Cryptocurrency Smart Contracts and dApps 5

Question 1

What is 'MEV' (Maximal Extractable Value) in blockchain networks?

Accepted Answer

Profit extracted by reordering, inserting, or censoring transactions within a block

Answer

MEV refers to extra profit that block producers (or searchers) can capture by manipulating the order of transactions — through front-running, sandwich attacks, or liquidation sniping.

Question 2

Which Layer 2 scaling solution bundles many transactions off-chain and posts a validity proof to Ethereum?

Accepted Answer

ZK rollup

Answer

ZK (zero-knowledge) rollups compress transactions off-chain and submit a cryptographic validity proof to Ethereum Layer 1, allowing instant finality without a fraud-proof challenge period.

Question 3

What is the function of 'Chainlink VRF' in smart contract development?

Accepted Answer

It validates that randomness used in a contract is provably fair and tamper-resistant

Answer

Chainlink VRF (Verifiable Random Function) generates random numbers with cryptographic proof that the output was not manipulated, enabling fair on-chain lotteries, NFT trait reveals, and games.

Question 4

In Solidity, what is the purpose of the 'payable' keyword on a function?

Accepted Answer

It allows the function to receive ETH along with the call

Answer

Without the 'payable' modifier, a Solidity function will revert if ETH is sent to it; adding 'payable' lets the function accept and hold incoming ETH.

Question 5

What is a 'timelock controller' commonly used for in DeFi protocols?

Accepted Answer

Delaying execution of governance decisions to give users time to react or exit

Answer

A timelock enforces a mandatory waiting period between a proposal passing and its on-chain execution, giving the community and security researchers a window to detect and respond to malicious changes.

Cryptocurrency Practice Test

Cryptocurrency Practice Test

Cryptocurrency Smart Contracts and dApps 5