Hard Blockchain Developer questions

32 questions · 20 points each for a correct first answer.

1. 1.Lending protocol price oraclesecurity, oracles, defihard
2. 2.Replaying a signed messagesecurity, signatureshard
3. 3.First depositor in a vaultdefi, security, erc-4626hard
4. 4.Reentrancy through a view functionsecurity, reentrancyhard
5. 5.Rollup withdrawal timeslayer-2, scalinghard
6. 6.Paying everyone in a loopsecurity, gas, design-patternshard
7. 7.delegatecall to user inputsecurity, evmhard
8. 8.Account abstractionaccount-abstraction, walletshard
9. 9.Reentrancy through safeMintsmart-contract-security, token-standardshard
10. 10.EIP-7702 and "only EOAs" checkssmart-contract-security, evm-fundamentalshard
11. 11.Namespaced storage layoutupgradeability, openzeppelinhard
12. 12.Using a signature as a noncecryptography, smart-contract-securityhard
13. 13.Domain separator after a chain splitcryptography, smart-contract-securityhard
14. 14.Hash collision with encodePackedsolidity, smart-contract-securityhard
15. 15.msg.value inside a multicallsmart-contract-security, evm-fundamentalshard
16. 16.Which way to round in a vaulttoken-standards, smart-contract-securityhard
17. 17.Constant product swap outputdefi, solidityhard
18. 18.Trade-offs of a TWAP oracledefi, smart-contract-securityhard
19. 19.Checking a Chainlink pricedefi, smart-contract-securityhard
20. 20.Flash-loaned voting powerdefi, smart-contract-securityhard
21. 21.Return data gas griefingsmart-contract-security, evm-fundamentalshard
22. 22.Relayer forwards too little gassmart-contract-security, evm-fundamentalshard
23. 23.Indexer shows phantom depositsdapp-frontend, blockchain-fundamentalshard
24. 24.Using block.number for time on L2layer-2, solidityhard
25. 25.Deployment fails on one chainevm-fundamentals, deploymenthard
26. 26.Trusting a cross-chain messagelayer-2, smart-contract-securityhard
27. 27.Why transparent proxies split callersupgradeability, evm-fundamentalshard
28. 28.A fee that rounds to zerosolidity, smart-contract-securityhard
29. 29.Commit-reveal that can be copiedsmart-contract-security, cryptographyhard
30. 30.Missing account checks on Solanasmart-contract-security, solanahard
31. 31.Why ZK rollups still post datalayer-2, cryptographyhard
32. 32.Expensive loop over storagegas-optimisation, solidityhard