CBC CBC Blockchain Architecture & Design 2

Question 1

What distinguishes an 'on-chain' transaction from an 'off-chain' transaction?

Accepted Answer

On-chain transactions are recorded directly on the blockchain; off-chain occur outside it

Answer

On-chain transactions are validated and permanently recorded on the distributed ledger, while off-chain transactions occur outside the main blockchain and are settled later.

Question 2

Which design pattern separates the data layer from the logic layer in upgradeable smart contract architecture?

Accepted Answer

Proxy-delegate pattern

Answer

The proxy-delegate pattern keeps data in a permanent storage contract while routing logic calls to an upgradeable implementation contract.

Question 3

What is the purpose of a blockchain 'oracle' in system design?

Accepted Answer

To provide smart contracts with verified real-world external data

Answer

Oracles bridge the gap between blockchains and the real world by feeding verified off-chain data (prices, weather, events) into smart contracts.

Question 4

In designing a blockchain solution, which factor primarily determines the choice between UTXO and account-based models?

Accepted Answer

Whether parallelism or state simplicity is prioritized

Answer

UTXO models enable parallelism and privacy but are complex for stateful apps, while account models simplify state management for smart contracts.

Question 5

What is a 'hard fork' in blockchain architecture?

Accepted Answer

A backwards-incompatible protocol change that creates a permanent chain split

Answer

A hard fork introduces protocol changes that are not backwards-compatible, requiring all nodes to upgrade or risk operating on a diverging chain.

(CBC) Certified Blockchain Consultant Practice Test

(CBC) Certified Blockchain Consultant Practice Test

CBC CBC Blockchain Architecture & Design 2