Blockchain Developer Fundamentals and Cryptography 3

Question 1

What is a nonce in the context of proof-of-work mining?

Accepted Answer

A value miners vary to find a valid block hash

Answer

Miners repeatedly change the nonce until the block hash meets the difficulty target.

Question 2

What does 'immutability' mean for a blockchain ledger?

Accepted Answer

Recorded data cannot be feasibly altered after confirmation

Answer

Immutability means confirmed records cannot be changed without redoing all subsequent work.

Question 3

How is a blockchain address typically derived from a public key?

Accepted Answer

By hashing the public key

Answer

Addresses are usually generated by applying hash functions to the public key.

Question 4

What problem does the Byzantine Generals Problem describe in distributed systems?

Accepted Answer

Achieving agreement despite faulty or malicious participants

Answer

It describes reaching consensus when some participants may be unreliable or deceptive.

Question 5

What is the role of the previous block hash field in each block?

Accepted Answer

It links blocks into a tamper-evident chain

Answer

Each block references the prior block's hash, chaining them so any change breaks the chain.

Blockchain Practice Test