Current Affairs, Defence & Computer Basics

Missiles and rocket propulsion

A rocket engine is classified by the state of its propellant, and the two main families are solid and liquid propulsion. A solid propellant is a pre-mixed composite of fuel and oxidiser that burns once the igniter starts, with no throttle and no shutdown once lit. Composite solid propellants such as ammonium perchlorate mixtures often contain aluminium powder, which raises the energy released and the combustion temperature. Liquid engines store fuel and oxidiser separately and pump them into the chamber, which allows throttling and restart. The key performance measure is specific impulse, I_{sp} = \frac{F}{\dot{m}g_0}, where F is thrust, \dot{m} is the propellant mass flow rate and g_0 is standard gravity. Liquid propellant engines generally have a higher specific impulse, so they give more thrust per unit of propellant burned, while solid motors win on simplicity, storage and readiness. Missile types must also be separated: a cruise missile flies within the atmosphere on a wing-supported aerodynamic path, whereas a ballistic missile follows an unpowered arc after a boosted phase. Among Indian systems, BrahMos is the supersonic cruise missile, Agni-I is a surface-to-surface ballistic missile and Dhanush is a naval ballistic missile. Foreign systems are often tested by origin, for example the Kh-47M2 Kinzhal is an air-launched hypersonic missile of Russia carried by MiG-31 aircraft. Reusable launchers such as Falcon 9 are a separate topic, since its first stage is designed to land for reuse, and the company that builds it is SpaceX.

Indian Navy deployments and defence diplomacy

The Indian Navy is the service that operates India's maritime security missions and its defence diplomacy in the Indian Ocean Region. Operation Sankalp, launched in 2019, was a naval escort mission to protect Indian-flagged merchant ships in the Gulf of Oman and the Persian Gulf, so it is a naval, not an army or air force, operation. India also gives defence hardware to neighbours to build maritime domain awareness, and coastal surveillance radar systems are a common form of this assistance to Indian Ocean partners such as the Maldives. The Navy also runs sail-training and outreach voyages; the Navika Sagar Parikrama programme uses sailing vessels with mixed or all-women crews to circumnavigate the globe, and INSV Tarini completed an intercontinental voyage under it. Do not confuse these sailing vessels with training ships such as INS Tarangini or INS Mandovi, which serve different roles. Important terms for the exam are 'maritime domain awareness' (knowledge of all activity at sea that can affect security), 'HADR' (humanitarian assistance and disaster relief) and 'SAGAR' (Security and Growth for All in the Region), the vision India uses for the Indian Ocean.

Computer memory, storage and bus architecture

A computer moves information through a bus, which is a set of parallel wires that carries data, memory addresses and control signals among the CPU, memory and other components inside the machine. The bus is an internal transfer path, unlike a port, which is an external socket for connecting a peripheral, or a hub and a router, which are networking devices. The memory hierarchy is organised by speed, size and cost: registers are fastest and smallest, cache memory sits close to the CPU and is small, fast and expensive per bit, main memory (RAM) is larger and cheaper per bit, and secondary storage such as hard disks or SSDs is the largest and slowest. The cache exists because the CPU is much faster than main memory, so frequently used data is kept close to it. Units of storage follow the binary system, in which 1\text{ KB} = 1024\text{ bytes}, 1\text{ MB} = 1024\text{ KB} and 1\text{ GB} = 1024\text{ MB}. So one gigabyte in binary terms equals 1024 \times 1024 = 1{,}048{,}576 kilobytes. Exam questions often mix the binary and decimal systems, so check which is intended.

Climate change and greenhouse gas mitigation

Climate change governance is built on the United Nations Framework Convention on Climate Change (UNFCCC), which set the framework for later agreements, and the Paris Agreement, which sets the global target of holding warming well below 2 degrees Celsius. Action for Climate Empowerment (ACE) is a UNFCCC term for the work programme under Article 6 of the Convention, covering education, training, public awareness, public participation and public access to information. Its links to the Paris Agreement come through Article 12, which covers climate change education and public awareness, so ACE is both a UNFCCC and a Paris-related concept. Climate Neutral Now is a UNFCCC initiative launched in 2015 that invites organisations, cities and other stakeholders to measure and publicly report their greenhouse gas emissions, reduce them and offset what remains. It is a voluntary reporting initiative, and its aims derive from the Paris Agreement, but it does not set a specific carbon neutral deadline for the whole world. Key terms to know are 'mitigation' (cutting emissions), 'adaptation' (adjusting to impacts), 'carbon neutrality' (net zero emissions) and 'offsetting' (compensating for emissions elsewhere).

Geographic Information System basics

A Geographic Information System (GIS) captures, stores, analyses and displays data that is linked to locations on the Earth's surface. Its standard components are hardware (the computer and devices on which it runs), software (the tools for spatial analysis and mapping), data (spatial and attribute information), people (the operators and analysts) and methods (the procedures for using the system). Data in a GIS is stored in two main formats. The raster format divides a surface into a regular grid of equal-sized cells, each holding one value; its simple structure matches satellite and remote sensing imagery, which is also gridded. The vector format represents features as points, lines and polygons with defined coordinates. The resolution of a raster depends on the relationship between cell size and the number of cells covering an area, so smaller cells give finer detail but more storage. When studying GIS, remember that the raster format suits continuous surfaces such as elevation or satellite images, while the vector format suits discrete objects such as roads, boundaries and utility lines.

TCP/IP protocol layers

The TCP/IP model organises network communication into layers, usually described as the network access (link), internet, transport and application layers. Each layer offers services to the layer above it and uses the layer below. The application layer contains protocols that serve end-user programs, such as FTP for file transfer, HTTP for web communication and DNS for converting domain names into IP addresses. The internet layer is responsible for logical addressing and routing packets between networks, and its main protocol is the Internet Protocol (IP), which is therefore not an application-layer protocol. The transport layer uses TCP for reliable, connection-oriented delivery and UDP for faster connectionless delivery. A quick way to classify any protocol is to ask whether it serves the user's program directly (application), moves data reliably between two hosts (transport), or finds the route between networks (internet). Remember that IP addresses the packet, while the application protocol defines the meaning of the messages.

NITI Aayog SDG India Index

The SDG India Index is a tool developed by NITI Aayog, the government's policy think tank, to track the performance of States and Union Territories against the United Nations Sustainable Development Goals. Based on scores, the States and UTs are placed in four categories: Aspirants, Performers, Front Runners and Achievers. These labels describe progress levels, with Achievers being the highest and Aspirants the lowest band. In exam questions, the most common trap is an invented category name that sounds plausible, such as a term implying speed, so the exact official labels must be memorised. Along with the index, NITI Aayog publishes dashboards and reports that compare states across goals such as health, education, clean energy and gender equality. When answering, match each category name exactly against the official list rather than relying on how the word sounds.

Border Roads Organisation

The Border Roads Organisation (BRO) is a force under the Ministry of Defence that builds and maintains roads in border areas and other strategically sensitive regions. Its work includes strategic roads, tunnels and bridges in the Himalayas and in the north-east, which support both defence logistics and civilian access. Because many of these roads run over high passes, the BRO also carries out snow clearance and maintenance so that routes such as those to Ladakh stay open for much of the year. The BRO is therefore associated with both the construction and the upkeep of high-altitude and border roads. Students often confuse it with other bodies, so remember that the BRO is a Defence Ministry organisation, not a civil road agency such as the National Highways Authority of India. Exam statements often test this combination of construction, maintenance and snow clearance, and all of these are standard BRO functions.

Naval aircraft launch technology

Launching aircraft from a warship is a central problem in naval aviation, because a carrier's deck is much shorter than a land runway. The Electromagnetic Aircraft Launch System (EMALS) is an electromagnetic catapult that accelerates an aircraft to take-off speed over a short distance using electrical energy and magnetic force, instead of the steam pressure used in older catapults. It was developed for large US Navy aircraft carriers, and it allows heavier and more varied aircraft to be launched more smoothly. Other launch methods include the steam catapult, used on many carriers, and the ski-jump ramp, which gives an aircraft upward lift at the end of the deck; India's INS Vikrant uses a ski-jump. Keep these three methods distinct, since the exam tests which technology is used for aircraft launching. Electromagnetic launching is unrelated to missile silos, submarine navigation or the reuse of rockets.

Indian military helicopters

Indian military helicopters are grouped by role: attack or armed helicopters, light utility helicopters, and transport helicopters. The Rudra is the weaponised version of the Advanced Light Helicopter (ALH) and carries a turret gun, rocket pods and air-to-air missiles, so it is the attack helicopter in this group. The Cheetah and Chetak are light utility helicopters used for transport, reconnaissance and logistic support, and they are not fitted with the combined armament carried by the Rudra. The Cheetah is a derivative of the Lama series, and the Chetak is an Alouette-based light helicopter. A useful exam tip is to link each weapon system to its helicopter. A turret gun, rockets and air-to-air missiles together signal an armed attack helicopter, while a plain utility role signals a helicopter with no integrated armament.

Fighter aircraft: Mirage, Tejas, Rafale

Fighter aircraft are distinguished by their engine count, wing shape and role, and exam statements test these features. The Mirage 2000, developed by Dassault Aviation of France, is a single-engine fighter with a delta wing. The HAL Tejas, a light combat aircraft designed in India, has a tailless delta wing and a single engine. The Rafale, also from Dassault, is a twin-engine multirole fighter that can perform many roles, but it is not a hypersonic aircraft, since hypersonic flight refers to speeds above Mach 5 and no fighter in service is a hypersonic type of this kind. A quick checklist helps: count the engines first, then identify the wing configuration, and then identify whether the aircraft is a multirole or a light combat type. The delta wing is a triangular wing used by several types, including the Mirage 2000 and the Tejas, so its presence alone does not identify a particular aircraft.

Russia–Ukraine conflict geography

Geographic questions on the Russia–Ukraine conflict usually test the location of the cities and seas that appear in the news. Mariupol is a port city in the Donetsk region of eastern Ukraine, located on the northern coast of the Sea of Azov. The Sea of Azov is linked to the Black Sea through the Kerch Strait, which makes it a strategically important waterway. The Aral Sea, the Caspian Sea and the Baltic Sea are located in other parts of Eurasia, and none of them borders Mariupol. Knowing the seas that border Ukraine, which are the Black Sea and the Sea of Azov, is therefore the key to this type of question. Also note that the Caspian and Aral seas are both landlocked, whereas the Baltic is an arm of the Atlantic linked to northern Europe.

Central Armed Police Forces

The Central Armed Police Forces (CAPF) are the central paramilitary forces that come under the Ministry of Home Affairs and assist in internal security, border guarding and counter-insurgency. They include the Assam Rifles, the Border Security Force, the Central Reserve Police Force, the Central Industrial Security Force, the Indo-Tibetan Border Police, the Sashastra Seema Bal and the National Security Guard. Their origins differ widely, and the exam often asks which is the oldest. The Assam Rifles, raised in 1835, is the oldest of the Central Paramilitary Forces, while the Central Reserve Police Force dates from 1939, the Border Security Force from 1965, and the Commando Battalion for Resolute Action from 2008. Remember that the oldest force is the one with the earliest founding year, and that the year of raising is the most reliable clue for these questions.

Operating systems and software types

Software is divided into system software and application software. System software manages the hardware and gives application programs a platform to run, and the operating system is its central part. Operating systems include MS-Windows, Linux and Ubuntu, where Ubuntu is a distribution built on the Linux kernel. Application software performs tasks for the user, and a spreadsheet program such as MS-Excel, a word processor and a web browser are all examples. An application runs on top of the operating system and depends on it for memory, file access and input-output. When an exam asks which item is not an operating system, check whether it manages hardware or whether it performs a user task. A program that calculates and charts data is application software, not system software.

NFTs and blockchain

A blockchain is a distributed, tamper-resistant ledger in which records are grouped into blocks linked by cryptographic hashes. A non-fungible token (NFT) is a unique digital token recorded on a blockchain that certifies ownership of a specific digital item, such as an artwork, a music file or a collectible. The term 'non-fungible' means that each token is unique and cannot be swapped one-for-one with another, in contrast with fungible assets such as a currency unit, where any unit is interchangeable with another. Cryptocurrencies such as Bitcoin are fungible tokens, which is why they differ from NFTs. NFTs are therefore a digital-asset concept and have no direct link to banking channels, such as banking correspondents, multifactor authentication or small finance banks. Exam options that mix NFTs with banking security or banking categories should be rejected.

CERT-In cyber security directions

The Indian Computer Emergency Response Team (CERT-In) is the national nodal agency for responding to cyber security incidents, and it issues directions under the Information Technology Act. The 2022 directions require service providers, data centres, body corporates and intermediaries to report specified cyber security incidents to CERT-In within six hours of noticing them, which is a shorter period than the figure of 24 hours that some statements use as a distractor. The directions also require the maintenance of logs for a specified period, and Virtual Private Network (VPN) providers must register and keep subscriber data for five years and share it with authorities when required. These record-keeping and reporting rules are the features most often tested. For exam purposes, memorise the six-hour reporting window and the five-year VPN data retention period as the two most frequently tested facts.

IPL cricket tournament records

The Indian Premier League (IPL) is a franchise-based Twenty20 cricket tournament held in India, and its records are a common source of exam statements. Chennai Super Kings and Mumbai Indians have each won the title five times, which makes them the most successful franchises in the tournament's history. Runner-up records are as important as winners, and Chennai Super Kings have finished as runner-up several times over the tournament's history. Some editions were moved outside India for reasons such as elections or the pandemic, so the venue of a final must be checked against the edition, since a final can be held in another country. The tournament is also important for its player auction and franchise structure. When answering record-based questions, verify each claim separately, because one wrong detail in a statement can make the whole option false.

Khelo India sports events

Khelo India is a government programme that promotes sport at the grassroots, school and university levels, and it includes events such as the Khelo India University Games (KIUG). These games are a multi-sport competition for university students, organised under the programme and hosted by different states in different editions. Exam questions test edition-wise details, such as the host state of the first edition, the mascot of a later edition, and whether an edition was postponed by the pandemic. Edition-specific facts are easy to confuse, so learn them as a table of edition, host and mascot. The first edition was held in Odisha, which is the fact tested in one statement, but the claim that it was postponed due to COVID does not match the record of that edition. Always check the year, host and mascot separately.