Question 1

In the Ethereum EVM there are two types of memory areas. (Select two.)

Accepted Answer

Storage and Memory are the two types of memory areas in the Ethereum EVM. Storage is persistent and used for contract state, while Memory is temporary and used during contract execution.

Question 2

The gas price is a value set by the creator of the blockchain transaction? Select best answer.

Accepted Answer

The gas price is a value set by the creator of the transaction, who has to pay gas_price * gas up front from the sending account. If some gas is left after the execution, it is refunded in the same way. If the gas is used up at any point (i.e. it is negative), an out-of-gas exception is triggered, which reverts all modifications made to the state in the current call frame.

Question 3

You currently using the Metamask Chrome plugin and you see a selection for Etherescan in the plugin. What is Etherscan used for?

Accepted Answer

A search engine that allows users to easily lookup, confirm and validate transactions that have taken place on the Ethereum Blockchain

Question 4

Regarding Ethereum contracts, the contracts can call (perform) two specific message calls. The message calls are either _____________ or __________? (Select two.)

Accepted Answer

Contracts can call other contracts or send Ether to non-contract accounts by the means of message calls. Message calls are similar to transactions, in that they have a source, a target, data payload, Ether, gas and return data. In fact, every transaction consists of a top-level message call which in turn can create further message calls.

Question 5

Which of the following would NOT be true about what a smart contract gives your organization?

Accepted Answer

Smart contracts generally are not legal contracts. However, its possible that a smart contract could be accepted as a legal contract but not normally. Read more about Smart contracts here

Question 6

A ____________cipher basically means it is using a fixed key which replaces the message with a pseudorandom string of characters. It is basically the encryption of each letter one at a time. What is the cipher type?

Accepted Answer

Stream cipher basically means using a fixed key which replaces the message with a pseudorandom string of characters. It is basically the encryption of each letter one at a time. Reference: https://blockgeeks.com/guides/cryptocurrencies-cryptography/

Question 7

In the EVM every account has a persistent key-value store mapping 256-bit words to 256-bit words called ________

Accepted Answer

Every account has a persistent key-value store mapping 256-bit words to 256-bit words called storage.

Question 8

Contracts live on the blockchain in an Ethereum-specific binary format called _____________?

Accepted Answer

The Ethereum Virtual Machine (EVM) is the runtime environment for smart contracts in Ethereum. It is not only sandboxed, but actually completely isolated, which means that code running inside the EVM has no access to network, filesystem, or other processes. Smart contracts even have limited access to other smart contracts.

Question 9

You are considering writing smart contracts and there are a few different languages you can consider. (Select two.)

Accepted Answer

To write smart contracts there are a few different languages: Solidity, which is like JavaScript and has .sol as a file extension, Serpent, Python-like with extension .se, and a 3rd, LLL, based on Lisp. Serpent was popular a while back but Solidity is the most popular right now and more robust, so just use Solidity. You prefer Python? Use Solidity.

Question 10

Secure Hash Algorithm (SHA-256) output is always 256 bits or 32 bytes in length regardless of the length of the input (even if input is millions of bytes). Select best answer.

Accepted Answer

SHA stands for Secure Hash Algorithm. This is used to prove data integrity. The same input(s) will always produce the exact same output. This output is always 256 bits or 32 bytes in length regardless of the length of the input (even if input is millions of bytes).

Question 11

Which of the following blockchain is NOT a permissioned blockchain?

Accepted Answer

Ethereum is a public blockchain, meaning it is not permissioned and anyone can participate in the network.

Question 12

What blockchain is considered Blockchain 1.0, the first blockchain?

Accepted Answer

Blockchain 1.0, Grandpa Bitcoin

Question 13

The key difference between encryption and hashing is that encrypted strings can be reversed back into their original decrypted form if you have the right key?

Accepted Answer

Encryption is a reversible process using a key, while hashing is a one-way function that cannot be reversed to retrieve the original data.

Question 14

Vitalik Buterin referred to this concept of trust beyond just currency as 'smart contracts' or even blockchain-based "decentralized autonomous organizations" (DAOs). Ethereum is considered Blockchain version?

Accepted Answer

2.0 Ethereum came after Bitcoin. Vitalik Buterin, one of the writers for Bitcoin Magazine that tried to popularize the technology in the early 2012. He witnessed first-hand the problems in the Bitcoin implementation like wasteful mining hardware, centralized mining community, and lack of network scalability. In 2013, the then 19 year old Vitalik described his vision for Ethereum by extending the concept of Bitcoin beyond just currency. He proposed a platform where developer community and entrepreneurs to build distributed application (Dapps) for the Blockchain network. He referred to this concept of trust beyond just currency as 'smart contracts' or even blockchain-based "decentralized autonomous organizations" (DAOs).

Question 15

In the Bitcoin blockchain the "block creation time" is set to 10 minutes and this can never change.

Accepted Answer

Remember, that the block creation time is set to 10 minutes and this can never change. So after a fixed time of approximately 2 weeks or exactly 2016 blocks the difficulty is re-adjusted. Increase in difficulty means target decreases.

Question 16

What type of attack would be considered a very large flaw in public blockchains such as Bitcoin's Blockchain where the majority of hashpower could possibly be controlled thru an attack? What is the specific attack Bitcoin could be exposed to?

Accepted Answer

A 51% attack occurs when a single entity gains control of more than 50% of the network's mining hash rate, allowing them to potentially double-spend coins and prevent new transactions from being confirmed. This is a significant vulnerability in public blockchains like Bitcoin.

Question 17

R3 Corda does not organize time into blocks. What does Corda actually perform and use?

Accepted Answer

Review Technical Whitepaper https://www.corda.net/ Corda network has one or more notary services which provide transaction ordering and timestamping services, thus abstracting the role miners play in other systems into a pluggable component.

Question 18

What are two cryptocurrencies that you would expect to see mining equipment with ASICS? (Select two.)

Accepted Answer

The answer of What are two cryptocurrencies that you would...

Question 19

The___________________ is the runtime environment for smart contracts in Ethereum?

Accepted Answer

EVM The Ethereum Virtual Machine (EVM) is the runtime environment for smart contracts in Ethereum. It is not only sandboxed, but actually completely isolated, which means that code running inside the EVM has no access to network, filesystem, or other processes. Smart contracts even have limited access to other smart contracts.

Question 20

Ethereum is considered to be a ______________type of blockchain.

Accepted Answer

Permissionless - anyone can join Anyone can run a node, run mining software/hardware, access a wallet and write data onto and transact within the blockchain (as long as they follow the rules of the bitcoin blockchain). There is no way to censor anyone, ever, on the permissionless bitcoin blockchain.

Exam 4: BTA Certified Blockchain Solution Architect

In the Ethereum EVM there are two types of memory areas. (Select two.)

The gas price is a value set by the creator of the blockchain transaction? Select best answer.

You currently using the Metamask Chrome plugin and you see a selection for Etherescan in the plugin. What is Etherscan used for?

Regarding Ethereum contracts, the contracts can call (perform) two specific message calls. The message calls are either ___ or ? (Select two.)

Which of the following would NOT be true about what a smart contract gives your organization?

A ____________cipher basically means it is using a fixed key which replaces the message with a pseudorandom string of characters. It is basically the encryption of each letter one at a time. What is the cipher type?