CBSA Blockchain Network Architectures 5 — Questions and Answers
Question 1: What is the key difference between a 'light client' and a 'full node' in blockchain network participation?
- Light clients create new blocks while full nodes only validate
- Light clients only download block headers and rely on full nodes for transaction verification (Correct answer)
- Light clients store more data than full nodes
- Light clients use a different consensus algorithm
Correct answer: Light clients only download block headers and rely on full nodes for transaction verification
Light clients (SPV nodes) download only block headers and use Merkle proofs to verify transactions, trusting full nodes for complete validation instead of processing the entire chain.
Question 2: In a blockchain network, what problem does the 'nothing-at-stake' attack specifically target?
- Proof of Work mining pools
- Proof of Stake consensus mechanisms (Correct answer)
- Smart contract execution environments
- Cross-chain bridge protocols
Correct answer: Proof of Stake consensus mechanisms
The nothing-at-stake problem in PoS occurs when validators can simultaneously vote on multiple chain forks at no cost, potentially undermining consensus security.
Question 3: A blockchain architect needs to ensure data written five years ago cannot be altered even if current encryption is broken. Which design approach addresses this?
- Increasing block size limits
- Using hash chaining with periodic re-anchoring to immutable external systems
- Migrating to quantum-resistant cryptography before deployment (Correct answer)
- Storing data in encrypted off-chain databases
Correct answer: Migrating to quantum-resistant cryptography before deployment
Designing with quantum-resistant (post-quantum) cryptographic algorithms before deployment ensures long-term immutability even as computational capabilities advance.
Question 4: Which Hyperledger Fabric component is responsible for simulating chaincode execution and generating read-write sets for endorsement?
- Orderer node
- Certificate Authority (CA)
- Peer node (endorser) (Correct answer)
- Membership Service Provider (MSP)
Correct answer: Peer node (endorser)
In Fabric's execute-order-validate flow, endorsing peers simulate chaincode transactions and produce read-write sets that are then collected by clients for ordering.
Question 5: What is the role of a 'Merkle tree' in blockchain network architecture?
- It determines the order in which transactions are processed
- It enables efficient and secure verification of large datasets by creating a tree of cryptographic hashes (Correct answer)
- It manages the routing of transactions between nodes
- It stores validator identity certificates
Correct answer: It enables efficient and secure verification of large datasets by creating a tree of cryptographic hashes
Merkle trees allow any transaction within a block to be verified with minimal data (a Merkle proof) by hashing pairs of transactions upward to a single root hash stored in the block header.
Question 6: When designing a blockchain network for a regulated financial industry, which network architecture feature is most critical for compliance?
- Maximum transaction throughput above all else
- Identity management with KYC/AML-compliant permissioning and auditability (Correct answer)
- Fully anonymous transaction capability
- Proof of Work consensus for maximum security
Correct answer: Identity management with KYC/AML-compliant permissioning and auditability
Financial regulations require knowing participant identities and maintaining audit trails, making permissioned identity management and auditability the most critical architectural feature.
Question 7: In a multi-organizational blockchain network, what is the architectural purpose of a 'channel' in Hyperledger Fabric?
- To increase transaction processing speed
- To create an isolated private subnet with its own ledger shared only among designated members (Correct answer)
- To connect the Fabric network to external blockchain networks
- To manage the lifecycle of chaincode deployments
Correct answer: To create an isolated private subnet with its own ledger shared only among designated members
Channels in Hyperledger Fabric create isolated communication subnets where only designated member organizations share a private ledger, enabling data partitioning within a larger network.
CBSA Blockchain Network Architectures 5
What is the key difference between a 'light client' and a 'full node' in blockchain network participation?