Hub: Hub acts as a device that connects all the
computer in a network to each other. Any request
that comes from a client computer first received by
hub and then hub transmit this request over a
network. 4. Router: It is a device that forwards data
packets between computer networks. Router
joins multiple computer networks to each other.

8. Computer Network
Topology
Geometric representation of how the computer are connected to each other is known as topology. There are
five types of topology.
Types of Network Topology
Mesh
Topology
Star
Topology
Bus
Topology
Ring
Topology
Hybrid
Topology

9. Bus Topology
Mesh Topology Star Topology
Hybrid TopologyRing Topology

10. Computer Network
A computer network is a group of computers connected with each other through a transmission medium
such as cable, wires etc. Types of computer network
PAN
The network used to connect
different devices like connect
pc, mobile, PDA to one another.
This type of network has not
wide range.
LAN
Local area network is a group
of computers connected with
each other in a small places
such as school, hospital,
apartment etc.
In metropolitan
network various LAN
are connected with
each other through
telephone lines.
MAN WAN
Wide area network
provides long distance
transmission of data. The
size of the WAN is larger
than LAN and MAN. A
WAN can cover country,
continent.

11. CRITERIA LAN MAN WAN
Distance • Limited
• 2500m-2miles
• Limited
• 200km
• Unlimited
Speed • High
• Excess of 10mbps
• -10, 100 and 1000 are
standards.
• High
• 100mbps
• Slower
• 1-5mbps
Media • Twisted-pair wires
• Fibres optic cable
• Wireless
• Twisted-pair wires
• Fibres optic cable
• Coascial cable
• Fibres optic cable
• Wireless to include
satellite
Example • Ethernet
• Wifi
• Cable TV network • Internet

12. OSI MODEL
• OSI Model stands for Open System
Inerconnection model.
• OSI Model defines how data is transferred
from one computer to another computer.
• It describes how information from a software
application in one computer moves through a
physical medium to the software application in
another computer.
• OSI consists of seven layers, and each layer
performs a particular network function.
• OSI model was introduced by ISO in 1980.
The OSI Model was first
defined in raw in 1978 by
Hubert Zimmermann but draft
standard was published by ISO
in 1980.

13. Seven layers of OSI Model-
Presentation Layer
Session Layer
Transport Layer
Network Layer
Data Link Layer
Physical Layer
Application Layer
Sender
Receiver
Software Layers
Hardware Layer
Heart of OSI

14. • Application layer is used by computer applications such as Google chrome, outlook, firefox , Skype etc.
• Application layer defines the protocols that are used by computer applications for example
- HTTP and HTTPS protocol are used by web browser such as chrome, firefox etc.
- FTP protocol is used for file transfer between two or more computers.
- SMTP protocol is used for emails.
• There are dozens of other protocol that forms the application layer.
Application Layer:

15. Function of presentation layer:
Translation
Encryption
Compression
1. The data received from application layer is in form of characters and
numbers such as 2367, CCBH. This layer converts these characters and
number into machine understandable format.
2. SSL is used by the presentation layer for encryption and decryption.
3. Compress the data to small size so that it can be transferred faster.
Presentation Layer:

16. Authentication
Authorization
Session management
1. Before a computer can be connected to server, the computer has to
provide user name and password for the authentication.
2. Session layer checks whether the connected computer is authorized
to access of data.
3. Session also checks that the data which is received from the server
in the form of data packets belongs to which application.
Session Layer:
Functions:

17. Segementation
Flow Control
Error Control
1. Data received from Session Layer is divided into small data units called segments.
Each segment contains the sender and receiver port number and sequence
number.
2. It controls the flow of data. It checks the capability of the receiver device receiving
capability before transmitting data.
3. Transport layer also performs error control using automatic repeat request.
Transport Layer:
Functions:

18. Logical Addressing
Routing
Path
Determination
1. Network layer assigns the sender and receiver IP address to the data packets
before transmitting them so that the data packet reach the correct destination.
2. Routing is a method of transferring data packet from source to destination.
3. Network layer determines the optimal path for data transmission so that data
can be transmitted faster to the receiver. OSPF , BGP protocols are best possible
path for data delivery.
Network Layer:
Functions:

19. 1. Data link layer receives the data from network layer.
2. Logical Addressing and Physical Addressing are two types of addressing done to the packets
transfers from one computer to another computer.
3. Data unit in the data link is called frame. A frame is transferred from one computer to another and
transmission is done through a transmission media such as wire, cable etc.
Data Link Layer:

20. Digital Transmission
1 Physical Layer is to transfer data in form of signals. A data can be
either analog or digital.
2. Physical layer must need to convert the data to its digital signal.
3. It converts digital data to digital signal. A digital data is in form of
binary sequences in the form of signals that can be transferred.
Physical Layer:
Functions:

21. TCP / IP Model
• The TCP/IP Model is developed before than OSI Model.
• It was developed by Defence Project Research Agency.
• TCP/IP stands for Transmission Control Protocol/ Internet Protocol.
• TCP/IP Model has four layers different from OSI Model.
Host -to-network
Layer
Network Layer
Transport Layer
Application Layer
Layers in TCP/IP Model

22. Application
Presentation
Sessions
SMTP FTP DNS ……HTTP
Transport SCTP TCP UDP
Network IP
ICMP IGMP
ARPRARP
Host-to-network
Data Link
Physical

23. 1. Physical and Data Link Layer:
Physical and Data Link Layers in TCP/IP model does not
define any protocol , they support all the standard
protocols. They are combined know as Host –to-
network layer.
A network in TCP/IP internetwork can be LAN orWAN.
2. Network Layer:
In the network layer, the TCP/IP model
supports internetworking protocol know as IP.
The IP uses four protocols internally:
• ARP
• RARP
• ICMP
• IGMP
3. Transport Layer:
Transport layer in TCP Model can be represented by
three protocols:
• TCP
• UDP
• SCTP
These three protocols in transport layer are responsible
for delivery of messages from one process to another.
4. Application Layer:
This is the top most layer of TCP/IP model. It is
used for intercation between user and application.
There are several protocols used by the application
layer for user interaction such as:
• HTTP
• SNMP
• SMTP
• DNS
• FTP etc.

24. Internet
The internet is a global network of billion of
computers and other electronic devices.
With the internet, it’s possible to access
almost any information, communicate with
anyone else in the world, and do much
more.
When someone says a computer is online,
it’s just another way of saying it is connected
to the internet.
The internet is an increasingly important
part of everyday life for people around the
world.

25. Internet Governs by:
Internet has no president or chief operating officer and it is governed by a number of authorities.
Internet
Society
(ISOC)
Internet
Engineering
Task Force
(IETF)
Internet
Architecture
Board
(IAB)
A voluntary membership organisation
with an objective to promote global
interchange of information.
IAB authority is a group of invited
volunteers. The IAB sets standard
and provide internet addresses.
IETF discusses the technical and
operational problems in internet.
No one pays to use the internet, instead everyone pays for it's part.

26. Working of Internet:
Computer A sends message to computer B’s IP address.
Message is broken into smaller pieces called Packets.
Packets are sent along packet routing network to correct IP
Address.
Packets are subject to Transfer Control Protocol to maintain
Quality.
Packets are received and reassembled at Computer B’s IP
Address.

27. Internet Service Provider:
A company that provides a subscription service to
enable the user or organisation to access the
internet is ISP. An ISP has a network of computers
permanently linked to the internet.
If anyone wants to surf the web, use e-mail, or chat
online, then he needs an internet provider through
which computer can communicate with the rest of
the world. ISP
Web Email VOIPS

28. Types of ISPs:
Hosting ISPs:
Offer email, FTP,
web- hosting
services, virtual
machines, cloud
and physical
servers.
Transit ISPs:
Provide large
amounts of
bandwidth needed
to connect hosting
IPSs and access IPSs
together.
Access ISPs:
Employ a variety
of technologies to
facilitate
consumer
connection to
their network.
Virtual ISPs:
Purchase services
from other ISPs to
allow customers
internet access.
Free ISPs:
Provide service free
of charge and often
display ads while
users are
connected.

29. Examples of ISPs in India:

30. Main Applications of Internet:
Remote
Login
E-MAILS
NEWS
FILE TRANSFER
RESEARCH
Remote
Login

31. • It is the transmission of text-based messages
among networked computers.
• Ray Tomlinson is universally credited as the
creator of email as part of a program for
ARPANET in 1971.
• Meanwhile in 1978, a 14- year old boy, Shiva
Ayyadurai began his work on email system for
the university of Medicine and Dentistry of
New Jersey.
Electronic Mail
Ray Tomlinson

32. Email Address:
• An email address is a unique address, which identifies a location to send and receive email. It contains
username followed by an @ symbol and then domain name, i.e, username@domainname.
• Example: mansig094@gmail.com abc@yahooo.co.in
Username Domain name
Type of organisation
Country name
• Domain name it is the unique name that identifies an interest site or website. Domain name
always have two or more parts separated by dots. The part on the left is most specific and the
part on the right is the most general.
.com: Commercial institution
.edu: Educational institutions
.gov: Government sites
.mil: Military sites
.net: Gateways
.org: Private Organisations
Suffix indicates Organisation
Australia: .au
China: .cn
Germany: .de
India: .in
United States: .uk
United Kingdom: .us
Suffix indicates Geographic area

33. Structure of Email:

34. Types of Email Account:
POP
ACCOUNT
IMAP
ACCOUNT
EMAIL
BOUNCER
Types of Email Services:
Priced
Web-based
Email
Services
Priced
Web-based
Email
Services
Free web-
based email
Services

35. 1. NTA UGC NET/ SET/ JRF Paper 1 Teaching and Research Aptitude by KVS Madaan.
2. https://beginnersbook.com/2019/03/introduction-to-computer-network/
3. https://store.hp.com/us/en/tech-takes/how-does-the-internet-work
Reference