Bitcoin Blockchain Architecture and Network Transactions BFC Practice Questions (Page 6)

Questions 26–30

1. 26expert · hard

   A blockchain developer is building a system that needs to verify that a bitcoin transaction is included in the blockchain without downloading the entire blockchain. Which technique should they use?

   • ADownload the entire blockchain and validate every block.
   • BUse a block explorer API to check the transaction status.
   • CAsk a miner to provide a signed receipt for the transaction.
   • DUse a lightweight node that downloads block headers and requests merkle proofs from full nodes.
   Reveal Solution Discussion Select an answer first
2. 27foundation · easy

   In a standard Pay-to-Public-Key-Hash (P2PKH) transaction, what does the unlocking script (scriptSig) typically contain?

   • AThe sender's public key and a digital signature
   • BThe transaction fee and a timestamp
   • CThe recipient's public key and a digital signature
   • DThe sender's private key
   Reveal Solution Discussion Select an answer first
4. 28foundation · easy

   What mechanism primarily prevents double-spending in Bitcoin?

   • AThe combination of the UTXO set, consensus rules, and the longest-chain rule
   • BThe encryption of all transactions with a unique key
   • CThe requirement that each transaction be signed by both sender and recipient
   • DThe requirement that all transactions be approved by a central bank
   Reveal Solution Discussion Select an answer first
5. 29application · medium

   A bitcoin exchange is setting transaction fees for its users. They want to ensure transactions are confirmed quickly during periods of high network congestion. Which strategy is most effective?

   • AUse a dynamic fee estimator that adjusts fees based on current mempool conditions.
   • BSet a fixed fee of 1 sat/vB for all transactions.
   • CSet a fixed fee of 100 sat/vB for all transactions.
   • DSet fees based on the transaction amount, with higher amounts paying higher fees.
   Reveal Solution Discussion Select an answer first
6. 30application · medium

   A developer is building a blockchain explorer and needs to verify that a block is part of the canonical Bitcoin chain. Which property of the block header should they check?

   • AThe block's merkle root matches the previous block's merkle root.
   • BThe block's timestamp is within 2 hours of the current time.
   • CThe block's hash is less than the current difficulty target.
   • DThe block contains at least 10 transactions.
   Reveal Solution Discussion Select an answer first