Internet, IoT & LAN/MAN/WAN — Ultimate Guide for CS Exams

Internet, IoT & LAN/MAN/WAN

Ultimate Guide for CS Competitive Exams — GATE, UGC NET, NIELIT, Rajasthan BCI, Informatics Assistant, DSSSB & More
High Scoring
8–15 marks in most exams
Internet & TCP/IP
Core networking concepts
IoT Protocols
MQTT, CoAP, Zigbee, LoRaWAN
LAN · MAN · WAN
Coverage, speed, devices

Contents

Why This Topic Matters

Computer Networks is one of the highest-scoring topics in almost every Computer Science competitive examination. Every year, several direct and conceptual questions are asked from LAN, MAN, WAN, Internet Architecture, TCP/IP Model, IPv4 & IPv6, DNS, HTTP, IoT Architecture, MQTT, CoAP, Zigbee, Network Devices, and Internet Protocols.

If you master these concepts, you can easily score 8–15 marks in most Computer Science examinations including GATE, UGC NET, NIELIT, Rajasthan BCI, Informatics Assistant, and DSSSB.

What is a Computer Network?

A Computer Network is a collection of interconnected computers and devices that communicate with one another to share:

  • Data
  • Resources
  • Hardware
  • Internet connection
  • Applications
Real-Life Example: Imagine a school.
  • All computers in one lab → LAN
  • All schools within Jaipur city → MAN
  • Schools connected across India → WAN

LAN vs MAN vs WAN

Computer Networks │ ┌───────────────┼───────────────┐ │ │ │ PAN LAN MAN │ │ └───────────────┬───────────────┘ │ WAN │ Internet
Feature LAN MAN WAN
Full Form Local Area Network Metropolitan Area Network Wide Area Network
Coverage Up to 1 km 10–50 km More than 100 km
Speed Highest Medium Lowest to High
Cost Low Medium High
Ownership Private Public / Private Public
Delay Very Low Moderate High
Error Rate Lowest Medium Highest
Example Office / Home City Network Internet
L → M → W   Local → Metropolitan → World   (Coverage always increases)

Network Devices Used

Hub — Broadcasts to every device
Switch — Sends only to destination
Router — Connects different networks
Gateway — Connects different protocols
Modem — Digital ↔ Analog conversion
Access Point — Wireless connectivity

Internet: The World's Largest Network

The Internet is simply a network of interconnected networks. It follows the TCP/IP Protocol Suite, which enables billions of devices to communicate reliably.

TCP/IP Model

Application Layer │ HTTP   HTTPS   FTP   SMTP   DNS   MQTT   CoAP ────────────── Transport Layer │ TCP   UDP ────────────── Internet Layer │ IPv4   IPv6   ICMP   ARP   RARP ────────────── Network Access Layer │ Ethernet   Wi-Fi   PPP

TCP vs UDP

TCPUDP
Connection-OrientedConnectionless
ReliableFaster
Error Checking & RecoveryNo Recovery
Ordered DeliveryNo Ordering
Used by HTTP, HTTPS, FTPUsed by DNS, VoIP, Streaming
TCP = Trustworthy  ·  UDP = Ultra Fast

IPv4 vs IPv6

FeatureIPv4IPv6
Address Size32-bit128-bit
Example192.168.1.12001:db8::1
Address Count2³² (4.3 billion)2¹²⁸ (340 undecillion)
NotationDecimalHexadecimal
HeaderVariable lengthFixed length
SecurityOptional (IPSec)Built-in (IPSec)
IPv4 → 4 parts   192.168.1.10  ·  IPv6 → 8 hex groups   2001:db8:85a3::8a2e

DNS, HTTP & HTTPS

DNS (Domain Name System) converts:
www.google.com     142.250.182.14

Think of DNS as the phonebook of the Internet.

Port Number = 53   Uses UDP (mostly) and TCP (zone transfer).

HTTP vs HTTPS

HTTPHTTPS
Port 80Port 443
Not SecureSecure
Plain TextTLS/SSL Encryption
No CertificateSSL Certificate Required

ARP vs RARP

IP Address

ARP

MAC Address
MAC Address

RARP

IP Address
ARP = IP → MAC  ·  RARP = MAC → IP

Introduction to IoT

The Internet of Things (IoT) connects physical devices to the Internet, enabling them to collect, share, and analyse data automatically.

Examples: Smart Homes, Smart Agriculture, Smart Healthcare, Wearable Devices, Smart Traffic Systems, Industrial Automation.

IoT Architecture

Application Layer │ Smart Home   Health   City   Agriculture ────────────── Middleware Layer │ Cloud   AI   Big Data   Database ────────────── Network Layer │ Wi-Fi   5G   LoRaWAN   Zigbee ────────────── Perception Layer │ Sensors & Actuators   RFID   Cameras

Common IoT Sensors

Temperature — Weather
Humidity — Agriculture
Motion — Security
Gas — Leakage Detection
Light — Smart Lighting
Pressure — Industry

IoT Communication Protocols

ProtocolTransportBest Use
MQTTTCPPublish/Subscribe Messaging
CoAPUDPLightweight RESTful API
ZigbeeIEEE 802.15.4Home Automation
LoRaWANLong RangeSmart Cities, Agriculture
Bluetooth LELow EnergyWearables, Fitness
NFCShort RangeContactless Payment
6LoWPANIPv6Low-Power IoT Networks
MQTT = Message Queue  ·  CoAP = Compact HTTP  ·  Zigbee = Home Automation  ·  LoRaWAN = Long Distance

Quick Revision Sheet

LANLocal, High Speed
MANCity Network
WANWorldwide Network
EthernetIEEE 802.3
Wi-FiIEEE 802.11
ARPIP → MAC
RARPMAC → IP
DNSPort 53
HTTPPort 80
HTTPSPort 443
MQTTTCP + Pub/Sub
CoAPUDP + REST
IPv432-bit
IPv6128-bit
TCPConnection-Oriented
UDPConnectionless

Exam Booster (Most Expected)

⭐ LAN Full FormLocal Area Network
⭐ WAN ExampleInternet
⭐ Ethernet StandardIEEE 802.3
⭐ Wi-Fi StandardIEEE 802.11
⭐ ARP FunctionIP → MAC
⭐ DNS Port53
⭐ HTTPS Port443
⭐ IPv4 Size32-bit
⭐ IPv6 Size128-bit
⭐ MQTT ModelPublish/Subscribe
⭐ CoAP TransportUDP
⭐ Zigbee UseHome Automation
⭐ TCP FeatureConnection-Oriented
⭐ UDP FeatureConnectionless

Interactive MCQ Practice 30 Questions

Click an option to check your answer. Track your progress below.

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Final Revision Tips
  • ✅ Remember IEEE 802.3 = Ethernet and 802.11 = Wi-Fi.
  • ✅ Learn the common ports: HTTP (80), HTTPS (443), DNS (53).
  • ✅ Memorise ARP = IP → MAC and RARP = MAC → IP.
  • ✅ Understand the TCP/IP model and the role of each layer.
  • ✅ Revise IoT protocols: MQTT, CoAP, Zigbee, LoRaWAN, and 6LoWPAN.
  • ✅ TCP is connection-oriented; UDP is connectionless.

Master these concepts to score 8–15 marks in your exam. Good luck!

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