Data and Transaction Flow in Blockchain BDC Practice Questions (Page 2)

Questions 6–10

1. 6application · medium

   A company is building a supply chain tracking system on a blockchain. They need to store large documents (e.g., certificates of origin) but want to minimize on-chain storage costs. What is the best approach?

   • AStore the documents in the mempool until they are needed.
   • BStore the documents off-chain and store only a cryptographic hash on-chain.
   • CStore the documents in the block header to save space.
   • DStore the documents on-chain and reference them in transactions.
   Reveal Solution Discussion Select an answer first
2. 7application · medium

   A developer is explaining to a client how a blockchain guarantees that a historical block cannot be altered without detection. The developer points to the block header's previous hash and the Merkle root. Which property do these two elements together provide?

   • AThey ensure that all nodes agree on the order of transactions within a block
   • BThey allow any node to verify that a transaction was included in a block without downloading the entire block
   • CThey encrypt the transaction data so that only authorized parties can read it
   • DThey create a cryptographic link between blocks and a compact summary of all transactions in the block
   Reveal Solution Discussion Select an answer first
4. 8foundation · easy

   How is a newly mined block propagated to the rest of the blockchain network?

   • AStored locally and only shared when the next block is mined
   • BPublished on a public website for nodes to download
   • CSent directly to a central server that updates all nodes
   • DBroadcast to neighboring nodes, which validate and relay it to their peers
   Reveal Solution Discussion Select an answer first
5. 9application · medium

   A developer is building a custom blockchain client and wants to ensure that a transaction with an invalid signature is not added to the mempool. Which validation step should be performed first?

   • ACheck that the transaction's nonce matches the sender's account state.
   • BEnsure the transaction's fee is above the network's minimum threshold.
   • CConfirm that the transaction's inputs reference unspent outputs.
   • DVerify the cryptographic signature of the transaction against the sender's public key.
   Reveal Solution Discussion Select an answer first
6. 10application · medium

   A developer is explaining to a client why a transaction on a Proof-of-Work blockchain is not immediately final after being included in a block. Which factor contributes to the lack of immediate finality?

   • AThe block may be orphaned if another miner produces a competing block at the same time.
   • BThe transaction's signature is not verified until several blocks are added.
   • CThe block's Merkle root is not finalized until the next block is mined.
   • DThe transaction is not broadcast to all nodes until the block is confirmed.
   Reveal Solution Discussion Select an answer first