Fundamental Concepts and Working Principles of Blockchain Technology BFC Practice Questions (Page 8)

Questions 36–40

1. 36application · medium

   A developer is building a blockchain-based supply chain tracker. The system records each step of a product's journey. The developer wants to ensure that if a malicious actor changes a record, the change is immediately detectable. Which mechanism should be used?

   • AUse a digital signature from a trusted authority on each record, but store records in a plain text file.
   • BEncrypt each record with a symmetric key and store the key on a central server.
   • CStore records in a database with a timestamp column and rely on database audit logs.
   • DStore the hash of each record in a Merkle tree, with the root hash included in the block header.
   Reveal Solution Discussion Select an answer first
2. 37application · medium

   A remittance company wants to reduce the time and cost of cross-border payments. Currently, payments take 3–5 days due to correspondent banking. The company wants to provide near-instant settlement with lower fees while maintaining a transparent audit trail. Which blockchain-based approach is most suitable?

   • AUse a permissioned blockchain shared with partner banks, where transactions are settled directly between parties using smart contracts.
   • BUse email-based payment instructions between banks, with manual reconciliation.
   • CUse a public cryptocurrency like Bitcoin and wait for six confirmations.
   • DUse a centralized database with a payment gateway that batches transactions daily.
   Reveal Solution Discussion Select an answer first
4. 38application · medium

   A startup is building a blockchain-based voting system for a large public election. The system must be open to all voters, and any participant should be able to verify the integrity of the results. The startup is concerned about energy consumption. Which consensus mechanism is most appropriate?

   • AProof of Work (PoW), which requires miners to solve complex puzzles.
   • BProof of Authority (PoA), where a few known validators are pre-approved.
   • CA centralized server that counts votes and publishes results.
   • DProof of Stake (PoS), where validators are selected based on the amount of cryptocurrency they hold and stake.
   Reveal Solution Discussion Select an answer first
5. 39application · medium

   A developer is designing a private blockchain for a supply-chain finance application. They need to ensure that each block is cryptographically linked to the previous one so that any attempt to alter an earlier block is immediately detectable. Which field in the block header is essential for this linkage?

   • AThe nonce used in mining
   • BThe previous block's hash
   • CThe block's timestamp
   • DThe Merkle root of transactions
   Reveal Solution Discussion Select an answer first
6. 40application · medium

   A blockchain developer is designing a system to store financial audit records. The requirement is that if any single record is altered after being written, the change must be detectable by any participant without needing to compare against a trusted central copy. Which design feature is essential to achieve this?

   • AEach block stores the cryptographic hash of the previous block's header, forming a chain where any change to an earlier record alters all subsequent hashes.
   • BThe system uses a checksum of the entire database stored on a single central server.
   • CRecords are stored in a sorted list with timestamps, and any change requires updating the timestamp.
   • DEach participant maintains a local backup of the entire database on their personal device, updated nightly.
   Reveal Solution Discussion Select an answer first