Blockchain and Consensus Mechanisms 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 Blockchain and Consensus Mechanisms flashcards as text
What is 'Proof of History' (PoH) used by Solana?
Answer: A cryptographic clock that creates a verifiable sequence of events over time
Proof of History is a verifiable delay function that encodes the passage of time cryptographically, allowing Solana nodes to agree on event ordering without network communication.
In blockchain terminology, what is a 'fork choice rule'?
Answer: The algorithm nodes use to determine which chain to follow when multiple valid chains exist
A fork choice rule (like Bitcoin's longest chain or Ethereum's LMD-GHOST) is the algorithm that determines the canonical chain when the network sees competing block proposals.
What is 'Proof of Burn' as a consensus mechanism?
Answer: Participants send coins to an unspendable address to earn the right to mine new coins
Proof of Burn requires participants to provably destroy cryptocurrency by sending it to a verifiably unspendable address, granting mining rights proportional to coins burned.
What is the 'nothing-at-stake' problem in early proof-of-stake designs?
Answer: Validators could vote on multiple competing forks at no cost, undermining consensus
Unlike PoW where mining one fork means wasting hash rate on another, early PoS validators had no computational cost to vote on every fork simultaneously, undermining security.
What is a 'checkpoint' in the context of blockchain consensus?
Answer: A block or state designated as finalized, before which reorganization is disallowed
Checkpoints mark blocks as irreversible anchors in the chain history, preventing deep reorganizations beyond that point.
What is the primary trade-off of increasing block size in a proof-of-work blockchain?
Answer: Larger blocks take longer to propagate, increasing orphan rates and centralization risk
Bigger blocks take longer to propagate across the network, giving large mining pools a propagation advantage and pushing smaller miners toward centralized pools.
What role does the 'mempool' play in blockchain transaction processing?
Answer: It is a holding area for unconfirmed transactions waiting to be included in a block
The mempool (memory pool) is each node's local queue of broadcast transactions that have not yet been confirmed in a block, from which miners or validators select transactions to include.