CBSA Blockchain Scalability & Performance 2 — Questions and Answers
Question 1: What is the key difference between a ZK-Rollup and an Optimistic Rollup?
- ZK-Rollups use zero-knowledge validity proofs for instant finality; Optimistic Rollups use fraud proofs with a challenge period (Correct answer)
- ZK-Rollups are faster but inherently less secure than Optimistic Rollups
- ZK-Rollups operate entirely on sidechains while Optimistic Rollups are Layer 1 solutions
- ZK-Rollups only support simple token transfers and cannot execute smart contracts
Correct answer: ZK-Rollups use zero-knowledge validity proofs for instant finality; Optimistic Rollups use fraud proofs with a challenge period
ZK-Rollups generate cryptographic validity proofs (zk-SNARKs or STARKs) enabling immediate finality, whereas Optimistic Rollups rely on a fraud-proof challenge window before finality.
Question 2: In the context of Ethereum scaling, what is 'Plasma'?
- A proof-of-stake consensus mechanism designed for high throughput
- A Layer 2 framework for creating child chains that periodically commit compressed state roots to the Ethereum main chain (Correct answer)
- A privacy protocol that hides transaction amounts using range proofs
- A standardized cross-chain asset bridge protocol
Correct answer: A Layer 2 framework for creating child chains that periodically commit compressed state roots to the Ethereum main chain
Plasma is a framework, proposed by Vitalik Buterin and Joseph Poon, for spinning up child chains anchored to Ethereum's main chain for scalable off-chain computation.
Question 3: What is the primary scalability trade-off when simply increasing blockchain block size?
- Transaction fees increase proportionally to block size
- Higher hardware requirements for running full nodes raise centralization risk (Correct answer)
- Larger blocks slow down the consensus mechanism significantly
- Smart contract functionality is reduced to compensate for larger data
Correct answer: Higher hardware requirements for running full nodes raise centralization risk
Larger blocks demand more storage, bandwidth, and processing power, making it harder for smaller operators to run full nodes and pushing the network toward centralization.
Question 4: Which technology category enables separate blockchain networks to transfer tokens and arbitrary data with each other?
- Intra-chain sharding protocols
- Cross-chain interoperability protocols (e.g., Polkadot, Cosmos IBC) (Correct answer)
- Bidirectional state channels
- Block pruning and archival nodes
Correct answer: Cross-chain interoperability protocols (e.g., Polkadot, Cosmos IBC)
Cross-chain interoperability protocols such as Polkadot's XCMP and Cosmos's IBC enable different blockchains to communicate and transfer assets or messages.
Question 5: In blockchain performance, what does 'finality' mean?
- The process of closing a payment channel and settling funds on-chain
- The guarantee that a confirmed transaction is irreversible and permanently recorded on the blockchain (Correct answer)
- The final block produced in a blockchain's lifecycle
- The maximum transaction count permitted per block
Correct answer: The guarantee that a confirmed transaction is irreversible and permanently recorded on the blockchain
Finality is the property that once a transaction is sufficiently confirmed, it cannot be reversed, rolled back, or altered.
Question 6: What is the purpose of EIP-4844 (Proto-Danksharding) in Ethereum's scaling roadmap?
- To replace Ethereum's proof-of-work with a faster consensus algorithm
- To introduce blob-carrying transactions that allow Layer 2 rollups to post data to Ethereum at significantly lower cost (Correct answer)
- To enable native cross-chain messaging between Ethereum and Polkadot
- To improve smart contract execution by supporting parallel transaction processing
Correct answer: To introduce blob-carrying transactions that allow Layer 2 rollups to post data to Ethereum at significantly lower cost
EIP-4844 adds a new blob transaction type that allows rollups to attach large data blobs at a fraction of the cost of regular calldata, making Layer 2 solutions much cheaper.
Question 7: What does 'throughput' specifically measure in a blockchain performance context?
- The total cryptocurrency rewards distributed per block
- The volume of transactions the network can process per unit of time (Correct answer)
- The byte size of each individual transaction
- The total count of full nodes participating in the network
Correct answer: The volume of transactions the network can process per unit of time
Throughput measures the total transaction volume a blockchain can handle within a given timeframe, most commonly expressed as transactions per second (TPS).
CBSA Blockchain Scalability & Performance 2
What is the key difference between a ZK-Rollup and an Optimistic Rollup?