UPSC Prelims 2026 Question:

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 selective data access. public and private blockchains allowing

4. Mathematical algorithms make it impossible to change or delete any data once recorded and accepted.

Select the answer using the code given below:

Answer: 3 

Explanation:  

Blockchain is a distributed ledger technology in which records are stored in blocks and linked using  cryptographic techniques. Once validated and added to the chain, records become difficult to alter without  consensus from the network, which makes blockchain useful for transparent and tamper-resistant record-keeping. 

• Records stored on a blockchain may be made visible to relevant stakeholders, depending on the type  of blockchain and access permissions. Since validated records are cryptographically linked and cannot be  altered unilaterally, they can be shared without the normal risk of unauthorised alteration. So, statement  1 is correct. 
• In a distributed blockchain network, copies of the ledger are maintained on multiple computers or  nodes. These copies are periodically synchronised across the network so that participants work with the  same validated version of the database. So, statement 2 is correct. 
• A consortium blockchain is not simply a blend of public and private blockchains allowing selective  data access. It is a permissioned blockchain governed by a group of organisations rather than by a single  entity or by unrestricted public participation. The statement is loosely worded and does not correctly  define consortium blockchain. So, statement 3 is not correct. 
• Blockchain uses cryptographic hashing, consensus mechanisms and mathematical algorithms to make  alteration or deletion of accepted records extremely difficult. Once data is recorded and validated,  changing it would require altering linked blocks and gaining network consensus, making tampering  practically infeasible. So, statement 4 is correct. 

Therefore, option (3) is the correct answer.