Question 1

To compare a String in Solidity you use:

Accepted Answer

A)  string1 == string2 
B)  the internal function "str_compare(str1,str2)" 
C)  you can't directly compare two strings, but one method would be to hash both strings and compare the hashes. 
D)  bytes32(string1) == bytes32(string2) 
A)  string1 == string2 
B)  the internal function "str_compare(str1,str2)" 
C)  you can't directly compare two strings, but one method would be to hash both strings and compare the hashes. 
D)  bytes32(string1) == bytes32(string2)

Question 2

With the truffle config file you can manage:

Accepted Answer

A)  the amount of gas your contract deployment and transactions, against your contract, will need. This way you can essentially lower the gas costs over traditional web3.js dApps. 
B)  different Networks to deploy your contracts to. This way you can easily deploy to a local blockchain, the main-net or the Ropsten/Rinkeby Test-Net with only one parameter. 
C)  you can manage your secret API keys to the Ethereum Network. This way you can get access to several different Ethereum nodes at the same time without the need to switch your keyfiles. 
A)  the amount of gas your contract deployment and transactions, against your contract, will need. This way you can essentially lower the gas costs over traditional web3.js dApps. 
B)  different Networks to deploy your contracts to. This way you can easily deploy to a local blockchain, the main-net or the Ropsten/Rinkeby Test-Net with only one parameter. 
C)  you can manage your secret API keys to the Ethereum Network. This way you can get access to several different Ethereum nodes at the same time without the need to switch your keyfiles.

Question 3

To store almost all data in the Ethereum Blockchain:

Accepted Answer

A)  a Linked List with pointers to previous blocks hashes is used. 
B)  a Merkle Patricia Trie is used. 
C)  a Radix Trie is used because the Merkle Patricia Trie is too inefficient. 
A)  a Linked List with pointers to previous blocks hashes is used. 
B)  a Merkle Patricia Trie is used. 
C)  a Radix Trie is used because the Merkle Patricia Trie is too inefficient.

Question 4

When a new block is mined:

Accepted Answer

A)  a list of transactions as well as uncles is incorporated in the block. All gas that is used during those transactions is added to the miners' balance. Also, the block reward is added to the miner. Then the same transactions are run again by every participating node in the network to achieve consensus. 
B)  a list of transactions is incorporated in that block. Gas used during the execution is attached to the executing contracts while the block reward is automatically spread across the mining pool to ensure a fair spread. Consensus is reached by a special form of hash code. 
A)  a list of transactions as well as uncles is incorporated in the block. All gas that is used during those transactions is added to the miners' balance. Also, the block reward is added to the miner. Then the same transactions are run again by every participating node in the network to achieve consensus. 
B)  a list of transactions is incorporated in that block. Gas used during the execution is attached to the executing contracts while the block reward is automatically spread across the mining pool to ensure a fair spread. Consensus is reached by a special form of hash code.

Question 5

In order to implement an ERC20 token contract, you'd need at least to implement the following functions and events in order to fulfill the interface requirements:

Accepted Answer

A)  totalSupply(), balanceOf(address), allowance(address,address), transfer(address,uint256), approve(address,uint256), transferFrom(address,address,uint256). Events: Transfer(address,address,uint256), Approval(address,address,uint256) 
B)  name(), symbol(), totalSupply(), balanceOf(address), ownerOf(uint26),approve(address,uint256), takeOwnership(uint256),transfer(address,uint256),Events: Transfer(address,address,uint256), Approval(address,address,uint256) 
A)  totalSupply(), balanceOf(address), allowance(address,address), transfer(address,uint256), approve(address,uint256), transferFrom(address,address,uint256). Events: Transfer(address,address,uint256), Approval(address,address,uint256) 
B)  name(), symbol(), totalSupply(), balanceOf(address), ownerOf(uint26),approve(address,uint256), takeOwnership(uint256),transfer(address,uint256),Events: Transfer(address,address,uint256), Approval(address,address,uint256)

Question 6

Events:

Accepted Answer

A)  are stored on chain and are a great way to get a return value when a contract calls another contract. 
B)  are stored in something like a side-chain and cannot be accessed by contracts. 
C)  are used primarily for debugging exceptions in solidity. 
A)  are stored on chain and are a great way to get a return value when a contract calls another contract. 
B)  are stored in something like a side-chain and cannot be accessed by contracts. 
C)  are used primarily for debugging exceptions in solidity.

Question 7

According to the official Style Guide:

Accepted Answer

A)  you should capitalize function names, events and contract names, to avoid confusion with JavaScript. You should use Tabs to indentation and a maximum of 80 characters per line. 
B)  contract names should be capitalized, while functions should be mixedCase. You should use 4 spaces as indentation and a maximum of 79 (or 99) characters per line. 
C)  contract should be mixedCase, as well as function names. Events should be capitalized. 2 spaces should be used as indentation and a maximum of 120 characters per line. 
A)  you should capitalize function names, events and contract names, to avoid confusion with JavaScript. You should use Tabs to indentation and a maximum of 80 characters per line. 
B)  contract names should be capitalized, while functions should be mixedCase. You should use 4 spaces as indentation and a maximum of 79 (or 99) characters per line. 
C)  contract should be mixedCase, as well as function names. Events should be capitalized. 2 spaces should be used as indentation and a maximum of 120 characters per line.

Question 8

Inheritance is useful, because a contract that is derived from another contract can make use of:

Accepted Answer

A)  all public state variables and properties, public and internal functions and modifiers. 
B)  all public and private state variables, public, internal and external functions, but not modifiers 
C)  all public state variables and properties, public functions and modifiers, but not internal, external or private ones. 
A)  all public state variables and properties, public and internal functions and modifiers. 
B)  all public and private state variables, public, internal and external functions, but not modifiers 
C)  all public state variables and properties, public functions and modifiers, but not internal, external or private ones.

Question 9

Truffle boxes are a great way:

Accepted Answer

A)  to contribute to the box community which is the distributed file system for truffle. 
B)  to start with a pre-configured environment for most web-development needs. 
C)  to use tools that makes boxing of Dapps for different platforms very easy. 
A)  to contribute to the box community which is the distributed file system for truffle. 
B)  to start with a pre-configured environment for most web-development needs. 
C)  to use tools that makes boxing of Dapps for different platforms very easy.

Question 10

A Private Network is:

Accepted Answer

A)  a side Channel to the Ethereum Main Net which costs less gas to run smart contracts. 
B)  an exact clone of the Rinkeby Test-Network which can be started as virtual machine in the Azure Cloud. 
C)  a Network running only in a private area, where people cannot join freely and openly. 
A)  a side Channel to the Ethereum Main Net which costs less gas to run smart contracts. 
B)  an exact clone of the Rinkeby Test-Network which can be started as virtual machine in the Azure Cloud. 
C)  a Network running only in a private area, where people cannot join freely and openly.

Question 11

Which statement is true about the EVM?

Accepted Answer

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. 
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.

Question 12

The Fallback function:

Accepted Answer

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. 
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.

Question 13

Address.send():

Accepted Answer

A)  will cascade exceptions and address.transfer() will return a false on error. 
B)  will return false on error while address.transfer() will cascade transactions. 
A)  will cascade exceptions and address.transfer() will return a false on error. 
B)  will return false on error while address.transfer() will cascade transactions.

Question 14

It's easy to write clean-room unit-tests with truffle:

Accepted Answer

A)  for Java, JavaScript, and C++ 
B)  for JavaScript using Web3.js 
C)  for Solidity and JavaScript 
D)  for any language, as long as it adheres to the open Testing-Interface from Truffle 
A)  for Java, JavaScript, and C++ 
B)  for JavaScript using Web3.js 
C)  for Solidity and JavaScript 
D)  for any language, as long as it adheres to the open Testing-Interface from Truffle

Question 15

When using assert to check invariants 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 16

A Blockchain Node:

Accepted Answer

A)  can never become a mining node. 
B)  can always become a mining node. 
C)  can become a mining node, depending if the implementation has the functionality implemented. 
A)  can never become a mining node. 
B)  can always become a mining node. 
C)  can become a mining node, depending if the implementation has the functionality implemented.

Question 17

Using selfdestruct(beneficiary) with the beneficiary being a contract without a payable fallback function:

Accepted Answer

A)  will throw an exception, because the fallback function is non-payable and thus cannot receive ether. 
B)  it's impossible to secure a contract against receiving ether, because selfdestruct will always send ether to the address in the argument. This is a design decision of the Ethereum platform. 
C)  selfdestruct doesn't send anything to a contract, it just re-assigns the owner of the contract to a new person. Sending ether must be done outside of selfdestruct. 
A)  will throw an exception, because the fallback function is non-payable and thus cannot receive ether. 
B)  it's impossible to secure a contract against receiving ether, because selfdestruct will always send ether to the address in the argument. This is a design decision of the Ethereum platform. 
C)  selfdestruct doesn't send anything to a contract, it just re-assigns the owner of the contract to a new person. Sending ether must be done outside of selfdestruct.

Question 18

You interact with a smart contract and see a gas usage of 50,000 gas with a gas cost of 15Gwei. How much Ether would you have to pay to the miner?

Accepted Answer

A)  750,000,000,000,000 Wei 
B)  750,000,000,000 Wei 
C)  750,000,000 Wei 
D)  A flat fee of 1 Ether 
A)  750,000,000,000,000 Wei 
B)  750,000,000,000 Wei 
C)  750,000,000 Wei 
D)  A flat fee of 1 Ether

Question 19

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

Accepted Answer

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. 
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.

Question 20

What's the difference between Ethereum Request for Comments (ERC) and Ethereum Improvement Proposals (EIP)?

Accepted Answer

A)  ERC are here to define standards for the usage of Ethereum. EIP are here to improve the Ethereum Protocol itself. 
B)  ERC are here to propose new distributed applications on top of the Ethereum layer, while EIP are here to improve existing mining software. 
C)  ERC are an open platform to discuss continuous forking of the Ethereum platform. Successful forks are then incorporated in the EIP for further voting by the Ethereum Consortium. 
A)  ERC are here to define standards for the usage of Ethereum. EIP are here to improve the Ethereum Protocol itself. 
B)  ERC are here to propose new distributed applications on top of the Ethereum layer, while EIP are here to improve existing mining software. 
C)  ERC are an open platform to discuss continuous forking of the Ethereum platform. Successful forks are then incorporated in the EIP for further voting by the Ethereum Consortium.

To compare a String in Solidity you use:

With the truffle config file you can manage:

To store almost all data in the Ethereum Blockchain:

When a new block is mined:

In order to implement an ERC20 token contract, you'd need at least to implement the following functions and events in order to fulfill the interface requirements:

Events:

According to the official Style Guide:

Inheritance is useful, because a contract that is derived from another contract can make use of:

Truffle boxes are a great way:

A Private Network is:

Which statement is true about the EVM?

The Fallback function:

Address.send():

It's easy to write clean-room unit-tests with truffle:

When using assert to check invariants and it evaluates to false:

A Blockchain Node:

Using selfdestruct(beneficiary) with the beneficiary being a contract without a payable fallback function:

You interact with a smart contract and see a gas usage of 50,000 gas with a gas cost of 15Gwei. How much Ether would you have to pay to the miner?

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

What's the difference between Ethereum Request for Comments (ERC) and Ethereum Improvement Proposals (EIP)?

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Exam 2: BTA Certified Blockchain Developer - Ethereum

To compare a String in Solidity you use:

With the truffle config file you can manage:

To store almost all data in the Ethereum Blockchain:

When a new block is mined:

In order to implement an ERC20 token contract, you'd need at least to implement the following functions and events in order to fulfill the interface requirements:

Events:

According to the official Style Guide:

Inheritance is useful, because a contract that is derived from another contract can make use of:

Truffle boxes are a great way:

A Private Network is:

Which statement is true about the EVM?

The Fallback function:

Address.send():

It's easy to write clean-room unit-tests with truffle:

When using assert to check invariants and it evaluates to false:

A Blockchain Node:

Using selfdestruct(beneficiary) with the beneficiary being a contract without a payable fallback function:

You interact with a smart contract and see a gas usage of 50,000 gas with a gas cost of 15Gwei. How much Ether would you have to pay to the miner?

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

What's the difference between Ethereum Request for Comments (ERC) and Ethereum Improvement Proposals (EIP)?

Certified Blockchain Business Foundations

BTA Certified Blockchain Developer - Hyperledger

BTA Certified Blockchain Solution Architect

Filters