Ch1 Introduction.pptx

Chapter One
Introduction to Computer Network
and Security

History and Overview of Networks
Each of the past three centuries was
dominated by a single new technology.
The 18th century was the era of the Industrial
Revolution.
The 19th century was the age of the steam
engine.

 The 20th century, the key technology was information
gathering, processing, and distribution.
Among other developments, we saw
 The installation of worldwide Telephone networks,
The invention of radio and television,
The birth and unprecedented growth of the computer
industry,
The launching of communication satellites, and, of
course, the Internet.

What is a Network?
A network consists of two or more computing
systems connected together, and they can
communicate and share resources (e.g.
information)

Applications of Computer Networks
Computer systems and peripherals are connected
to form a network. They provide numerous
advantages:
Resource and Information sharing.
Centralized administration
Communication using emails over internet.
Access to remote information.
Video conferences
Electronic commerce(e.g. Amazon,ebay).
Interactive entertainments(e.g. Netflix).

Disadvantages of computer network
Security issues
-Computer hackers can get access to our system
using different tools.
-Hackers are someone who break our system
and have unauthorized access.
Virus attack vulnerability increase
Expensive setup cost
– Cost of hardware and technician
Dependency on the main server(single point of
failure)

How many kinds of networks?
Depending on different perspectives , we can
classify networks in different ways:
Based on network size/Geo-area coverage
(LAN,MAN & WAN)
Based on management method/functionality
(peer-to-peer & client-server)
Based on physical layout/shape/topology
(bus, star, ring, mesh etc)

Network Architectures
A communication network can be categorized
into two broad models depending upon its
architecture.
1. Peer-to-peer network model
2. Client-Server network model

Peer-to-peer architecture
 In a p2p network, all computers on the
network are considered equal, with
each workstation offering access to
resources and data(e.g Bluetooth
connection).

Client-Server architecture
 The client-server model structure is a
centralized network in which the server hosts,
provides, and maintains the majority of the
client’s data and services(e.g Database server
for SMIS).

Servers
 A server commonly has multiple processors, large
hard drives, and large amounts of RAM.
 A server provides centralized management of
resources, security, and expanded access to
networked resources in a network.
 Two types
Non-dedicated – provides many different services
to its client computers such as file retrieval,
printing, and emailing.
Dedicated – provides only one type of resource to
its clients, such as printing.

Types of Servers
File Servers
Print Servers
Application Servers
Mail Servers
Communication Servers
Directory Services Servers
Database Servers
Etc.

Other network components
Shared peripherals – a device that is connected
to a computer and controlled by its
microprocessor(e. g printers)
Media – physical pieces used to transport data
from one computer to another computer or
peripheral on the network(e.g. network cables).
Data – packets

Network Devices
Typical network devices include:
Hub
Switch
Bridge
Router
Firewall
Gateway
etc.

Transmission Medium
On basis of physical medium, there are 2
types of networks:
(a) Wired Network and
(b) Wireless Network

Wired Network
“Wired” as the name suggests refers to
any physical medium connected through
wires and cables.
The wires/cables can be copper wire,
twisted pair or even fiber optic.
Wired connectivity is responsible for
providing high security with high
bandwidth provisioned for each user.

Benefits of wired network
Greater speed
 Higher resistance to noise
Highly reliable
Greater security

Wireless Network
“Wireless” as the term refers, uses air as
a medium to send electromagnetic
waves or infrared waves.
Wireless devices have antennas for
communication.
Wireless becomes more useful in areas
where wires can’t be reached. E.g. Wi-Fi,
Bluetooth, etc.

Benefits of wireless network
Greater mobility
No difficulty of network cables
Best for mobile devices
Easy installation and management

Ch1 Introduction.pptx

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