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Bitcoin Mining and Consensus Flashcards

7 cards from real CBP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Bitcoin Mining and Consensus flashcards as text

  1. What distinguishes an ASIC miner from a GPU miner?

    Answer: ASICs are custom chips designed for a single algorithm, offering far higher efficiency

    ASICs (Application-Specific Integrated Circuits) are purpose-built for one hashing algorithm, making them orders of magnitude more efficient than general-purpose GPUs.

  2. In the PPLNS (Pay Per Last N Shares) pool payment scheme, what does N represent?

    Answer: A sliding window of recent shares used to calculate payouts

    PPLNS pays miners based on their shares submitted within a recent window, rewarding long-term consistent miners over pool hoppers.

  3. What is a 'finney attack' in Bitcoin?

    Answer: A pre-mined block used to double-spend against a merchant before broadcast

    In a Finney attack, a miner mines a block containing a double-spend transaction and uses it before broadcasting to defraud a zero-confirmation merchant.

  4. What role does the 'bits' field in a block header serve?

    Answer: It is a compact representation of the current difficulty target

    The 'bits' field encodes the difficulty target in a compact 4-byte format that miners must beat with their block hash.

  5. What is the expected number of leading zeros in a Bitcoin block hash at high difficulty?

    Answer: A variable number determined by the current target

    The number of leading zeros in a valid hash varies with difficulty — more zeros mean higher difficulty, but the exact count shifts with the precise target value.

  6. Which of the following would constitute a hard fork change to Bitcoin's consensus rules?

    Answer: Reducing the maximum block size from 1 MB to 500 KB

    Reducing the block size is a tightening rule (hard fork) because old nodes would accept blocks the new rules reject, causing a chain split.

  7. What is the purpose of 'checkpoints' historically used in Bitcoin Core?

    Answer: To hardcode known-good block hashes to protect against certain history-rewriting attacks

    Checkpoints in early Bitcoin Core hardcoded hashes of key historical blocks to prevent attackers from forking the chain before those points.