Consensus mechanism

What is the main goal of a consensus mechanism in a blockchain network?

• To increase transaction fees

• To ensure all nodes agree on the same ledger

• To hide transaction details

• To allow double spending

Which consensus mechanism does Bitcoin use?

• Proof-of-Stake (PoS)
  

• Delegated Proof-of-Stake (DPoS)

• Proof-of-Work (PoW)

• Practical Byzantine Fault Tolerance (PBFT)

In Proof-of-Work, what must miners do to add a new block?

• Vote for delegates
  

• Solve a cryptographic puzzle

• Lock their coins

• Verify user identities

What problem does Practical Byzantine Fault Tolerance (PBFT) solve?

• High transaction fees
  

• Malicious or faulty nodes in the network

• Energy wastage

• Block size limitation

Which type of blockchain commonly uses PBFT?

• Permissionless blockchain
  

• Permissioned blockchain

• Hybrid blockchain

• Public blockchain

What is the role of delegates in Delegated Proof-of-Stake (DPoS)?

• To mine new coins
  

• To validate transactions on behalf of users

• To design smart contracts

• To secure wallets

How does DPoS achieve faster transaction speeds?

• By removing consensus

• By using fewer elected block producers

• By increasing block size

• By reducing transaction verification

Between PoW and PoS, which offers greater scalability?

• Proof-of-Stake (PoS)

• Proof-of-Work (PoW)

• Both are equal

• PBFT

What is the native cryptocurrency of the Bitcoin blockchain?

• Ether (ETH)
  

• Ripple (XRP)

• Bitcoin (BTC)

• Tether (USDT)

What programming language is used to write Ethereum smart contracts?

• Python

• C++

• Java

• Solidity