CBCP Consensus Mechanisms 4 — Questions and Answers
Question 1: What is 'Proof of Burn' and what problem was it designed to address?
- Destroying old blocks to free storage; addresses blockchain bloat
- Permanently sending coins to an unspendable address to gain mining rights; addresses energy waste of PoW (Correct answer)
- Burning transaction fees to reduce inflation; addresses token supply
- Validators forfeit rewards for missed blocks; addresses liveness
Correct answer: Permanently sending coins to an unspendable address to gain mining rights; addresses energy waste of PoW
Proof of Burn requires validators to 'burn' (destroy) tokens by sending them to a verifiably unspendable address, demonstrating commitment without the energy cost of PoW mining.
Question 2: Which property of PBFT makes it unsuitable for large public blockchain networks?
- It requires Proof of Work as a fallback
- Its O(n²) message complexity makes it unscalable to thousands of nodes (Correct answer)
- It does not support smart contracts
- It produces blocks too slowly for public use
Correct answer: Its O(n²) message complexity makes it unscalable to thousands of nodes
PBFT requires each node to communicate with every other node during each consensus round, resulting in O(n²) messages that become prohibitive as node count grows.
Question 3: In Avalanche consensus, what is a 'snowball' query and how does it build confidence?
- A cryptographic puzzle that gets harder over time
- Repeatedly sampling random validator subsets; accumulating sequential same-color responses increases confidence (Correct answer)
- A transaction batching mechanism that grows with network load
- A staking process where rewards compound like rolling snowballs
Correct answer: Repeatedly sampling random validator subsets; accumulating sequential same-color responses increases confidence
Avalanche's Snowball protocol repeatedly samples small random subsets of validators; when consecutive rounds yield the same preference, confidence in that choice grows until a threshold is reached.
Question 4: What is the primary advantage of using a Verifiable Random Function (VRF) in consensus leader selection?
- It eliminates the need for cryptographic signatures
- It allows a node to privately prove it won the lottery without revealing the result until needed (Correct answer)
- It speeds up block propagation across the network
- It enables validators to stake without locking tokens
Correct answer: It allows a node to privately prove it won the lottery without revealing the result until needed
VRF allows a node to self-select as leader and generate a cryptographic proof verifiable by others, while keeping the selection secret until the block is announced — preventing targeted attacks.
Question 5: In Proof of Authority (PoA) consensus, what is the trade-off compared to Proof of Work?
- PoA is faster and more efficient but sacrifices decentralization by relying on a set of approved validators (Correct answer)
- PoA consumes more energy but provides stronger security guarantees
- PoA is slower but achieves full decentralization
- PoA eliminates the need for transaction fees entirely
Correct answer: PoA is faster and more efficient but sacrifices decentralization by relying on a set of approved validators
PoA achieves high throughput and energy efficiency by having known, approved validators, but this means trusting those authorities, which reduces decentralization and censorship resistance.
Question 6: What is 'equivocation' in the context of blockchain consensus, and why is it considered an attack?
- Using ambiguous smart contract language to exploit loopholes
- A validator signing two different blocks at the same height, attempting to create conflicting chains (Correct answer)
- Refusing to validate transactions from certain addresses
- Broadcasting invalid transactions to waste network resources
Correct answer: A validator signing two different blocks at the same height, attempting to create conflicting chains
Equivocation occurs when a validator double-signs conflicting messages at the same blockchain height, which can destabilize consensus and is treated as a slashable offense in most PoS systems.
Question 7: How does Stellar's Federated Byzantine Agreement (FBA) differ from traditional BFT consensus?
- FBA uses Proof of Work for final settlement
- FBA allows each node to choose its own trust quorum slices rather than requiring global agreement on validator sets (Correct answer)
- FBA requires all nodes to be staked with equal amounts
- FBA eliminates the need for any voting rounds
Correct answer: FBA allows each node to choose its own trust quorum slices rather than requiring global agreement on validator sets
In FBA, nodes individually define their own 'quorum slices' (trusted peers), enabling open network membership while still achieving consensus through overlapping trust relationships.
CBCP Consensus Mechanisms 4
What is 'Proof of Burn' and what problem was it designed to address?