Question 1

If we divide two integers: 5/2, the result is:

Accepted Answer

A)  2, because the decimal is truncated. 
B)  3, because it's always rounded. 
C)  2.5, because it's automatically converted into a float. 
A)  2, because the decimal is truncated. 
B)  3, because it's always rounded. 
C)  2.5, because it's automatically converted into a float.

Question 2

View and Pure Functions:

Accepted Answer

A)  a function marked as pure can change the state, while a view function can only return static calls. 
B)  a function marked as view can never access state variables, while pure functions are here to return only one value. 
C)  a view function can access state variables, but not write to them. A Pure function cannot modify or read from state. 
A)  a function marked as pure can change the state, while a view function can only return static calls. 
B)  a function marked as view can never access state variables, while pure functions are here to return only one value. 
C)  a view function can access state variables, but not write to them. A Pure function cannot modify or read from state.

Question 3

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

Accepted Answer

A)  always having the same signature. 
B)  having a different signature because of the nonce which changes upon every transaction. 
A)  always having the same signature. 
B)  having a different signature because of the nonce which changes upon every transaction.

Question 4

To Iterate through a mapping, you:

Accepted Answer

A)  can use the length parameter of the mapping. 
B)  you need an external helper variable. 
C)  you cannot iterate any mapping to make the overall language design more safe. 
A)  can use the length parameter of the mapping. 
B)  you need an external helper variable. 
C)  you cannot iterate any mapping to make the overall language design more safe.

Question 5

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

Accepted Answer

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. 
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.

Question 6

GETH:

Accepted Answer

A)  is the reference implementation of the Ethereum protocol and every other node implementation internally uses the closed-source from Geth. 
B)  is the library that is used for the blockchain node Go-Ethereum. It is also used by Parity is parts, because it's closed source. 
C)  is one of the many blockchain nodes that implement the Ethereum Protocol. It's open source and everyone can contribute. 
A)  is the reference implementation of the Ethereum protocol and every other node implementation internally uses the closed-source from Geth. 
B)  is the library that is used for the blockchain node Go-Ethereum. It is also used by Parity is parts, because it's closed source. 
C)  is one of the many blockchain nodes that implement the Ethereum Protocol. It's open source and everyone can contribute.

Question 7

Go-Ethereum vs. Ganache:

Accepted Answer

A)  both are the same, just implemented in a different language. 
B)  with Go-Ethereum you get a real blockchain node where you can create your own local private network, connect to Test-Networks or the Main-Net, while with Ganache you get an in-memory blockchain simulation. 
C)  with Ganache you get a real blockchain node where you can connect to the Test-Networks Rinkeby and Ropsten. 
A)  both are the same, just implemented in a different language. 
B)  with Go-Ethereum you get a real blockchain node where you can create your own local private network, connect to Test-Networks or the Main-Net, while with Ganache you get an in-memory blockchain simulation. 
C)  with Ganache you get a real blockchain node where you can connect to the Test-Networks Rinkeby and Ropsten.

Question 8

All low-level functions on the address, so address.send(), address.call.valueQQ, address.callcode and address.delegatecall:

Accepted Answer

A)  are interrupting execution on error, because they throw an exception. 
B)  continuing execution on error silently, which is the reason why they are so dangerous. 
C)  returning Booleans to indicate an error during execution. 
D)  .send() throws an exception, while the other functions are returning Booleans during execution to indicate an error. 
A)  are interrupting execution on error, because they throw an exception. 
B)  continuing execution on error silently, which is the reason why they are so dangerous. 
C)  returning Booleans to indicate an error during execution. 
D)  .send() throws an exception, while the other functions are returning Booleans during execution to indicate an error.

Question 9

Assert is used:

Accepted Answer

A)  to check internal states that should never happen. 
B)  to check input arguments from users. 
A)  to check internal states that should never happen. 
B)  to check input arguments from users.

Question 10

If you are starting a new ERC20 token:

Accepted Answer

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. 
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.

Question 11

When defining a new datatype:

Accepted Answer

A)  its best to use a contract with public storage variables, so it can be used like a class. 
B)  it's best to use a struct, which is cheaper than deploying a new contract. 
C)  it's not possible to generate new datatypes in Solidity. 
A)  its best to use a contract with public storage variables, so it can be used like a class. 
B)  it's best to use a struct, which is cheaper than deploying a new contract. 
C)  it's not possible to generate new datatypes in Solidity.

Question 12

When you do external calls to other smart contracts:

Accepted Answer

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. 
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.

Question 13

Solidity gets compiled:

Accepted Answer

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

Question 14

Truffle has an integrated in-memory blockchain which makes unit-testing very easy:

Accepted Answer

A)  True, but it's still good to use Ganache, or even a real private network for testing. 
B)  False, it's necessary to use Ganache or even a real private network for testing. 
A)  True, but it's still good to use Ganache, or even a real private network for testing. 
B)  False, it's necessary to use Ganache or even a real private network for testing.

Question 15

Which is the right order for Denominations?

Accepted Answer

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

Question 16

The JSON-RPC Protocol:

Accepted Answer

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. 
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.

Question 17

PoS:

Accepted Answer

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. 
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.

Question 18

Why is it important to follow the same Interfaces?

Accepted Answer

A)  Websites that try to interface with the Token would have to know the exact ABI. It is upfront clear how the interaction has to be with the standard Interfaces. 
B)  The Ethereum Foundation can easily validate the Tokens and approve any audits by following the standard interface. 
A)  Websites that try to interface with the Token would have to know the exact ABI. It is upfront clear how the interaction has to be with the standard Interfaces. 
B)  The Ethereum Foundation can easily validate the Tokens and approve any audits by following the standard interface.

Question 19

When using require to check input parameters and it evaluates to false:

Accepted Answer

A)  all gas is consumed 
B)  all remaining gas is returned. 
A)  all gas is consumed 
B)  all remaining gas is returned.

Question 20

Address.send() and address.transfer() are considered:

Accepted Answer

A)  safe against reentrancy because of the small gas stipend of 2300 gas. 
B)  dangerous because they send all gas along, it's better to use address.call.value()(). 
A)  safe against reentrancy because of the small gas stipend of 2300 gas. 
B)  dangerous because they send all gas along, it's better to use address.call.value()().

If we divide two integers: 5/2, the result is:

View and Pure Functions:

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

To Iterate through a mapping, you:

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

GETH:

Go-Ethereum vs. Ganache:

All low-level functions on the address, so address.send(), address.call.valueQQ, address.callcode and address.delegatecall:

Assert is used:

If you are starting a new ERC20 token:

When defining a new datatype:

When you do external calls to other smart contracts:

Solidity gets compiled:

Truffle has an integrated in-memory blockchain which makes unit-testing very easy:

Which is the right order for Denominations?

The JSON-RPC Protocol:

PoS:

Why is it important to follow the same Interfaces?

When using require to check input parameters and it evaluates to false:

Address.send() and address.transfer() are considered:

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Exam 2: BTA Certified Blockchain Developer - Ethereum

If we divide two integers: 5/2, the result is:

View and Pure Functions:

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

To Iterate through a mapping, you:

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

GETH:

Go-Ethereum vs. Ganache:

All low-level functions on the address, so address.send(), address.call.valueQQ, address.callcode and address.delegatecall:

Assert is used:

If you are starting a new ERC20 token:

When defining a new datatype:

When you do external calls to other smart contracts:

Solidity gets compiled:

Truffle has an integrated in-memory blockchain which makes unit-testing very easy:

Which is the right order for Denominations?

The JSON-RPC Protocol:

PoS:

Why is it important to follow the same Interfaces?

When using require to check input parameters and it evaluates to false:

Address.send() and address.transfer() are considered:

Certified Blockchain Business Foundations

BTA Certified Blockchain Developer - Hyperledger

BTA Certified Blockchain Solution Architect

Filters