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 :
- (a) 1 and 3
- (b) 2 and 4 only
- (c) 1, 2 and 4 ✓ UPSC's answer
- (d) 1 and 4 only
Why the answer is (c)
• A blockchain is a distributed ledger: every participating node holds a full copy that is updated and synchronised as new blocks are added — statement 2 is correct.
• Records are visible to authorised participants, and because each block is cryptographically linked to the previous one, they can be shared without risk of undetected alteration — statement 1 is correct.
• Cryptographic hashing and consensus make it practically impossible to change or delete data once a block is accepted (immutability) — statement 4 is correct.
• Statement 3 is wrong: a consortium blockchain is a permissioned ledger governed jointly by a group of organisations; the 'blend of public and private with selective access' describes a hybrid blockchain.
• Hence 1, 2 and 4, option (c).
Why the other options are wrong
- (a) 1 and 3
- Statement 3 misdescribes consortium blockchains; statements 2 and 4 are correct too.
- (b) 2 and 4 only
- Statement 1 on tamper-evident visibility is also correct.
- (d) 1 and 4 only
- Statement 2 on distributed synchronised copies is also correct.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2026, held on 24 May 2026. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.