Fundamental Concepts and Working Principles of Blockchain Technology BBLC Practice Questions (Page 1)

Questions 1–5

1. 1expert · hard

   A pharmaceutical company is implementing a blockchain to track the cold chain of vaccines. They need to ensure that temperature data recorded by IoT sensors is trustworthy and cannot be falsified by a malicious sensor. Which combination of blockchain features would best address this concern?

   • ADigital signatures and hardware-based identity for IoT sensors, combined with a permissioned blockchain that only accepts data from registered sensors.
   • BImmutability and transparency, because once data is recorded, it cannot be changed and is visible to all participants.
   • CSmart contracts that automatically reject temperature readings outside a valid range.
   • DDecentralization and consensus, because multiple nodes must agree on the validity of transactions.
   Reveal Solution Discussion Select an answer first
2. 2expert · hard

   A blockchain auditor is verifying the integrity of a private blockchain used for medical records. The auditor has access to the full ledger and wants to confirm that a specific record in block 500 has not been altered since it was written. Which approach provides the strongest cryptographic evidence?

   • ACheck the block size of block 500 to ensure it matches the expected size.
   • BCompare the hash of block 500's header with the hash stored in block 501's header.
   • CVerify the digital signature of the transaction that created the record, using the sender's public key.
   • DCheck the timestamp of block 500 to ensure it is within the expected time range.
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4. 3application · medium

   A consortium of five banks wants to use a shared blockchain for interbank reconciliation. They need fast finality, low energy consumption, and the ability to control which nodes can participate. They do not require a mechanism that prevents Sybil attacks from unknown actors. Which consensus approach is most appropriate for this scenario?

   • AProof of Work (PoW) on a public blockchain, because it provides the highest level of security against malicious insiders.
   • BA permissioned consensus mechanism such as Practical Byzantine Fault Tolerance (PBFT) on a private/consortium blockchain, where only approved nodes validate transactions.
   • CA delegated Proof of Stake (DPoS) mechanism on a public blockchain, because it combines energy efficiency with democratic governance.
   • DProof of Stake (PoS) on a public blockchain, because it is energy-efficient and allows any stakeholder to participate.
   Reveal Solution Discussion Select an answer first
5. 4foundation · easy

   How does blockchain provide transparency to its participants?

   • AOnly the network administrator can view transactions.
   • BTransactions are visible only after they are encrypted with a private key.
   • CAll participants can view the entire transaction history on the ledger.
   • DParticipants can view only their own transactions.
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6. 5application · medium

   A startup is building a decentralized marketplace where buyers and sellers transact directly without a central intermediary. They are considering using a public blockchain. What is the primary trade-off they must accept when choosing a fully decentralized public blockchain over a centralized platform?

   • AReduced need for trust in a central authority, but slower transaction throughput and higher latency
   • BSimpler regulatory compliance because there is no central entity to regulate
   • CLower operational costs because there is no need to maintain infrastructure
   • DIncreased transaction speed because there is no central server to bottleneck
   Reveal Solution Discussion Select an answer first