CBCP Blockchain Fundamental 2 — Questions and Answers
Question 1: Which property of a blockchain ensures that once a block is added, its data cannot be altered without invalidating all subsequent blocks?
- Decentralization
- Immutability (Correct answer)
- Transparency
- Tokenization
Correct answer: Immutability
Immutability means that altering any block's data changes its hash, breaking the chain link to every block that follows.
Question 2: In the context of blockchain, what does the term 'fork' refer to?
- A cryptographic key-splitting technique
- A change in the blockchain protocol that creates two diverging chains (Correct answer)
- A method for merging two separate blockchains
- A type of smart contract upgrade pattern
Correct 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.
Question 3: What distinguishes a 'hard fork' from a 'soft fork' in blockchain protocol upgrades?
- Hard forks require miner approval; soft forks do not
- Hard forks are backward-incompatible; soft forks are backward-compatible (Correct answer)
- Hard forks only affect smart contracts; soft forks affect the entire chain
- Hard forks increase block size; soft forks decrease block size
Correct 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.
Question 4: Which component of a block header links it cryptographically to the previous block?
- Merkle root
- Nonce
- Previous block hash (Correct answer)
- Timestamp
Correct answer: Previous block hash
The previous block hash stored in each block header creates the cryptographic chain that makes tampering detectable.
Question 5: In blockchain terminology, what is a 'genesis block'?
- The block with the highest transaction volume
- The very first block in a blockchain (Correct answer)
- The block that triggers a smart contract deployment
- The most recently confirmed block
Correct 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.
Question 6: What role does a Merkle tree serve within a blockchain block?
- It encrypts wallet private keys
- It provides an efficient summary of all transactions enabling fast verification (Correct answer)
- It determines the mining difficulty target
- It stores validator identity information
Correct 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.
Question 7: Which of the following best describes the 'double-spend problem' that blockchain technology solves?
- The risk of a miner earning two block rewards simultaneously
- The ability to fraudulently use the same digital asset in two separate transactions (Correct answer)
- The overhead cost of processing duplicate transactions on-chain
- The risk of a smart contract executing the same function twice
Correct 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.
CBCP Blockchain Fundamental 2
Which property of a blockchain ensures that once a block is added, its data cannot be altered without invalidating all subsequent blocks?