CBDE Questions and Answers

it's good to use the block timestamp, as this is always different.

it's good to use the block hash as this is clearly always very different.

it's good to use the RANDAO smart contract.

it's not possible to have a random number in a deterministic environment such as the Ethereum blockchain.

to deploy to the main-network as quickly as possible.

to use in-memory blockchain simulations, because mining works instantaneously.

to use a private network at all times, because this is the closest you get to the real network.

Keccack256 while internally to hash values it's easy to use the Dagger-Hashimoto to create a meaningful hash.

the Dagger-Hashimoto hashing while internally the EVM uses SHA256 which is an alias for Keccack256.

the Dagger-Hashimoto hashing while internally the EVM uses Keccack256 which is almost similar to SHA256, but has a different padding so produces different hashes.

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.

a side Channel to the Ethereum Main Net which costs less gas to run smart contracts.

an exact clone of the Rinkeby Test-Network which can be started as virtual machine in the Azure Cloud.

a Network running only in a private area, where people cannot join freely and openly.

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.

you should follow the checks-effects-interactions pattern and avoid state changes after the call.

you should follow the effects-checks-interactions pattern and avoid state changes before the call.

you should follow the checks-effects-interactions pattern, which is only necessary when you do calls to contracts where a direct contract call is not possible.

will cascade exceptions and address.transfer() will return a false on error.

will return false on error while address.transfer() will cascade transactions.

both are the same, just implemented in a different language.

with Go-Ethereum you get a real blockchain node where you can create your own local private network, connect to Test-Networks or the Main-Net, while with Ganache you get an in-memory blockchain simulation.

with Ganache you get a real blockchain node where you can connect to the Test-Networks Rinkeby and Ropsten.

are interrupting execution on error, because they throw an exception.

continuing execution on error silently, which is the reason why they are so dangerous.

returning Booleans to indicate an error during execution.

.send() throws an exception, while the other functions are returning Booleans during execution to indicate an error.