Blockchain Blockchain Other Certification CBDE Questions & Answers

• Question 81:

  To communicate with an Ethereum node via JavaScript:

  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.

  Correct Answer: A

• Question 82:

  PoS:

  A. would be better, because it can reduce the amount of energy needed for mining.

  B. would be worse, because it would increase the amount of energy needed for mining.

  Correct Answer: A

• Question 83:

  Externally Owned Accounts (EoA):

  A. are changing their address every time a Transaction is sent because of the nonce.

  B. are keeping their address, but on the blockchain a nonce is increased every time they send a transaction to avoid replay attacks.

  Correct Answer: A

• Question 84:

  Hashing Mining uses:

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

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

  C. 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.

  Correct Answer: C

• Question 85:

  Sending one Ether is actually internally translated:

  A. to Wei, so it will send the equivalent of 10^18 Wei.

  B. to Finney, so it will send the equivalent of 10^3 Finney.

  C. to Szabo, so it will send the equivalent of 10^6 Szabo.

  Correct Answer: A

• Question 86:

  Transactions containing the same data to create the same smart contract are:

  A. always having the same signature.

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

  Correct Answer: B

• Question 87:

  Smart Contracts:

  A. are always living on the same address, because the blockchain is deterministic. So, one account can always have one smart contract.

  B. are having the same address as the EOA.

  C. are sitting on their own address. The Address is created from the nonce and the EOA address and could be known in advance before deploying the smart contract.

  D. the address of the smart contract is a random address which gets generated by the miner who mines the contract-creation transaction.

  Correct Answer: C

• Question 88:

  Externally Owned Accounts:

  A. 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.

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

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

  Correct Answer: B

• Question 89:

  Proof of Work (PoW) vs. Proof of Stake.

  A. PoW is computationally intensive which requires lots of energy. On the other hand, miners earn straightforward a reward for mining a block and incorporating transactions.

  B. PoW is better than PoS, because with PoS we increase the amount of energy spent on the network.

  C. PoS is mining with specialized new hardware that has to be purchased with a stack of Ether in the network. Hence the Name: Proof of Stake, which derives from Stack.

  Correct Answer: A

• Question 90:

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

  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.

  Correct Answer: B