CBSA Smart Contract Design 4

Question 1

What is the key difference between 'delegatecall' and 'call' in Solidity?

Accepted Answer

delegatecall executes the callee's code in the caller's storage context, while call executes in the callee's own context

Answer

With delegatecall, the called contract's code runs using the calling contract's storage, msg.sender, and msg.value — making it the foundation of upgradeable proxy contracts.

Question 2

In the context of Ethereum smart contracts, what is 'front-running' and how does a commit-reveal scheme mitigate it?

Accepted Answer

Front-running is submitting a transaction with knowledge of a pending transaction; commit-reveal hides intent until after commitment

Answer

In a commit-reveal scheme, users first submit a hash of their action (commit phase) and reveal the actual value later, so miners cannot exploit knowledge of pending transactions.

Question 3

What is the significance of the 'selector clash' vulnerability in smart contract proxy patterns?

Accepted Answer

When a function in the proxy has the same 4-byte selector as a function in the logic contract, calls may be routed incorrectly

Answer

Since Solidity routes calls using 4-byte function selectors, a collision between proxy admin functions and logic contract functions can allow unauthorized access to admin operations.

Question 4

Which Solidity data location must be used for function parameters of complex types (structs, arrays) when the function modifies the data?

Accepted Answer

memory

Answer

The 'memory' location creates a mutable copy for the function's execution, unlike 'calldata' which is read-only and 'storage' which would reference persistent state.

Question 5

What problem does the EIP-712 standard solve for smart contract interactions?

Accepted Answer

It standardizes structured data hashing and signing so users can read what they're approving in wallet UIs

Answer

EIP-712 provides a structured, human-readable format for off-chain signatures, preventing users from blindly signing opaque hex data they cannot understand.

(CBSA) Certified Blockchain Solution Architect Practice Test

(CBSA) Certified Blockchain Solution Architect Practice Test

CBSA Smart Contract Design 4