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Blockchain Interoperability and Scalability Flashcards

6 cards from real CBE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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

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

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

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

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

    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.

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

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

    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.

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

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

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

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

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

    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.

  6. What is the key security risk of a 'trusted' or 'custodial' cross-chain bridge?

    Answer: A compromised custodian or multisig can steal all locked assets, making bridges high-value hack targets

    Custodial bridges (e.g., early Ronin Bridge) concentrate risk in a multisig or custodian; the $625M Ronin hack exploited compromised validator keys controlling the bridge.