Free Cryptocurrency Blockchain Technology Fundamentals Questions and Answers — Questions and Answers
Question 1: A development team is launching a new cryptocurrency designed to minimize energy consumption. Instead of requiring intensive computational work, the protocol selects validators to create new blocks based on the amount of currency they have staked as collateral. Which consensus mechanism does this describe?
- Proof-of-Work (PoW)
- Proof-of-Stake (PoS) (Correct answer)
- Proof-of-Authority (PoA)
- Proof-of-Burn (PoB)
Correct answer: Proof-of-Stake (PoS)
Proof-of-Stake (PoS) is a consensus mechanism that selects validators based on the quantity of the native currency they hold and are willing to 'stake' or lock up as collateral. This method is significantly more energy-efficient than Proof-of-Work (PoW), which relies on computational power to solve complex puzzles.
Question 2: Within a standard blockchain block header, what is the data structure that is created by recursively hashing pairs of transaction IDs together to efficiently summarize and verify the integrity of all transactions in the block?
- Transaction Ledger
- Nonce
- Genesis Hash
- Merkle Root (Correct answer)
Correct answer: Merkle Root
The Merkle Root is a single hash that represents the root of a Merkle tree, which is constructed by hashing all transaction IDs in a block. This structure allows for efficient verification of transactions without needing to download and process the entire block's transaction data.
Question 3: Which of the following is a primary characteristic that distinguishes a private or permissioned blockchain from a public blockchain like Bitcoin?
- The requirement for participants to be vetted and granted access. (Correct answer)
- The use of cryptographic hashes to link blocks chronologically.
- The ability for the ledger to be distributed across multiple nodes.
- The immutable nature of recorded transactions.
Correct answer: The requirement for participants to be vetted and granted access.
The core difference between public and private blockchains is access control. Public blockchains are 'permissionless,' allowing anyone to join. Private blockchains are 'permissioned,' meaning participants must be invited and authorized by a central administrator or consortium. The other options are fundamental characteristics of most blockchains, both public and private.
Question 4: What is the fundamental purpose of a smart contract on a blockchain?
- To provide a user-friendly interface for wallet applications.
- To encrypt all transaction data for maximum privacy.
- To act as a self-executing agreement with predefined rules. (Correct answer)
- To store large files in a decentralized manner.
Correct answer: To act as a self-executing agreement with predefined rules.
A smart contract is a program stored on a blockchain that automatically executes the terms of an agreement when predefined conditions are met. This removes the need for a traditional intermediary, automating workflows and ensuring outcomes are carried out as programmed.
Question 5: A user controls a single Unspent Transaction Output (UTXO) worth 5 ETH. They initiate a transaction to send 1 ETH to a friend. In a UTXO-based blockchain, how is this transaction typically processed?
- The original 5 ETH UTXO is consumed, and two new UTXOs are created: one for 1 ETH to the friend and one for approximately 4 ETH back to the sender as change. (Correct answer)
- The original 5 ETH UTXO's value is updated to 4 ETH, and a new 1 ETH UTXO is created for the friend.
- The transaction is rejected because the UTXO value does not exactly match the amount being sent.
- A 1 ETH portion is 'chipped off' the 5 ETH UTXO, leaving the original UTXO intact with a reduced balance.
Correct answer: The original 5 ETH UTXO is consumed, and two new UTXOs are created: one for 1 ETH to the friend and one for approximately 4 ETH back to the sender as change.
In the UTXO model, transaction inputs are consumed in their entirety. The original 5 ETH UTXO is spent, and the transaction creates new outputs: one for the recipient (1 ETH) and a 'change' output (the remainder, minus transaction fees) that is sent back to the original user under their control.
Question 6: The 'Blockchain Trilemma' refers to the widely held belief that it is difficult for a decentralized network to optimize three key properties at once. Which of the following correctly lists these three properties?
- Speed, Cost, and Anonymity
- Decentralization, Security, and Scalability (Correct answer)
- Immutability, Transparency, and Usability
- Mining, Staking, and Hashing
Correct answer: Decentralization, Security, and Scalability
Coined by Vitalik Buterin, the Blockchain Trilemma posits that it is challenging to build a blockchain that is simultaneously decentralized (lacks a central point of failure), secure (resistant to attacks), and scalable (able to process a high volume of transactions). Often, improving one area requires a trade-off in one or both of the others.
Free Cryptocurrency Blockchain Technology Fundamentals Questions and Answers
A development team is launching a new cryptocurrency designed to minimize energy consumption.
Instead of requiring intensive computational work, the protocol selects validators to create new blocks based on the amount of currency they have staked as collateral.
Which consensus mechanism does this describe?