Role of DLT in Decentralized Finance (DeFi) BFC Practice Questions (Page 11)

Questions 51–53

1. 51application · medium

   A DeFi lending protocol has suffered a major exploit because an attacker manipulated the price feed used by its smart contracts to liquidate undercollateralized loans. Which combination of DLT-related risks does this incident most directly illustrate?

   • AScalability and regulatory uncertainty
   • BSmart contract vulnerability and oracle manipulation
   • CInteroperability failure and tokenization error
   • DConsensus failure and immutability issues
   Reveal Solution Discussion Select an answer first
2. 52expert · hard

   A DeFi protocol wants to enable cross-chain asset transfers between Ethereum and a sidechain. Which approach best balances security and usability for the protocol's users?

   • AUse a simple lock-and-mint bridge without additional verification
   • BUse a multi-signature bridge controlled by a trusted committee of validators
   • CUse a centralized exchange as the bridge to convert assets between chains
   • DUse a light-client bridge that verifies consensus proofs from the other chain
   Reveal Solution Discussion Select an answer first
3. 53expert · hard

   A DeFi protocol has been exploited due to a reentrancy attack on its smart contract. The team is deciding between two fixes: (1) adding a reentrancy guard to the contract, or (2) rewriting the contract to use a pull-payment pattern. Which consideration is most important in choosing between these fixes?

   • APull-payment patterns eliminate the need for external calls entirely
   • BPull-payment patterns are always more gas-efficient than reentrancy guards
   • CReentrancy guards are the only way to prevent reentrancy attacks
   • DReentrancy guards are easier to implement but may not be sufficient if the contract has complex cross-contract calls
   Reveal Solution Discussion Select an answer first