CBCP Smart Contracts and dApps 3

Question 1

Which consensus-related attack involves a miner reordering transactions in a block to profit from price movements in a DeFi protocol?

Accepted Answer

Maximal Extractable Value (MEV)

Answer

MEV refers to the profit miners or validators can extract by including, excluding, or reordering transactions within the blocks they produce.

Question 2

What does the term 'gas limit' represent in an Ethereum transaction?

Accepted Answer

The maximum amount of computational work the sender is willing to pay for

Answer

Gas limit is the maximum units of gas a sender authorizes for a transaction; if execution requires more gas, it reverts but the gas is still consumed.

Question 3

Which Solidity function visibility modifier makes a function accessible only within the contract that defines it and not by derived contracts?

Accepted Answer

private

Answer

Private functions are only accessible within the contract they are defined in, unlike internal functions which are also accessible in derived (child) contracts.

Question 4

What is the main advantage of using the ERC-1155 multi-token standard over separate ERC-20 and ERC-721 contracts?

Accepted Answer

It allows a single contract to manage multiple fungible and non-fungible token types, reducing deployment costs

Answer

ERC-1155 lets a single contract manage any combination of fungible and non-fungible tokens, enabling batch transfers and significantly lower gas costs.

Question 5

In the context of DApps, what is the purpose of the Web3.js or Ethers.js library?

Accepted Answer

To provide a JavaScript interface for interacting with Ethereum nodes and smart contracts

Answer

Web3.js and Ethers.js are JavaScript libraries that enable frontend DApp code to communicate with Ethereum nodes via JSON-RPC, call contract functions, and listen for events.

CBCP - Certified Blockchain Professional Practice Test

CBCP - Certified Blockchain Professional Practice Test

CBCP Smart Contracts and dApps 3