Activity: Network Addressing & Protocols

Topologies, OSI Model, IP addressing, DNS, and MAC addressing with interactive tools

Grade XII • Computer Science ⏱ ~20 min

Brief Intro — Network Addressing & Protocols

Behind every click on a website lies a complex system of rules and addresses that ensure your data reaches the right destination. From the physical cables to the high-level protocols, network addressing and standard models like OSI provide the language that computers use to talk to each other.

In this activity, you'll explore network topologies, the seven layers of the OSI model, and how IP addresses and DNS work together to navigate the global internet.

Prerequisites

Completed Pair 1 (Data Communication Fundamentals) and Pair 2 (Networking Infrastructure).
Understanding of basic network concepts from previous activities.
Familiarity with binary number system and basic networking terminology.

Objectives Learning Goals & Outcomes

By the end of this activity, you will be able to:

Identify and compare different network topologies.
Understand the seven layers of the OSI Reference Model.
Classify IP addresses by class (A, B, C, D, E).
Distinguish between public and private IP addresses.
Calculate subnet masks and network addresses.
Understand static vs dynamic IP assignment.
Explain DNS resolution process and MAC addressing.

Part 1 Network Topologies

Network topology defines the physical or logical arrangement of nodes and connections in a network, impacting its cost and reliability.

Interactive Simulator: Topology Explorer

Select a topology to see its structure, advantages, and disadvantages.

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Bus Topology

All devices connected to a central cable

Structure: All devices connected to a single central cable (backbone).

Advantages: Simple, inexpensive, easy to install for small networks.

Disadvantages: Single point of failure, limited cable length, difficult troubleshooting.

Task 1: Topology Comparison

Topology	Structure	Advantages	Disadvantages	Use Cases
Bus	Single central cable	Simple, cheap	Single point of failure	Small networks, temporary setups
Star	All devices connect to central hub	Easy to manage, fault isolation	Hub failure affects all	Modern LANs, office networks
Ring	Devices connected in a circle	No collisions, equal access	One break affects all	Token ring networks, campus LANs
Mesh	Every device connects to every other	Highly redundant, reliable	Expensive, complex cabling	Critical systems, data centers
Tree	Hierarchical star topology	Scalable, organized	Root failure affects all	Large organizations, WANs
Hybrid	Combination of topologies	Flexible, customizable	Complex to design	Enterprise networks

Part 2 OSI Reference Model

The Open Systems Interconnection (OSI) model standardizes network functions into seven distinct layers to ensure different systems can communicate.

Interactive Simulator: OSI Layer Explorer

Click on each layer to learn its function and protocols.

Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

Task 2: OSI Layer Functions

Layer	Function	Protocols/Devices
Physical	Transmits raw bit stream over physical medium	Ethernet cables, hubs, repeaters
Data Link	Error-free transfer of frames between nodes	MAC addresses, switches, bridges
Network	Routing and logical addressing (IP)	IP, routers, ICMP
Transport	End-to-end connection and reliability	TCP, UDP, ports
Session	Session establishment and management	NetBIOS, RPC
Presentation	Data translation, encryption, compression	SSL/TLS, JPEG, MPEG
Application	User interface and network services	HTTP, FTP, SMTP, DNS

Part 3 IP Addressing

IP addresses are the logical identifiers that allow data to be routed across networks, organized into classes with specific ranges and masks.

Interactive Simulator: IP Address Analyzer

Enter an IP address to analyze its class, subnet mask, and other properties.

IP Address: 192.168.1.10

Class: C

Default Subnet Mask: 255.255.255.0

Type: Private

Network Address: 192.168.1.0

Broadcast Address: 192.168.1.255

Task 3: IP Address Classes

Class	First Octet Range	Default Subnet Mask	Network Size	Use Case
A	1 - 126	255.0.0.0	16M hosts	Large organizations
B	128 - 191	255.255.0.0	65K hosts	Medium organizations
C	192 - 223	255.255.255.0	254 hosts	Small networks
D	224 - 239	N/A	Multicast	Multicasting
E	240 - 255	N/A	Reserved	Experimental/Research

Task 4: Public vs Private IP Addresses

Address Type	Definition	Address Ranges	Accessibility
Public IP	Globally routable on Internet	All other addresses	Accessible from anywhere
Private IP	Local network use only	10.0.0.0 - 10.255.255.255 172.16.0.0 - 172.31.255.255 192.168.0.0 - 192.168.255.255	Not routable on Internet

Task 5: Static vs Dynamic IP Assignment

Aspect	Static IP	Dynamic IP
Assignment	Manually configured	Automatically assigned by DHCP
Stability	Permanent until changed	Can change over time
Administration	Requires manual management	Automated, less management
Use Cases	Servers, printers, network devices	Workstations, mobile devices
Pros	Reliable, good for services	Easy setup, efficient address use
Cons	Configuration overhead	Address can change unexpectedly

Part 4 DNS and MAC Addressing

While IP addresses handle logical routing, MAC addresses provide unique physical identification, and DNS translates human-friendly names into numbers.

Interactive Simulator: DNS Resolution Visualizer

See how DNS resolves domain names to IP addresses.

User enters www.example.com in browser

Computer checks local DNS cache

If not cached, query goes to DNS resolver (ISP)

DNS resolver queries root server (.)

Root server directs to TLD server (.com)

TLD server directs to authoritative server (example.com)

Authoritative server returns IP address

IP address is cached and returned to browser

Task 6: DNS (Domain Name System)

Purpose: Translates human-readable domain names to IP addresses
Hierarchy: Root servers → TLD servers → Authoritative servers
Record Types: A (IPv4), AAAA (IPv6), MX (Mail), CNAME (Alias), NS (Name Server)
Caching: Results are cached to reduce resolution time
Distributed: No single DNS server contains all mappings

Task 7: MAC Address

Definition: Media Access Control address - unique identifier for network interfaces
Format: 48-bit (6-byte) hexadecimal address (e.g., 00:1A:2B:3C:4D:5E)
Structure: First 24 bits = OUI (Vendor ID), Last 24 bits = Device ID
Layer: Data Link Layer (Layer 2) of OSI model
Scope: Local network only (not routable)
Permanence: Usually burned into hardware (can be spoofed)
Uniqueness: Globally unique (theoretically)

Task 8: Subnet Mask and Network Address

Subnet Mask: Defines which portion of IP address is network vs host portion

Network Address: First address in subnet (all host bits = 0)

Broadcast Address: Last address in subnet (all host bits = 1)

Example: For IP 192.168.1.10 with mask 255.255.255.0:

Network Address: 192.168.1.0
Broadcast Address: 192.168.1.255
Usable Host Range: 192.168.1.1 - 192.168.1.254
Total Hosts: 254 (256 - 2)

✓ Completion Checklist

Explored the Topology Explorer simulator
Understood different network topologies and their characteristics
Used the OSI Layer Explorer simulator
Learned the seven layers of the OSI model and their functions
Experimented with the IP Address Analyzer simulator
Understood IP address classes (A, B, C, D, E)
Distinguished between public and private IP addresses
Compared static vs dynamic IP assignment
Visualized DNS resolution process
Learned about MAC addressing and subnet masks

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