Crypto Jobs Blockchain Fundamentals 2 — Questions and Answers
Question 1: What is the primary purpose of a consensus mechanism in a blockchain network?
- To compress transaction data
- To agree on the valid state of the ledger without a central authority (Correct answer)
- To encrypt user wallet passwords
- To set the price of the native token
Correct answer: To agree on the valid state of the ledger without a central authority
Consensus mechanisms let distributed nodes agree on a single valid ledger state without trusting a central party.
Question 2: In Proof of Work, what are miners actually competing to do?
- Find a hash below a target value by varying a nonce (Correct answer)
- Vote on the next block leader
- Stake the most coins
- Sign the most transactions
Correct answer: Find a hash below a target value by varying a nonce
Miners repeatedly hash block data with different nonces until they find a hash below the network's difficulty target.
Question 3: What distinguishes Proof of Stake from Proof of Work?
- It requires more electricity
- Validators are chosen based on coins staked rather than computational power (Correct answer)
- It eliminates the need for any validators
- It stores no transaction history
Correct answer: Validators are chosen based on coins staked rather than computational power
Proof of Stake selects validators based on the amount of cryptocurrency they lock up as stake, avoiding heavy computation.
Question 4: What is a 51% attack?
- When 51% of users sell their tokens
- When an entity controls a majority of mining or staking power and can rewrite recent blocks (Correct answer)
- A bug affecting half the nodes
- A fee increase of 51%
Correct answer: When an entity controls a majority of mining or staking power and can rewrite recent blocks
Controlling over half the network's hashing or staking power lets an attacker double-spend and reorganize recent blocks.
Question 5: What does 'immutability' mean in the context of a blockchain?
- Blocks can be edited only by admins
- Once confirmed, recorded data is extremely difficult to alter (Correct answer)
- The chain never adds new blocks
- Tokens cannot be transferred
Correct answer: Once confirmed, recorded data is extremely difficult to alter
Cryptographic linking of blocks makes altering confirmed records practically infeasible without redoing all subsequent work.
Question 6: Why does each block contain the hash of the previous block?
- To reduce storage size
- To create a tamper-evident chain linking blocks in order (Correct answer)
- To speed up transactions
- To hide sender identities
Correct answer: To create a tamper-evident chain linking blocks in order
Including the prior block's hash chains blocks together so any change breaks all following hashes, revealing tampering.
Question 7: What is the role of a node in a blockchain network?
- It only stores private keys
- It validates and relays transactions and may keep a copy of the ledger (Correct answer)
- It exclusively mines new coins
- It sets transaction fees centrally
Correct answer: It validates and relays transactions and may keep a copy of the ledger
Nodes verify, propagate, and often store the ledger, keeping the network decentralized and synchronized.
Crypto Jobs Blockchain Fundamentals 2
What is the primary purpose of a consensus mechanism in a blockchain network?