CCE Blockchain Fundamentals & Architecture 5 — Questions and Answers
Question 1: What is the primary difference between Layer 1 and Layer 2 blockchain solutions?
- Layer 1 uses Proof-of-Stake while Layer 2 uses Proof-of-Work exclusively
- Layer 1 refers to the base blockchain protocol; Layer 2 refers to solutions built on top to improve scalability (Correct answer)
- Layer 1 handles token transfers while Layer 2 handles only smart contract execution
- Layer 1 is public and Layer 2 is always private and permissioned
Correct answer: Layer 1 refers to the base blockchain protocol; Layer 2 refers to solutions built on top to improve scalability
Layer 1 is the base chain (Bitcoin, Ethereum) with its own consensus and security; Layer 2 solutions (Lightning, Rollups) extend L1 capacity by processing transactions off-chain while inheriting L1 security.
Question 2: What is a 'zero-knowledge proof' and how is it used in blockchain?
- A proof that a block was mined without consuming energy
- A cryptographic method allowing one party to prove knowledge of information without revealing the information itself (Correct answer)
- A consensus mechanism where validators stake zero tokens to participate
- A transaction type that hides the sender address using a zero-value dummy output
Correct answer: A cryptographic method allowing one party to prove knowledge of information without revealing the information itself
Zero-knowledge proofs (e.g., zk-SNARKs) let a prover demonstrate a statement is true (e.g., 'I have enough balance') without revealing the underlying data, enabling privacy and efficient rollups.
Question 3: In blockchain architecture, what is the 'Byzantine Generals Problem' and why is it relevant?
- A historical analogy for transaction fee disputes between competing miners
- A distributed computing problem describing how decentralized nodes can reach consensus despite some acting maliciously (Correct answer)
- A cryptographic puzzle used to generate the genesis block's private key
- An energy efficiency paradox where more validators consume exponentially more power
Correct answer: A distributed computing problem describing how decentralized nodes can reach consensus despite some acting maliciously
The Byzantine Generals Problem describes the challenge of achieving reliable consensus in a distributed system where some participants may be faulty or malicious — solving it is the core challenge of blockchain consensus.
Question 4: What does 'immutability' mean in the context of a public blockchain?
- Transactions are automatically reversible within a 24-hour window
- Once confirmed with sufficient depth, data on the chain is practically impossible to alter without redoing all subsequent proof-of-work (Correct answer)
- All blockchain data is encrypted and unreadable to unauthorized parties
- Smart contract code cannot be deployed after the genesis block is created
Correct answer: Once confirmed with sufficient depth, data on the chain is practically impossible to alter without redoing all subsequent proof-of-work
Blockchain immutability means that altering a historical transaction would require redoing the proof-of-work (or stake) for that block and all blocks after it, making it economically infeasible on large networks.
Question 5: What is the 'double-spend problem' and how does blockchain solve it without a central authority?
- The problem of miners receiving double the block reward; solved by halving events
- The risk of spending the same digital token twice; solved by distributed consensus that orders transactions globally (Correct answer)
- The issue of transaction fees being charged twice; solved by mempool deduplication
- The challenge of running two blockchain clients simultaneously; solved by network checkpoints
Correct answer: The risk of spending the same digital token twice; solved by distributed consensus that orders transactions globally
Without a central ledger, digital money can be copied and spent twice; blockchain solves this by having the entire network agree on a single ordered transaction history, making double-spends visible and rejectable.
Question 6: What is a 'hard fork' in blockchain and what are its consequences?
- A scheduled maintenance window where nodes pause to upgrade simultaneously
- A non-backward-compatible protocol change that creates two separate incompatible chains if not all nodes upgrade (Correct answer)
- A security patch that permanently rolls back the chain to before an exploit occurred
- A governance vote that splits block rewards between two competing development teams
Correct answer: A non-backward-compatible protocol change that creates two separate incompatible chains if not all nodes upgrade
A hard fork introduces rules that old nodes reject, so unupgraded nodes continue on the old chain while upgraded nodes follow the new rules, potentially creating two permanent chains (e.g., ETH/ETC split after The DAO hack).
Question 7: What is the purpose of the 'gas' mechanism in Ethereum's blockchain architecture?
- To incentivize miners to include only high-value token transfers and skip smart contracts
- To meter computational work done by the EVM, preventing infinite loops and spam while compensating validators (Correct answer)
- To measure how much ETH is burned in each block to control inflation
- To prioritize block propagation speed based on transaction complexity
Correct answer: To meter computational work done by the EVM, preventing infinite loops and spam while compensating validators
Gas assigns a computational cost to every EVM operation; users pay gas fees (in ETH) to compensate validators and the system rejects transactions that exceed the gas limit, preventing denial-of-service via infinite loops.
CCE Blockchain Fundamentals & Architecture 5
What is the primary difference between Layer 1 and Layer 2 blockchain solutions?