Unit 1: Introduction to Blockchain and Decentralization - Practice Quiz

1 Which development helped blockchain technology expand beyond digital currency?

2 Why have organizations explored blockchain technology?

3 Who published the Bitcoin white paper under a pseudonym?

4 In which year was the Bitcoin white paper published?

5 What is a distributed system?

6 What is a node in a distributed system?

7 How are blocks commonly connected in a blockchain?

8 What does a block in a blockchain usually contain?

9 What is the main purpose of a consensus mechanism?

10 Which of the following is a blockchain consensus mechanism?

11 What does decentralization generally mean in a blockchain network?

12 Which feature supports decentralization in a blockchain?

13 Which method removes an intermediary from a transaction?

14 Which method decentralizes decision-making through competition among participants?

15 Which action is a practical route toward decentralizing an application?

16 What does full ecosystem decentralization aim to distribute?

17 What is a hash in blockchain terminology?

18 What is a public key commonly used for in blockchain systems?

19 Which blockchain platform is widely known for supporting smart contracts?

20 What does DeFi refer to in blockchain technology?

21 A group of competing logistics companies wants to share shipment histories without allowing one company to control the database. Which blockchain characteristic most directly supports this use case?

22 Before Bitcoin, digital cash systems struggled with double-spending. What was Bitcoin's key contribution to addressing this problem without a central authority?

23 During a network partition, two groups of nodes continue accepting conflicting updates instead of pausing. Which property is the system prioritizing?

24 An attacker changes a transaction in an old block. Why would nodes normally detect this alteration?

25 A Byzantine fault-tolerant network has 10 validators and follows the condition . What is the maximum number of Byzantine validators it can tolerate?

26 A charity stores donations on a blockchain, but one employee can transfer all funds using a single private key. Which change would most improve decentralization of fund control?

27 An online marketplace currently approves every listing through a central administrator. Which change most directly decentralizes its decision-making process?

28 A new blockchain network initially uses one operator for rapid development but plans to distribute control later. Which action best represents progressive decentralization?

29 A decentralized exchange uses smart contracts and distributed validators, but its website is hosted on one server controlled by the founding company. What risk remains?

30 A protocol upgrade introduces new optional transaction rules, while nodes running the old software can still accept blocks produced under those rules. What is this upgrade called?

31 A consortium of banks needs a permissioned ledger with known identities, restricted data access, and configurable consensus. Which platform is the most suitable?

32 A blockchain application moves transaction execution off the main chain, bundles many results, and posts compressed data or proofs back to the main chain. Which trend does this describe?

33 Which earlier idea most directly influenced Bitcoin's proof-of-work mechanism by requiring computational effort to create a valid value?

34 In a distributed payment network, one node sends different transaction histories to different peers. What type of fault is this behavior?

35 A light client wants to verify that one transaction is included in a block without downloading every transaction. What should it request?

36 Two valid Bitcoin branches temporarily exist. Under normal operation, which branch will nodes eventually prefer?

37 A document registry stores complete files on one company server but records each file's hash on a public blockchain. What does the blockchain primarily guarantee?

38 A protocol team wants to prevent one company from controlling software development. Which method best distributes development authority?

39 A lending protocol is governed by a DAO and runs on a decentralized blockchain, but it uses price data signed by one exchange. Which component most threatens full ecosystem decentralization?

40 A user must prove that their account balance exceeds a required amount without revealing the exact balance. Which technology is best suited to this requirement?

41 A blockchain's transaction volume and total value locked increase tenfold, while its validator count falls and one client implementation reaches 85% usage. Which conclusion is best supported?

42 Which mapping most accurately identifies ideas that Bitcoin combined from earlier work?

43 In a fully asynchronous message-passing system, a deterministic consensus protocol must tolerate one crash failure. What does the FLP result imply?

44 A Byzantine fault-tolerant protocol has replicas and requires votes to commit. Why can two conflicting commits not both be certified by honest replicas?

45 During a network partition, every replica continues accepting writes and immediately acknowledges them. Under the CAP model, which property is necessarily at risk?

46 A light client knows a trusted block header containing a Merkle root for transactions. What is sufficient to verify that transaction is included in that block?

47 In a simplified proof-of-work random-walk model, an attacker controls fraction of the hash power, honest miners control , and the attacker begins blocks behind. What is the probability that the attacker eventually catches up?

48 A BFT blockchain experiences a partition in which neither side contains the quorum required to finalize a block. Both sides stop finalizing until communication recovers. Which property profile does this exhibit?

49 After withdrawing their stake, former validators use old keys to construct a conflicting proof-of-stake history beginning far in the past. Which mechanism most directly helps new nodes reject this long-range attack?

50 A lending protocol executes through immutable contracts, but collateral prices come from one company-controlled server. Which assessment is most accurate?

51 A protocol replaces one administrator key with a 3-of-5 multisignature. Three keys are held by employees of one company, while two are held by independent organizations. What is the resulting effective control structure?

52 A project wants to decentralize progressively without allowing early token holders to capture permanent control. Which route best addresses this objective?

53 A censorship-resistant contract has thousands of validators, but almost all users access it through one hosted front end and one RPC provider. Which change most improves full ecosystem decentralization?

54 Which statement most accurately distinguishes a trust-minimized system from a system commonly described as trustless?

55 A decentralized application stores its interface under an IPFS content identifier, but only the developer's node pins the files. What does the content identifier guarantee?

56 A validity rollup posts state roots and validity proofs to a base chain but keeps transaction data on a committee-controlled server. What is the primary limitation?

57 A project claims that using zero-knowledge validity proofs automatically makes all user transactions private. Why is this claim incorrect?

58 A researcher wants to compare the economic security of two rapidly growing proof-of-stake networks. Which measure is more informative than raw total value locked?

59 What was Bitcoin's key systems-level contribution to the double-spending problem in an open network?

60 In a modular blockchain, light clients use data availability sampling against erasure-coded blocks. What can sufficiently successful random sampling establish with high probability?