CBCP Blockchain Fundamental 3 — Questions and Answers
Question 1: What is the primary function of a cryptographic hash function in a blockchain?
- To encrypt wallet balances from public view
- To produce a fixed-size digest that uniquely represents input data (Correct answer)
- To establish network routing between nodes
- To compress transaction data for storage efficiency
Correct answer: To produce a fixed-size digest that uniquely represents input data
A cryptographic hash function takes arbitrary input and produces a fixed-length output (digest) that is deterministic, one-way, and collision-resistant.
Question 2: In a Proof of Work blockchain, what is the 'nonce'?
- A unique transaction identifier assigned by the network
- An arbitrary number miners adjust to find a valid block hash (Correct answer)
- The cryptographic signature of the block's creator
- A counter tracking how many times a smart contract has been called
Correct answer: An arbitrary number miners adjust to find a valid block hash
Miners repeatedly increment the nonce until the resulting block hash meets the network's difficulty target (e.g., starts with a required number of zeros).
Question 3: What characteristic makes blockchain data structures suitable for auditability?
- All data is stored in encrypted private vaults
- The append-only, hash-linked structure provides a tamper-evident record (Correct answer)
- Nodes automatically delete old blocks to save space
- Only validators can read historical transaction data
Correct answer: The append-only, hash-linked structure provides a tamper-evident record
Because each block's hash includes data from all previous blocks, any modification to historical records is immediately detectable by any participant.
Question 4: Which type of blockchain network restricts participation to a set of pre-approved organizations?
- Public blockchain
- Consortium (federated) blockchain (Correct answer)
- Sidechain
- Mainchain
Correct answer: Consortium (federated) blockchain
A consortium blockchain is governed by a group of organizations, limiting read and write access to vetted participants rather than the general public.
Question 5: What is the significance of 'block time' in a blockchain network?
- The maximum age a transaction can be before it is discarded
- The average interval between successive block additions to the chain (Correct answer)
- The time required for a node to download the full ledger
- The duration a validator is locked in a staking pool
Correct answer: The average interval between successive block additions to the chain
Block time determines how quickly transactions are finalized; shorter block times increase throughput but may raise the orphan rate.
Question 6: What happens to a blockchain transaction that is included in an 'orphaned block'?
- It is permanently recorded on the chain as confirmed
- It is discarded along with the orphaned block and must be rebroadcast (Correct answer)
- It is automatically moved to the next block by the network
- It triggers a network-wide rollback to the last common block
Correct answer: It is discarded along with the orphaned block and must be rebroadcast
When two miners solve a block simultaneously, only one chain branch survives; transactions in the discarded (orphaned) block return to the mempool.
Question 7: Which consensus mechanism relies on validators putting up cryptocurrency as collateral that can be 'slashed' for dishonest behavior?
- Proof of Work
- Proof of Stake (Correct answer)
- Proof of Authority
- Proof of Elapsed Time
Correct answer: Proof of Stake
In Proof of Stake, validators lock (stake) cryptocurrency as collateral, and slashing — losing a portion of that stake — deters malicious behavior.
CBCP Blockchain Fundamental 3
What is the primary function of a cryptographic hash function in a blockchain?