Information & Communication Technologies (ICT) is a fast-evolving General Studies section tested in ESE Paper I. This module spans Computer Fundamentals (generations, number systems, architecture, data representation), Operating Systems (functions, types, scheduling, memory management), Computer Networking (OSI model, TCP/UDP, IP addressing, devices), Internet and Web Technologies (protocols, web technologies, cloud computing), Cybersecurity (CIA triad, threats, cryptography, Indian cyber laws), and Emerging Technologies (AI, IoT, blockchain, big data, 5G, India's digital initiatives) — with every definition, port number, and standard carried over, plus worked examples and diagrams for each topic.
After studying this chapter you will be able to:
ICT complements the other General Studies subjects by testing awareness of digital infrastructure and technology that increasingly underpins engineering practice itself — from IoT-enabled monitoring to AI-assisted design. Once you've worked through the chapters below, head to the ICT hub page to generate practice tests, or explore Study Material for other subjects.
A computer is an electronic device that processes data according to instructions (programs). Modern computers are built on the von Neumann architecture with CPU, memory, I/O, and storage as core components.
| Generation | Period | Technology | Example |
|---|---|---|---|
| 1st | 1940–1956 | Vacuum tubes | ENIAC, UNIVAC |
| 2nd | 1956–1963 | Transistors | IBM 7094 |
| 3rd | 1964–1971 | Integrated Circuits (ICs) | IBM 360 |
| 4th | 1971–present | Microprocessors (VLSI) | Intel 4004, modern PCs |
| 5th | Present+ | AI, parallel processing | AI chips, quantum computers |
| System | Base | Digits | Conversion |
|---|---|---|---|
| Binary | 2 | 0, 1 | Multiply by \(2^n\) for positional value |
| Octal | 8 | 0–7 | Group binary digits by 3 |
| Decimal | 10 | 0–9 | Natural number system |
| Hexadecimal | 16 | 0–9, A–F | Group binary digits by 4 |
| Term | Definition |
|---|---|
| Clock speed | CPU cycles per second (GHz); higher = faster |
| MIPS | Millions of Instructions Per Second |
| Cache memory | L1 (on-chip, fastest), L2 (on-chip/near chip), L3 (shared) — reduces memory access time |
| Pipeline | Overlapping instruction execution stages — fetch, decode, execute, write-back |
| Multi-core | Multiple CPU cores on single chip for parallel execution |
ASCII: 7-bit code representing 128 characters. Unicode/UTF-8: international standard supporting all world scripts. 2's complement: standard representation for signed integers in computers (invert all bits, then add 1). IEEE 754: standard for floating-point representation (single: 32-bit, double: 64-bit).
\(1\text{ B} = 8\text{ bits}\); \(1\text{ KB} = 1024\text{ B}\)
Invert all bits, then add 1
L1 (fastest) → L2 → L3 (shared)
Single: 32-bit; Double: 64-bit
Given: Represent \(-5\) in 8-bit 2's complement.
Solution: \(5\) in binary is \(00000101\). Invert all bits: \(11111010\). Add 1: \(11111011\).
Answer: \(11111011\).
Given: Convert decimal 202 to hexadecimal.
Solution: \(202 = 12 \times 16 + 10\), so the hex digits are \(C\) (12) and \(A\) (10).
Answer: \(202_{10} = CA_{16}\).
Given: A file is 3,145,728 bytes. How many megabytes is this?
Solution: \(1\text{ MB} = 1024 \times 1024 = 1{,}048{,}576\) bytes. \(3{,}145{,}728 / 1{,}048{,}576 = 3\).
Answer: 3 MB.
Fig. 1.1 — The von Neumann architecture: CPU, memory, storage, and I/O devices linked by a common bus.
An Operating System (OS) is system software that manages hardware resources and provides a platform for application programs. It acts as an intermediary between users and hardware, handling process management, memory management, file systems, device management, security, and the user interface.
| Type | Description | Example |
|---|---|---|
| Batch OS | Jobs collected and processed in batches; no user interaction | Early mainframe OS |
| Time-sharing (Multitasking) | Multiple users/processes share CPU time; each gets time slice | UNIX, Linux |
| Real-time OS (RTOS) | Guarantees response within strict time deadlines | VxWorks, FreeRTOS |
| Distributed OS | Manages resources across multiple networked computers | Amoeba, Plan 9 |
| Mobile OS | Optimised for touch, low power, wireless | Android, iOS |
| Network OS | Manages network resources and services | Windows Server, Novell |
| Algorithm | Description | Key Property |
|---|---|---|
| FCFS | First Come First Served — non-preemptive | Simple; convoy effect |
| SJF | Shortest Job First — non-preemptive | Minimum average waiting time; starvation possible |
| Round Robin | Each process gets fixed time quantum cyclically | Fair; widely used in time-sharing |
| Priority | Highest priority process runs first | Starvation of low-priority possible; aging solves it |
| SRTF | Shortest Remaining Time First — preemptive SJF | Optimal but requires burst time prediction |
| File System | OS | Max File Size |
|---|---|---|
| FAT32 | Windows (older) | 4 GB |
| NTFS | Windows | 16 TB (practical) |
| ext4 | Linux | 16 TB |
| APFS | macOS/iOS | Very large |
Non-preemptive; simple; suffers convoy effect
Minimum avg. waiting time; SRTF is preemptive SJF
Fixed time quantum, cyclic — fair scheduling
FIFO, LRU, Optimal
Given: Three processes P1, P2, P3 arrive at time 0 with burst times 5, 3, 8 ms respectively, scheduled FCFS in that order. What is P3's waiting time?
Solution: P1 runs 0–5, P2 runs 5–8, P3 starts at 8. P3's waiting time = start time − arrival time = \(8 - 0 = 8\) ms.
Answer: 8 ms.
Given: A system uses Round Robin with a very small time quantum (e.g., 1 ms) for processes with large burst times. What is the main drawback?
Solution: A very small quantum causes frequent context switches. Since each context switch has fixed overhead, an excessive number of switches wastes significant CPU time on overhead rather than useful work.
Answer: Excessive context-switching overhead, reducing effective CPU utilisation.
Given: A system's CPU utilisation drops sharply even though many processes are "running," and disk activity (paging) is very high. What is this phenomenon called?
Solution: This is thrashing — the system has too few frames allocated per process, so processes spend more time paging data in/out than executing, causing CPU utilisation to collapse.
Answer: Thrashing.
Fig. 2.1 — Round Robin scheduling: processes cycle through fixed time quanta, ensuring fairness.
A computer network connects multiple devices to share resources and communicate. Networking is fundamental to the internet, cloud computing, and modern digital infrastructure.
| Type | Scale | Example |
|---|---|---|
| PAN | Personal Area Network (~10 m) | Bluetooth headset, smartwatch |
| LAN | Local Area Network (building/campus) | Office network, home Wi-Fi |
| MAN | Metropolitan Area Network (city) | City cable network |
| WAN | Wide Area Network (country/globe) | Internet, MPLS networks |
| Layer | Name | Function | Protocols/Examples |
|---|---|---|---|
| 7 | Application | User interface; network services | HTTP, FTP, SMTP, DNS |
| 6 | Presentation | Data format, encryption, compression | SSL/TLS, JPEG, MPEG |
| 5 | Session | Session management; checkpointing | NetBIOS, RPC |
| 4 | Transport | End-to-end reliable delivery; ports | TCP, UDP |
| 3 | Network | Routing; logical addressing (IP) | IP, ICMP, OSPF, BGP |
| 2 | Data Link | MAC addressing; error detection; frames | Ethernet, Wi-Fi (802.11), PPP |
| 1 | Physical | Bit transmission over medium | Cables, hubs, repeaters |
| Feature | TCP | UDP |
|---|---|---|
| Connection | Connection-oriented (3-way handshake) | Connectionless |
| Reliability | Guaranteed delivery, ordering, error-checking | Best effort; no guarantee |
| Speed | Slower (overhead) | Faster |
| Use cases | HTTP, FTP, email, file transfer | Video streaming, DNS, VoIP, gaming |
| Device | OSI Layer | Function |
|---|---|---|
| Hub | Layer 1 | Broadcasts to all ports; no intelligence |
| Switch | Layer 2 | Forwards frames based on MAC address; creates collision domains |
| Router | Layer 3 | Routes packets between networks using IP addresses |
| Gateway | Layer 4–7 | Protocol translation between different networks |
| Firewall | Layer 3–7 | Filters traffic based on security rules |
| Access Point (AP) | Layer 2 | Wireless connection to LAN |
| Standard | Name | Max Speed | Frequency |
|---|---|---|---|
| 802.11b | Wi-Fi 1 | 11 Mbps | 2.4 GHz |
| 802.11g | Wi-Fi 3 | 54 Mbps | 2.4 GHz |
| 802.11n | Wi-Fi 4 | 600 Mbps | 2.4/5 GHz |
| 802.11ac | Wi-Fi 5 | 3.5 Gbps | 5 GHz |
| 802.11ax | Wi-Fi 6 | 9.6 Gbps | 2.4/5/6 GHz |
| Bluetooth 5.0 | PAN | 2 Mbps | 2.4 GHz |
Application → Presentation → Session → Transport → Network → Data Link → Physical
TCP: reliable, connection-oriented; UDP: fast, connectionless
32-bit (~4.3 billion) vs 128-bit (\(\sim 3.4\times10^{38}\))
Switch: Layer 2 (MAC); Router: Layer 3 (IP)
Given: At which OSI layer does a router primarily operate, and which protocol does it use for logical addressing?
Solution: Routers operate at Layer 3 (Network layer), using IP for logical addressing and routing packets between different networks.
Answer: Layer 3 (Network layer); IP protocol.
Given: A live video-conferencing application needs low latency and can tolerate occasional dropped frames. Should it use TCP or UDP?
Solution: TCP's reliability guarantees come with retransmission delays, which harm real-time video. UDP is connectionless and faster, tolerating occasional loss without stalling — the standard choice for real-time media.
Answer: UDP.
Given: A device has the IP address 192.168.1.50. Is this a public or private IP address?
Solution: 192.168.0.0/16 is one of the reserved private IP ranges, so 192.168.1.50 falls within it.
Answer: Private IP address (within the 192.168.0.0/16 range).
Fig. 3.1 — The OSI model's seven layers, from Physical (bottom, bit transmission) to Application (top, user services).
The Internet is a global network of networks using the TCP/IP protocol suite. The World Wide Web (WWW) is a service running over the internet. Understanding both is essential for IES ICT questions.
| Protocol | Port | Function |
|---|---|---|
| HTTP | 80 | Web page transfer (HyperText Transfer Protocol) |
| HTTPS | 443 | Secure web (HTTP + TLS encryption) |
| FTP | 21 | File transfer |
| SFTP | 22 | Secure file transfer |
| SMTP | 25 | Send email (Simple Mail Transfer Protocol) |
| POP3 | 110 | Receive email (Post Office Protocol) |
| IMAP | 143 | Email access (syncs across devices) |
| DNS | 53 | Domain name resolution |
| Telnet | 23 | Remote terminal (unencrypted) |
| SSH | 22 | Secure remote terminal |
| Model | Full Form | Description | Example |
|---|---|---|---|
| IaaS | Infrastructure as a Service | Virtual machines, storage, networking | AWS EC2, Azure VMs |
| PaaS | Platform as a Service | Development environment and tools | Google App Engine, Heroku |
| SaaS | Software as a Service | Ready-to-use applications over internet | Gmail, Office 365, Salesforce |
Deployment models: Public cloud (shared infrastructure, provider-managed), Private cloud (dedicated infrastructure, higher security), Hybrid cloud (mix of public and private), Community cloud (shared among organisations with common concerns, e.g. government, healthcare).
80 / 443
21 / 25 / 53
1991, Tim Berners-Lee, CERN
Infrastructure / Platform / Software as a Service
Given: A network administrator sees traffic on port 443. Which protocol is most likely in use, and what does it indicate?
Solution: Port 443 is the standard port for HTTPS — HTTP secured with TLS encryption. Traffic on this port indicates an encrypted web session.
Answer: HTTPS (secure web traffic).
Given: A company uses Gmail for email without managing any servers, software, or infrastructure. Which cloud service model does this represent?
Solution: The company consumes a ready-to-use application over the internet without managing any underlying infrastructure or platform — this is Software as a Service (SaaS).
Answer: SaaS (Software as a Service).
Given: A web form needs to submit new user registration data to a server. Which HTTP method should it use?
Solution: Submitting new data to be processed and stored is the classic use case for the POST method, as opposed to GET (retrieve), PUT (update), or DELETE (remove).
Answer: POST.
Fig. 4.1 — IaaS, PaaS, and SaaS: as you move right, the provider manages progressively more of the stack.
Cybersecurity protects computer systems and networks from theft, damage, and unauthorised access. With increasing digitalisation of infrastructure, it is critical for engineers to understand security principles.
| Objective | Meaning | Threat |
|---|---|---|
| Confidentiality | Only authorised users can access data | Eavesdropping, data breach |
| Integrity | Data is accurate and unaltered | Tampering, man-in-the-middle |
| Availability | Systems and data accessible when needed | DoS/DDoS attacks, ransomware |
| Threat | Description |
|---|---|
| Malware | Malicious software: virus (self-replicating), worm (spreads without host), Trojan (disguised), ransomware (encrypts files for ransom), spyware |
| Phishing | Deceptive emails/websites to steal credentials; spear phishing = targeted |
| DoS / DDoS | Denial of Service / Distributed DoS — floods system to deny legitimate access |
| SQL Injection | Malicious SQL code inserted into input fields to access database |
| Cross-site Scripting (XSS) | Malicious scripts injected into trusted websites to attack users |
| Man-in-the-Middle | Attacker intercepts communication between two parties |
| Zero-day exploit | Attack on unknown vulnerability before patch released |
| Social engineering | Manipulating people to reveal information (not technical) |
Confidentiality, Integrity, Availability
AES = symmetric; RSA = asymmetric
Sec 43 (civil); Sec 66 (criminal, up to 3 yr)
3 copies, 2 media types, 1 off-site
Given: An attacker intercepts a bank transfer message and modifies the destination account number before forwarding it. Which CIA triad objective is violated?
Solution: Modifying data in transit without authorisation is a violation of integrity — the data is no longer accurate and unaltered.
Answer: Integrity.
Given: Two parties who have never communicated before need to securely exchange a session key over an insecure channel. Should they use symmetric or asymmetric encryption for this initial exchange?
Solution: Symmetric encryption requires both parties to already share a secret key, which is unsafe to exchange over an insecure channel. Asymmetric encryption (e.g., RSA) allows a public key to encrypt data that only the corresponding private key can decrypt, making it suitable for this initial key exchange.
Answer: Asymmetric encryption (e.g., RSA) for the initial key exchange.
Given: An individual gains unauthorised access to a company's database and deletes several records. Under India's IT Act 2000, which section(s) apply, and is this civil or criminal?
Solution: Unauthorised access falls under Section 43 (civil liability, compensation), while the associated computer-related offence (data deletion) falls under Section 66, which carries criminal liability of imprisonment up to 3 years.
Answer: Both Section 43 (civil) and Section 66 (criminal, up to 3 years) can apply.
Fig. 5.1 — The CIA triad: the three pillars of information security, each with a distinct threat category.
Emerging technologies are transforming engineering, governance, and society. IES General Studies tests awareness of these technologies and their applications, implications, and Indian government initiatives.
| The 5 V's of Big Data | Meaning |
|---|---|
| Volume | Massive scale of data (terabytes to zettabytes) |
| Velocity | Speed of data generation and processing |
| Variety | Structured, semi-structured, unstructured data |
| Veracity | Accuracy and trustworthiness of data |
| Value | Insights derived from data analysis |
| Initiative | Year | Focus |
|---|---|---|
| Digital India | 2015 | Digital infrastructure, e-governance, digital literacy |
| BharatNet | 2011 | Optical fibre broadband to all gram panchayats |
| UMANG | 2017 | Unified Mobile Application for New-age Governance |
| DigiLocker | 2015 | Digital document wallet for citizens |
| GeM | 2016 | Government e-Marketplace for procurement |
| COWIN | 2021 | COVID-19 vaccination management platform |
| India AI Mission | 2024 | AI compute, startups, responsible AI |
| SemiconIndia | 2021 | ₹76,000 Cr semiconductor manufacturing incentives |
The ESE syllabus specifically flags ICT-based tools in networking, e-governance and technology-based education — the applications that carry ICT into public service and learning.
Use of ICT to deliver government services, exchange information and integrate back-office processes. Interaction models:
Benefits: transparency, reduced corruption, speed and reach; challenges: the digital divide, data privacy and cyber-security.
ICT applied to teaching and learning — often called e-learning / EdTech:
Volume, Velocity, Variety, Veracity, Value
Launched 2022; peak 20 Gbps; latency <1 ms
Proof of Work (energy intensive) vs Proof of Stake (efficient)
Launched 2015
Given: A hospital's sensor network generates readings that are occasionally inaccurate due to faulty sensors, requiring careful validation before use. Which of the 5 V's does this concern relate to?
Solution: Concern about the accuracy and trustworthiness of data relates to Veracity, distinct from Volume (scale), Velocity (speed), Variety (format diversity), or Value (insight extraction).
Answer: Veracity.
Given: A blockchain network wants to reduce its energy consumption significantly while maintaining decentralised consensus. Should it use Proof of Work or Proof of Stake?
Solution: Proof of Work requires miners to solve computationally expensive puzzles, consuming large amounts of energy. Proof of Stake instead selects validators based on their stake, drastically reducing energy consumption.
Answer: Proof of Stake.
Given: A citizen wants to store digital copies of their certificates and access them across devices without carrying physical documents. Which Indian government initiative supports this?
Solution: DigiLocker, launched in 2015, is India's digital document wallet, allowing citizens to store and access official documents digitally.
Answer: DigiLocker.
Fig. 6.1 — The five V's of Big Data: Volume, Velocity, Variety, Veracity, and Value.
8 bits; 1 KB = 1024 bytes
1st: vacuum tubes; 2nd: transistors; 3rd: IC; 4th: microprocessor; 5th: AI
Invert all bits, then add 1
Smaller quantum → more context switches → more overhead
Excessive swapping from insufficient frames; CPU utilisation collapses
Application → Presentation → Session → Transport → Network → Data Link → Physical
TCP: reliable, connection-oriented; UDP: fast, connectionless
80 / 443
21 / 25 / 53
32-bit (~4.3 billion) vs 128-bit (\(\sim3.4\times10^{38}\))
Tim Berners-Lee, 1991
1969; first packet-switched network
Infrastructure / Platform / Software as a Service
Confidentiality, Integrity, Availability
AES = symmetric; RSA = asymmetric
India's cyber law; Sec 43 (civil), Sec 66 (criminal, up to 3 yr)
India's cybersecurity incident response body, under MeitY
Volume, Velocity, Variety, Veracity, Value
Decentralised, immutable distributed ledger
2022; peak 20 Gbps; latency <1 ms
Launched 2015 / optical fibre to gram panchayats
| Topic | Paper I Focus |
|---|---|
| Computer Fundamentals | Number system conversions; 2's complement; byte/KB/MB conversions |
| Operating Systems | Scheduling algorithm comparison; Round Robin quantum trade-off; thrashing |
| Computer Networking | OSI layer recall; TCP vs UDP; device-to-layer matching |
| Internet & Web Tech | Port number recall; IaaS/PaaS/SaaS classification |
| Cybersecurity | CIA triad application; symmetric vs asymmetric encryption; IT Act sections |
| Emerging Technologies | Big Data 5 V's; blockchain consensus mechanisms; India ICT initiative-year matching |
Q1. Represent −12 in 8-bit 2's complement.
Q2. Which OSI layer is responsible for end-to-end reliable delivery using port numbers?
Q3. A file server needs guaranteed, ordered delivery of large files. Should it use TCP or UDP?
Q4. An attacker floods a web server with traffic, making it unavailable to legitimate users. Which CIA triad objective is violated?
Q5. Digital India was launched in 2015; 5G was launched in India in 2022. How many years apart are these two milestones?