Networking & Cyber Security notes for competitive exams — topologies, devices, cyber threats & protection measures with revision tables.
What is Networking?
Networking refers to connecting two or more computers/devices together so they can share data, resources (printers, files), and communicate with each other.
A network requires: Sender, Receiver, Medium (channel), and Protocol (set of rules)
Types of Networks (Based on Area Covered)
Type Full Form Area Covered Example PAN Personal Area Network Very small (few meters) Bluetooth, USB connection LAN Local Area Network Small area (office, building) Office/school network MAN Metropolitan Area Network City-wide Cable TV network WAN Wide Area Network Country/globe-wide Internet
Network Topologies (Important — Diagram-Based Questions)
Topology Description Bus Topology All devices connected to a single central cable (backbone) Star Topology All devices connected to a central hub/switch Ring Topology Devices connected in a circular manner, data flows in one direction Mesh Topology Every device connected to every other device Tree Topology Combination of star and bus topology in a hierarchical structure Hybrid Topology Combination of two or more different topologies
Star Topology is the most commonly used topology in offices/homes due to easy troubleshooting.
Networking Devices
Device Function Modem Converts digital signals to analog and vice versa Router Directs data packets between different networks Switch Connects devices within a single network, sends data to specific device Hub Connects devices within a network, sends data to all devices (broadcast) Repeater Boosts/regenerates a weak signal over long distances Bridge Connects two similar networks/network segments Gateway Connects two different types of networks NIC Network Interface Card — hardware that connects a computer to a network
Network Models (Basic Concept)
Model Description Client-Server Central server provides resources/services to multiple client computers Peer-to-Peer (P2P) All computers have equal status, share resources directly without a central server
Important Networking Terms
Term Meaning Bandwidth Data transfer capacity of a network Node Any device connected to a network Protocol Set of rules governing data communication IP Address Unique address assigned to a device on a network MAC Address Unique hardware address of a network device Wi-Fi Wireless networking technology Bluetooth Short-range wireless technology for data transfer Ethernet Wired LAN technology/standard
What is Cyber Security?
Cyber Security refers to the practice of protecting computers, networks, programs, and data from unauthorized access, damage, or attack.
Also known as Information Technology (IT) Security
Types of Cyber Threats/Attacks (Very Important)
Threat Description Virus Malicious program that attaches to files and spreads when the file is executed Worm Self-replicating malware that spreads across networks without user action Trojan Horse Malware disguised as legitimate software to gain unauthorized access Spyware Secretly monitors user activity and steals information Ransomware Locks/encrypts data and demands payment (ransom) to release it Phishing Fraudulent emails/websites designed to steal sensitive information Spoofing Disguising communication to appear from a trusted source Hacking Unauthorized access to a computer system/network Denial of Service (DoS) Overloading a system with traffic to make it unavailable Keylogger Records keystrokes to steal passwords/data Adware Displays unwanted advertisements, often bundled with free software
Types of Hackers
Type Description White Hat Hacker Ethical hacker; hacks with permission to find security flaws Black Hat Hacker Hacks with malicious intent for personal gain Grey Hat Hacker Works between ethical and unethical hacking, without malicious intent but without permission
Cyber Security Protection Measures
Measure Purpose Antivirus Software Detects and removes viruses/malware Firewall Monitors and controls incoming/outgoing network traffic Encryption Converts data into a coded format to prevent unauthorized access Two-Factor Authentication (2FA) Adds an extra layer of security beyond just a password VPN Virtual Private Network — creates a secure, encrypted connection over the Internet Strong Passwords Reduces risk of unauthorized access Regular Software Updates Fixes security vulnerabilities
Law Detail IT Act, 2000 Main law in India dealing with cybercrime and electronic commerce IT (Amendment) Act, 2008 Added provisions for data protection and cyber terrorism CERT-In Indian Computer Emergency Response Team — national agency for handling cyber security incidents
Quick Revision Table (Most Asked Facts)
Fact Answer Network covering the entire globe WAN (Wide Area Network) Network covering a small office/building LAN Topology using a central hub Star Topology Device that boosts weak signal Repeater Device connecting different types of networks Gateway Malware disguised as legitimate software Trojan Horse Malware that locks data for ransom Ransomware Fraudulent method to steal information via email Phishing Ethical hacker White Hat Hacker Law dealing with cybercrime in India IT Act, 2000 National agency for cyber security in India CERT-In Secure encrypted network connection VPN
