Crypto Jobs Advanced Topics 2

Question 1

In a layer-2 rollup, what distinguishes an optimistic rollup from a zk-rollup?

Accepted Answer

Optimistic rollups assume validity and allow fraud-proof challenges, while zk-rollups submit validity proofs

Answer

Optimistic rollups assume transactions are valid and rely on fraud proofs during a challenge window, whereas zk-rollups post cryptographic validity proofs for each batch.

Question 2

A protocol engineer must reduce MEV extraction harming users. Which approach directly addresses this?

Accepted Answer

Implementing encrypted mempools or proposer-builder separation

Answer

Encrypted mempools and proposer-builder separation reduce front-running by hiding transaction details or separating who orders transactions from who proposes blocks.

Question 3

Which statement about a 51% attack on a Proof-of-Work chain is most accurate?

Accepted Answer

It allows double-spending and transaction censorship but not altering protocol rules

Answer

Controlling majority hash power enables double-spends and reorg-based censorship but cannot break cryptographic ownership or change consensus rules unilaterally.

Question 4

In smart contract security, what is a reentrancy vulnerability?

Accepted Answer

When an external call lets a malicious contract re-invoke the function before state updates complete

Answer

Reentrancy occurs when an external call allows attacker code to call back into the vulnerable function before its state is updated, as in the DAO hack.

Question 5

What is the primary purpose of a Merkle tree in a blockchain?

Accepted Answer

To enable efficient and verifiable proof that a transaction is included in a block

Answer

Merkle trees let a light client verify a transaction's inclusion using only a small proof path rather than the full block.

Crypto Jobs Practice Test

Crypto Jobs Practice Test

Crypto Jobs Advanced Topics 2