Fundamental Concepts and Working Principles of Blockchain Technology BFC Practice Questions (Page 9)

Questions 41–45

1. 41application · medium

   A developer is building a blockchain-based voting system for a corporate shareholder meeting. They need to ensure that once a vote is cast, it cannot be changed without detection. Which use of cryptographic hashing best supports this requirement?

   • AStoring the voter's IP address in the block header
   • BEncrypting each vote with the voter's private key
   • CUsing a random nonce to make each block unique
   • DStoring the hash of each vote in a Merkle tree and including the Merkle root in the block header
   Reveal Solution Discussion Select an answer first
2. 42foundation · easy

   How does a blockchain achieve immutability?

   • ABy using a central authority that approves all changes
   • BBy linking blocks with cryptographic hashes and requiring consensus to add new blocks
   • CBy storing all data in a read-only memory that cannot be modified
   • DBy encrypting all data with a private key that only the network owner holds
   Reveal Solution Discussion Select an answer first
4. 43expert · hard

   A financial regulator is evaluating a permissioned blockchain for interbank settlement. The network has 15 member banks. The regulator requires that no single bank can unilaterally finalize a block, but also demands that the network remain operational even if up to 4 banks are compromised. The network must also be energy-efficient. Which consensus configuration best satisfies these constraints?

   • AA Proof of Work consensus requiring 51% of the network's hashing power.
   • BA Byzantine Fault Tolerant (BFT) consensus requiring at least 10 of 15 validators to agree.
   • CA single designated leader bank that proposes all blocks, with other banks auditing after the fact.
   • DA simple majority vote requiring 8 of 15 validators to agree.
   Reveal Solution Discussion Select an answer first
5. 44foundation · easy

   In what way does blockchain enhance transparency in financial services?

   • ABy encrypting all transactions so that no one can see them
   • BBy providing a shared, immutable record of transactions that all authorized participants can view
   • CBy hiding transaction details from all participants except the central bank
   • DBy allowing only auditors to see transaction records
   Reveal Solution Discussion Select an answer first
6. 45application · medium

   A fintech startup is building a cross-border payment system where multiple banks need to jointly maintain a shared record of transactions, but no single bank should have unilateral control over the ledger. The system must allow each bank to verify the integrity of the entire transaction history independently. Which approach best meets these requirements?

   • ADeploy a distributed ledger where each bank runs a node, blocks are linked via cryptographic hashes, and consensus is required before appending new transactions.
   • BImplement a peer-to-peer file sharing system where each bank stores a copy of a signed transaction log, updated via email.
   • CCreate a shared spreadsheet on a cloud drive with version history enabled for all banks to edit.
   • DUse a centralized database hosted by one bank, with read-only replicas provided to the other banks for verification.
   Reveal Solution Discussion Select an answer first