CBSA Smart Contract Design 3

Question 1

Which Solidity visibility modifier should be used for functions that are only intended to be called internally and not inherited by child contracts?

Accepted Answer

private

Answer

The 'private' modifier restricts a function to the defining contract only, excluding derived contracts, unlike 'internal' which is accessible in child contracts.

Question 2

What is the main advantage of using 'events' in smart contracts over storing data in contract state?

Accepted Answer

Events are cheaper to emit than writing to storage and can be indexed for efficient off-chain querying

Answer

Emitting events costs significantly less gas than writing to storage, and indexed event parameters enable efficient filtering by off-chain applications.

Question 3

In a multi-signature smart contract wallet requiring M-of-N approvals, what data structure is most appropriate for tracking which owners have signed a pending transaction?

Accepted Answer

A mapping from owner address to boolean

Answer

A mapping(address => bool) provides O(1) lookup to check if a specific owner has already signed, preventing duplicate approvals efficiently.

Question 4

What does 'ABI encoding' refer to in the context of smart contract interaction?

Accepted Answer

The standardized encoding of function calls and return values for EVM interoperability

Answer

ABI (Application Binary Interface) encoding defines how function signatures and parameters are serialized into bytes for EVM calls and how return data is decoded.

Question 5

Which anti-pattern describes a smart contract that performs too many operations in a single transaction, risking hitting the block gas limit?

Accepted Answer

Gas griefing through unbounded iteration

Answer

Iterating over an unbounded array or mapping in one transaction can exceed the block gas limit, causing the transaction to fail and potentially locking contract functionality.

(CBSA) Certified Blockchain Solution Architect Practice Test

(CBSA) Certified Blockchain Solution Architect Practice Test

CBSA Smart Contract Design 3