How to Pass the Blockchain CBDE Exam: Comprehensive BTA Certified Blockchain Developer - Ethereum Guide and Tips

it would be best to start from scratch, just looking at the required interface.

it is beneficial to copy and paste the already existing code from the Ethereum wiki and modify this until you like it.

best is to start with an audited implementation, for example from OpenZeppelin, in order to reuse already existing code.

is determined by the Ethereum Committee every fortnight to reflect the average amount of transaction and it cannot be influenced by the network itself.

increases when the time between mined blocks is below 10 seconds, while it decreases when the time is above 20 seconds.

increases when the time between mined blocks is below 20 seconds, while it decreases when the time is above 60 seconds.

totalSupply(), balanceOf(address), allowance(address,address), transfer(address,uint256), approve(address,uint256), transferFrom(address,address,uint256). Events: Transfer(address,address,uint256), Approval(address,address,uint256)

name(), symbol(), totalSupply(), balanceOf(address), ownerOf(uint26),approve(address,uint256), takeOwnership(uint256),transfer(address,uint256),Events: Transfer(address,address,uint256), Approval(address,address,uint256)

cannot receive Ether, not even by adding the payable modifier.

can contain as much logic as you want, but it’s better to keep it short and not exceed the gas stipend of 2300 gas.

can be used to avoid receiving ether.

Programs implementing the Ethereum Protocol to talk to each other and JSON-RPC interfaces to talk to the outside world.

A Java-Script library to compile and run Solidity Code.

A Framework for deploying and running smart contract in a decentralized way.

for Java, JavaScript, and C++

for JavaScript using Web3.js

for Solidity and JavaScript

for any language, as long as it adheres to the open Testing-Interface from Truffle

doesn't cost any gas.

cost gas every time we check the balance.

a Linked List with pointers to previous blocks hashes is used.

a Merkle Patricia Trie is used.

a Radix Trie is used because the Merkle Patricia Trie is too inefficient.

are changing their address every time a Transaction is sent because of the nonce.

are keeping their address, but on the blockchain a nonce is increased every time they send a transaction to avoid replay attacks.

can't be split across multiple files, everything should be in one single file.

can be split across multiple files, but every contract must be in a file with the same name as the contract itself.

can be spread across multiple files. To import all contract from a file you can use "import 'myfile.sol'. To import Contract MyContract from myfile.sol you use "import {MyContract as SomeContract} from 'myfile.sol';".