CBCP Consensus Mechanisms and Mining 3

Question 1

What is the '51% attack' vulnerability in Proof of Work blockchains?

Accepted Answer

An entity controlling the majority of hash power can double-spend and reverse recent transactions

Answer

If a single entity controls more than 50% of the network's hash rate, they can rewrite recent blockchain history and execute double-spend attacks.

Question 2

In the context of mining pools, what is a 'share'?

Accepted Answer

A proof-of-work solution that meets a lower difficulty target, submitted to demonstrate mining effort

Answer

Shares are partial proof-of-work solutions with a lower difficulty than the actual network target, used by pools to measure each miner's contributed work for reward distribution.

Question 3

Which property of Byzantine Fault Tolerance (BFT) consensus describes the guarantee that all honest nodes agree on the same value?

Accepted Answer

Safety

Answer

Safety in BFT consensus ensures that no two honest nodes decide on different values, preventing forks or conflicting chain states.

Question 4

What is the primary trade-off when a blockchain prioritizes 'liveness' over 'safety' in consensus?

Accepted Answer

The chain always makes progress but may temporarily allow conflicting states

Answer

Prioritizing liveness means the network keeps producing blocks even under adverse conditions, but may create forks or temporary inconsistencies that require later resolution.

Question 5

In Proof of Stake, what is 'nothing at stake' problem and how is it typically addressed?

Accepted Answer

Validators can vote for multiple chain forks at no cost; addressed by slashing penalties for equivocation

Answer

Without cost for voting on multiple forks, validators could support all competing chains; slashing economically punishes this behavior by destroying stake for signing conflicting blocks.

CBCP - Certified Blockchain Professional Practice Test

CBCP - Certified Blockchain Professional Practice Test

CBCP Consensus Mechanisms and Mining 3