Question 1

To communicate with an Ethereum node via [removed]

Options :

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

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

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

Answer: A

Question 2

Unit-Testing on a local chain is important, because it helps you:

Options :

A : to run tests quickly and especially for free, compared to continuous deployment on the MainNetwork. This way you save a lot of fees, time and costs

B : to run tests in an environment where logging is activated. On the Main-Net you have no access to transaction logs and this is ultimately the information you need to debug your contracts

C : to avoid regression bugs with contracts that are updated constantly on the main-net. Once you update a contract on the main-net, the address stays the same, but the code changes and this can have disastrous side-effects.

Answer: A

Question 3

The Fallback function:

Options :

A : cannot receive Ether, not even by adding the payable modifier

B : 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

C : can be used to avoid receiving ether

Answer: B

Question 4

The JSON-RPC Protocol:

Options :

A : is used to communicate between blockchain nodes

B : is used to ensure safe communication between miners

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

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

Answer: D

Question 5

Public Keys vs. Private Keys. Which statement is true?

Options :

A : The Public Key is for Signing Transactions, the Private Key must be given out to verify the signature.

B : The Private Key signs transactions, the Public Key can verify the signature

C : The Private Key is to generate a Public Key. The Public Key can sign transactions, the address is here to verify the transactions

Answer: B

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