Smart Contracts and dApps Flashcards
7 cards from real Blockchain Technology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Smart Contracts and dApps flashcards as text
What is the primary purpose of a DAO (Decentralized Autonomous Organization) smart contract?
Answer: To encode governance rules so token holders can vote on proposals without central control
DAO contracts implement on-chain governance where token holders submit and vote on proposals, with approved actions executed automatically by the contract.
In Solidity, what is the difference between 'storage' and 'memory' variable locations?
Answer: Storage persists on-chain between calls; memory is temporary within a single call
Storage variables are permanently written to the blockchain state, while memory variables exist only during a function execution and are discarded afterward.
What does EIP-1559 change about Ethereum transaction fees?
Answer: It introduces a base fee that is burned and a priority tip paid to validators
EIP-1559 replaced the first-price auction with a protocol-set base fee (burned) plus an optional priority tip, making fees more predictable.
What is 'contract self-destruct' (selfdestruct) and why is it considered dangerous?
Answer: A function to delete contract code and send ETH to a target; dangerous because it can break dependent contracts
selfdestruct removes contract bytecode from state and forces ETH to a recipient, which can break contracts expecting to interact with the now-deleted address.
Which concept describes bundling multiple smart contract interactions into one atomic transaction?
Answer: Multicall
Multicall allows a single transaction to execute multiple contract calls atomically, saving gas and ensuring all-or-nothing execution.
What security risk does 'tx.origin' authentication introduce in Solidity?
Answer: It enables phishing attacks where a malicious contract tricks the original signer into authorizing actions
tx.origin returns the original external account that initiated the call chain, so a malicious intermediary contract can impersonate a trusted user; msg.sender should be used instead.
What is 'impermanent loss' in the context of providing liquidity to an AMM?
Answer: The temporary loss in dollar value compared to holding assets, caused by price divergence in the pool
Impermanent loss occurs when the price ratio of pooled assets changes from deposit time; the LP would have been better off simply holding the assets instead.