Computer Literacy and Digital Awareness · Chapter 8

Internet, Email, Networking and E-commerce

What to remember

The Internet is a global network of networks that works on TCP/IP. Every device has an IP address, and DNS converts website names into IP addresses.
Network layout is called topology (bus, star, ring, mesh, tree). Star topology is the most common today; a failure of the central hub or switch stops the whole star network.
Digital payments such as UPI, cards and net banking support e-commerce. UPI is built by NPCI and works with a virtual payment address and a PIN.

Internet and the Web

The Internet is a worldwide network of connected networks. The World Wide Web (WWW) is a service that runs on the Internet: it is a collection of web pages linked by hyperlinks. The Web was invented by Tim Berners-Lee. The Internet and the Web are not the same thing; email and file transfer also use the Internet.

An ISP (Internet Service Provider) gives you access to the Internet. A URL is the full address of a web page, such as `https://www.example.com/page`. It has the protocol, the domain name and the path. A web server stores web pages; a web browser requests and shows them.

Common browsers are Chrome, Firefox, Edge, Safari and Opera. A search engine such as Google or Bing finds pages by keywords; it is not a browser. Cookies are small files a site stores on your device to remember you. A bookmark saves a page address. Incognito (private) mode does not save history on your device.

Protocols

A protocol is a set of rules for communication.

Protocol	Use
TCP/IP	Basic rules of the Internet; TCP breaks data into packets, IP addresses and routes them
HTTP	Transfers web pages
HTTPS	Secure HTTP using encryption (SSL/TLS)
FTP	Transfers files between computers
SMTP	Sends email
POP3	Downloads email to your device
IMAP	Reads email on the server, keeps it in sync across devices
Telnet	Remote login (not secure)
SSH	Secure remote login
UDP	Fast, connectionless delivery (no guarantee)

IP address, DNS and related terms

An IP address identifies a device on a network. IPv4 has 32 bits, written as four numbers from 0 to 255 separated by dots. IPv6 has 128 bits, written in hexadecimal, and was made because IPv4 addresses are running out. A MAC address is a fixed hardware address on the network card. Bandwidth is the amount of data a link can carry in a given time.

DNS (Domain Name System) works like a phone book. It converts a domain name such as a website name into the IP address that computers use. Without DNS, you would need to remember numbers.

Domain suffixes: .com (commercial), .org (organisation), .edu (education), .gov (government), .net (network). Indian sites often use .in, .gov.in, .nic.in and .ac.in. A website needs a domain name and web hosting.

Types of network and devices

Network	Area covered
PAN	Very small, around one person (Bluetooth)
LAN	A room, building or campus
MAN	A city
WAN	Country or world; the Internet is the largest WAN

An intranet is a private network inside an organisation using Internet technology. An extranet shares part of an intranet with chosen outside users.

Network devices:

Modem: converts digital to analog and back, to connect to the Internet over a line.
Router: connects different networks and chooses the path for packets.
Switch: connects devices inside a LAN and sends data only to the right device.
Hub: sends data to all connected devices.
Gateway: connects networks that use different protocols.
Repeater: boosts a weakening signal.
NIC: network interface card, which connects a computer to a network.

Network topologies

Topology	Layout	Point to remember
Bus	All devices on one main cable	Cheap; the main cable failing stops all
Star	All devices connected to a central hub or switch	Easy to add and fix; centre failure stops all
Ring	Each device joined to two neighbours in a circle	Data moves in one direction
Mesh	Devices connected to many others	Most reliable; costly; many cables
Tree	Star networks joined to a bus backbone	Used in large organisations

Wi-Fi is wireless networking inside a local area. Bluetooth works over short range. Optical fibre carries light signals and gives high speed; twisted pair and coaxial cables carry electric signals.

Email

Email (electronic mail) sends messages over the Internet. An address looks like `name@domain.com`; the part before @ is the user name and the part after is the domain.

Terms:

To: main receiver.
Cc (carbon copy): other receivers who can be seen by everyone.
Bcc (blind carbon copy): hidden receivers; others cannot see them.
Attachment: a file sent with the message.
Inbox, Sent, Drafts, Spam, Trash: standard folders.

Email uses SMTP to send and POP3 or IMAP to receive. Spam is unwanted bulk email. Never share your password by email.

E-commerce and digital payments

E-commerce means buying and selling goods and services over the Internet.

Type	Meaning	Example idea
B2B	Business to business	A maker sells to a wholesaler
B2C	Business to consumer	An online shop sells to you
C2C	Consumer to consumer	People resell used items
C2B	Consumer to business	A freelancer sells services to a firm
G2C	Government to citizen	Online certificate services

Digital payment modes:

Net banking: pay from a bank account through the bank website.
Debit and credit cards: debit takes money from your account at once; credit lets you pay later.
UPI (Unified Payments Interface): instant bank-to-bank transfer from a mobile app using a virtual payment address (VPA) and a PIN. It was developed by NPCI (National Payments Corporation of India), which also runs RuPay.
IMPS, NEFT, RTGS: bank transfer systems regulated by the RBI. RTGS is for large-value, real-time payments; NEFT works in batches.
Mobile wallets: money stored in an app.
BHIM: a UPI-based app launched by the Government of India.
QR code: a square code scanned to pay.

An OTP (one-time password) adds a second step of safety. Never share your UPI PIN or OTP with anyone; a PIN is needed only to send money, not to receive it.

Wireless, mobile and cloud terms

Wi-Fi gives wireless access inside a limited area through a router or access point. Bluetooth is for very short range. Mobile data uses generations: 2G brought digital voice and text, 3G brought mobile Internet, 4G brought fast broadband, and 5G gives much higher speed and low delay. Data speed is measured in bits per second (bps, Kbps, Mbps, Gbps).

Cloud computing means using servers on the Internet to store data and run programs, instead of using only your own computer. The main service models are IaaS (infrastructure), PaaS (platform) and SaaS (software). Google Drive and web email are everyday examples of SaaS. Benefits are low cost, easy sharing and access from anywhere. The Internet of Things (IoT) connects everyday devices such as sensors and meters to the Internet.

Downloading means receiving a file from the Internet to your device; uploading means sending a file from your device to the Internet. Streaming plays audio or video while it arrives. A hyperlink is a clickable link to another page. A home page is the first page of a website. A web portal gives one entry point to many services. Blogs, wikis and social networks are forms of web content. Video calls and online meetings use the Internet for live voice and picture.

Exam traps

Internet vs WWW: the Web is one service on the Internet.
Browser vs search engine: Chrome is a browser; Google is a search engine.
POP3 downloads mail; IMAP keeps it on the server; SMTP only sends.
Hub sends to all devices; switch sends to the target device only.
Router joins networks; switch joins devices inside one network.
Cc is visible to all; Bcc is hidden.
HTTP is open; HTTPS is encrypted.
IPv4 is 32 bits; IPv6 is 128 bits.

One-liners

1. Tim Berners-Lee invented the World Wide Web.
2. DNS maps domain names to IP addresses.
3. IPv4 uses four numbers from 0 to 255.
4. HTTPS protects data with SSL/TLS encryption.
5. SMTP is the protocol used to send email.
6. A router connects different networks.
7. A modem converts digital and analog signals.
8. Star topology uses one central switch or hub.
9. Mesh topology is the most reliable but costly.
10. NPCI built UPI.
11. The Internet is the largest WAN.
12. The @ symbol separates user name and domain in an email address.

Practice questions

Which service runs on the Internet and uses hyperlinked pages?
1. Modem
2. Bluetooth
3. Intranet
4. World Wide Web
Answer
D. World Wide Web
WWW is a service on the Internet.
The World Wide Web was invented by:
1. Vint Cerf only
2. E. F. Codd
3. Bill Gates
4. Tim Berners-Lee
Answer
D. Tim Berners-Lee
Berners-Lee invented the Web.
Which of these is a web browser?
1. Google Search
2. Bing
3. Gmail
4. Firefox
Answer
D. Firefox
Firefox is a browser; Google and Bing are search engines.
A search engine is used to:
1. Find web pages by keywords
2. Send email
3. Encrypt files
4. Connect to a modem
Answer
A. Find web pages by keywords
Search engines index and find pages.
The basic set of rules on which the Internet works is:
1. TCP/IP
2. HTTP only
3. FTP
4. SMTP
Answer
A. TCP/IP
TCP/IP is the base protocol suite.
Which protocol is used to transfer web pages?
1. POP3
2. SMTP
3. FTP
4. HTTP
Answer
D. HTTP
HTTP carries web pages.
Which protocol sends email?
1. IMAP
2. POP3
3. HTTP
4. SMTP
Answer
D. SMTP
SMTP sends mail.
Which protocol downloads email to a local device?
1. FTP
2. SMTP
3. POP3
4. SSH
Answer
C. POP3
POP3 downloads mail.
Which protocol is used to transfer files between computers?
1. FTP
2. SMTP
3. HTTPS
4. DNS
Answer
A. FTP
FTP = File Transfer Protocol.
The secure version of HTTP is:
1. UDP
2. SMTP
3. FTPS only
4. HTTPS
Answer
D. HTTPS
HTTPS encrypts data with SSL/TLS.
How many bits are in an IPv4 address?
1. 16
2. 64
3. 32
4. 128
Answer
C. 32
IPv4 is 32 bits.
How many bits are in an IPv6 address?
1. 32
2. 128
3. 256
4. 64
Answer
B. 128
IPv6 is 128 bits.
DNS is used to:
1. Block viruses
2. Send email
3. Store web pages
4. Convert domain names to IP addresses
Answer
D. Convert domain names to IP addresses
DNS maps names to IP numbers.
In the URL https://www.example.com, the "https" part is the:
1. Protocol
2. Server
3. Domain
4. Path
Answer
A. Protocol
The scheme names the protocol.
Which domain suffix is usually used by educational institutions?
1. org
2. net
3. edu
4. gov
Answer
C. edu
.edu is for education.
Which device connects different networks and chooses the path for data?
1. NIC
2. Hub
3. Router
4. Repeater
Answer
C. Router
Routers join networks.
Which device sends data only to the intended device inside a LAN?
1. Hub
2. Switch
3. Modem
4. Repeater
Answer
B. Switch
A switch forwards to the target port.
Which device sends incoming data to all connected devices?
1. Router
2. Switch
3. Gateway
4. Hub
Answer
D. Hub
A hub broadcasts to all.
A modem converts:
1. Digital signals to analog and back
2. Email to files
3. IP to MAC
4. Text to speech
Answer
A. Digital signals to analog and back
Modulator-demodulator.
Which network covers a single building or campus?
1. WAN
2. LAN
3. PAN
4. MAN
Answer
B. LAN
LAN = local area network.
The largest example of a WAN is the:
1. Bluetooth
2. Intranet
3. Extranet
4. Internet
Answer
D. Internet
The Internet is the biggest WAN.
In which topology are all devices connected to a central hub or switch?
1. Star
2. Mesh
3. Ring
4. Bus
Answer
A. Star
Star uses a central device.
Which topology is the most reliable but needs the most cables?
1. Star
2. Ring
3. Mesh
4. Bus
Answer
C. Mesh
Each device has many links.
In which topology do all devices share one main cable?
1. Mesh
2. Star
3. Ring
4. Bus
Answer
D. Bus
Bus uses a backbone cable.
In an email, the receivers who are hidden from others are placed in:
1. Bcc
2. Cc
3. To
4. Subject
Answer
A. Bcc
Bcc = blind carbon copy.
In an email address name@domain.com, what separates the user name from the domain?
1. Slash
2. Dot symbol
3. @ symbol
4. Hash symbol
Answer
C. @ symbol
@ separates them.
A person buying goods from an online shop is an example of:
1. C2B
2. B2C
3. G2G
4. B2B
Answer
B. B2C
Business to consumer.
A manufacturer selling to a wholesaler online is an example of:
1. C2C
2. G2C
3. B2B
4. B2C
Answer
C. B2B
Business to business.
UPI was developed by:
1. NPCI
2. UIDAI
3. SEBI
4. IRDAI
Answer
A. NPCI
NPCI built UPI.
To send money using UPI, a user needs to enter a:
1. Aadhaar number
2. Email password
3. Card expiry only
4. UPI PIN
Answer
D. UPI PIN
The PIN authorises sending money.
Which payment system is meant for large-value real-time transfers?
1. NEFT
2. RTGS
3. BHIM
4. QR code
Answer
B. RTGS
RTGS = real-time gross settlement.
Statement 1: The Internet and the World Wide Web are the same thing. Statement 2: Email also uses the Internet. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
B. 2 only
The Web is only one service on the Internet.
Statement 1: IPv6 was created because IPv4 addresses are running out. Statement 2: IPv4 has 128 bits. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
IPv4 has 32 bits.
Statement 1: HTTPS uses SSL/TLS encryption. Statement 2: HTTP is encrypted by default. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
HTTP is not encrypted.
Statement 1: A switch sends data to all devices. Statement 2: A hub sends data only to the target device. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
D. Neither 1 nor 2
Both are reversed.
Statement 1: In star topology, failure of the central switch stops the network. Statement 2: Mesh topology uses many links between devices. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
C. Both 1 and 2
Both are correct.
Statement 1: SMTP is used to receive email only. Statement 2: IMAP keeps email on the server. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
B. 2 only
SMTP sends mail.
Statement 1: Cc recipients can be seen by all. Statement 2: Bcc recipients can be seen by all. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
Bcc recipients are hidden.
Statement 1: Google is a web browser. Statement 2: Chrome is a web browser. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
B. 2 only
Google (search) is a search engine; Chrome is a browser.
Statement 1: A router connects different networks. Statement 2: A repeater boosts a weak signal. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
C. Both 1 and 2
Both correct.
Statement 1: UPI works only with a credit card. Statement 2: UPI uses a virtual payment address. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
B. 2 only
UPI links to bank accounts, not only credit cards.
Statement 1: DNS works like a phone book of the Internet. Statement 2: DNS converts a MAC address to a URL. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
DNS maps domain names to IP addresses.
Statement 1: A MAC address is a hardware address on a network card. Statement 2: An IPv4 number can go above 255 in each part. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
Each IPv4 part is 0 to 255.
Statement 1: A WAN covers a larger area than a LAN. Statement 2: PAN covers a city. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
PAN is a very small personal area; MAN covers a city.
Statement 1: An intranet is a private network of an organisation. Statement 2: Anyone in the world can freely use an intranet. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
Intranets are restricted to the organisation.

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Chapter quiz · 10 questions

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1.The file that is linked with an e-mail and sent to the receiver of the e-mail is referred to as _ _
2.The __ _____ enables you to simultaneously keep multiple Web pages open in one browser window.
3.Sending and E-mail is similar to
4.Telnet is a(n)____ __ based computer protocol.
5.The software that allows users to surf the Internet is called a/an
6.The Internet is an example of a
7.The process of a computer receiving information from a server on the Internet is known as
8.The process of trading goods over the Internet is known as
9.Programs that automatically submit your search request to several search engines simultaneously are called
10.is the process whereby media files such as a video start playing as they are downloading.

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