ARPANET was the first network established by the U.S. Defense Department in the 1960s during the Cold War to enable communication between computers and allow for alternative routes in case of damage. The main goals of computer networks are resource sharing between computers, high reliability through alternative data sources, security, providing a powerful communication medium, and scalability through adding more processors. Computer networks enable applications like e-commerce, remote access, electronic commerce, and home automation applications. The key components of a computer network include hardware like network interface controllers, servers, clients, transmission media, routers, bridges, hubs, switches, gateways, and repeaters. Software and cables/connectors are also essential network components.

1. Notes On
‘Introduction To Computer Networks’
Submitted To
Pranab Bandhu Nath
Senior Lecturer
Dept. Of CSE
Submitted By
Md. Mizanur Rahman
1834902576
49th

2. ARPANET:
ARPANET stands for Advanced Research Projects Agency Network.
It was founded by U.S defense department in late 1960s.
ARPANET was the basis level network for internet. It was created to make
communication method easier for the military.
During the time of cold war, computer communication became a much needed
thing. From this necessity, the idea of ARPANET first came. Later, in 1960s the
idea gets implemented fully.
Goals Of Computer Network:
 Resource Sharing: The main goal of a computer network is to sharing
resources from one computer to another computer over a network .It also
makes all programs, data available to anyone connected to the network
without any physical location sharing.
 High Reliability: It’s goal is to provide an alternative sources of supplying
data in case of any hardware failure or connectivity issues.
 Security: In computer network one can take the necessary steps to protect
his/her data from unauthorized access
 Powerful Medium: It provides a powerful communication medium.
Anything updated or added on a network can be seen by the other users
immediately.
 Scalability: It increases the performance of its system by adding more
processors.
Applications Of Computer Network:
 eCommerce: It’s a way to do business over the internet. Seller and buyer
interacts with each other through internet and do business. Online ticket,
Online products like, gadget, book etc are some of the business products of
eCommerce system.
 Remote Access: Through remote access a person who has authorization can
access a computer or a network over the internet.

3.  Electronic Commerce: It’s the way of selling or buying thing through a
network over internet and make the payment in online system.
 Home Application: It’s also known as home automation app. It is used to
remotely control non computing devices in the home and it’s a done by
network system.
Network Hardware & Software:
There are three kinds of components of a computer network.
They are:
i)Hardware components
ii)Software
iii) Cables and Connectors
Hardware:
 NIC: Network interface controller is a hardware components which works
as a node . It connects a computer to a computer network.
 Server: A server is a system that serves data, resources, services to a
computer .
 Client: Those who access data ,resources etc from server are called client.
 Peers: A peer is one kind of node that provides same functionality as
another .
 Transmission: It means transferring data between two devices.
 Medium: It’s a physical channel through which data is sent and received.
 Router: It’s a device that connects many networks using mac address and ip
address.
 Bridge: A bridge is a network device that connects multiple LANs and form
a huge Lan .
 Hub: A hub helps multiple computer to connect with each other and share
data over a network.
 Switches: It’s a device that connects many networks using mac address over
a network.
 Gateway: It’s a network point that allows data to flow from one distance to
another over a network.
 Repeater: It works as an extender to extend the coverage area of an
network.

4. Software:
i)Operating System
ii)Protocol switches
Cables & Connectors:
i)Twisted Pair Cable
ii)Coaxial cable
iii) Fiber Optic cable