Blockchain Developer FREE Blockchain Developer Consensus Algorithms and Protocols Questions and Answers 2 — Questions and Answers
Question 1: What mechanism does Delegated Proof of Stake (DPoS) use to achieve consensus?
- Token holders vote for a fixed number of delegates who validate blocks (Correct answer)
- All nodes compete to solve cryptographic puzzles
- Validators are randomly selected based on coin age
- Nodes reach agreement through repeated rounds of binary voting
Correct answer: Token holders vote for a fixed number of delegates who validate blocks
DPoS allows token holders to elect a limited set of delegates responsible for producing blocks and validating transactions.
Question 2: Which consensus algorithm is specifically designed to tolerate up to one-third of nodes acting maliciously?
- Proof of Work
- Practical Byzantine Fault Tolerance (PBFT) (Correct answer)
- Proof of Authority
- Proof of Elapsed Time
Correct answer: Practical Byzantine Fault Tolerance (PBFT)
PBFT can tolerate up to f Byzantine faulty nodes in a network of 3f+1 total nodes, meaning it handles just under one-third malicious participants.
Question 3: In Proof of Stake systems, what is the primary risk that slashing conditions are designed to prevent?
- Double spending through 51% attacks
- Validators signing conflicting blocks or performing equivocation (Correct answer)
- Excessive gas consumption during smart contract execution
- Network congestion from too many pending transactions
Correct answer: Validators signing conflicting blocks or performing equivocation
Slashing penalizes validators who sign two different blocks at the same height or otherwise act dishonestly, deterring equivocation.
Question 4: What is the key advantage of the Nakamoto consensus used in Bitcoin compared to classical BFT protocols?
- It achieves instant transaction finality
- It supports an open and permissionless set of participants (Correct answer)
- It requires no computational resources to operate
- It guarantees zero probability of chain reorganization
Correct answer: It supports an open and permissionless set of participants
Nakamoto consensus allows any node to join or leave the network freely, making it suitable for open permissionless blockchains.
Question 5: In the Raft consensus algorithm, what happens when a follower node does not receive a heartbeat from the leader within the election timeout?
- It shuts down and waits for manual restart
- It becomes a candidate and initiates a new leader election (Correct answer)
- It automatically assumes the role of leader without an election
- It begins mining the next block independently
Correct answer: It becomes a candidate and initiates a new leader election
When a follower's election timeout elapses without receiving a heartbeat, it transitions to candidate state and starts a new election term.
Question 6: What problem does the Longest Chain Rule solve in Proof of Work blockchains?
- It determines which miner receives the highest reward
- It resolves temporary forks by having nodes adopt the chain with the most cumulative work (Correct answer)
- It prevents nodes from joining the network without authorization
- It ensures all transactions have identical gas fees
Correct answer: It resolves temporary forks by having nodes adopt the chain with the most cumulative work
The longest chain rule ensures that when forks occur, nodes converge on the chain representing the greatest cumulative proof of work.
Blockchain Developer FREE Blockchain Developer Consensus Algorithms and Protocols Questions and Answers 2
What mechanism does Delegated Proof of Stake (DPoS) use to achieve consensus?