Networking II: IP Addressing, Subnetting & Protocols

Introduction

Every time you visit a website, send a WhatsApp message, or stream a video on your phone, something invisible is happening in the background. There is a system of addresses and rules that makes all of it possible. This system is the backbone of computer networking, and understanding it is one of the most valuable things you can learn as a technology-aware student in Nigeria today.

Think about how electricity distribution companies assign a meter number to every household in your neighbourhood. No two houses share the same meter number, and the company uses those numbers to identify who is using power and how much. Networking works in a very similar way. Every device connected to the internet has its own unique address called an IP address, and there are established rules called protocols that govern how data travels between those devices.

In this lesson, we go deeper than the basics covered in Networking I. We will break down IP addressing fully, explore how large networks are divided into smaller ones through a process called subnetting, and study the key protocols that keep our digital world running. Whether you are preparing for WAEC, planning to study Computer Science at university, or simply curious about how MTN or Airtel routes your data, this guide is written for you.

Learning Objectives

By the end of this lesson, students should be able to:

Define an IP address and explain its role in computer networking

Identify and describe the five classes of IP addresses with their ranges

Explain the concept of subnetting and interpret a simple subnet mask

Describe at least five major network protocols and state their individual functions

Differentiate between IPv4 and IPv6 addressing systems

Apply knowledge of networking concepts to real-life situations in Nigeria

What Is IP Addressing?

IP stands for Internet Protocol. An IP address is a unique numerical label assigned to every device — phone, computer, tablet, printer, or smart TV — that is connected to a network. It serves two main purposes: identifying the device (like a name) and showing its location on the network (like a physical address).

Without IP addresses, the internet would have no way of knowing where to send your data. When you open your browser and type www.google.com, your request travels across the internet using your device's IP address so that Google's server knows exactly where to send the results back to.

IPv4 — The Most Common Format

The version of IP addressing that most people are familiar with is IPv4 (Internet Protocol version 4). An IPv4 address is written as four groups of numbers separated by full stops (dots). Example:

192 . 168 . 1 . 10

Each number is called an octet and can range from 0 to 255. Together, the four octets form one complete IP address. This system gives us approximately 4.3 billion unique addresses — a number that seemed enormous in the 1980s but is now running out because of the global explosion of smartphones and connected devices.

How to read an IPv4 address:

192 — First octet (helps determine the class of the address)
168 — Second octet
1 — Third octet
10 — Fourth octet (identifies the specific device on the network)

IPv6 — The Future of Addressing

Because IPv4 addresses are running out, a newer system called IPv6 was introduced. An IPv6 address looks like this:

2001:0db8:85a3:0000:0000:8a2e:0370:7334

IPv6 uses 128-bit addresses and can produce a nearly limitless number of unique addresses — roughly 340 undecillion (a number with 38 zeros after it). Nigeria's own ICT infrastructure is gradually moving towards IPv6 as internet usage continues to grow rapidly across the country.

Quick Fact: The Nigerian Communications Commission (NCC) has been encouraging Internet Service Providers (ISPs) to adopt IPv6 to ensure that Nigeria does not run out of internet addresses as more Nigerians come online.

Classes of IP Addresses

IPv4 addresses are grouped into five classes — A, B, C, D, and E. Each class serves a different purpose and is designed for networks of different sizes. The class of an address is determined by the value of the first octet.

Class A

First Octet Range: 1 – 126

Default Subnet Mask: 255.0.0.0

Number of Networks: 126

Hosts Per Network: Up to 16,777,214

Best For: Very large networks such as major ISPs and multinational organisations

Class B

First Octet Range: 128 – 191

Default Subnet Mask: 255.255.0.0

Number of Networks: 16,384

Hosts Per Network: Up to 65,534

Best For: Medium-sized networks such as universities and large companies

Class C

First Octet Range: 192 – 223

Default Subnet Mask: 255.255.255.0

Number of Networks: Over 2 million

Hosts Per Network: Up to 254

Best For: Small networks such as offices, schools, and small businesses

Class D

First Octet Range: 224 – 239

Purpose: Reserved exclusively for multicasting (sending data to multiple destinations at once)

Not used for regular device addressing

Class E

First Octet Range: 240 – 255

Purpose: Reserved for research and experimental use only

Not used in public or commercial networks

IP Address Class Summary Table

Class First Octet Subnet Mask Networks Hosts Per Network

A 1 – 126 255.0.0.0 126 16,777,214

B 128 – 191 255.255.0.0 16,384 65,534

C 192 – 223 255.255.255.0 2,097,152 254

D 224 – 239 N/A Multicast N/A

E 240 – 255 N/A Reserved N/A

Nigerian Example: The University of Lagos (UNILAG) is a large institution with thousands of computers on its campus network. It would likely use a Class B address range to accommodate thousands of devices — student laptops, library computers, administrative systems, and lecture hall projectors — all connected on the same institutional network.

Class	First Octet	Subnet Mask	Networks	Hosts Per Network
A	1 – 126	255.0.0.0	126	16,777,214
B	128 – 191	255.255.0.0	16,384	65,534
C	192 – 223	255.255.255.0	2,097,152	254
D	224 – 239	N/A	Multicast	N/A
E	240 – 255	N/A	Reserved	N/A

Private vs Public IP Addresses

Not every IP address is visible on the open internet. Some address ranges are reserved for use only inside private networks, such as your home Wi-Fi or your school's local area network. These are called private IP addresses.

The most common private address ranges are:

10.0.0.0 – 10.255.255.255 (Class A private)

172.16.0.0 – 172.31.255.255 (Class B private)

192.168.0.0 – 192.168.255.255 (Class C private — your home router most likely uses this)

When you check your phone's IP address while connected to home Wi-Fi, you will almost always see something starting with 192.168. That is your private IP address, assigned automatically by your router.

Understanding Subnetting

Imagine a large secondary school in Abuja with separate departments — Sciences, Arts, Administration, and the School Library. If all these departments shared one single network, it could become very slow and difficult to manage. A network administrator would divide the school's main network into smaller, more manageable sections. These smaller sections are called subnets, and the process of creating them is called subnetting.

Subnetting is the technique of dividing one large network (or IP address block) into smaller sub-networks. Each subnet then operates semi-independently, improving performance, security, and network management across the whole organisation.

What Is a Subnet Mask?

A subnet mask is a 32-bit number that works alongside an IP address to identify which part of the address represents the network and which part represents the specific device (host) on that network.

Example:

IP Address   :  192.168.1.10
Subnet Mask  :  255.255.255.0

Network Part :  192.168.1    ← identifies the network
Host Part    :  .10          ← identifies the specific device

CIDR Notation:  192.168.1.10/24
(The /24 means the first 24 bits are used for the network)

The part covered by 255 in the subnet mask belongs to the network. The part covered by 0 is available for assigning to individual devices.

Why Subnetting Matters

Improved Performance Smaller networks mean less traffic congestion. Data does not have to travel across the entire organisation's network before reaching its destination.

Better Security Each subnet can be given different security rules. For instance, the Finance department at Zenith Bank can have its subnet isolated from the general staff network, protecting sensitive financial data.

Efficient IP Address Management Instead of assigning a large block of addresses to one location and wasting unused ones, subnetting allows administrators to allocate exactly what is needed to each section.

Easier Troubleshooting When a network problem occurs, it is much easier to locate and fix faults within a smaller subnet than to search through one massive network.

Nigerian Scenario — Banking Network: Access Bank Nigeria has branches in Lagos, Abuja, Port Harcourt, Kano, and over 600 locations nationwide. Each branch uses a separate subnet. The Lagos Island branch might use 192.168.10.0/24, while the Abuja headquarters uses 192.168.20.0/24. This way, the IT team can manage each branch's network independently, enforce security, and fix problems in one location without disrupting others.

Network Protocols

A network protocol is a set of rules and standards that determines how data is formatted, transmitted, received, and acknowledged between devices on a network. Think of protocols as the common language that computers agree to speak when communicating. Without them, a phone made in China, a laptop assembled in the USA, and a server sitting in Lagos would have no way to exchange information reliably.

There are many protocols in use today, each designed for a specific task. Here are the most important ones for your SSS 3 examination:

TCP/IP — Transmission Control Protocol / Internet Protocol

This is the foundational protocol suite of the internet. TCP handles the reliable delivery of data by breaking it into packets and reassembling them in the correct order at the destination. IP handles addressing and routing. Every internet communication you perform uses TCP/IP at its core.

HTTP and HTTPS — HyperText Transfer Protocol (Secure)

HTTP is used by web browsers to request and receive web pages. HTTPS is the secure, encrypted version of HTTP. When you see a padlock icon in your browser while visiting a banking website or a school portal, HTTPS is actively protecting your data during that session.

FTP — File Transfer Protocol

FTP is used for transferring files between computers over a network. Organisations like NIMC or INEC might use FTP internally to share large database files between departments and offices across Nigeria.

SMTP — Simple Mail Transfer Protocol

This is the protocol responsible for sending your emails from your device to a mail server and then on to the recipient's inbox. When you send your school assignment to a teacher via Gmail or Yahoo Mail, SMTP is working in the background to deliver it.

DNS — Domain Name System

DNS translates human-friendly website names like uba.com or mtn.ng into machine-readable IP addresses. It acts as the internet's phone directory — you supply a name and DNS finds the corresponding address automatically so your browser knows where to go.

DHCP — Dynamic Host Configuration Protocol

DHCP automatically assigns IP addresses to devices when they join a network. When your phone connects to a Wi-Fi hotspot at a restaurant in Lekki or a cybercafé in Onitsha, DHCP is what gives your device a temporary IP address without you having to configure anything manually.

UDP — User Datagram Protocol

UDP is similar to TCP but faster and without guaranteed delivery. It is used where speed matters more than perfection. During a Zoom class or a WhatsApp video call, a few lost data packets might cause a brief glitch, but the call continues because UDP prioritises speed over completeness.

SNMP — Simple Network Management Protocol

SNMP is used by network administrators to monitor and manage network equipment — routers, switches, and servers. A telecoms company like Globacom or 9Mobile would use SNMP to keep track of hundreds of network devices spread across its nationwide infrastructure.

Protocol Summary Table

Protocol Full Name Primary Function

TCP/IP Transmission Control Protocol / Internet Protocol Core internet communication and data delivery

HTTP/HTTPS HyperText Transfer Protocol (Secure) Loading websites; HTTPS adds encryption

FTP File Transfer Protocol Transferring files between computers

SMTP Simple Mail Transfer Protocol Sending emails

DNS Domain Name System Translating domain names to IP addresses

DHCP Dynamic Host Configuration Protocol Automatically assigning IP addresses

UDP User Datagram Protocol Fast data transmission (streaming, calls)

SNMP Simple Network Management Protocol Monitoring and managing network devices

Protocol	Full Name	Primary Function
TCP/IP	Transmission Control Protocol / Internet Protocol	Core internet communication and data delivery
HTTP/HTTPS	HyperText Transfer Protocol (Secure)	Loading websites; HTTPS adds encryption
FTP	File Transfer Protocol	Transferring files between computers
SMTP	Simple Mail Transfer Protocol	Sending emails
DNS	Domain Name System	Translating domain names to IP addresses
DHCP	Dynamic Host Configuration Protocol	Automatically assigning IP addresses
UDP	User Datagram Protocol	Fast data transmission (streaming, calls)
SNMP	Simple Network Management Protocol	Monitoring and managing network devices

The OSI Model — Understanding Where Protocols Work

To better understand how different protocols work together, networking professionals use a framework called the OSI (Open Systems Interconnection) Model. It divides network communication into seven layers, each with a specific role.

Memory Tip: To remember the OSI layers from top (Layer 7) to bottom (Layer 1), use the phrase: "All People Seem To Need Data Processing" — Application, Presentation, Session, Transport, Network, Data Link, Physical.

OSI Model Layers:

Layer 7 — Application This is the layer closest to the end user. It provides the interface for applications like browsers and email clients. Examples: HTTP, FTP, SMTP, DNS

Layer 6 — Presentation Responsible for data formatting, encryption, and compression so that the receiving device can understand what was sent. Examples: SSL/TLS, JPEG, MPEG

Layer 5 — Session Manages and controls the dialogue (session) between two computers — opening, maintaining, and closing connections. Examples: NetBIOS, RPC

Layer 4 — Transport Handles reliable end-to-end data delivery, error checking, and flow control. Examples: TCP, UDP

Layer 3 — Network Responsible for logical addressing and routing — determining the best path for data to travel across networks. Examples: IP, ICMP, Routers

Layer 2 — Data Link Handles physical addressing using MAC addresses and detects errors in the physical transmission. Examples: Ethernet, Wi-Fi, Switches

Layer 1 — Physical The actual hardware — cables, radio waves, electrical signals — that transmit raw bits from one device to another. Examples: Fibre optic cable, Network Interface Card (NIC)

Practical Applications in Nigeria

Networking concepts are not just textbook material — they power some of the most critical services in Nigeria today.

Mobile Money and Fintech When you use Opay, Palmpay, or Flutterwave to send money, your transaction data travels through secure networks using HTTPS and TCP/IP. The payment servers are assigned public IP addresses so that millions of users across Nigeria can reach them simultaneously without conflict.

JAMB CBT Centres The Joint Admissions and Matriculation Board's Computer-Based Test centres across Nigeria use Local Area Networks with dedicated subnets for each examination hall. DHCP assigns IP addresses to all exam computers automatically, and DNS resolves server names so the system knows where to send and retrieve your responses.

Telecoms Networks (MTN, Airtel, Glo) Mobile network operators manage millions of devices simultaneously using Class A IP addresses and sophisticated subnetting. When you make a data call or browse the internet on your phone, DHCP gives your SIM card a temporary IP address from the network's available address pool.

Hospital Management Systems Hospitals like LASUTH (Lagos State University Teaching Hospital) use internal subnets to separate patient record systems from the general staff network. This protects sensitive health data while keeping the overall hospital system fast and reliable.

University Campus Networks Nigerian universities like OAU, ABU, and UNILAG have campus-wide networks where different faculties sit on different subnets. The Science Faculty might be on 10.1.1.0/24 while the Arts Faculty uses 10.1.2.0/24, keeping traffic organised and manageable.

Advantages and Disadvantages

Advantages

Subnetting reduces network congestion, making networks faster and more responsive for all users

Security is greatly improved because traffic between subnets can be controlled and closely monitored

IP addresses are used efficiently — no large blocks are left idle and wasted

Standardised protocols ensure that devices from different manufacturers communicate without problems

Protocols like HTTPS protect sensitive information such as bank details and personal data during transmission

Disadvantages

Subnetting requires skilled network administrators — a technical resource still in short supply in parts of Nigeria

Incorrectly configured subnet masks can cause network failures and complete communication breakdowns

Managing many subnets adds complexity to an organisation's overall network infrastructure

Older protocols like FTP and plain HTTP do not encrypt data, making them vulnerable to interception by attackers

IPv4's limited address space continues to be a growing challenge that Nigeria must address through gradual IPv6 adoption

Safety and Ethical Considerations

Important: Understanding networking also means understanding how to stay safe online. Knowledge of IP addresses and protocols can be misused. Using this knowledge to intercept someone else's data, access networks without permission, or disrupt online services is illegal under Nigeria's Cybercrime (Prohibition, Prevention, etc.) Act 2015. It can result in serious fines or imprisonment.

Always use HTTPS When entering personal information online — school portals, banking apps, registration forms — make sure the website address begins with https://. This confirms that your data is being encrypted during transmission.

Protect your IP address Your IP address can reveal your approximate geographic location. Avoid visiting untrusted websites or clicking suspicious links that could expose your IP address to bad actors.

Responsible network use In a school lab or office setting, do not attempt to scan or probe other devices on the network without clear permission from the network administrator.

Report vulnerabilities If you discover a security weakness in a school or institutional network, report it to the administrator rather than exploiting it. Ethical behaviour is the hallmark of a true computing professional.

Respect privacy Network logs record activity. Always behave on a network as though your actions are visible — because technically, to a network administrator, they are.

Classroom and Home Activities

Activity 1 — Find Your IP Address On a Windows computer, open the Command Prompt (search for "cmd") and type ipconfig, then press Enter. On an Android phone, go to Settings → Wi-Fi → tap your connected network → Advanced. Write down the IP address displayed. Identify which class it belongs to and state whether it is a private or public address.

Activity 2 — Subnet Mapping Exercise On paper, draw a simple diagram of your school divided into four departments — Administration, Library, Science Lab, and Classrooms. Assign each department a subnet using the 192.168.x.0/24 range. For example: Administration = 192.168.1.0/24, Library = 192.168.2.0/24. Present your diagram to the class and explain your choices.

Activity 3 — Protocol Identification Game Your teacher will write ten everyday internet activities on cards (for example: "sending an email", "loading a website", "downloading a file", "video calling a friend"). In groups, each team matches the correct protocol to each activity. The team with the most correct matches wins.

Activity 4 — DNS Investigation Open a Command Prompt or Terminal and type nslookup google.com, then press Enter. The result will display the IP address that DNS has resolved for Google. Try the same command for mtn.ng, jambcbt.gov.ng, or any Nigerian website. Record and compare the IP addresses found, then share your findings with the class.

Assessment Questions

Section A — Objective Questions (Circle the correct answer)

Question 1 Which of the following is a valid Class C IP address?

A. 10.0.0.1

B. 172.16.0.5

C. 192.168.1.100 ✓

D. 240.10.5.1

Question 2 What is the primary purpose of a subnet mask?

A. To encrypt data during transmission

B. To identify the network and host portions of an IP address ✓

C. To assign domain names to IP addresses

D. To increase internet connection speed

Question 3 Which protocol automatically assigns IP addresses to devices when they join a network?

A. DNS

B. FTP

C. DHCP ✓

D. SMTP

Question 4 IPv6 uses how many bits for its address space?

A. 32 bits

B. 64 bits

C. 128 bits ✓

D. 256 bits

Question 5 The protocol responsible for translating domain names like uba.com into IP addresses is called:

A. HTTP

B. SNMP

C. UDP

D. DNS ✓

Section B — Theory Questions

Theory Question 1 Explain the concept of subnetting and state THREE reasons why a large organisation in Nigeria — such as a commercial bank or a federal university — would benefit from dividing its network into subnets.

Theory Question 2 Distinguish between IPv4 and IPv6. Why is Nigeria being encouraged to transition to IPv6, and what challenges might this transition face?

Theory Question 3 List and explain FIVE network protocols. For each protocol, give one practical example of how it is used in everyday life in Nigeria.

Summary

An IP address is a unique numerical label that identifies every device on a network. IPv4 uses 32-bit dotted decimal notation while IPv6 uses 128 bits.

IP addresses are grouped into five classes (A through E), each designed for networks of different sizes and purposes.

Private IP addresses (such as 192.168.x.x) are used inside local networks and are not directly visible on the public internet.

Subnetting divides a large network into smaller subnetworks, improving performance, security, and efficient use of IP addresses.

A subnet mask defines which portion of an IP address represents the network and which portion represents the individual host device.

Protocols are the agreed rules governing how data is transmitted and received. Key protocols include TCP/IP, HTTP/HTTPS, FTP, SMTP, DNS, DHCP, UDP, and SNMP.

The OSI Model provides a seven-layer framework that shows how protocols operate at different levels of network communication.

These technologies are actively used in Nigerian banking, education, telecommunications, healthcare, and government systems every single day.

Conclusion

Networking is no longer the exclusive domain of IT professionals sitting in air-conditioned server rooms. As a Nigerian student today, you live in a world where networking decisions affect how fast your data loads, how secure your bank transactions are, how your JAMB results are stored, and how hospitals manage patient records across the country.

Understanding IP addressing, subnetting, and protocols does not just prepare you for examinations — it prepares you to participate meaningfully in a growing digital economy. Companies like Flutterwave, Paystack, Interswitch, and every major telecoms operator in Nigeria depend on the exact fundamentals you have studied in this lesson.

As you advance in your education, you may one day be the network engineer designing the systems that power the next generation of Nigerian innovation. That journey starts right here, in your SSS 3 classroom, with the knowledge you are building today.

Frequently Asked Questions

Q. What is the difference between an IP address and a MAC address?

An IP address is a logical address that can change depending on the network a device joins — it is assigned by software. A MAC (Media Access Control) address is a physical address permanently built into the hardware of the network card inside your device. Think of the MAC address as your National Identity Number — fixed for life — while your IP address is like a residential address that can change when you move to a new location.

Q. Why does my home IP address start with 192.168?

Addresses starting with 192.168 fall within the Class C private address range. When your internet service provider (like Spectranet or IPNX) gives you a router, that router uses private IP addresses to assign unique addresses to all devices inside your home. The router itself has one public IP address visible to the wider internet.

Q. Is subnetting only used in large organisations?

Not at all. Even your home router performs a basic form of subnetting by separating your home network from the wider internet. However, subnetting becomes significantly more important and complex in organisations with hundreds or thousands of devices, such as Nigerian banks, government ministries, and university campuses.

Q. What happens when two devices on the same network have the same IP address?

This is known as an IP address conflict. When it occurs, both devices may lose network access or behave erratically. You may have seen a notification on your device saying "IP address conflict detected." This is precisely why DHCP is so important — it automatically ensures each device receives a unique address, preventing such conflicts from occurring.

Q. How does DNS work in simple terms?

DNS works like the contacts list on your phone. Instead of memorising a numerical IP address every time you want to visit a website, you simply type a name like google.com or alat.ng. DNS looks up that name in its database and returns the corresponding IP address automatically, directing your browser to the correct server without you having to know any numbers.

Q. Will networking knowledge be relevant after SSS 3?

Absolutely. Networking is foundational for university courses in Computer Science, Computer Engineering, Information Technology, and Electrical Engineering. It is also directly applicable to careers in cybersecurity, cloud computing, software development, and telecommunications — all fast-growing sectors within Nigeria's digital economy.

Nigerian NERDC Curriculum · SSS 3 Computer Studies · Original educational content suitable for classroom instruction, WAEC/NECO revision, and self-directed study.

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Networking II for SS3 – IP Addressing, Subnetting and Protocols Explained