Blockchain Fundamental Flashcards

Which property of a blockchain ensures that once a block is added, its data cannot be altered without invalidating all subsequent blocks?

Answer: Immutability

Immutability means that altering any block's data changes its hash, breaking the chain link to every block that follows.

In the context of blockchain, what does the term 'fork' refer to?

Answer: A change in the blockchain protocol that creates two diverging chains

A fork occurs when a change in protocol rules causes nodes to split, potentially following two different versions of the chain.

What distinguishes a 'hard fork' from a 'soft fork' in blockchain protocol upgrades?

Answer: Hard forks are backward-incompatible; soft forks are backward-compatible

A hard fork introduces rules incompatible with the old protocol, while a soft fork's new rules still accept old-format blocks.

Which component of a block header links it cryptographically to the previous block?

Answer: Previous block hash

The previous block hash stored in each block header creates the cryptographic chain that makes tampering detectable.

In blockchain terminology, what is a 'genesis block'?

Answer: The very first block in a blockchain

The genesis block is block zero — the hardcoded first block that has no predecessor and anchors the entire chain.

What role does a Merkle tree serve within a blockchain block?

Answer: It provides an efficient summary of all transactions enabling fast verification

A Merkle tree hashes transactions in a binary tree structure, allowing a single root hash to represent all transactions and enabling efficient proof of inclusion.

Which of the following best describes the 'double-spend problem' that blockchain technology solves?

Answer: The ability to fraudulently use the same digital asset in two separate transactions

The double-spend problem is the risk that a digital asset can be copied and spent more than once; blockchain's consensus prevents this by establishing a single agreed-upon transaction history.