CBCP Consensus Mechanisms and Mining 2 — Questions and Answers
Question 1: In a Delegated Proof of Stake (DPoS) system, what role do 'witnesses' or 'delegates' play?
- They verify transactions off-chain before submission
- They are elected nodes responsible for producing blocks on behalf of token holders (Correct answer)
- They mine blocks using specialized hardware
- They act as arbiters in dispute resolution between validators
Correct answer: They are elected nodes responsible for producing blocks on behalf of token holders
In DPoS, token holders vote to elect a fixed set of delegates/witnesses who produce blocks and validate transactions on behalf of the network.
Question 2: What is the primary purpose of the 'nonce' field in a Bitcoin block header?
- To store the miner's wallet address
- To record the timestamp of the previous block
- To provide a variable miners iterate to find a valid proof-of-work hash (Correct answer)
- To encode the Merkle root of transactions
Correct answer: To provide a variable miners iterate to find a valid proof-of-work hash
Miners repeatedly increment the nonce value until the resulting block header hash meets the network's difficulty target.
Question 3: Which consensus mechanism is used by Ripple (XRP Ledger)?
- Proof of Work
- Federated Byzantine Agreement (FBA) (Correct answer)
- Delegated Proof of Stake
- Proof of Authority
Correct answer: Federated Byzantine Agreement (FBA)
The XRP Ledger uses Federated Byzantine Agreement, where each node maintains a Unique Node List (UNL) of trusted validators to reach consensus.
Question 4: What happens to mining difficulty in Bitcoin when blocks are found faster than the 10-minute target?
- Difficulty decreases to slow down miners
- Difficulty increases to make finding valid blocks harder (Correct answer)
- Block rewards are reduced immediately
- The network halts until difficulty is manually adjusted
Correct answer: Difficulty increases to make finding valid blocks harder
Bitcoin's difficulty adjustment algorithm increases difficulty every 2016 blocks when the average block time falls below 10 minutes.
Question 5: What is 'selfish mining' in the context of blockchain consensus?
- Mining without contributing to a mining pool
- A strategy where miners withhold discovered blocks to gain a disproportionate reward advantage (Correct answer)
- Refusing to validate transactions from competing miners
- Using ASICs to outcompete GPU miners
Correct answer: A strategy where miners withhold discovered blocks to gain a disproportionate reward advantage
Selfish mining involves a miner secretly keeping a discovered block, continuing to mine on it privately, then releasing multiple blocks to orphan honest miners' work.
Question 6: In Ethereum's Casper proof-of-stake, what is 'slashing'?
- Reducing transaction fees for frequent validators
- A penalty that destroys a portion of a validator's staked ETH for provably malicious behavior (Correct answer)
- Cutting block rewards in half on a schedule
- Removing inactive nodes from the validator set
Correct answer: A penalty that destroys a portion of a validator's staked ETH for provably malicious behavior
Slashing penalizes validators who sign conflicting blocks or make other provably dishonest attestations by burning part of their staked ETH.
Question 7: What distinguishes Proof of Elapsed Time (PoET) from traditional Proof of Work?
- PoET requires validators to hold tokens as collateral
- PoET uses trusted execution environments to randomly assign wait times, replacing energy-intensive computation (Correct answer)
- PoET selects block producers based on transaction history
- PoET relies on a central authority to certify elapsed time
Correct answer: PoET uses trusted execution environments to randomly assign wait times, replacing energy-intensive computation
PoET, developed by Intel for Hyperledger Sawtooth, uses SGX trusted hardware to generate verifiable random wait times, achieving lottery-style leader election without mining energy costs.
CBCP Consensus Mechanisms and Mining 2
In a Delegated Proof of Stake (DPoS) system, what role do 'witnesses' or 'delegates' play?