CBSA Blockchain Architecture & Design Principles 3

Question 1

In Byzantine Fault Tolerant systems, what is the maximum fraction of faulty nodes a network can tolerate while maintaining safety?

Accepted Answer

Less than 1/3

Answer

Classical BFT consensus (e.g., PBFT) requires fewer than one-third of nodes to be Byzantine faulty to guarantee both safety and liveness.

Question 2

Which pattern separates the execution of business logic from the storage of state to enable contract upgradability?

Accepted Answer

Proxy-delegate pattern

Answer

The proxy-delegate (or transparent proxy) pattern stores state in a proxy contract and delegates logic calls to an implementation contract that can be swapped.

Question 3

What is the key architectural difference between a permissioned and a permissionless blockchain?

Accepted Answer

Permissioned chains restrict who can join and transact, while permissionless chains are open to anyone

Answer

Permissioned blockchains require identity verification and authorization to participate, enabling stronger privacy controls and higher throughput for enterprise use.

Question 4

Which Ethereum scaling solution batches many transactions off-chain and posts compressed data plus a validity proof to L1?

Accepted Answer

ZK-rollups

Answer

ZK-rollups execute transactions off-chain and submit a succinct cryptographic validity proof to L1, enabling high throughput with L1 security guarantees.

Question 5

In blockchain architecture, what is the 'nothing-at-stake' problem associated with?

Accepted Answer

Proof of Stake consensus

Answer

In naive PoS, validators have no cost in voting on multiple competing forks, so they may support all forks simultaneously; slashing mechanisms address this.

(CBSA) Certified Blockchain Solution Architect Practice Test

(CBSA) Certified Blockchain Solution Architect Practice Test

CBSA Blockchain Architecture & Design Principles 3