Deploy and Manage dApps BDC Practice Questions (Page 7)

Questions 31–35

1. 31foundation · easy

   What is the purpose of a multi-signature (multisig) wallet in dApp governance?

   • ATo store the private keys of all users in one place
   • BTo require approval from multiple parties before executing administrative actions
   • CTo speed up transaction processing by using multiple signatures
   • DTo allow anyone to execute administrative functions
   Reveal Solution Discussion Select an answer first
2. 32foundation · easy

   What is a common strategy for upgrading a smart contract while preserving its state?

   • AModifying the existing contract's bytecode directly on-chain
   • BUsing a hard fork to change the contract's code
   • CUsing a proxy contract that delegates calls to an upgradable implementation
   • DDeploying a new contract and manually migrating all user balances
   Reveal Solution Discussion Select an answer first
4. 33application · medium

   A dApp is being migrated from the Ethereum mainnet to a new EVM-compatible chain to reduce fees. The team must preserve all user balances and transaction history. Which step is essential for a successful migration?

   • AKeep the old contract running and point the frontend to the new chain without migrating data.
   • BDeploy the same contract bytecode to the new chain; the state will automatically carry over.
   • CUse a cross-chain bridge to transfer the contract's storage directly.
   • DExport the contract's state (e.g., balances) and recreate it in the new contract on the target chain.
   Reveal Solution Discussion Select an answer first
5. 34expert · hard

   A dApp's frontend loads slowly because it fetches large amounts of data from the blockchain on every page load. The team wants to improve performance without compromising data freshness. Which approach is most effective?

   • AIncrease the number of RPC endpoints the frontend uses.
   • BFetch all data on page load and store it in the browser's local storage.
   • CUse a centralized API that returns pre-aggregated data.
   • DImplement a caching layer that stores blockchain data and refreshes it at a configurable interval.
   Reveal Solution Discussion Select an answer first
6. 35application · medium

   A team deployed a dApp to the Sepolia testnet. The frontend loads, but every transaction fails with 'execution reverted'. The contract address and ABI are correct, and the contract was verified on Etherscan. The team can read public state variables successfully. What is the most likely cause?

   • AThe user's wallet is connected to the wrong network (e.g., Mainnet instead of Sepolia).
   • BThe contract has a require() statement that is failing because the frontend is not passing the correct parameters.
   • CThe frontend is using the wrong RPC endpoint for Sepolia.
   • DThe contract's constructor arguments were not included in the deployment script.
   Reveal Solution Discussion Select an answer first