Blockchain Developer Consensus Algorithms and Protocols 3 — Questions and Answers
Question 1: In the Raft consensus algorithm, what role is responsible for handling all client requests?
- Follower
- Candidate
- Leader (Correct answer)
- Observer
Correct answer: Leader
In Raft, the elected leader handles client requests and replicates the log to followers.
Question 2: What is the primary purpose of a 'slashing' mechanism in Proof of Stake?
- To reward validators
- To penalize validators for misbehavior (Correct answer)
- To increase token supply
- To speed up block times
Correct answer: To penalize validators for misbehavior
Slashing destroys part of a validator's stake to punish malicious or faulty behavior.
Question 3: Which consensus property guarantees that all honest nodes eventually agree on the same value?
- Liveness
- Agreement (safety) (Correct answer)
- Availability
- Partition tolerance
Correct answer: Agreement (safety)
Agreement, a safety property, ensures all honest nodes decide on the same value.
Question 4: In Proof of Stake, what generally determines a validator's chance of being selected to propose a block?
- CPU power
- Amount of stake committed (Correct answer)
- Internet speed
- Account age only
Correct answer: Amount of stake committed
Selection probability typically scales with the amount of tokens a validator stakes.
Question 5: What does the FLP impossibility result state about distributed consensus?
- Consensus is impossible with any faults
- No deterministic protocol guarantees consensus in an async system with one faulty process (Correct answer)
- Consensus requires a leader
- Consensus needs unlimited nodes
Correct answer: No deterministic protocol guarantees consensus in an async system with one faulty process
FLP proves no deterministic asynchronous protocol can guarantee consensus if even one process may fail.
Question 6: Which consensus mechanism is commonly used by permissioned blockchains like Hyperledger Fabric?
- Proof of Work
- Raft / BFT-style ordering (Correct answer)
- Proof of Stake
- Proof of Burn
Correct answer: Raft / BFT-style ordering
Hyperledger Fabric uses ordering services based on Raft or BFT rather than mining.
Question 7: What is the main goal of a Sybil attack on a consensus network?
- To create many fake identities to gain disproportionate influence (Correct answer)
- To double-spend a single coin
- To delay block propagation
- To corrupt the genesis block
Correct answer: To create many fake identities to gain disproportionate influence
A Sybil attack floods the network with fake nodes to gain outsized control.
Blockchain Developer Consensus Algorithms and Protocols 3
In the Raft consensus algorithm, what role is responsible for handling all client requests?