CBE Blockchain Interoperability and Scalability 3

Question 1

What is a Hash Time-Locked Contract (HTLC) primarily used for?

Accepted Answer

Enabling trustless cross-chain atomic swaps by combining hash locks and time locks

Answer

HTLCs use a cryptographic hash lock (reveal preimage to claim) and time lock (refund if unclaimed) to enable atomic swaps without a trusted intermediary.

Question 2

What does 'finality' mean in the context of blockchain scalability and interoperability?

Accepted Answer

The point at which a transaction is considered irreversible and cannot be reorganized out of the chain

Answer

Finality guarantees that a confirmed transaction is permanent; fast finality is critical for interoperability because bridges need certainty before releasing assets on the destination chain.

Question 3

What is 'data availability' and why is it critical for Layer 2 rollup security?

Accepted Answer

The guarantee that transaction data posted to L1 is publicly accessible so anyone can reconstruct the L2 state and detect fraud

Answer

If rollup transaction data is unavailable, users cannot verify or challenge the L2 state, so rollups post data to Ethereum mainnet to ensure public auditability.

Question 4

What is Ethereum's EIP-4844 (Proto-Danksharding) designed to improve?

Accepted Answer

Reducing the cost of posting rollup data to Ethereum by introducing temporary 'blob' data storage

Answer

EIP-4844 introduces blob-carrying transactions that provide cheap, temporary data storage specifically for rollups, dramatically reducing L2 transaction costs.

Question 5

Which interoperability approach uses 'light clients' to verify cross-chain transactions without trusting a centralized bridge?

Accepted Answer

IBC's on-chain light client verification, where each chain runs a light client of the other

Answer

IBC's trust model requires each chain to maintain an on-chain light client of the counterparty, verifying block headers cryptographically rather than trusting human validators.

CBE - Certified Blockchain Expert Practice Test

CBE - Certified Blockchain Expert Practice Test

CBE Blockchain Interoperability and Scalability 3