Computer networks allow computers to be connected and share information. They are used for communication, sharing devices and files, and accessing information remotely. The goals of computer networks are to share resources between computers, ensure performance and reliability, increase scalability, and provide security. Computer networks use hardware like network interface cards, servers, routers, and cables to transmit data and software like network operating systems and protocols to facilitate communication. Early computer networks included ARPANET, which served as the basis for the modern Internet.

1. NOTE-01
Topic: Basic concept of computer
networks goal.
Course Code: CSE-317
Course Title: Computer Networks Theory
Submitted To
Pranab Bandhu Nath
Senior Lecturer, Department of CSE
City University
Submitted By
Md.Mejbah Uddin Rafi
BSc in CSE (Day)
Batch: 49th
(B)
ID: 1834902584

2. What is computer network?
Computer networks are the basis of communication in IT. They are used
in a huge variety of ways and can include many different types of
network. A computer network is a set of computers that are connected
together so that they can share information.
What Do Networks Do?
Computer networks are used to carry out a large number of tasks
through the sharing of information.
Some of the things that networks are used for include:
Communicating using email, video, instant messaging and other
methods.
Sharing devices such as printers, scanners and photocopiers
Sharing files.
Sharing software and operating programs on remote systems.
Allowing network users to easily access and maintain information.
Goals of Computer Networks:
1. Sharing Resource from one computer to another computer over a
network.
2. Performance by measuring the speed of data transmission with
number of users ,connectivity and the software used.
3. Reliability makes easy to use an alternative source for data
communication in case of hardware failure or connectivity issues.

3. 4.Scalability increases the system performance by adding more
processors.
5.Security is the main characteristics of computer network where you
can take necessary steps for protecting your data from unauthorized
access.
Application Of Computer Network
• Bussiness Applications
• Communication Medium
• e-commerce
• Home Applications
• Electrinic commerce
• Mobile users
There are 2 types of network applications:
1. Pure network applications
2. Standalone network application
Pure Network Applications
1. Email Programs
2. File Transfer Protocol (FTP)
3. Terminal Emulation (TELNET)
4. Groupware
Groupware
#.Video Conferencing

4. #.Chatting
Stand Alone Applications
These are applications that run on stand-alone computers (computers not
connected to any other). In order to extend their activity, they are rebuilt
to run on network environments, e.g., word processors, spreadsheets,
and database management systems. They function even when the
computer is offline.
Arpanet
• Advanced Research Projects Agency Network (ARPANET)
ARPANET was the network that became the basis for the Internet.
Based on a concept first published in 1967, ARPANET was developed
under the direction of the U.S. Advanced Research Projects Agency
(ARPA). In 1969, the idea became a modest reality with the
interconnection of four university computers. The initial purpose was to
communicate with and share computer resources among mainly
scientific users at the connected institutions. ARPANET took advantage
of the new idea of sending information in small units called packets that
could be routed on different paths and reconstructed at their destination.
The development of the TCP/IP protocols in the 1970s made it possible
to expand the size of the network, which now had become a network of
networks, in an orderly way.
Network Hardware & Software
There are three component of computer network:
1. Hardware Equipment
2. Software
3. Cables and Connectors

5. Hardware
NIC
A network interface card (NIC) is a hardware component without which
a computer cannot be connected over a network. It is a circuit board
installed in a computer that provides a dedicated network connection to
the computer.
Server
A server is a computer or system that provides resources, data, services,
or programs to other computers, known as clients, over a network. In
theory, whenever computers share resources with client machines they
are considered servers
Peer
In networking, a peer is a node that provides the same functionality as
another.
Transmission
A transmission is a machine in a power transmission system, which
provides controlled application of power.
Medium
Medium is a open platform where readers find dynamic thinking,and
where expert and undiscovered voices can share there writing on any
type.
Router
The router is a physical or virtual internetworking device that is
designed to receive, analyze, and forward data packets between
computer networks.
Bridge

6. A bridge is a structure built to span a physical obstacle, such as a body
of water, valley, or road, without closing the way underneath. It is
constructed for the purpose of providing passage over the obstacle,
usually something that is otherwise difficult or impossible to cross
HUB
A hub is a common connection point, also known as a network hub,
which is used for connection of devices in a network. It works as a
central connection for all the devices that are connected through a hub.
Switch
A network switch is networking hardware that connects devices on a
computer network by using packet switching to receive and forward data
to the destination device.
Gateway
A gateway is a piece of networking hardware or software used in
telecommunications for telecommunications networks that allows data to
flow from one discrete network to another.
Repeater
a repeater is an electronic device that receives a signal and retransmits
it. Repeaters are used to extend transmissions so that the signal can
cover longer distances or be received on the other side of an obstruction.
Software
Network operating System

7. A network operating system (NOS) is a computer operating system (OS)
that is designed primarily to support workstations, personal computers
and, in some instances, older terminals that are connected on a local area
network (LAN). The software behind a NOS allows multiple devices
within a network to communicate and share resources with each other.
Protocols Switches
TCP/IP
TCP/IP helps you to determine how a specific computer should be
connected to the internet and how you can transmit data between them.
It helps you to create a virtual network when multiple computer
networks are connected together
OSI
The OSI Model is a logical and conceptual model that defines network
communication used by systems open to interconnection and
communication with other systems. The Open System Interconnection
(OSI Model) also defines a logical network and effectively describes
computer packet transfer by using various layers of protocols
Cables And Connectors
Twisted Pair cable
A twisted pair cable comprises of two separate insulated copper wires,
which are twisted together and run in parallel. The copper wires are
typically 1mm in diameter. One of the wires is used to transmit data and
the other is the ground reference.
Coaxial cable

8. Coaxial cable, or coax (pronounced /ˈkoʊ.æks/) is a type of electrical
cable consisting of an inner conductor surrounded by a concentric
conducting shield, with the two separated by a dielectric.
Fiber-optic Cable
A fiber-optic cable, also known as an optical-fiber cable, is an assembly
similar to an electrical cable, but containing one or more optical fibers
that are used to carry light.
Reference:
1. https://www.fieldengineer.com/blogs/what-is-a-computer-network
2. https://www.geeksforgeeks.org/goals-of-networks
3. https://turbofuture.com/computers/Network-
Application#:~:text=Computer%20network%20applications%20are%20
network,to%20another%20within%20the%20network.
4. https://www.tutorialspoint.com/what-is-network-interface-card-nic
5. https://www.paessler.com/it-explained/server
6. https://www.pcmag.com/encyclopedia/term/peer

9. 7. https://en.wikipedia.org/wiki/Transmission_(mechanics)
8. https://searchnetworking.techtarget.com/definition/network-operating-
system
9. https://www.guru99.com/difference-tcp-ip-vs-osi-model.html
10. https://www.tutorialspoint.com/Twisted-Pair-Cable
11. https://en.wikipedia.org/wiki/Coaxial_cable
12. https://en.wikipedia.org/wiki/Fiber-optic_cable
13. https://searchnetworking.techtarget.com/definition/ARPANET