Blockchain Scalability and Layer 2 Solutions Flashcards
7 cards from real Blockchain Technology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Blockchain Scalability and Layer 2 Solutions flashcards as text
What is the purpose of EIP-4844 (Proto-Danksharding) introduced in the Ethereum Dencun upgrade?
Answer: To introduce a new blob-carrying transaction type that provides cheaper temporary data storage for rollups
EIP-4844 adds 'blob' transactions that carry large data payloads at lower cost than calldata, enabling rollups to post transaction data more cheaply and significantly reducing Layer 2 user fees.
What is a 'blob' in the context of EIP-4844?
Answer: A large data object (~128 KB) attached to a transaction that is stored temporarily by Ethereum nodes and not accessible to the EVM
Blobs are ~128 KB data chunks attached to blob-carrying transactions that nodes store for approximately 18 days; they are not accessible to smart contracts but can be verified via KZG commitments.
What cryptographic commitment scheme does EIP-4844 use to verify blob data?
Answer: KZG (Kate-Zaverucha-Goldberg) polynomial commitments
EIP-4844 uses KZG polynomial commitments, which allow efficient cryptographic verification that a blob contains specific data without revealing the full blob, enabling compact on-chain proofs.
In the Lightning Network, what is the role of Hash Time-Locked Contracts (HTLCs)?
Answer: To enable conditional payments across multiple payment channel hops, ensuring atomicity without trusting intermediaries
HTLCs use cryptographic hash locks and time locks to route payments atomically across multiple channels — either the full payment succeeds along the entire path or it is fully refunded.
What is 'calldata' and why is it relevant to Ethereum rollup costs?
Answer: The input data field of an Ethereum transaction, used by rollups to post compressed transaction data on-chain at a per-byte gas cost
Rollups post their compressed transaction data as calldata in Layer 1 transactions; prior to EIP-4844, calldata costs dominated rollup fees, making cheap calldata critical to Layer 2 economics.
What is the key difference between a ZK-Rollup and an Optimistic Rollup regarding withdrawal finality?
Answer: ZK-Rollups finalize withdrawals as soon as the validity proof is verified on-chain, whereas Optimistic Rollups require waiting out the full challenge period
A valid ZK proof immediately proves correctness, allowing near-instant withdrawal finality; Optimistic Rollups must wait the full 7-day challenge window before a withdrawal is considered final.
What is 'sequencer centralization' and why is it considered a risk in current rollup deployments?
Answer: A single entity controlling transaction ordering, giving it the power to censor transactions, extract MEV, or cause liveness failures with no immediate fallback
Most production rollups currently rely on a single centralized sequencer operated by the rollup team, creating censorship risk and a single point of failure, which many projects are actively working to decentralize.