The layers, protocols and protections that make the internet work — and the law that governs misuse of it in India.
The OSI (Open Systems Interconnection) model conceptually divides network communication into 7 layers — Physical, Data Link, Network, Transport, Session, Presentation, and Application — each handling a distinct part of getting data from one device to another. In practice, the internet runs on the simpler, 4-layer TCP/IP model, which combines several OSI layers. IPv4 (32-bit addresses, ~4.3 billion possible addresses) is the older addressing scheme, gradually being supplemented by IPv6 (128-bit addresses) to accommodate the much larger number of internet-connected devices today.
DNS (Domain Name System) translates human-readable domain names (like "example.com") into numerical IP addresses that computers use to locate each other. HTTP (HyperText Transfer Protocol) governs how web browsers and servers communicate; HTTPS adds an encryption layer (via TLS/SSL) to secure that communication, now the default for most websites.
Common malware types: a virus (attaches to a host file, spreads when that file is run), a worm (self-replicates independently across networks without needing a host file), a Trojan (disguises itself as legitimate software), ransomware (encrypts a victim's data and demands payment), and spyware (covertly monitors user activity). Phishing is a social-engineering attack tricking users into revealing sensitive information, typically via fake emails or websites; firewalls are a defensive layer that filters network traffic based on security rules.
Symmetric encryption uses the same key to encrypt and decrypt data (faster, but the key must be securely shared). Asymmetric encryption uses a public-private key pair — data encrypted with the public key can only be decrypted with the corresponding private key — enabling secure communication without pre-sharing a secret key. A digital signature uses asymmetric cryptography in reverse (signing with a private key, verified with the public key) to prove a message's authenticity and integrity.
The Information Technology Act, 2000 is India's primary law governing cybercrime and electronic commerce — it gives legal recognition to electronic records and digital signatures, and criminalises offences like hacking, identity theft, and cyberterrorism. It has been amended (notably in 2008) to widen its scope covering data protection and a broader range of cyber offences.
Binary-to-hexadecimal conversion (and vice versa) is a basic computing skill, since hexadecimal is often used as a more compact, human-readable representation of binary data (e.g., in colour codes, memory addresses). In office computing, key MS Excel functions — VLOOKUP (looks up a value in a table), IF (conditional logic), and PivotTables (summarising and analysing large datasets interactively) — are commonly tested practical skills for administrative roles.
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