Blockchain Technology Smart Contracts and dApps 5

Question 1

What is the primary purpose of a DAO (Decentralized Autonomous Organization) smart contract?

Accepted Answer

To encode governance rules so token holders can vote on proposals without central control

Answer

DAO contracts implement on-chain governance where token holders submit and vote on proposals, with approved actions executed automatically by the contract.

Question 2

In Solidity, what is the difference between 'storage' and 'memory' variable locations?

Accepted Answer

Storage persists on-chain between calls; memory is temporary within a single call

Answer

Storage variables are permanently written to the blockchain state, while memory variables exist only during a function execution and are discarded afterward.

Question 3

What does EIP-1559 change about Ethereum transaction fees?

Accepted Answer

It introduces a base fee that is burned and a priority tip paid to validators

Answer

EIP-1559 replaced the first-price auction with a protocol-set base fee (burned) plus an optional priority tip, making fees more predictable.

Question 4

What is 'contract self-destruct' (selfdestruct) and why is it considered dangerous?

Accepted Answer

A function to delete contract code and send ETH to a target; dangerous because it can break dependent contracts

Answer

selfdestruct removes contract bytecode from state and forces ETH to a recipient, which can break contracts expecting to interact with the now-deleted address.

Question 5

Which concept describes bundling multiple smart contract interactions into one atomic transaction?

Accepted Answer

Multicall

Answer

Multicall allows a single transaction to execute multiple contract calls atomically, saving gas and ensuring all-or-nothing execution.

Blockchain Practice Test

Blockchain Practice Test

Blockchain Technology Smart Contracts and dApps 5