B.D. PUBLIC SCHOOL
BUDDHA COLONY,PATNA -1
Networking
TEACHER: PANKAJ KUMAR GUPTA
PGT, COMPUTER SCIENCE
B.D.PUBLIC SCHOOL, PATNA
1
COMPUTER NETWORK:
A computer network is a group of computers that use a set of common
communication protocols over digital interconnections for the purpose of sharing resources located on or provided by
the network nodes.
NEED OF NETWORKING:
DISADVANTAGES OF NETWORK
 Resource Sharing
 Reliability
 Cost Factor
 Communication medium
ADVANTAGES OF NETWORK:
 Share resources
 Share Storage
 Share software
 Improve communication
Purchasing the network cabling and file servers
can be expensive. Managing a large network is
complicated,
requires
training
and
a network manager usually needs to be employed.
If the file server breaks down the files on the file
server become inaccessible.
Evolution of Networking:
ARPANET :-ARPANET was a large wide-area network created by the United States Defense Advanced Research Project
Agency (ARPA). Established in 1969, ARPANET served as a test bed for new networking technologies, linking many universities
and research centers.
INTERNET:-The internet in simple terms is a network of the interlinked computer networking worldwide, which
is accessible to the general public. These interconnected computers work by transmitting data through a special
type of packet switching which is known as the IP or the internet protocol.
INTRANET :- An intranet is a private network that is contained within an enterprise. It may consist of many
interlinked local area networks and also use leased lines in the wide area network. Typically, an intranet includes
connections through one or more gateway computers to the outside Internet.
EXTRANET :- An extranet is a private network that uses Internet technology and the public telecommunication
system to securely share part of a business's information. Two intranet can share information to each other.
INTERSPACE:-Interspace is a client/server software program that allows multiple users to communicate online
with real-time audio, video and text chat in dynamic 3D environments. Interspace provides the most advanced
form of communication available on the Internet today.
NETWORK TOPOLOGIES AND TYPES
Physical layout of computers to form the network is called topology.
bi-directional.
1. Star Topology: In a star network, every host is connected to a central hub. Data Transfer is bi-directional.
Advantages:
 Easy of service
 One device per connection
 Centralized control
 Simple access protocol
Disadvantages:
 Long cable length
 Difficult to expand
 Central node dependency
2. Bus Topology: A bus topology is a type of network setup where each computer and network
device is connected to a single cable or backbone. Below, is a visual example of a simple computer
setup on a network using the bus topology.
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Advantages:
Short cable length and simple wiring layout.
Easy to expand.
Disadvantages:

Entire network shuts down if there is a break in the main cable.

Difficult to identify the problem if the entire network shuts down.

Not meant to be used as a stand-alone solution.
3. Ring Topology: A ring topology is a network configuration where device connections create a
circular data path. Each networked device is connected to two others, like points on a circle. Together, devices in
a ring topology are referred to as a ring network. It is also called Token topology. In this topology data transfer is
unidirectional.
Advantages:
 Short cable length.
 No wiring closet space required.
 Suitable for optical fibers.
Disadvantages:
 Node failure cause network failure.
 Difficult to identify the problem.
• Network reconfiguration is difficult
TREE TOPOLOGY :- A tree topology connects multiple star networks to other star networks.
A mesh topology is a network setup where each computer and network device is interconnected with one
another.
TRANSMISSION MEDIA
In data communication terminology, a transmission medium is a physical path between the transmitter and the
receiver i.e it is the channel through which data is sent from one place to another. Transmission Media is broadly
classified into the following types:
Guided Media:
It is also referred to as Wired or Bounded transmission media. Signals being transmitted are directed and confined in
a narrow pathway by using physical links.
1. Twisted Pair Cable –
It consists of 2 separately insulated conductor wires wound about each other. Generally, several such pairs are
bundled together in a protective sheath. They are the most widely used Transmission Media. Twisted Pair is of two
types:
a) Unshielded Twisted Pair (UTP):
b) Shielded Twisted Pair (STP)
Advantages:
 Least expensive
 Easy to install
 It is physically flexible
 It has low weight
 Easily connected
o
Disadvantages:
•
Less bandwidth
•
Slow transmission of data ( 723 kbps to 1 mbps)
2. Coaxial Cable –
It has an outer plastic covering containing 2 parallel conductors each having a separate
insulated protection cover. Coaxial cable transmits information in two modes: Baseband
mode(dedicated cable bandwidth) and Broadband mode(cable bandwidth is split into separate
ranges). Cable TVs and analog television networks widely use Coaxial cables.
Advantages:
 High Bandwidth
 Better noise Immunity
 Easy to install and expand
 Inexpensive
Disadvantages:
 Single cable failure can disrupt the entire network
3. Optical Fibre Cable –
It uses the concept of reflection of light through a core made up of glass or plastic. The core is surrounded
by a less dense glass or plastic covering called the cladding. It is used for transmission of large volumes
of data.
Advantages:

Increased capacity and bandwidth

Most fastest data transmission medium)

Less signal attenuation

Immunity to electromagnetic interference

Resistance to corrosive materials
Disadvantages:

Difficult to install and maintain
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High cost

Fragile
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unidirectional, ie, will need another fibre, if we need bidirectional communication
Unguided Transmission
•An unguided transmission transmits the electromagnetic waves without using any physical medium. Therefore it is also known
as wireless transmission.
•In unguided media, air is the media through which the electromagnetic energy can flow easily.
Unguided transmission is broadly classified into three categories:
Radio waves
•Radio waves are the electromagnetic waves that are transmitted in all the directions of free space.
•Radio waves are omnidirectional, i.e., the signals are propagated in all the directions.
•The range in frequencies of radio waves is from 3Khz to 1 Ghz.
•In the case of radio waves, the sending and receiving antenna are not aligned, i.e., the wave sent by the sending antenna can be
received by any receiving antenna.
•An example of the radio wave is FM radio.
Applications Of Radio waves:
•A Radio wave is useful for multicasting when there is one sender and many receivers.
•An FM radio, television, cordless phones are examples of a radio wave.
Advantages Of Radio transmission:
•Radio transmission is mainly used for wide area networks and mobile cellular phones.
•Radio waves cover a large area, and they can penetrate the walls.
•Radio transmission provides a higher transmission rate.
Microwaves
Advantages Of Microwave:
•Microwave transmission is cheaper than using cables.
•Operates at high frequency of 3 to 10 GHz.
•Transmission of large quantity of data and with higher bandwidth.
•Transmission of data in line of light.
• When communication through microwave, sender and receiver need to be aligned and required repeater for long distance
communication.
•Communication over oceans can be achieved by using microwave transmission.
•Data Transmission is unidirectional.
•Used in cellular phone, satellite network, Wireless LAN.
Disadvantages of Microwave transmission:
•Eavesdropping: An eavesdropping creates insecure communication. Any malicious user can catch the signal in the air by using its
own antenna.
•Out of phase signal: A signal can be moved out of phase by using microwave transmission.
•Susceptible to weather condition: A microwave transmission is susceptible to weather condition. This means that any
environmental change such as rain, wind can distort the signal.
•Bandwidth limited: Allocation of bandwidth is limited in the case of microwave transmission.
Satellite Microwave
•A satellite is a physical object that revolves around the earth at a known height.
•Satellite communication is more reliable nowadays as it offers more flexibility than cable and fibre optic systems.
•We can communicate with any point on the globe by using satellite communication.
How Does Satellite work?
The satellite accepts the signal that is transmitted from the earth station, and it amplifies the signal. The amplified signal is
retransmitted to another earth station.
Advantages Of Satellite Microwave Communication:
•The coverage area of a satellite microwave is more than the terrestrial microwave.
•The transmission cost of the satellite is independent of the distance from the centre of the coverage area.
•Satellite communication is used in mobile and wireless communication applications.
•It is easy to install.
•It is used in a wide variety of applications such as weather forecasting, radio/TV signal broadcasting, mobile communication, etc.
Disadvantages Of Satellite Microwave Communication:
•Satellite designing and development requires more time and higher cost.
•The Satellite needs to be monitored and controlled on regular periods so that it remains in orbit.
•The life of the satellite is about 12-15 years. Due to this reason, another launch of the satellite has to be planned before it becomes
non-functional.
Infrared
•An infrared transmission is a wireless technology used for communication over short ranges.
•The frequency of the infrared in the range from 300 GHz to 400 THz.
•It is used for short-range communication such as data transfer between two cell phones, TV remote operation, data transfer
between a computer and cell phone resides in the same closed area.
Characteristics Of Infrared:
•It supports high bandwidth, and hence the data rate will be very high.
•Infrared waves cannot penetrate the walls. Therefore, the infrared communication in one room cannot be interrupted by the
nearby rooms.
•An infrared communication provides better security with minimum interference.
•Infrared communication is unreliable outside the building because the sun rays will interfere with the infrared waves.
Other wireless media
Laser communications systems are wireless connections through the atmosphere. They work similarly to fiber optic links,
except the beam is transmitted through free space.
Bluetooth is a short-range wireless communication technology that allows devices such as mobile phones, computers, and
peripherals to transmit data or voice wirelessly over a short distance
TYEPS OF NETWORK
A LAN (local area network) is a group of computers and network devices connected together, usually
within the same building.
A MAN (metropolitan area network) Connection of LAN with in a city.
A WAN (wide area network), in comparison to a MAN, is not restricted to a geographical location,
although it might be confined within the bounds of a state or country. A WAN connects several LANs,
and may be limited to an enterprise (a corporation or an organization) or accessible to the public. The
technology is high speed and relatively expensive. The Internet is an example of a worldwide public
WAN.
A PAN (Personal area network) connection of devices through bluetooth.
Network Devices
MODEM(modulator-demodulator) :-
A modem is a device or program that enables a computer to
transmit data over the internet. for example, telephone or cable lines. Computer information is stored digitally, whereas
information transmitted over telephone lines is transmitted in the form of analog waves. A modem converts between
these two forms.
RJ45 CONNECTOR:-
RJ45 is a type of connector commonly used for Ethernet networking. It looks
similar to a telephone jack, but is slightly wider. Since Ethernet cables have an RJ45 connector on each end,
Ethernet cables are sometimes also called RJ45 cables. The "RJ" in RJ45 stands for "registered jack," since it is a
standardized networking interface. The "45" simply refers to the number of the interface standard. Each RJ45
connector has eight pins, which means an RJ45 cable contains eight separate wires.
ETHERNET CARD (NIC):-
An Ethernet card is one kind of network adapter.
These adapters
support the Ethernet standard for high-speed network connections via cables. Ethernet cards are
sometimes known as network interface cards (NICs).
HUB:- A hub is used in a wired network to connect Ethernet cables from a number of
devices together. The hub allows each device to talk to the others.
SWITCH:-
A network switch is a small hardware device that joins multiple computers
together within one local area network (LAN).
Hub


Switch
Repeats the incoming traffic to all connection.
Offers single lane connection, hence either send
or receive at a time

Share bandwidth among its connection.

Inexpensive choice.
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Repeater :-
Send traffic only to appropriate connection.
Establishes two – lane communication,
facilitating send and receives at the same time.
Does not share bandwidth, each connection gets
full bandwidth.
Expansive than hubs.
A repeater is a Network device that amplifies and restores signals for long distance
transmission.
Bridge :-
A bridge is network device that establishes wan intelligent connection between two local
networks with the same standard but with different types of cables.
Router :- A Router is a network device that is used to separate different segment in network to
improve performance and reliability. A router works like a bridge but can handle different protocols.It
finds the convenient route for data packets over the internet.
GATEWAY:- A node on a network that serves as an entrance to another network. In enterprises, the gateway is
the computer that routes the traffic from a workstation to the outside network that is serving the Web pages. In
homes, the gateway is the ISP that connects the user to the internet.
Introduction to Internet
URL:- URL stands for Uniform Resource Locator. A URL is a formatted text string used by Web browsers,
email clients and other software to identify a network resource on the Internet. Network resources are files that
can be plain Web pages, other text documents, graphics, or programs.
DOMAIN NAME EXTENSION:-These are used to identify the type of website.Ex:Gov
- Government agencies
org
- Organizational agencies
Com
- Commercial business
ca
- Canada website
Edu
- Educational site
mil
- Military site
Net
- Network Organization
th
- Thailand site
in
- india
IP ADDRESS:- Internet Protocol Address (or IP Address) is an unique address that computing devices use to identify itself and
communicate with other devices in the Internet Protocol network. Any device connected to the IP network must have an unique IP
address within its network.
DNS (Domain Name System/Server):- It translate domain into IP Address.
WEBSITE:- A website is a collection of web pages (documents that are accessed through the Internet).
WEBPAGE:-It is the basic unit of WWW.Information of the webpage can include data in the form of text, graphics,
audio and video.
BLOG:- A blog refers to an online diary where entries are posted.
HOME PAGE :-First page of the website is called Home page.
WEB BROWSER:- Browser, short for web browser, is a software application used to enable computers users to
locate and access web pages. some familiar common web browsers:

Mozilla FireFox

Netscape Navigator
Microsoft Internet Explorer
NETSURFING:- Exploring the web is known as Net Surfing.

Chatting:- Online textual talk is called chatting.
VIDEO CONFERENCING :- Video conferencing is a communications technology that integrates video and audio to
connect users anywhere in the world as if they were in the same room.
Wi-Fi (Wireless Fedility):- "Wi-Fi" is a type of wireless networking protocol that allows devices to communicate
without cords or cables. It's the most popular means of communicating data wirelessly, within a fixed location.
Downloading :-It refers to transfer of files from FTP server on to our computer.
Uploading :-It refers to transfer of files from our computer on to FTP server.
Email
: messages distributed by electronic means from one computer user to one or more recipients via a
network.
Spams : Email spam, also referred to as junk email, is unsolicited messages sent in bulk by email (spamming).
VOIP : Voice over Internet Protocol (VoIP), is a technology that allows you to make voice calls using a broadband Internet
connection instead of a regular (or analog) phone line.
Some important abbreviation: MMS :-Multi Media Services
SMS :- Short Message Service
 VPN :- Virtual Private Network
SIM :- Subscriber Identity Module
 MODEM:- Modulator and Demodulator
WLL:-Wireless in Local Loop
 FTP:-File Transfer Protocol
TCP/IP:-Transmission Control Protocol/Internet Protocols
 XML:-Extensible Markup Language
CDMA:-Code Division Multiple Access
 TDMA:- Time Division Multiple Access
GSM:-Global System for Mobile
 NFS:-Network File System
FSF:- Free Software Foundation.
Protocols:-A protocol means the rules that are applicable for a network or we can say that the common set of
rules used for communication in a network. Different types of ptotocols are : HTTP:-Hyper Text Transfer Protocol
FTP:-File Transfer Protocol
 SLIP:-Serial Line Internet Protocol
PPP:-Point to Point Protocol
 NTP:-Network Time Protocol
SMTP:-Simple Mail Transfer Protocol
 POP:-Post Office Protocol
IMAP:-Internet Mail Access Protocol
OPEN SOURCE SOFTWARE :-
Open source software is a computer software whose source code is
available openly in internet and programmers can modify it to add new features and capabilities without any cost.
PROPRIETARY SOFTWARE: Proprietary software or closed source software is a computer software where
the source codes are not publicly not available only the company which has created can modify it.
FREEWARE:-
Freeware is software, most often proprietary, that is distributed at no monetary cost to the end
user.
SHAREWARE:-
Shareware is software that is distributed free on a trial basis with the understanding that the
user may need or want to pay for it later.
Societal Impact
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Digital Footprint
Communication Etiquettes
Ethical Issues (Intellectual property right, Digital property rights), Plagiasm
Open Source Philosophy ( Free software, Open source software)
FLOSS
GNU
FSF
OSI
W3C
Proprietary software(Close source software)
Shareware
Copyleft software
Copyright and other linceses
Cyber Crime
Hacking
Spoofing
Phishing
Cyber bullying
Cyber Trolling
Cyber Stalking
Scam
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Illegal download
Child Pornography
Cyber law and IT Act
E-waste
management(Disposal,Benefit)
Health concern with Technology uses