CBP Bitcoin Mining and Consensus 2

Question 1

What is the primary purpose of the nonce field in a Bitcoin block header?

Accepted Answer

To provide a value miners iterate over to find a valid hash

Answer

Miners increment the nonce repeatedly until the block header hash meets the difficulty target.

Question 2

What happens to the Bitcoin block subsidy approximately every 210,000 blocks?

Accepted Answer

It is cut in half

Answer

The halving event cuts the block subsidy in half roughly every four years, reducing new coin issuance.

Question 3

Which consensus rule determines which chain Bitcoin nodes consider valid when two chains of equal length exist?

Accepted Answer

The chain with the most accumulated proof-of-work

Answer

Bitcoin nodes follow the chain with the greatest cumulative proof-of-work, often called the 'heaviest' chain.

Question 4

What is an 'orphan block' in Bitcoin mining?

Accepted Answer

A valid block that is not part of the main chain because another block won the race

Answer

Orphan blocks are valid blocks that were not selected as part of the longest chain when two miners solved a block simultaneously.

Question 5

What is the significance of the 'extraNonce' field used by miners?

Accepted Answer

It extends the nonce search space within the coinbase transaction

Answer

Since the 32-bit nonce space exhausts quickly, miners use the extraNonce in the coinbase to expand their search space.

(CBP) Certified Bitcoin Professional Practice Test