Network Examples and Protocols: One Mark Questions, Book Back Answers and Notes

About Network Examples and Protocols

Medium ~90 min study

The previous unit defined what a network is. This unit puts names to real networks and explains the rules that let them talk. You meet three network types that sound alike but differ in who is allowed in: the Internet is open to everyone, an Intranet is open only to a company's own staff, and an Extranet lets selected outsiders such as suppliers and customers into part of that private network.

The second half moves from examples to standards. Mobile networks are traced through their generations, starting with analog 1G systems like Nordic Mobile Telephone (NMT) and ending with 4G and 5G. Wi-Fi, Li-Fi and RFID show three different ways of sending data without a wire. Finally, the OSI and TCP/IP models split the job of communication into layers, so each layer handles one part of the work.

Book-back questions from this unit are mostly one-mark items. Expect to be asked which network type suits a given situation, which IEEE number belongs to Wi-Fi, how many layers each model has, and what a protocol like FTP or SMTP is used for. Learn the layer names in order and the full form of every abbreviation, because many options differ by only one word.

What you'll learn

• State the difference between the Internet, an Intranet and an Extranet, and pick the right one for a given organisation.
• List the mobile network generations from 1G to 5G with one feature of each.
• Explain how Wi-Fi, Li-Fi and RFID send data without wires, and name the IEEE standard for Wi-Fi.
• Name the seven OSI layers in order and say what each layer does.
• Compare the seven-layer OSI model with the four-layer TCP/IP model.
• Match the protocols HTTP, HTTPS, FTP and SMTP to their uses.

Before you start

• The basic network terms from Unit 10, such as node, server, client and network topology.
• What an IP address looks like and the idea that data moves in packets.
• Everyday familiarity with web browsers, websites and URLs.

Network Examples and Protocols explained

Network Types, Wireless Technologies and Reference Models

Internet, Intranet and Extranet

These three are separated by who can access them. The Internet is a worldwide network of networks. Anyone with a connection can use it, and it runs over wired, fibre and wireless links using open standards. An Intranet is a private network inside one organisation. Only employees can log in, and it is used to share circulars, policies, staff directories, files and internal databases. An Extranet is a private network that gives controlled access to people outside the organisation, such as vendors, suppliers, partners and customers. It usually travels over public telecommunication lines, so firewalls and passwords protect it.

Mobile Networks and Their Generations

A mobile network divides an area into cells. Each cell has a base station (a transceiver) that sends and receives voice and data. When you travel from one cell to the next, your call is handed over without being cut. The generations show how the technology grew: 1G was analog voice (for example NMT), 2G was digital and added SMS, 2.5G brought packet data through GPRS, EDGE (Enhanced Data rates for GSM Evolution) raised data speeds, 3G gave mobile Internet and video calls, and 4G and 5G give broadband speeds good enough for HD streaming.

Wi-Fi, Li-Fi and RFID

Wi-Fi (Wireless Fidelity) follows the IEEE 802.11 standard. It uses radio waves to connect laptops and phones to each other and to the Internet without cables, which makes it cheap and convenient in homes and offices. Li-Fi (Light Fidelity) sends data using light from LEDs instead of radio waves. It is still an emerging technology but can reach very high speeds. RFID (Radio Frequency Identification) is a different idea: a reader uses radio waves to identify a tag attached to an object, which is how shops, libraries and toll plazas track items over short distances.

OSI Model, TCP/IP Model and Protocols

Sending data between two machines involves many small jobs, so standards bodies grouped those jobs into layers. The OSI (Open Systems Interconnection) model, published by ISO, has seven layers: Physical, Data Link, Network, Transport, Session, Presentation and Application. It is a reference model used to explain and design networks. The TCP/IP model is the one the Internet actually runs on, with four layers: Network Interface (Link), Internet, Transport and Application. In this suite, IP addresses and routes each packet but does not promise delivery, while TCP sets up a connection, checks for errors and resends lost packets. Application protocols sit on top: HTTP for web pages, HTTPS for secure web pages, FTP for file transfer and SMTP for sending e-mail.

Common mistakes to avoid

• Using Internet and World Wide Web as if they mean the same thing. The Internet is the global network itself; the Web is one service that runs on it, just as e-mail is another.
• Mixing up IP addresses and MAC addresses. An IP address is a logical address that can change when you join another network. A MAC address is fixed to the network card by the manufacturer.
• Calling IP a reliable protocol. IP is connectionless and does not guarantee delivery. Reliability comes from TCP running above it.
• Writing that a crossover cable connects any two devices. A crossover cable joins two devices of the same type directly, such as two computers. A computer to a switch needs a straight-through cable.
• Thinking HTTP is safe for passwords or payments. HTTP sends data as plain text. HTTPS encrypts it, which is why bank sites show https in the address bar.

Test yourself on these with the practice test, then check the worked reasoning in the solved MCQs.

Frequently asked questions

What is the difference between an Intranet and an Extranet?

Both are private networks. An Intranet is used only by the organisation's own employees to share internal data and resources. An Extranet extends part of that private network to selected outsiders, such as suppliers, vendors and business partners, so they can place orders or check information securely.

Why are TCP and IP used together?

IP decides where each packet goes and routes it across networks, but it does not check whether the packet arrived. TCP works above IP. It breaks data into segments, checks for errors and resends anything that was lost, so the complete message reaches the other end in the right order.

How does HTTPS keep web communication secure?

HTTPS is HTTP with encryption added through SSL (now its successor, TLS). The browser and server set up an encrypted channel before any data is sent. Anyone who intercepts the traffic sees only scrambled data, so passwords and card numbers stay private.

What is a crossover cable used for?

A crossover cable connects two devices of the same type directly, for example two computers, without a hub or switch in between. The transmit wires at one end are crossed to the receive pins at the other, so the two machines can exchange files straight away.

What is the main purpose of the OSI model?

The OSI model splits network communication into seven layers and defines what each layer must do. Because every maker follows the same layer rules, hardware and software from different companies can work together. It is mainly used as a reference for teaching and designing networks.

How are IPv4 and IPv6 addresses different?

An IPv4 address is 32 bits long and written in dotted-decimal form, such as 192.168.1.1. That gives about 4.3 billion addresses. An IPv6 address is 128 bits long and written as eight groups of hexadecimal digits separated by colons, which gives an enormously larger address space for the growing number of devices.

What does the Domain Name System do?

DNS works like a phone directory for the Internet. It converts a name you can remember, such as www.tnschools.gov.in, into the numeric IP address that computers use to find the server. Without it you would have to type the IP address of every site.