Blockchain Developer Blockchain Scalability and Layer 2 Solutions 1 — Questions and Answers
Question 1: What is the primary goal of Layer 2 (L2) scaling solutions in blockchain?
- To replace the base layer blockchain entirely
- To increase transaction throughput while inheriting security from the base layer (Correct answer)
- To create independent blockchains with no connection to Layer 1
- To reduce the number of nodes required to run a blockchain
Correct answer: To increase transaction throughput while inheriting security from the base layer
Layer 2 solutions process transactions off-chain and settle on Layer 1, increasing throughput while still relying on Layer 1 for security guarantees.
Question 2: Which Layer 2 solution was designed specifically to scale Bitcoin by enabling off-chain payment channels?
- Polygon
- Optimism
- Lightning Network (Correct answer)
- Plasma
Correct answer: Lightning Network
The Lightning Network is a Layer 2 protocol built on Bitcoin that allows two parties to open a payment channel and transact off-chain, only settling the final balance on-chain.
Question 3: What is a state channel in the context of blockchain scalability?
- A channel that broadcasts state changes to all network nodes simultaneously
- An off-chain communication channel where participants exchange signed state updates without touching the blockchain for each transaction (Correct answer)
- A sidechain that mirrors the main chain state
- A smart contract that manages on-chain governance voting
Correct answer: An off-chain communication channel where participants exchange signed state updates without touching the blockchain for each transaction
State channels allow participants to lock funds on-chain, then exchange signed messages off-chain, only posting the final state to the blockchain when closing the channel.
Question 4: In Optimistic Rollups, how is transaction fraud prevented?
- Zero-knowledge proofs are submitted with every transaction batch
- A challenge period allows validators to submit fraud proofs if invalid transactions are detected (Correct answer)
- All transactions are verified by a committee of trusted nodes before submission
- Transactions are re-executed on Layer 1 immediately upon submission
Correct answer: A challenge period allows validators to submit fraud proofs if invalid transactions are detected
Optimistic Rollups assume transactions are valid by default and rely on a challenge (dispute) period during which anyone can submit a fraud proof to revert invalid state transitions.
Question 5: What is database sharding as applied to blockchain scalability?
- Splitting the blockchain's validator set into smaller groups that process different transaction subsets in parallel (Correct answer)
- Compressing block data to reduce storage requirements
- Dividing smart contract logic across multiple contracts
- Routing transactions to different Layer 2 chains based on fee
Correct answer: Splitting the blockchain's validator set into smaller groups that process different transaction subsets in parallel
Sharding splits the network into shards, each processing a subset of transactions in parallel, increasing overall throughput without every node needing to process all transactions.
Question 6: Which type of rollup uses cryptographic validity proofs to immediately finalize transaction batches on Layer 1?
- Optimistic Rollups
- Plasma Rollups
- ZK-Rollups (Correct answer)
- State Channel Rollups
Correct answer: ZK-Rollups
ZK-Rollups generate a zero-knowledge proof (such as a SNARK or STARK) for each batch, allowing Layer 1 to verify correctness instantly without a challenge period.
Question 7: What is the main security trade-off when using a sidechain compared to the Ethereum mainnet?
- Sidechains have higher gas fees than mainnet
- Sidechains rely on their own consensus mechanism and validator set, which may be less decentralized or secure than the main chain (Correct answer)
- Sidechains cannot support EVM-compatible smart contracts
- Sidechains require zero-knowledge proofs for every transaction
Correct answer: Sidechains rely on their own consensus mechanism and validator set, which may be less decentralized or secure than the main chain
Unlike rollups that inherit Ethereum's security, sidechains have their own validators and consensus rules, meaning users must trust that sidechain's security model independently.
Blockchain Developer Blockchain Scalability and Layer 2 Solutions 1
What is the primary goal of Layer 2 (L2) scaling solutions in blockchain?