CBSA Solution Architecture Design 3 — Questions and Answers
Question 1: A blockchain architect is designing tokenomics for a decentralized marketplace. Which mechanism best prevents token hoarding and encourages circulation?
- Fixed supply with no inflation
- Demurrage fees on idle token balances (Correct answer)
- Burn-and-mint equilibrium model
- Quadratic voting for token allocation
Correct answer: Demurrage fees on idle token balances
Demurrage fees penalize holding tokens idle, creating an economic incentive for token holders to actively use or circulate their tokens within the ecosystem.
Question 2: When designing a cross-chain asset transfer solution, which protocol provides atomic swap guarantees without requiring a trusted third party?
- Wrapped token bridges
- Hash Time-Locked Contracts (HTLCs) (Correct answer)
- Centralized exchange custody
- Cross-chain messaging with oracles
Correct answer: Hash Time-Locked Contracts (HTLCs)
HTLCs enforce atomicity by requiring both parties to reveal a cryptographic secret within a time window, ensuring either both transfers complete or both are refunded.
Question 3: An enterprise blockchain solution requires that specific transaction data be auditable by regulators but invisible to other network participants. Which Hyperledger Fabric feature addresses this?
- World state snapshots
- Private Data Collections with policy-based access (Correct answer)
- Zero-knowledge endorsement
- Encrypted chaincode state
Correct answer: Private Data Collections with policy-based access
Hyperledger Fabric's Private Data Collections allow specific data to be shared only with authorized organizations (like regulators) while only a hash is stored on the shared channel ledger.
Question 4: In designing a blockchain-based voting system, which architecture decision most directly prevents double-voting?
- Using a public blockchain for transparency
- Issuing unique non-transferable tokens (soulbound) per voter (Correct answer)
- Encrypting all votes with the voter's private key
- Requiring multi-signature approval for each vote
Correct answer: Issuing unique non-transferable tokens (soulbound) per voter
Soulbound (non-transferable) tokens tied to verified voter identities enforce the one-person-one-vote constraint at the protocol level, preventing transfer or duplication.
Question 5: A solution architect is choosing between optimistic rollups and ZK-rollups for a Layer 2 scaling solution. Which scenario favors ZK-rollups?
- General-purpose smart contract execution with low security requirements
- Applications requiring immediate withdrawal finality with strong cryptographic guarantees (Correct answer)
- Systems that need long challenge periods to resolve disputes
- Low-value micropayments with high transaction frequency
Correct answer: Applications requiring immediate withdrawal finality with strong cryptographic guarantees
ZK-rollups provide cryptographic validity proofs that enable immediate finality on L1, making them ideal when users cannot tolerate the 7-day withdrawal delay inherent in optimistic rollups.
Question 6: Which consensus mechanism is most Byzantine Fault Tolerant when designing a blockchain for a network where up to one-third of nodes may be malicious?
- Proof of Work (PoW)
- Delegated Proof of Stake (DPoS)
- Practical Byzantine Fault Tolerance (PBFT) (Correct answer)
- Proof of Authority (PoA)
Correct answer: Practical Byzantine Fault Tolerance (PBFT)
PBFT is mathematically proven to reach consensus as long as fewer than one-third of nodes are faulty or malicious, making it the classical choice for Byzantine fault tolerance.
Question 7: When architecting a blockchain solution that must handle regulatory changes over time, which design principle is most important?
- Immutable smart contracts for legal certainty
- Upgradeable proxy contract patterns with governance controls (Correct answer)
- Redeployment of contracts with state migration scripts
- Off-chain regulatory logic with on-chain enforcement
Correct answer: Upgradeable proxy contract patterns with governance controls
Upgradeable proxy patterns (like OpenZeppelin's transparent proxy) separate logic contracts from storage contracts, allowing business logic updates while preserving state and contract addresses.
CBSA Solution Architecture Design 3
A blockchain architect is designing tokenomics for a decentralized marketplace.
Which mechanism best prevents token hoarding and encourages circulation?