ExamTopics

Question 1

Consensus is reached:

A. by the miner nodes which make sure that a transaction is valid.
B. by every single node in the blockchain network executing the same transaction.
C. by a cryptographic secure signature algorithm called ECDSA which makes sure that cheating is impossible.

Answer 1

B

Question 2

Smart Contracts can be written in:

A. Java, C++, Solidity and JavaScript, because the Ethereum Blockchain is completely language agnostic and cross compilers exist for every major language.
B. Solidity, Viper, LLL and Serpent, because those are high level languages that are compiled down to bytecode.
C. Solidity and JavaScript, because those are the official first implementations for Distributed applications and the Blockchain supports those languages fully.

Answer 2

B

Question 3

Solidity gets compiled:

A. to bytecode that can’t be understood by humans.
B. to bytecodes which are essentially opcodes running instruction by instruction.

Answer 3

B

Question 4

Having a bug-bounty program early on:

A. can help to engage the community in testing your smart contracts and therefore help to find bugs early.
B. might be a burden as it is an administrative overhead mainly.
C. is completely useless. Who wants to test beta-ware software? It’s better to start with the bug-bounty program after the contract is released on the main-net.

Answer 4

A

Question 5

Which is the right order for Denominations?

A. Wei, Finney, Szabo, Ether, Tether.
B. Finney, Szabo, Mether, Gwei.
C. Gwei, Szabo, Finney, Ether.

Answer 5

C

Question 6

The nonce-field in a transaction is used:

A. to protect against replay attacks.
B. to have an additional checksum for transactions.
C. to sum up all ethers sent from that address.

Answer 6

A

Question 7

Which statement is true about the EVM?

A. While the EVM is Sandboxed, it isn’t as powerful as the Bitcoin Network, because it’s not Turing Complete.
B. The EVM can’t access hardware layers or anything outside a blockchain node because it’s sandboxed.
C. The EVM is extremely powerful, turing complete and perfect for doing computational intensive things, because of the direct access to the graphics card.

Answer 7

C

Question 8

DApps are:

A. great, because they cut the middle man, run on a trusted platform, apply logic to the blockchain where already economic assets are running and thus allow peer to peer trade.
B. an amazing way to create new applications. Those applications run entirely separated from other applications on the platform and allow for logical interactions. They can’t access any funds to add an additional layer of trust.
C. a new way of applying logical operations for banks and big financial institutions. This way they can reduce the staff while operating at increased security.

Answer 8

B

Question 9

To get most out of the blockchain, it is best:

A. to use it for the whole business logic. It’s always best to have everything in once place.
B. to use it only for things which need the benefits of the blockchain.

Answer 9

B

Question 10

A Hashing Algorithm is deterministic. What does it mean?

A. it always produces the same output given the same input.
B. it uses equally distributed data to produce the output given a long input.
C. it shouldn’t be possible to re-generate the input given the output.

Answer 10

A

Question 11

What’s the correct scientific notation?

A. 1 Ether = 10^18 wei, 10^9 Gwei, 10^3 Finney
B. 1 Ether = 10^19 wei, 10^13 Gwei, 10^3 Finney
C. 1 Ether = 10^16 wei, 10^13 Gwei, 10^3 Finney
D. 1 Ether = 10^18 wei, 10^6 Gwei, 10^6 Finney

Answer 11

A

Question 12

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.

Answer 12

B

Question 13

What are Private Keys used for?

A. To Protect the Public Keys by being cryptographically significant.
B. To Sign Transactions And To Derive an Address From.
C. To Generate An Address which can sign transactions.

Answer 13

B

Question 14

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.

Answer 14

A

Question 15

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.

Answer 15

B

Question 16

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.

Answer 16

C

Question 17

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.

Answer 17

B

Question 18

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.

Answer 18

A

Question 19

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.

Answer 19

C

Question 20

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.

Answer 20

A

Question 21

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.

Answer 21

A

Question 22

What are Ethereum Nodes?

A. Programs implementing the Ethereum Protocol to talk to each other and JSON-RPC interfaces to talk to the outside world.
B. A Java-Script library to compile and run Solidity Code.
C. A Framework for deploying and running smart contract in a decentralized way.

Answer 22

A

Question 23

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

Answer 23

A

Question 24

It’s possible to access the blockchain via an Ethereum Node:

A. only via JavaScript because there is the proprietary Web3.js library.
B. by any programming language, as long as it adheres to the JSON-RPC standard.

Answer 24

B