CBCP Consensus Mechanisms 2

Question 1

In Delegated Proof of Stake (DPoS), what is the primary role of 'witnesses' or 'delegates'?

Accepted Answer

To produce blocks on behalf of token holders who voted for them

Answer

In DPoS, token holders vote for delegates/witnesses who are then responsible for block production, making the system more democratic yet efficient.

Question 2

What distinguishes Byzantine Fault Tolerance (BFT) from Crash Fault Tolerance (CFT)?

Accepted Answer

BFT can handle malicious or arbitrary node behavior, CFT only handles node crashes

Answer

BFT tolerates nodes that act maliciously or send conflicting messages, while CFT only handles nodes that simply stop responding (crash).

Question 3

What is the 'nothing-at-stake' problem in early Proof of Stake designs?

Accepted Answer

Validators can vote on multiple blockchain forks simultaneously with no cost

Answer

Without a cost to validate multiple forks, validators in naive PoS could support all competing chains simultaneously, undermining consensus security.

Question 4

In the Tendermint consensus protocol, what happens if a validator fails to receive enough pre-commit messages?

Accepted Answer

The round times out and a new round begins with a potential new proposer

Answer

Tendermint uses rounds; if a block cannot gather sufficient pre-commits, the protocol moves to a new round where a different validator may propose a block.

Question 5

Which consensus mechanism does Hyperledger Fabric primarily use in its ordering service?

Accepted Answer

Crash Fault Tolerant ordering (e.g., Raft)

Answer

Hyperledger Fabric's ordering service uses CFT protocols like Raft by default, suitable for permissioned enterprise environments where Byzantine faults are less of a concern.

CBCP - Certified Blockchain Professional Practice Test

CBCP - Certified Blockchain Professional Practice Test

CBCP Consensus Mechanisms 2