Blockchain CBSA Practice Test - Questions Answers, Page 13

There are several redundant implementations of the Ethereum protocol to ensure the correctness of the implementation. Additionally, not all blockchain nodes operate the same way. Some are purely for developing and hold a blockchain inmemory and just simulate the mining. Real Blockchain Nodes: 1. Cpp-ethereum 2. Go-Etheruem (GETH) 3. Parity In-Memory Blockchain simulations for rapid development: 1. TestRPC 2. Ganache 3. Truffle Developer Console Clients to access the blockchain in a convenient way: 1. MetaMask browser Plugin through Infura 2. Status.IM Android/iOS app through Infura 3. MIST DApp Browser with integrated GETH

Ethereum Smart Contracts run on compiled bytecode, which means that there can be several high-level languages which code can be written in. In particular, Ethereum has a number of languages available: 1. Solidity - the most popular language now (2018). 2. Vyper - A Language by Vitalik Buterin with an emphasis on security 3. LLL - "Low Level Lisp-like Language" 4. Mutan - Golang-like, deprecated in 2015 5. Serpent, Python-like, but seems to be no longer maintained 6. Bamboo

Most widely used are Wei, Gwei, Finney and Ether. With the tool https://etherconverter.online/ you can easily convert different units.

If you send off a transaction, then several fields have to be set. These include: "¢ nonce: It is a sequence number for the sending account which counteracts replay attacks "¢ gasprice: price offered to pay per gas "¢ startgas: upper limit for the gas consumption "¢ to: destination address (EoA or contract address) "¢ value: Ether to transfer "¢ data: Data to transfer "¢ v, r, s: ECDA signature.

Reference: https://coingape.com/ethereum-founder-vitalik-buterin-consensus-algorithm-fight-attacks/

At the time of writing these lines, the Ethereum Blockchain still runs on Proof of Work. When a block is mined, the miner node selects some transactions from a pool of pending transactions. Usually they are sorted by how much gas they would bring in. These transactions are executed and incorporated in the new block. But a block also contains two very important parameters: a difficulty and a timestamp. The difficulty regulates how hard it is to find a block by the miner. The mining time is set to be between 10 and 20 seconds. If it's beyond 20 seconds, the difficulty is too high and will be automatically lowered going forward. If the mining happens below 10 seconds, then the difficulty increases. The timestamp is the time when a miner found the block. It is not automatically derived, rather it is set by the miner itself and can thus be influenced to a certain degree. The timestamp does not depend on the time zone, as it's the standard Unix timestamp.

The EVM is basically a sandboxed virtual machine running on every single node. It is Turing complete and a transaction-based state machine. The nodes reach consensus by executing all transactions. Only the miner node gets the block reward, all other nodes are just checking if the miner was "honest".

Provenance means recording the history of data, from its inception to various stages of the data lifecycle. Provenance provides a detailed record of how the data was collected, where it was stored and how it is used. Blockchain holds complete provenance details of each component of data transfer. It is accessible to all the participants in a business network. It improves the system utilization and increases trust.

Smart contracts generally are not legal contracts. However, its possible that a smart contract could be accepted as a legal contract but not normally. Reference:

https://blockgeeks.com/guides/smart-contracts/