Ethereum Developer Ethereum Upgrades and Layer 2 Scaling

Question 1

What major change did the Ethereum Merge (2022) introduce?

Accepted Answer

Replaced Proof of Work with Proof of Stake consensus

Answer

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?

Accepted Answer

A fee market reform that introduced a base fee burned per transaction, reducing fee unpredictability

Answer

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?

Accepted Answer

A protocol built on top of Ethereum that processes transactions off-chain while inheriting mainnet security

Answer

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?

Accepted Answer

Optimistic Rollups assume validity and use fraud proofs; ZK Rollups use cryptographic validity proofs

Answer

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?

Accepted Answer

Ensuring that the transaction data needed to reconstruct rollup state is accessible to anyone

Answer

Data availability ensures that the compressed transaction data posted by rollups to Ethereum can be downloaded and verified by any participant.

Ethereum Developer Practice Test

Ethereum Developer Practice Test

Ethereum Developer Ethereum Upgrades and Layer 2 Scaling