Ethereum Smart Contract Security Best Practices Quiz

1. What is the primary purpose of implementing secure access controls in smart contracts?

• To enhance user interface design for smart contracts.
• To improve transaction speed and efficiency in blockchain.
• To increase the size of the smart contract deployments.
• To prevent unauthorized use of smart contract functions.

2. What are the visibility modifiers in Solidity, and how do they affect function calls?

• `static`
• `public`, `external`, `private`, `internal`
• `global`
• `protected`

3. What is role-based access control in smart contracts?

• Role-based access control restricts access to all smart contract functions entirely.
• Role-based access control distributes access to sensitive functions among multiple trusted participants, reducing single points of failure and trust assumptions.
• Role-based access control grants unrestricted access to all participants in the smart contract.
• Role-based access control eliminates the need for security checks in smart contracts.

4. How can multi-signature wallets enhance smart contract security?

• Multi-signature wallets require signatures from multiple entities to execute transactions.
• Multi-signature wallets operate independently of any blockchain for transaction processing.
• Multi-signature wallets only need one signature to confirm and execute a transaction.
• Multi-signature wallets store all transaction data in a single location for easy access.

5. What are `require()`, `assert()`, and `revert()` statements used for in smart contracts?

• These statements enforce proper execution and handle errors in smart contracts.
• They are used to store data permanently on the blockchain.
• They enable users to send Ether between accounts securely.
• These statements are designed for optimizing gas fees in transactions.

6. Why is extensive testing and verification crucial for smart contract security?

• Extensive testing and verification only help with user interface issues.
• Extensive testing and verification are unnecessary if the code is well-written.
• Extensive testing and verification can only ensure the contract is deployed correctly.
• Extensive testing and verification improve security by detecting vulnerabilities and ensuring the contract works as expected.

7. What is formal verification in the context of smart contracts?

• Formal verification ensures that a contract has a user-friendly interface without bugs.
• Formal verification is a method to increase transaction speed in smart contracts.
• Formal verification conclusively proves the absence of errors in a smart contract by creating a formal specification.
• Formal verification audits the financial performance of a smart contract over time.

8. What is an emergency stop function in a smart contract?

• An emergency stop function increases the transaction speed in a smart contract by bypassing checks.
• An emergency stop function allows unlimited access to all contract functions for specific users.
• An emergency stop function blocks calls to vulnerable functions in a contract, typically using a global Boolean variable to indicate if the contract is in a stopped state.
• An emergency stop function automatically executes all transactions in a smart contract without restrictions.

9. Why is it important to include a fail-safe mode in smart contracts?

• It automatically freezes all contract functions forever.
• It ensures higher transaction speeds and efficiency.
• Including self-checks to maintain security.
• It allows for automatic contract deletion.

10. What are some common pitfalls in smart contract development?

• Common pitfalls include high gas fees, lack of community support, and missing user interfaces.
• Common pitfalls include centralization risks, lack of proper access controls, and insufficient testing.
• Common pitfalls include excessive documentation, over-optimization, and using outdated libraries.
• Common pitfalls include only deploying in test networks, ignoring user feedback, and focusing solely on design.

11. How can rate-limiting and maximum usage features enhance smart contract security?

• Rate-limiting and maximum usage features restrict the network`s mining capabilities to increase transaction speed.
• Rate-limiting and maximum usage features control the visual appearance of smart contracts.
• Rate-limiting and maximum usage features simplify user interface design in smart contracts.
• Rate-limiting and maximum usage features help manage transaction frequency and amounts to enhance security.

12. Why is hiring a trusted team for a smart contract security audit important?

• Hiring any team can save time, regardless of their credentials.
• Hiring a trusted team ensures vulnerabilities are identified and fixed before release.
• A trusted team is not necessary if the developer understands the code.
• Hiring a team is only important for large contracts.

13. What types of accounts exist on the Ethereum network?

• Federated Accounts
• Centralized Accounts
• Externally Owned Accounts (EOAs) and Contract Accounts
• Local Accounts

14. What is the significance of the nonce in Ethereum transactions?

• The nonce is an encrypted hash used for transaction verification.
• The nonce is a sequence number that ensures transaction uniqueness.
• The nonce is a fixed value that determines transaction fees.
• The nonce is a public key associated with each account.

15. How does the Ethereum Virtual Machine (EVM) store data?

• The EVM stores data in plain text files.
• The EVM uses big-endian ordering for data storage.
• The EVM uses hexadecimal notation for data storage.
• The EVM uses little-endian ordering for data storage.

16. What is the smallest unit of Ether, and how is it related to the total number of decimals in Ether?

• finney
• wei
• etheric
• gwei

17. What are the main differences between Bitcoin and Ethereum?

• The main differences involve the programming languages used, market capitalization, and supply limits.
• The main differences are transaction speed, community focus, and regulatory compliance.
• The main differences are mining rewards, transaction fees, and historical origins.
• The main differences include smart contract support, the underlying tokens (Bitcoin vs Ether), and the consensus algorithm (Nakamoto Consensus).

18. What are the components of an Ethereum transaction?

• An Ethereum transaction contains a nonce, gas price, gas limit, recipient address, and value.
• An Ethereum transaction contains a recipient address, fee amount, input data, block hash, and transaction type.
• An Ethereum transaction contains a nonce, block number, transaction hash, sender address, and signature.
• An Ethereum transaction contains a gas price, gas limit, sender address, signature, and contract code.

19. How does the EVM handle block-related data?

• The EVM tracks user activities across multiple blocks.
• The EVM analyzes transaction fees and miner statistics.
• The EVM can obtain real-time block rewards and user balances.
• The EVM can gather block number and block hash data.

20. What is the purpose of security audits for smart contracts?

• Security audits help remove vulnerabilities and reduce risk by thoroughly examining the contract`s code for potential security issues.
• Security audits are performed to increase transaction speed and efficiency for smart contracts.
• Security audits verify the aesthetic design and user interface of smart contracts.
• Security audits are intended to enhance the marketing strategy of smart contracts before they are released.

21. What high-level languages are typically used for writing Ethereum smart contracts?

• C++
• Solidity
• Python
• Java

22. How does the EVM handle gas tracking?

• The EVM tracks gas usage, and low gas cost is typically 40 wei, affecting the transaction gas price.
• The EVM imposes a fixed gas price for every transaction regardless of their complexity.
• The EVM ignores gas calculations, treating all transactions equally with no cost.
• Gas tracking in the EVM is limited only to contract creation transactions.

23. What determines the number of transactions in an Ethereum block?

• The number of transactions in an Ethereum block is fixed and does not change.
• The number of transactions in an Ethereum block depends on the gas used by transactions and the block gas limit.
• The number of transactions in an Ethereum block is determined by the miner`s personal preference.
• The number of transactions in an Ethereum block is solely based on the size of each transaction.

24. Who is responsible for setting the block gas limit?

• Developers
• Validators
• Users
• Miners

25. Which EVM components are non-volatile across transactions?

• The storage component is non-volatile across transactions.
• The code component is non-volatile across transactions.
• The gas limit is non-volatile across transactions.
• The nonce is non-volatile across transactions.

26. Which operation touches storage in the EVM?

• The DUP operation touches storage in the EVM.
• The SLOAD operation touches storage in the EVM.
• The JUMP operation touches storage in the EVM.
• The ADD operation touches storage in the EVM.

27. Can smart contracts on Ethereum be deployed by anyone?

• Yes, only government entities can deploy smart contracts.
• Yes, smart contracts on Ethereum may be deployed by anyone.
• No, only verified developers can deploy smart contracts.
• No, deployment is limited to large corporations only.

28. What type of instructions are EVM opcodes?

• Text-based instructions executed at high-level.
• Multi-byte commands that require extensive processing.
• Script commands that interact with external APIs.
• Single-byte instructions that take operands on the stack.

29. What does the security of Ethereum DApps depend on?

• The amount of Ether locked in the DApp.
• The popularity of the DApp among users.
• The security of their smart contracts, off-chain components, and the Ethereum network itself.
• The hardware used to mine Ether in the network.

30. Why are security audits for smart contracts performed?

• To allow unlimited access for developers.
• To increase the transaction speed of smart contracts.
• To help remove vulnerabilities and reduce risk.
• To add more features to the existing contract.