Data and Transaction Flow in Blockchain BDC Practice Questions (Page 4)

Questions 16–20

1. 16expert · hard

   A developer is designing a blockchain for a financial application that requires immediate finality. Which consensus mechanism should they choose to meet this requirement?

   • AProof-of-Work (PoW) with a low difficulty target.
   • BDelegated Proof-of-Stake (DPoS) with frequent block production.
   • CProof-of-Stake (PoS) with a long epoch duration.
   • DProof-of-Authority (PoA) with a fixed set of validators.
   Reveal Solution Discussion Select an answer first
2. 17application · medium

   A blockchain developer is explaining to a colleague how a Merkle tree helps verify the integrity of transactions in a block. Which property of the Merkle tree is most relevant?

   • AIt orders the transactions in a specific sequence for mining.
   • BIt allows a node to verify a single transaction without downloading the entire block.
   • CIt encrypts the transactions to prevent unauthorized access.
   • DIt compresses the transactions to reduce the block size.
   Reveal Solution Discussion Select an answer first
4. 18application · medium

   A blockchain developer is explaining to a client why a transaction that received one confirmation on a proof-of-work network is not considered absolutely final. Which statement accurately describes the situation?

   • AThe transaction is final because it was included in a valid block
   • BThe transaction is final only after the block is propagated to all nodes
   • CThe transaction could be reversed if a longer competing chain is built that does not include it
   • DThe transaction is final only if the sender's wallet shows it as confirmed
   Reveal Solution Discussion Select an answer first
5. 19application · medium

   A developer is testing a private Ethereum network and submits a transaction with a gas price of 1 gwei. The network's current base fee is 2 gwei, and the mempool is nearly empty. The transaction has been pending for several minutes. What is the most likely reason the transaction has not been mined?

   • AThe transaction lacks a sufficient nonce, so it is being held for reordering.
   • BThe transaction's gas price is below the network's base fee, so it is not eligible for inclusion in a block.
   • CThe transaction was not broadcast to enough peers, so it has not reached a miner.
   • DThe mempool is empty, so the node is waiting for more transactions to batch before mining.
   Reveal Solution Discussion Select an answer first
6. 20foundation · easy

   Which of the following is a standard validation check performed by a node when verifying a transaction?

   • AEnsuring the transaction fee is the highest in the mempool
   • BConfirming that the transaction was created by a known miner
   • CVerifying that the digital signature is valid and the inputs have sufficient balance
   • DChecking that the transaction timestamp is in the future
   Reveal Solution Discussion Select an answer first