Bitcoin Mining and Consensus Flashcards

What information is stored in a Bitcoin block header?

Answer: Version, previous block hash, merkle root, timestamp, bits, and nonce

The 80-byte block header contains version, previous block hash, merkle root, timestamp, difficulty bits, and nonce.

In Bitcoin mining pools, what does 'vardiff' refer to?

Answer: Dynamic share difficulty adjusted to a miner's hash rate

Vardiff automatically adjusts the difficulty of shares submitted by a miner to match their hash rate, keeping submission rates efficient.

What does the 'merkle root' in a block header represent?

Answer: A single hash summarizing all transactions in the block

The merkle root is the root hash of a binary hash tree built from all transaction IDs in the block.

What is a 'share' in the context of pooled mining?

Answer: A proof-of-work result that meets the pool's lower difficulty target

Shares are partial proof-of-work results that prove a miner is working, used by pools to allocate rewards proportionally.

What is 'merge mining'?

Answer: Mining two or more cryptocurrencies simultaneously using the same proof-of-work

Merge mining allows miners to simultaneously mine Bitcoin and an auxiliary chain like Namecoin with no extra computational cost.

How does Bitcoin prevent a miner from backdating a block's timestamp significantly?

Answer: Nodes reject blocks with timestamps more than 2 hours in the future or earlier than the median of the last 11 blocks

Bitcoin enforces a median-time-past rule and a 2-hour future limit to prevent extreme timestamp manipulation.

What is the maximum size of a Bitcoin block under the original pre-SegWit rules?

Answer: 1 MB

The original Bitcoin block size limit was 1 megabyte, introduced to prevent spam attacks on the network.