Blockchain and Crypto Blockchain Fundamentals & Architecture 2 — Questions and Answers
Question 1: What is a blockchain 'fork' and when does it occur?
- A backup copy of the blockchain stored on an alternate server
- A split in the blockchain that creates two divergent chains following a rule change or disagreement (Correct answer)
- A transaction that is rejected by the majority of nodes
- A scheduled network upgrade that temporarily halts block production
Correct answer: A split in the blockchain that creates two divergent chains following a rule change or disagreement
A fork occurs when nodes adopt different protocol rules, causing the chain to diverge; soft forks are backward-compatible while hard forks create a permanent split.
Question 2: Which type of blockchain allows anyone to join, read, and submit transactions without requiring permission?
- Private blockchain
- Consortium blockchain
- Permissioned blockchain
- Public blockchain (Correct answer)
Correct answer: Public blockchain
Public blockchains like Bitcoin and Ethereum are open to anyone; no authority grants access and all data is publicly verifiable.
Question 3: Which of the following best defines a smart contract?
- A legally binding digital agreement notarized on the blockchain
- Self-executing code stored on the blockchain that automatically enforces terms when conditions are met (Correct answer)
- A signed contract between two miners governing block reward sharing
- A consensus mechanism used by permissioned blockchains
Correct answer: Self-executing code stored on the blockchain that automatically enforces terms when conditions are met
Smart contracts are programs deployed on the blockchain that execute deterministically and automatically when predefined conditions are satisfied, with no intermediary required.
Question 4: In a Proof of Stake consensus mechanism, what primarily determines a validator's probability of being selected to create the next block?
- The computational hash rate the validator contributes
- The number of blocks the validator has previously produced
- The amount of cryptocurrency the validator has locked up as stake (Correct answer)
- The geographic location and uptime of the validator's node
Correct answer: The amount of cryptocurrency the validator has locked up as stake
In Proof of Stake, validators are selected proportionally to the amount of cryptocurrency they stake as collateral, which they risk losing (slashing) for dishonest behavior.
Question 5: What does the Byzantine Generals Problem describe in distributed computing?
- A cryptographic weakness discovered in Byzantine-era cipher systems
- The challenge of achieving reliable consensus when some participants may be faulty or malicious (Correct answer)
- A routing inefficiency in large peer-to-peer networks
- A denial-of-service vulnerability affecting Byzantine fault-tolerant blockchains
Correct answer: The challenge of achieving reliable consensus when some participants may be faulty or malicious
The Byzantine Generals Problem models the difficulty of coordinating agreement among distributed nodes when some nodes may send conflicting or false information.
Question 6: What is 'sharding' as a blockchain scalability solution?
- Splitting a private key into multiple pieces for distributed custody
- Partitioning the blockchain into smaller segments that process transactions in parallel (Correct answer)
- Distributing block rewards across multiple mining pools simultaneously
- Creating independent backup copies of the blockchain across data centers
Correct answer: Partitioning the blockchain into smaller segments that process transactions in parallel
Sharding divides the network into smaller partitions (shards), each handling a subset of transactions in parallel, increasing overall throughput.
Question 7: What is the 'double-spend problem' that blockchain technology is designed to prevent?
- The risk of a miner collecting block rewards from two different pools
- Attempting to use the same unit of digital currency in two separate transactions simultaneously (Correct answer)
- The overhead cost incurred when processing a transaction across two chains
- The scenario where a user accidentally sends twice the intended amount
Correct answer: Attempting to use the same unit of digital currency in two separate transactions simultaneously
The double-spend problem occurs when someone broadcasts two conflicting transactions spending the same coins; blockchain prevents this through distributed consensus and transaction ordering.
Blockchain and Crypto Blockchain Fundamentals & Architecture 2
What is a blockchain 'fork' and when does it occur?