CBP Bitcoin Mining and Consensus Mechanisms 3 — Questions and Answers
Question 1: What is the target block time for the Bitcoin network?
- 1 minute
- 5 minutes
- 10 minutes (Correct answer)
- 30 minutes
Correct answer: 10 minutes
Bitcoin targets a 10-minute average block interval, which the difficulty adjustment algorithm enforces across every 2,016-block epoch.
Question 2: How does the Bitcoin network calculate the next difficulty target?
- By averaging the last 10 block times
- By comparing the time to mine the last 2,016 blocks against 20,160 minutes (Correct answer)
- By polling miners for their reported hashrate
- By using a predictive algorithm based on mempool congestion
Correct answer: By comparing the time to mine the last 2,016 blocks against 20,160 minutes
Every 2,016 blocks, the protocol compares actual elapsed time to the 20,160-minute ideal and adjusts difficulty proportionally (capped at a 4x change).
Question 3: What is the significance of the coinbase transaction in each Bitcoin block?
- It carries the largest transaction fees in the block
- It is the first transaction that creates new bitcoin and claims block rewards (Correct answer)
- It is a mandatory burn transaction that destroys a fraction of the subsidy
- It records the miner's identity on-chain for regulatory compliance
Correct answer: It is the first transaction that creates new bitcoin and claims block rewards
The coinbase transaction is a special first transaction in every block that mints new bitcoin as the block subsidy plus claims all transaction fees.
Question 4: What is a 'stale share' in the context of mining pools?
- A share submitted for a block that has already been found by the pool or network (Correct answer)
- A share with an incorrect difficulty setting
- A share that carries no transaction fees
- A share submitted before the pool has synced its mempool
Correct answer: A share submitted for a block that has already been found by the pool or network
A stale share arrives at the pool server after the relevant block has already been discovered, so it contributes no value to the pool's earnings.
Question 5: In Proof of Work, what property must the resulting block hash satisfy?
- It must be larger than the target value
- It must equal a predetermined hash stored in the genesis block
- It must be less than or equal to the current difficulty target (Correct answer)
- It must contain the SHA-256 of the previous block's coinbase
Correct answer: It must be less than or equal to the current difficulty target
A valid block hash must be numerically less than or equal to the difficulty target, which is expressed as a hash with a required number of leading zero bits.
Question 6: What is the role of the Merkle root stored in a Bitcoin block header?
- It stores the hash of the previous block for chain linking
- It is a compact cryptographic commitment to all transactions in the block (Correct answer)
- It records the total fee amount paid to the miner
- It contains the difficulty target encoded in compact form
Correct answer: It is a compact cryptographic commitment to all transactions in the block
The Merkle root is the root hash of a binary Merkle tree built from all transaction IDs, allowing efficient proof that any transaction is included in the block.
Question 7: Which payout scheme pays miners a fixed amount per valid share regardless of when a block is found?
- PPS (Pay Per Share) (Correct answer)
- PPLNS (Pay Per Last N Shares)
- Solo mining
- Proportional
Correct answer: PPS (Pay Per Share)
PPS pays a fixed, expected-value amount per share submitted, transferring variance risk from the miner to the pool operator.
CBP Bitcoin Mining and Consensus Mechanisms 3
What is the target block time for the Bitcoin network?