Vendor: Blockchain Exam Code: CBDE Exam Name: BTA Certified Blockchain Developer - Ethereum Date: Oct 26, 2019 File Size: 24 KB

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## Demo Questions

##### Question 1
A Hashing Algorithm is deterministic. What does it mean?
1. it always produces the same output given the same input.
2. it uses equally distributed data to produce the output given a long input.
3. it shouldn't be possible to re-generate the input given the output.
##### Question 2
What's the correct scientific notation?
1. 1 Ether = 10^18 wei, 10^9 Gwei, 10^3 Finney
2. 1 Ether = 10^19 wei, 10^13 Gwei, 10^3 Finney
3. 1 Ether = 10^16 wei, 10^13 Gwei, 10^3 Finney
4. 1 Ether = 10^18 wei, 10^6 Gwei, 10^6 Finney
##### Question 3
What are Private Keys used for?
1. To Protect the Public Keys by being cryptographically significant.
2. To Sign Transactions And To Derive an Address From.
3. To Generate An Address which can sign transactions.
##### Question 4
Public Keys vs. Private Keys. Which statement is true?
1. The Public Key is for Signing Transactions, the Private Key must be given out to verify the signature.
2. The Private Key signs transactions, the Public Key can verify the signature.
3. The Private Key is to generate a Public Key. The Public Key can sign transactions, the address is here to verify the transactions.
##### Question 5
Proof of Work (PoW) vs. Proof of Stake.
1. 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.
2. PoW is better than PoS, because with PoS we increase the amount of energy spent on the network.
3. 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.
Explanation:
##### Question 6
Externally Owned Accounts:
1. 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.
2. are bound to a private key which is necessary to sign transactions outgoing from that account.
3. are logical opcodes running on the ethereum blockchain very similar to smart contracts.
##### Question 7
Smart Contracts:
1. are always living on the same address, because the blockchain is deterministic. So, one account can always have one smart contract.
2. are having the same address as the EOA.
3. 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.
4. the address of the smart contract is a random address which gets generated by the miner who mines the contract-creation transaction.
##### Question 8
Transactions containing the same data to create the same smart contract are:
1. always having the same signature.
2. having a different signature because of the nonce which changes upon every transaction.
##### Question 9
Sending one Ether is actually internally translated:
1. to Wei, so it will send the equivalent of 10^18 Wei.
2. to Finney, so it will send the equivalent of 10^3 Finney.
3. to Szabo, so it will send the equivalent of 10^6 Szabo.
##### Question 10
Hashing Mining uses:
1. Keccack256 while internally to hash values it's easy to use the Dagger-Hashimoto to create a meaningful hash.
2. the Dagger-Hashimoto hashing while internally the EVM uses SHA256 which is an alias for Keccack256.
3. 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.