Practice Test GeeksCryptocurrency Practice Test
← All Cryptocurrency Flashcard Decks

Consensus Mechanisms and Mining Flashcards

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

Read the first 7 Consensus Mechanisms and Mining flashcards as text

  1. What is 'Proof of Authority' (PoA) consensus and where is it typically used?

    Answer: Validators are pre-approved by identity rather than stake or compute, commonly used in private/consortium blockchains

    PoA uses a small set of vetted, identified validators, making it fast and energy-efficient but centralized — suited for enterprise or permissioned chains.

  2. What is the purpose of a 'nonce' in Bitcoin's Proof of Work mining?

    Answer: It is a number miners iterate through to find a block hash below the current difficulty target

    Miners repeatedly change the nonce (a 32-bit number) and rehash the block header until they find a hash that meets the difficulty target.

  3. What does 'finality' mean in blockchain consensus, and which type provides faster finality?

    Answer: Finality means a transaction cannot be reversed; BFT-style PoS provides near-instant finality vs. PoW's probabilistic finality

    PoW offers only probabilistic finality (more confirmations = more secure), while BFT-based PoS systems like Tendermint achieve absolute finality in a single round.

  4. What is 'Proof of Capacity' (PoC) or 'Proof of Space'?

    Answer: Miners allocate hard drive space to store precomputed plot files, and those with more space win more blocks

    PoC/Proof of Space (used by Chia and Burst) replaces energy-intensive computation with storage space — miners pre-plot large files on HDDs and scan them to win blocks.

  5. In Ethereum's Proof of Stake, what is the minimum ETH required to run a solo validator?

    Answer: 32 ETH

    Ethereum requires exactly 32 ETH to activate a validator node; users with less can pool ETH through liquid staking protocols like Lido.

  6. What is the 'Byzantine Generals Problem' and why does it matter for consensus?

    Answer: It describes the challenge of reaching agreement among distributed nodes when some may be malicious or unreliable

    The Byzantine Generals Problem shows that distributed systems need fault-tolerant protocols to reach consensus even when some participants lie or fail — the core challenge all consensus mechanisms solve.

  7. What is 'merge mining' (AuxPoW)?

    Answer: Mining two blockchains simultaneously using the same proof-of-work computation, like Bitcoin and Namecoin

    Merge mining (Auxiliary Proof of Work) lets miners simultaneously mine a parent chain (e.g., Bitcoin) and a child chain (e.g., Namecoin) with no additional computational cost.