Bitcoin and Bitcoin Blockchain Architecture BDC Practice Questions (Page 9)

Questions 41–45

1. 41expert · medium

   A developer is optimizing a mining pool's software. The pool wants to minimize the number of times the block header is hashed while still allowing miners to vary the hash. Which field should the pool software modify most frequently to generate new candidate blocks?

   • AThe previous block hash in the block header
   • BThe timestamp field in the block header
   • CThe nonce field in the block header
   • DThe Merkle root in the block header
   Reveal Solution Discussion Select an answer first
2. 42expert · hard

   A mining pool is considering whether to mine an empty block to collect the block reward faster. The pool has a large hash rate and can find a block quickly. What is the primary trade-off the pool should consider?

   • AEmpty blocks are less likely to be accepted by the network
   • BEmpty blocks are invalid because they do not include the coinbase transaction
   • CEmpty blocks forgo transaction fees, but they can be mined faster because they require less data to assemble
   • DEmpty blocks are more secure because they have a smaller Merkle tree
   Reveal Solution Discussion Select an answer first
4. 43application · medium

   A developer wants to create a Bitcoin transaction that requires two parties to sign before the funds can be spent. Which Bitcoin Script construct should be used in the locking script?

   • AA time-locked script with OP_CHECKLOCKTIMEVERIFY
   • BA single signature with OP_CHECKSIG
   • CA hash-locked script with OP_HASH160
   • DA multi-signature script with OP_CHECKMULTISIG
   Reveal Solution Discussion Select an answer first
5. 44foundation · easy

   How does a lightweight client (SPV wallet) verify that a transaction is included in a block?

   • ABy mining the block themselves to confirm it is valid
   • BBy asking a trusted third party to confirm the transaction
   • CBy requesting a Merkle proof from a full node and checking the block header
   • DBy downloading the entire blockchain and checking every transaction
   Reveal Solution Discussion Select an answer first
6. 45expert · hard

   A developer wants to create a Bitcoin transaction that requires two of three specified public keys to sign before the funds can be spent. The developer is considering using a P2SH script. What is the correct way to implement this, and what does the locking script contain?

   • AUse a CHECKMULTISIG opcode in the locking script with three public keys and a threshold of two, without a redeem script.
   • BUse a single signature from any of the three keys, since P2SH allows flexible spending conditions.
   • CPlace the full 2-of-3 multisig script directly in the locking script of the P2SH output.
   • DCreate a redeem script that is a 2-of-3 multisig script, hash it, and place the hash in the P2SH locking script; the redeem script is revealed when spending.
   Reveal Solution Discussion Select an answer first