UPSC Prelims 2026Question 86Science & Technology

Which of the following statements regarding the features of blockchain technology are correct ?
1. Records stored in the database may be made visible to relevant stakeholders without risk of alteration.
2. Copies of the entire database are stored on multiple computers on a network, syncing within seconds.
3. Consortium blockchain is a blend of public and private blockchains allowing selective data access.
4. Mathematical algorithms make it impossible to change or delete any data once recorded and accepted.
Select the answer using the code given below:

Options

(a)1 and 3
(b)2 and 4 only
(c)1, 2 and 4
(d)1 and 4 only

Correct answer: c

Decision rule

Consortium blockchain is group-governed and permissioned; the 'blend of public and private with selective access' description belongs to hybrid blockchain.

Explanation

Correct Answer

(c) 1, 2 and 4

Explanation of the Correct Answer

Blockchain is a distributed ledger technology where data is recorded in blocks, linked cryptographically, and maintained across multiple computers or nodes.

Statement 1 is correct

Blockchain records can be made visible to relevant stakeholders.
Since records are cryptographically secured and distributed across the network, they are difficult to alter without detection.
This allows transparency with integrity.

Statement 2 is correct

In many blockchain networks, copies of the ledger are stored on multiple computers called nodes.
These copies are updated and synchronized when new blocks are validated and added.
This distributed storage reduces dependence on a single central authority.

Statement 3 is incorrect

A consortium blockchain is a permissioned blockchain controlled by a group of organizations.
The description “blend of public and private blockchains allowing selective data access” more accurately refers to a hybrid blockchain, not a consortium blockchain.
Consortium blockchain is not simply a public-private blend; it is a federated / group-governed blockchain.

Statement 4 is correct

Blockchain uses cryptographic hashing, consensus mechanisms, and linked block structures.
Once a block is validated and added, changing or deleting data becomes extremely difficult because it would require altering subsequent blocks and gaining network consensus.
In examination language, this is treated as blockchain’s feature of immutability.

Thus, statements 1, 2 and 4 are correct.

Why Other Options Are Incorrect

Option	Verdict	Explanation
(a) 1 and 3	Incorrect	Statement 1 is correct, but Statement 3 is incorrect because it describes hybrid blockchain more than consortium blockchain.
(b) 2 and 4 only	Incorrect	Statements 2 and 4 are correct, but Statement 1 is also correct.
(c) 1, 2 and 4	Correct	These statements correctly describe transparency, distributed storage, synchronization, and immutability in blockchain.
(d) 1 and 4 only	Incorrect	Statements 1 and 4 are correct, but Statement 2 is also correct.

Relevant Supplementary Information

Key Features of Blockchain Technology

Feature	Meaning	Importance
Distributed ledger	Copies of the database are maintained across multiple nodes	Reduces single-point failure
Transparency	Relevant participants can view transactions depending on permission level	Builds trust among stakeholders
Immutability	Once validated, records are extremely difficult to alter	Prevents tampering and fraud
Cryptographic security	Data is secured using hashing and digital signatures	Ensures integrity and authentication
Consensus mechanism	Network participants validate transactions through agreed rules	Removes need for a central authority
Traceability	Transaction history can be tracked	Useful in supply chains, finance, and governance
Decentralization	Control is shared among participants	Reduces dependence on one central entity

Types of Blockchain

Type of Blockchain	Access	Control / Governance	Examples / Uses
Public blockchain	Open to everyone	Decentralized	Bitcoin, Ethereum
Private blockchain	Restricted access	Single organization controls participation	Internal enterprise records
Consortium blockchain	Restricted to selected organizations	Governed by a group or consortium	Banking networks, inter-company supply chains
Hybrid blockchain	Mix of public and private elements	Some data public, some restricted	Selective disclosure systems, enterprise-public interfaces

Type of Blockchain	Access	Control / Governance	Typical Use Cases
Public blockchain	Open to anyone	Highly decentralized	Cryptocurrencies, open decentralized applications
Private blockchain	Restricted to selected users	Controlled by one organization	Internal company records, enterprise data sharing
Consortium blockchain	Restricted to selected organizations	Controlled by a group of organizations	Banking networks, trade finance, supply chains
Hybrid blockchain	Combines public and private elements	Some data public, some data restricted	Selective data-sharing systems, regulated enterprise platforms

Key Takeaways from the Tables

Point	Explanation
Blockchain is distributed	Copies of the ledger are stored across multiple nodes.
Blockchain is tamper-resistant	Cryptography and consensus make alteration extremely difficult.
Transparency does not always mean public access	Visibility depends on whether the blockchain is public, private, consortium, or hybrid.
Consortium blockchain is group-governed	It is controlled by selected organizations, not merely a public-private blend.
Hybrid blockchain is the actual public-private blend	This distinction is important for eliminating Statement 3.

Point	Explanation
Blockchain is not just cryptocurrency	Cryptocurrency is one use case; blockchain is the underlying technology.
Immutability is central	Blockchain records are difficult to change once accepted by the network.
Distributed storage improves resilience	Multiple copies of the ledger reduce dependence on a central database.
Consortium blockchain is group-controlled	It is governed by selected organizations, not open to everyone.
Hybrid blockchain combines public and private features	This is the correct term for a public-private blend with selective disclosure.
Blockchain is useful where trust is limited	It works best in multi-party systems requiring auditability and tamper-resistance.

Context and Current Relevance

Blockchain is increasingly used in finance, supply-chain tracking, digital identity, land records, health records, and public service delivery.
Its value lies in creating trusted records among parties who may not fully trust each other.
However, blockchain does not automatically guarantee good governance; its usefulness depends on proper design, regulation, data quality, and cybersecurity.

Table: Core Features of Blockchain Technology

Feature	Meaning	Why It Matters
Distributed ledger	A copy of the ledger is maintained across multiple computers or nodes	Reduces dependence on a single central database
Immutability	Once data is recorded and validated, it becomes extremely difficult to alter or delete	Helps prevent tampering and fraud
Transparency	Records may be visible to relevant participants depending on the type of blockchain	Builds trust among stakeholders
Cryptographic security	Data is protected using hashing, encryption, and digital signatures	Ensures data integrity and authentication
Consensus mechanism	Participants follow agreed rules to validate transactions	Allows trust without a single central authority
Traceability	Transactions can be tracked from origin to current state	Useful in supply chains, land records, finance, and governance
Decentralization	Control is distributed among participants rather than concentrated in one entity	Reduces single-point control and failure
Programmability	Smart contracts can automate certain actions when conditions are met	Enables automated payments, compliance, and agreements

Table: Consortium vs Hybrid Blockchain

Basis	Consortium Blockchain	Hybrid Blockchain
Basic nature	Federated blockchain	Public-private mixed blockchain
Controlled by	Group of organizations	Single organization or group with public-private design
Access	Limited to members of the consortium	Some parts public, some parts private
Data visibility	Shared among authorized consortium members	Selective visibility depending on design
Best example use	Banks jointly maintaining a transaction network	Company keeping private data internal while publishing proofs publicly
Key idea	Shared governance among trusted institutions	Combination of openness and privacy

Table: Blockchain vs Traditional Database

Basis	Traditional Database	Blockchain Database
Control	Usually controlled by one central authority	Distributed among nodes or participants
Data modification	Data can generally be edited or deleted by authorized administrators	Validated records are extremely difficult to change or delete
Trust model	Trust is placed in the central authority	Trust is created through cryptography and consensus
Transparency	Visibility depends on administrator permissions	Visibility can be built into the network design
Failure risk	Central server failure can affect the system	Multiple copies reduce single-point failure
Best suited for	Internal databases, fast centralized processing	Multi-party trust, audit trails, tamper-resistant records
Speed	Generally faster	Can be slower due to consensus and validation
Governance	Centralized	Decentralized, federated, or permissioned depending on type

Table: Important Blockchain Terms

Term	Meaning	Importance
Block	A group of validated transactions or records	Basic unit of blockchain data
Chain	Blocks linked chronologically using cryptographic hashes	Creates tamper-resistant history
Node	A computer participating in the blockchain network	Stores, verifies, or transmits data
Hash	A fixed-length digital fingerprint of data	Helps detect any change in stored data
Consensus	Agreement mechanism for validating transactions	Prevents unauthorized or false entries
Smart contract	Self-executing code stored on blockchain	Automates transactions and agreements
Token	Digital unit of value or representation of an asset	Used in cryptocurrencies, assets, voting, or access systems
Mining	Process of validating blocks in some public blockchains	Used in proof-of-work systems like Bitcoin
Validator	Participant that verifies transactions in some blockchain systems	Used in proof-of-stake and permissioned systems
Ledger	Record of transactions	Blockchain is a distributed ledger

Table: Blockchain Applications

Sector	Use of Blockchain	Benefit
Finance	Payments, settlements, trade finance	Faster reconciliation and trusted records
Supply chain	Tracking goods from origin to destination	Improves traceability and reduces fraud
Land records	Recording ownership and transfers	Reduces tampering and disputes
Healthcare	Secure sharing of medical records	Improves data integrity and access control
Governance	Certificates, identity, welfare delivery records	Enhances transparency and auditability
Education	Degree and certificate verification	Prevents fake certificates
Agriculture	Farm-to-market traceability	Helps verify origin and quality
Insurance	Claims processing and smart contracts	Reduces fraud and delays

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