Free Practice Questions for Blockchain CBDE Exam

is used to communicate between blockchain nodes.

is used to ensure safe communication between miners.

is a mean of dumping the blockchain data in a so-called consensus export.

is used to communicate between the blockchain node and externally running applications.

by the miner nodes which make sure that a transaction is valid.

by every single node in the blockchain network executing the same transaction.

by a cryptographic secure signature algorithm called ECDSA which makes sure that cheating is impossible.

always having the same signature.

having a different signature because of the nonce which changes upon every transaction.

can be destroyed using the selfdestruct keyword. This way all remaining ether will be sent to the receiver address, regardless if they have a fallback function or not.

are bound to a private key which is necessary to sign transactions outgoing from that account.

are logical opcodes running on the ethereum blockchain very similar to smart contracts.

working with either // or ///

working with /* comment */ or /** @.. natspec style */

not possible, all comments must be multi-line.

a list of transactions as well as uncles is incorporated in the block. All gas that is used during those transactions is added to the miners' balance. Also, the block reward is added to the miner. Then the same transactions are run again by every participating node in the network to achieve consensus.

a list of transactions is incorporated in that block. Gas used during the execution is attached to the executing contracts while the block reward is automatically spread across the mining pool to ensure a fair spread. Consensus is reached by a special form of hash code.

you should capitalize function names, events and contract names, to avoid confusion with JavaScript. You should use Tabs to indentation and a maximum of 80 characters per line.

contract names should be capitalized, while functions should be mixedCase. You should use 4 spaces as indentation and a maximum of 79 (or 99) characters per line.

contract should be mixedCase, as well as function names. Events should be capitalized. 2 spaces should be used as indentation and a maximum of 120 characters per line.

the amount of gas your contract deployment and transactions, against your contract, will need. This way you can essentially lower the gas costs over traditional web3.js dApps.

different Networks to deploy your contracts to. This way you can easily deploy to a local blockchain, the main-net or the Ropsten/Rinkeby Test-Net with only one parameter.

you can manage your secret API keys to the Ethereum Network. This way you can get access to several different Ethereum nodes at the same time without the need to switch your keyfiles.

is great, because they often find bugs which weren't considered before.

is not good, because you might give out secrets.

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

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