CBSA Core Blockchain Principles 2 — Questions and Answers
Question 1: What property of a Merkle tree allows efficient proof that a specific transaction is included in a block without downloading the entire blockchain?
- Full node verification
- Merkle proof (SPV proof) (Correct answer)
- Zero-knowledge proof
- Ring signature
Correct answer: Merkle proof (SPV proof)
A Merkle proof (used in Simplified Payment Verification) requires only a logarithmic number of hashes to prove inclusion without the full dataset.
Question 2: In blockchain terminology, what does 'finality' refer to?
- The last block ever added to the chain
- The guarantee that a confirmed transaction cannot be reversed (Correct answer)
- The maximum block size limit
- The process of burning tokens permanently
Correct answer: The guarantee that a confirmed transaction cannot be reversed
Finality means a transaction is irrevocably settled and cannot be altered, rolled back, or double-spent after confirmation.
Question 3: Which type of blockchain fork occurs when nodes permanently diverge because they follow different protocol rules?
- Soft fork
- Hard fork (Correct answer)
- Orphan fork
- Temporary fork
Correct answer: Hard fork
A hard fork introduces backward-incompatible rule changes, causing non-upgraded nodes to follow a different chain permanently.
Question 4: What role does a cryptographic nonce serve in Proof of Work mining?
- It encrypts the transaction data
- It is a number miners increment to find a hash meeting the difficulty target (Correct answer)
- It identifies the miner's wallet address
- It stores the block timestamp
Correct answer: It is a number miners increment to find a hash meeting the difficulty target
Miners repeatedly change the nonce value until the resulting block hash falls below the network's current difficulty target.
Question 5: What is the primary purpose of the UTXO (Unspent Transaction Output) model used in Bitcoin?
- To compress block sizes
- To track coin ownership by recording spendable outputs rather than account balances (Correct answer)
- To enable smart contract execution
- To anonymize sender addresses
Correct answer: To track coin ownership by recording spendable outputs rather than account balances
The UTXO model represents value as discrete unspent outputs, preventing double-spend without requiring a global account ledger.
Question 6: Which characteristic makes blockchain data immutable in practice?
- Legal enforceability of the ledger
- Cryptographic chaining of blocks so altering one invalidates all subsequent blocks (Correct answer)
- Centralized backups maintained by validators
- Encryption of all stored data
Correct answer: Cryptographic chaining of blocks so altering one invalidates all subsequent blocks
Each block contains the hash of the previous block, so changing historical data requires recomputing all subsequent hashes—computationally infeasible on large networks.
Question 7: In a permissioned blockchain, what distinguishes it from a public blockchain regarding participation?
- Permissioned blockchains use no cryptography
- Participation requires identity verification and explicit authorization (Correct answer)
- Permissioned blockchains cannot execute smart contracts
- All nodes must be in the same geographic region
Correct answer: Participation requires identity verification and explicit authorization
Permissioned blockchains restrict who can read, write, or validate transactions, requiring known identities and approved membership.
CBSA Core Blockchain Principles 2
What property of a Merkle tree allows efficient proof that a specific transaction is included in a block without downloading the entire blockchain?