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Blockchain Technology Fundamentals Flashcards

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  1. What is a Merkle tree used for in a blockchain block?

    Answer: To efficiently verify transaction integrity

    A Merkle tree hashes transactions in pairs up to a single root hash, allowing efficient and tamper-evident verification of any transaction in the block.

  2. Which field in a block header links it cryptographically to the previous block?

    Answer: Previous block hash

    The previous block hash field contains the hash of the preceding block, creating the cryptographic chain that makes altering past blocks computationally infeasible.

  3. What does 'immutability' mean in the context of blockchain?

    Answer: Confirmed records cannot be altered without invalidating the chain

    Immutability means that once data is confirmed and buried under subsequent blocks, changing it requires re-mining all later blocks, making tampering practically impossible.

  4. In a public blockchain, who is allowed to participate as a node?

    Answer: Anyone with the required software

    Public blockchains are permissionless, meaning anyone can download the software and join the network as a full or light node without special approval.

  5. What is a '51% attack' on a Proof-of-Work blockchain?

    Answer: When a single entity controls the majority of hash rate and can rewrite recent history

    If one miner or pool controls over 50% of the network's hash rate, they can reverse recent transactions and perform double-spends, undermining chain integrity.

  6. What is the primary role of a 'full node' in a blockchain network?

    Answer: Storing the complete blockchain and independently validating all transactions

    Full nodes download and independently verify every block and transaction against consensus rules, serving as the backbone of network trustlessness.

  7. What term describes the situation when a blockchain permanently splits into two separate chains due to a protocol disagreement?

    Answer: Hard fork

    A hard fork introduces backwards-incompatible rule changes, causing nodes that don't upgrade to follow a different chain, resulting in a permanent split.