CBDE questions • Exam prepare

Exam contains 99 questions

Page 16 of 17

Question 91 🔥

If you are starting a new ERC20 token:

Which database solution meets these requirements?

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

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

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

Discussion of the question

Question 92 🔥

To generate a random number:

Which database solution meets these requirements?

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

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

C. it's good to use the RANDAO smart contract.

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

Discussion of the question

Question 93 🔥

When you do external calls to other smart contracts:

Which database solution meets these requirements?

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

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

C. 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.

Discussion of the question

Question 94 🔥

When you are programming a game like poker of battleships where you need to hide opponents values is:

Which database solution meets these requirements?

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

B. 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.

C. 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.

Discussion of the question

Question 95 🔥

When considering smart contracts and the blockchain it's good:

Which database solution meets these requirements?

A. 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.

B. 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.

C. 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.

Discussion of the question

Question 96 🔥

When a smart contract pays out money:

Which database solution meets these requirements?

A. it’s good to use a push over a pull method.

B. it’s good to use a push and a pull method to ensure that participants can get their money no matter the contract state. In addition to and pushing it should contain a withdraw method.

C. it's good to use only pull and no push method.

Discussion of the question

Ready to Pass Your Certification Test

blockchain CBDE

Exam contains 99 questions

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