Ch 11: Internet | Exam Fusion Prep

What is the Internet? / इंटरनेट क्या है?

World-wide network of computers that allows people to share information electronically.
PDF describes it as a large collection of web pages on different topics that can be accessed with an Internet connection.
Internet-protocol technology is used to share information, operational systems, or computing services.

Source visual: Internet as a world-wide connected computer network

Internet vs Intranet vs Extranet

Internet

Public network • Global access • Worldwide scope.

Intranet / इंट्रानेट

Private network within an organization; access restricted to employees or authorized users.

Extranet / एक्स्ट्रानेट

Controlled extension of intranet access to selected external partners, suppliers, or customers.

Source visual: relationship among Internet, Extranet and Intranet

Intranet Examples from the PDF

Company HR portalUniversity intranetOffice file-sharing system

Key Differences / मुख्य अंतर

Feature	Internet	Intranet	Extranet
Type	Public Network	Private Network	Private + Limited External Access
Access	Anyone (Global)	Employees / Authorized Users	Partners, Suppliers, Customers
Scope	Worldwide	Within Organization	Organization + External Members
Security	Less secure	More secure	Secure + Controlled Access
Example	Google, Facebook	Office HR portal	Supplier portal

⚡ CORE MEMORY

Internet = Public • Intranet = Private inside organization • Extranet = Controlled outside access

Internet Service Provider (ISP)

An ISP is a company that provides Internet access to customers.
Examples in the PDF: BSNL, Airtel, Vodafone.

How to Connect to the Internet

Wi-Fi

Router-based, limited-area wireless connection using radio signals.

Mobile Internet

Internet through 3G/4G/5G SIM cards.

Hotspot

One device shares Internet with others using Wi-Fi.

ISDN

Digital telephone network for voice, video and data.

Dial-Up

Telephone line + modem; PDF gives speed as 56 kbps.

Satellite

For remote/rural areas where cable/mobile network is unavailable.

Broadband

High-speed, always-ON connection using DSL, cable, or fiber.

DSL / Cable

DSL uses telephone line; Cable Internet uses coaxial TV cable.

Examples Listed in Source

Wi-Fi: Public Wi-Fi at airports/cafes.
Mobile: Jio 4G, Airtel 5G.
Hotspot: Phone hotspot to connect laptop.
ISDN: Old office video conferencing in the 1990s.
Dial-Up: 1990s Yahoo/Rediffmail via landline.
Satellite: Starlink example in villages/mountains.
Broadband: Airtel Xstream, BSNL broadband.
DSL: BSNL DSL connections.
Cable: Hathway Cable Internet, Den Networks.

Source wording

The PDF explicitly expands Wi‑Fi as Wireless Fidelity; this page preserves the PDF framing rather than independently verifying terminology.

ARPANET

The PDF describes ARPANET as one of the world’s first operational networks.
It states that it was developed by the U.S. Department of Defence and was fully completed in 1969.

Source-bound note

This statement is reproduced from the chapter as given; no outside historical correction has been added.

Data Communication / डेटा कम्युनिकेशन

Data Communication is the process of exchanging digital data between two or more devices through a wired or wireless transmission medium using predefined rules called protocols.

PDF Example

Laptop (Sender) → Internet (Medium) → another Laptop (Receiver) using SMTP Protocol.

Source visual: sender, message, medium, receiver and protocol

Source visual: five components of data communication

Five Essential Elements

Element	Meaning from source
Message / संदेश	Information to be communicated: text, numbers, pictures, audio, video.
Sender / प्रेषक	Device that sends the data message.
Receiver / प्राप्तकर्ता	Device that receives the message.
Transmission Medium	Physical path from sender to receiver; examples include twisted-pair and optical-fiber cable.
Protocol	Set of rules governing data communication; examples include HTTP and FTP.

Source visual: digital data transmission from sender to receiver

Classification of Data Transmission Techniques

A. Direction of Flow

Simplex: one-way only
Half Duplex: two-way, one at a time
Full Duplex: simultaneous two-way

B. Transmission Timing

Synchronous: continuous stream with clock
Asynchronous: character-by-character with start/stop bits

C. Number of Bits

Serial: one bit at a time, one channel
Parallel: multiple bits simultaneously

D. Signal Type

Analog: continuous signals
Digital: binary 0s and 1s

Examples from Source

Technique	Example	Key point
Simplex	Keyboard → Computer, TV broadcasting	One-way only
Half Duplex	Walkie-Talkie	Both ways, but one at a time
Full Duplex	Mobile phone call	Both ways simultaneously
Synchronous	Video streaming, online gaming	Continuous, clock synchronized
Asynchronous	Keyboard typing, SMS	Start/stop bits
Serial	USB cable, Internet data transfer	One bit at a time
Parallel	Old printer connection	Multiple bits over parallel lines
Analog	Traditional telephone, FM radio	Continuous signal
Digital	Computer-to-computer, Internet	Binary 0/1

Transmission Mode

Unicast

One sender → One receiver
Example: email to one person.

Broadcast

One sender → All receivers
Example: Radio/TV transmission.

Multicast

One sender → Selected group
Example: Zoom meeting, online classroom.

Communication Medium / संचार माध्यम

A communication medium is the physical path or channel through which information travels from sender to receiver.

Wired / GuidedTwisted Pair • Coaxial • Optical Fiber

Wireless / UnguidedRadio • Microwave • Infrared • Satellite • Wi‑Fi • Bluetooth

Wired / Guided Medium

Twisted Pair

Two insulated copper wires twisted together; reduces EMI.
UTP: cheaper, LAN
STP: extra shielding
Source speed: up to 1 Gbps; distance: 100 m.

Coaxial Cable

Central copper conductor + insulation + metallic shield. Better noise immunity than twisted pair. Source gives hundreds of Mbps and a few km.

Optical Fiber

Data as light through glass/plastic fiber; very high bandwidth, no electromagnetic interference, long-distance and secure. Source gives up to Tbps.

Source visual: STP vs UTP cable

Source visual: coaxial cable structure

Source visual: optical fiber cable

Wireless / Unguided Medium

Radio Waves

Source frequency: 3 KHz–1 GHz; long distance, can penetrate buildings, broadcasting use.

Microwaves

Source frequency: 1–300 GHz; point-to-point, line-of-sight, requires antennas.

Infrared

Source frequency: 300 GHz–430 THz; very short range, line-of-sight, cannot penetrate walls.

Satellite

Uses geostationary satellites; source gives ~36,000 km altitude and global coverage.

Wi-Fi

Based on IEEE 802.11; medium-range wireless Internet.

Bluetooth

Short-range wireless technology; source frequency 2.4 GHz ISM band.

Source visual: radio-wave communication

Source visual: microwave line-of-sight link

Source visual: infrared

Source visual: satellite uplink/downlink

Source visual: Wi‑Fi

Source visual: Bluetooth

Communication Medium Comparison

Medium	Transmission	Speed	Distance	Cost	Example
Twisted Pair	Electrical signal	Up to 1 Gbps	100 m	Cheap	LAN, Telephone
Coaxial Cable	Electrical signal	100 Mbps+	Few km	Medium	Cable TV
Optical Fiber	Light signal	Tbps	100s of km	Expensive	Jio Fiber
Radio Wave	EM wave	Medium	Many km	Cheap	FM Radio
Microwave	EM wave	High	10–50 km	Medium	Wi‑Fi, Mobile Tower
Infrared	Light wave	Low	<10 m	Cheap	Remote Control
Satellite	EM wave	High	Global	Very Expensive	GPS, DTH
Wi‑Fi	EM wave	High	30–100 m	Medium	Router Internet
Bluetooth	EM wave	Medium	10 m	Cheap	Wireless Earphones

Network Architecture

Peer-to-Peer

Decentralized and distributed architecture where peers act as both suppliers and consumers of resources.

Client-Server

Centralized model where client nodes request resources from central servers. Source also describes nodes/workstations as connection points/devices used in data communication.

Source visual: peer-to-peer network architecture

Source visual: client-server architecture

⚠ QUICK DIFFERENCE

P2P = decentralized peers share roles • Client-Server = centralized server provides resources to clients.

Web Browser

A web browser is a software application used to retrieve and present information resources on the World Wide Web.
Browsers are also described as web clients because they get information from a server.
The PDF states that MOSAIC was the first graphical web browser and gives the year 1993.
Common browsers listed: Google Chrome, Mozilla Firefox, Safari, Internet Explorer, Opera.

Source visual: examples of web browsers

The Web — Websites, Servers & Hosting

Website

Collection of web pages served by web servers; source says sites may be written with HTML, CSS, JavaScript and other web technologies.

Web Server

Stores website files and delivers them upon request. Source examples: Apache, Nginx, Microsoft IIS.

Web Hosting

Websites are hosted on servers. Hosting types listed: Shared, VPS, Dedicated, Cloud.

Source visual: website on multiple devices

Source visual: browser–Internet–web server request/response

Source visual: web hosting flow

Web Address / URL

The PDF describes a web address as an addressing system identifying where a web resource is located and identifies URL (Uniform Resource Locator) as the standard.

Protocol

Means of access

Server

Domain name of web server

Path

Location of document

Resource

Filename of resource

WWW (World Wide Web)

WWW stands for World Wide Web.
PDF states it was developed by Tim Berners-Lee and invented in 1989.
W3C is described as an international standards organization for the World Wide Web.

Source visual: domain types

Internet vs WWW — Source Comparison

S.No.	Internet	WWW
1	Global network of networks.	World Wide Web.
2	Means of connecting computers anywhere in the world.	Collection of information accessed via Internet.
3	Infrastructure.	Service on top of that infrastructure.
4	Can be viewed as a big book-store.	Collection of books on that store.
5	At an advanced level, source analogy treats Internet as hardware.	Source analogy treats WWW as software.
6	Primarily hardware-based.	More software-oriented.
7	Originated sometime in late 1960s.	Tim Berners-Lee invented WWW in 1989.
8	Superset of WWW.	Subset of Internet.
9	First version known as ARPANET.	PDF states that in the beginning WWW was known as NSFNET.
10	Uses IP address.	Uses HTTP.

Source-bound note

The table above preserves the chapter’s wording and comparisons as supplied, including the row about NSFNET; it has not been independently corrected or verified.

Ultra-Fast Revision

Internet Family

Internet = Public
Intranet = Private
Extranet = Controlled external access

Data Communication

Message • Sender • Receiver • Medium • Protocol

Flow Direction

Simplex • Half Duplex • Full Duplex

Transmission

Synchronous/Asynchronous • Serial/Parallel • Analog/Digital

Wired Media

Twisted Pair • Coaxial • Optical Fiber

Wireless Media

Radio • Microwave • Infrared • Satellite • Wi‑Fi • Bluetooth

Architecture

Peer-to-Peer • Client-Server

Web

Browser • Website • Web Server • Hosting • URL • WWW

Exam Traps from the PDF

Full Duplex = simultaneous two-way communication; Half Duplex = two-way but one at a time.
Synchronous uses a continuous clock-synchronized stream; Asynchronous uses start/stop bits.
Serial sends bits one by one; Parallel sends multiple bits simultaneously.
Unicast = one-to-one; Broadcast = one-to-all; Multicast = one-to-selected-group.
Optical Fiber uses light signals; twisted pair/coaxial use electrical signals in the source comparison table.
Wi‑Fi is linked with IEEE 802.11 in the source.
Bluetooth uses the 2.4 GHz ISM band in the source.
WWW is a subset/service over the Internet in the source comparison.

Chapter Boundary

Chapter 11 covers PDF pages 87–103. PDF page 104 starts Chapter 12: Networking.