CBSA Smart Contracts & Decentralized Applications 3

Question 1

Which Ethereum Improvement Proposal introduced the concept of a standardized event interface for token transfers, forming the basis of ERC-20?

Accepted Answer

EIP-20

Answer

EIP-20 formally defined the ERC-20 fungible token standard, including the `Transfer` and `Approval` events.

Question 2

What is the key difference between `call`, `delegatecall`, and `staticcall` in Solidity?

Accepted Answer

`call` runs code in the callee's context; `delegatecall` uses the caller's storage/context; `staticcall` disallows state changes

Answer

`delegatecall` executes the callee's logic in the caller's storage context, making it fundamental to proxy upgradeability patterns.

Question 3

In Hyperledger Fabric, what is chaincode equivalent to in Ethereum's smart contract ecosystem?

Accepted Answer

Smart contracts

Answer

Chaincode in Hyperledger Fabric is the equivalent of smart contracts, defining business logic that runs on the permissioned ledger.

Question 4

What problem does the 'checks-effects-interactions' pattern solve in smart contract development?

Accepted Answer

Reentrancy vulnerabilities by updating state before making external calls

Answer

By performing all checks, then updating state, then making external calls, this pattern prevents reentrancy attacks from exploiting stale state.

Question 5

Which Layer 2 scaling solution uses fraud proofs and requires a challenge period before withdrawals are finalized?

Accepted Answer

Optimistic Rollup

Answer

Optimistic Rollups assume transactions are valid by default and rely on a challenge period during which fraud proofs can be submitted to dispute invalid state.

(CBSA) Certified Blockchain Solution Architect Practice Test

(CBSA) Certified Blockchain Solution Architect Practice Test

CBSA Smart Contracts & Decentralized Applications 3