Network Layer, Consensus, Smart Contract, and Node Security Best Practices BDC Practice Questions (Page 6)

Questions 26–30

1. 26foundation · easy

   What is the primary goal of a smart contract security audit?

   • ATo identify vulnerabilities and weaknesses before deployment
   • BTo make the contract upgradeable
   • CTo increase the contract's functionality
   • DTo optimize gas usage
   Reveal Solution Discussion Select an answer first
2. 27expert · hard

   A team is threat modeling a new DeFi protocol that uses a PoS blockchain. The protocol includes a governance contract that allows token holders to propose and vote on upgrades. The team identifies a potential attack where an attacker accumulates a large number of tokens to influence governance and then proposes a malicious upgrade that drains the treasury. Which combination of mitigations would be most effective in reducing this risk while preserving decentralization?

   • AUse a delegated proof-of-stake system where only top delegates can propose, and remove time locks to speed up upgrades.
   • BAllow any token holder to propose upgrades and execute them immediately after a simple majority vote.
   • CImplement a time lock on governance actions and require a supermajority vote threshold, along with a monitoring system to detect large token accumulations.
   • DRestrict governance voting to a small committee of founding team members.
   Reveal Solution Discussion Select an answer first
4. 28application · medium

   A DeFi protocol has been deployed on mainnet, and the team wants to set up monitoring to detect anomalous activity, such as a sudden spike in gas usage or an unexpected large transfer. Which monitoring approach would best provide early warning of a potential attack?

   • ASet up real-time alerts on blockchain events, such as large transfers and unusual contract interactions, and monitor network metrics like gas price and mempool size.
   • BRely on the community to report suspicious activity through a Discord channel.
   • COnly monitor the protocol's own smart contract events, ignoring network-level metrics.
   • DReview the blockchain data manually once a week to look for suspicious transactions.
   Reveal Solution Discussion Select an answer first
5. 29foundation · easy

   Which Solidity modifier is commonly used to prevent reentrancy attacks by locking a contract until the current function call finishes?

   • Aview
   • Bpayable
   • CnonReentrant
   • DonlyOwner
   Reveal Solution Discussion Select an answer first
6. 30expert · hard

   A new blockchain project is choosing between Proof-of-Work (PoW) and Proof-of-Stake (PoS) for its consensus mechanism. The team is particularly concerned about the 'nothing at stake' problem and long-range attacks. Which consensus choice and additional measure would best mitigate these concerns?

   • AUse PoS with a checkpointing mechanism that periodically finalizes the chain, preventing attackers from rewriting history from an early block.
   • BUse PoW with a high block reward to incentivize miners to stay honest.
   • CUse PoS without any additional mechanisms, relying on economic incentives alone.
   • DUse PoW with a low difficulty to make mining cheap and fast.
   Reveal Solution Discussion Select an answer first