Blockchain Developer Blockchain Scalability and Layer 2 Solutions 2

Question 1

What is the 'data availability' problem in the context of Layer 2 rollups?

Accepted Answer

Ensuring that transaction data is published and accessible so anyone can reconstruct the rollup state and verify or challenge it

Answer

If transaction data is withheld, users cannot independently verify the rollup state or generate fraud/validity proofs, making data availability a critical security property.

Question 2

In ZK-Rollup terminology, what does the 'sequencer' do?

Accepted Answer

Orders, batches, and submits transactions to Layer 1 on behalf of users

Answer

The sequencer collects user transactions, determines their order, bundles them into batches, and posts batches (along with proofs) to Layer 1.

Question 3

What is Plasma in the context of Ethereum scalability?

Accepted Answer

A framework for creating child chains anchored to Ethereum, where only block roots are submitted to the main chain

Answer

Plasma allows the creation of child chains that periodically commit Merkle roots of their state to Ethereum, enabling high-throughput processing with Ethereum as the final arbiter.

Question 4

What is the primary function of a cross-chain bridge in a multi-chain ecosystem?

Accepted Answer

To enable the transfer of assets and data between two separate blockchain networks

Answer

A cross-chain bridge locks or burns assets on one chain and mints or releases equivalent assets on another chain, enabling interoperability between separate blockchains.

Question 5

What is the standard challenge period duration used by most Optimistic Rollups like Arbitrum and Optimism?

Accepted Answer

7 days

Answer

Most Optimistic Rollups use a 7-day challenge window to give honest validators sufficient time to detect and prove fraudulent transactions before they are finalized.

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Blockchain Developer Blockchain Scalability and Layer 2 Solutions 2