CBCP Ethereum 3

Question 1

What is the role of the 'receipts trie' in an Ethereum block?

Accepted Answer

It stores the outcome of each transaction including logs and gas used, enabling light client verification

Answer

The receipts trie root is committed in the block header, letting clients verify transaction outcomes without replaying them.

Question 2

Which Solidity visibility modifier makes a function only callable from within the contract or derived contracts?

Accepted Answer

internal

Answer

The 'internal' modifier restricts access to the contract itself and any contract that inherits from it.

Question 3

What attack vector does the 'checks-effects-interactions' pattern in Solidity primarily defend against?

Accepted Answer

Reentrancy attacks

Answer

By updating state before making external calls, the pattern prevents a malicious contract from re-entering a function in an inconsistent state.

Question 4

In Ethereum's EIP-4844 (Proto-Danksharding), what new transaction type was introduced?

Accepted Answer

Blob-carrying transactions

Answer

EIP-4844 introduced type-3 blob-carrying transactions that attach temporary data blobs to reduce L2 data availability costs.

Question 5

What is 'gas stipend' in the context of Ethereum's transfer() and send() functions?

Accepted Answer

A fixed 2300 gas forwarded to the recipient to prevent reentrancy while allowing basic logging

Answer

transfer() and send() forward exactly 2300 gas, enough for a log event but insufficient to execute complex code or re-enter.

CBCP - Certified Blockchain Professional Practice Test