Blockchain BTA Certified Blockchain Developer - Ethereum CBDE Exam Dumps: Updated Questions & Answers (June 2025)

safe against reentrancy because of the small gas stipend of 2300 gas.

dangerous because they send all gas along, it's better to use address.call.value()().

to move all existing logic to the blockchain, so everything runs on the same system. This way it might be more complex, but easier to maintain.

to move only those parts to the blockchain that really need the blockchain. This way smart contracts can be easier to read, easier to test and are not so complex.

to move those parts to the blockchain that deal with Ether transfers. All other parts can remain in traditional database systems. This way only the value-transfer is on the blockchain.

the Metadata contains the ABI Array, which defines the Interface to interact with the Smart Contract. Metadata can also contain the address of the smart contract when it gets deployed.

metadata contains the address, and the size of the smart contract. The ABI Array is generated externally upon deploying the smart contract.

the ABI array and the Metadata are not generated when solidity is compiled to bytecode, its generated by a migration software which deploys the smart contract on the blockchain.

True

False

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

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

the library you use must make use of the JSON-RPC Interface of an Ethereum Node.

must Implement the Ethereum Protocol to connect to other Ethereum Nodes.

must use Web3.js, which is closed source to communicate to other Ethereum Nodes.

the User.

contract A.

with private state variables. This way nobody else other than the smart contract itself can see the information

with external contracts holding those values. This way we can make sure that the information flow is following a clear logic and nobody else can access this information.

You can't hide anything on the blockchain, because the information is public, just the call is private which means only other smart contracts would be limited in accessing that information.

it’s good to start with a local in-memory blockchain with unit tests but then deploy to the mainnet as rapidly as possible.

it's good to start with a local in-memory blockchain with unit-tests. Then, in the next step, debug and test the smart contract on a test-net like Ropsten or Rinkeby with beta customers to iron out last issues before deploying it to the main-net.

it's good to start with a test-net with beta-customers like on the Rinkeby or Ropsten testnet, before testing it locally on an in-memory blockchain simulation such as Ganache. Then deploy it to the main-net.

It helps you to find bugs, regression bugs and sometimes also helps you to understand your code from different angles.

It is a great way to spend time on something that you get paid for. But ultimately it will just slow down the development process.