Ethereum Developer Ethereum Upgrades and Layer 2 Scaling 1 β Questions and Answers
Question 1: What major change did the Ethereum Merge (2022) introduce?
- Replaced Proof of Work with Proof of Stake consensus (Correct answer)
- Increased the block size to reduce fees
- Implemented sharding for parallel transaction processing
- Merged Ethereum mainnet with Polygon
Correct answer: Replaced Proof of Work with Proof of Stake consensus
The Merge transitioned Ethereum from energy-intensive Proof of Work mining to Proof of Stake, where validators stake ETH to propose blocks.
Question 2: What is EIP-1559 and what problem does it address?
- A fee market reform that introduced a base fee burned per transaction, reducing fee unpredictability (Correct answer)
- A proposal to double the block gas limit for scalability
- A standard for gasless meta-transactions
- An upgrade that enabled smart contracts on the Beacon Chain
Correct answer: A fee market reform that introduced a base fee burned per transaction, reducing fee unpredictability
EIP-1559 replaced the first-price auction gas model with a protocol-determined base fee that is burned, plus an optional priority tip for validators.
Question 3: What is an Ethereum layer-2 (L2) solution?
- A protocol built on top of Ethereum that processes transactions off-chain while inheriting mainnet security (Correct answer)
- A sidechain that runs independently with its own consensus
- An alternative client implementation of the Ethereum node
- A smart contract upgrade mechanism for existing dApps
Correct answer: A protocol built on top of Ethereum that processes transactions off-chain while inheriting mainnet security
Layer-2 solutions execute transactions off the Ethereum mainnet to increase throughput and reduce fees, periodically settling proofs or data on L1.
Question 4: What is the fundamental difference between Optimistic Rollups and ZK Rollups?
- Optimistic Rollups assume validity and use fraud proofs; ZK Rollups use cryptographic validity proofs (Correct answer)
- ZK Rollups are faster to withdraw from than Optimistic Rollups
- Optimistic Rollups use Ethereum data availability; ZK Rollups store data off-chain
- ZK Rollups require sequencer decentralization; Optimistic Rollups do not
Correct answer: Optimistic Rollups assume validity and use fraud proofs; ZK Rollups use cryptographic validity proofs
Optimistic Rollups post transactions optimistically and allow a challenge period, while ZK Rollups post cryptographic proofs that are immediately verifiable.
Question 5: What does 'data availability' mean in the context of Ethereum rollups?
- Ensuring that the transaction data needed to reconstruct rollup state is accessible to anyone (Correct answer)
- The uptime guarantee of an Ethereum RPC provider
- The percentage of nodes that have synced the latest block
- The availability of historical event logs on a node
Correct answer: Ensuring that the transaction data needed to reconstruct rollup state is accessible to anyone
Data availability ensures that the compressed transaction data posted by rollups to Ethereum can be downloaded and verified by any participant.
Question 6: What is a sequencer in a rollup network?
- A centralized or decentralized node that orders and batches transactions before posting them to L1 (Correct answer)
- A smart contract that verifies ZK proofs on Ethereum
- A validator node that proposes new Ethereum blocks
- A relay that bridges assets from L1 to L2
Correct answer: A centralized or decentralized node that orders and batches transactions before posting them to L1
The sequencer is responsible for receiving user transactions, ordering them, and periodically posting compressed batches to the Ethereum base layer.
Ethereum Developer Ethereum Upgrades and Layer 2 Scaling 1
What major change did the Ethereum Merge (2022) introduce?