CBE - Certified Blockchain Expert Consensus Mechanisms Questions and Answers

Question 1

A blockchain network is experiencing a significant increase in transaction volume.
The network's stakeholders are concerned about the environmental impact and rising operational costs associated with its current Proof of Work (PoW) consensus mechanism.
Which of the following consensus mechanisms would be the most suitable alternative to address both energy consumption and scalability concerns?

Accepted Answer

Proof of Stake (PoS)

Answer

Proof of Burn (PoB)

Answer

Practical Byzantine Fault Tolerance (PBFT)

Answer

Proof of Authority (PoA)

Question 2

In a Delegated Proof of Stake (DPoS) system, how are block producers (validators) chosen?

Accepted Answer

Token holders vote for a limited number of delegates to act as validators on their behalf.

Answer

They are selected randomly by the protocol based on the size of their stake.

Answer

They are appointed by a centralized foundation that governs the blockchain.

Answer

The node with the highest computational power is chosen to produce the next block.

Question 3

Which of the following statements best describes the concept of 'probabilistic finality' in the context of a Proof of Work (PoW) blockchain?

Accepted Answer

The likelihood of a transaction being reversed decreases as more blocks are added after it, but never reaches absolute certainty.

Answer

A transaction is considered final as soon as it is included in a block.

Answer

The network achieves absolute certainty of a transaction's immutability after a predetermined number of blocks.

Answer

Finality is guaranteed by a group of trusted validators who sign off on each block.

Question 4

A consortium of financial institutions is building a private blockchain for inter-bank settlements. The key requirements are high transaction throughput, low latency, and deterministic finality, meaning once a transaction is confirmed, it is irreversible. The number of participating nodes is known and relatively small. Which consensus mechanism is most appropriate for this scenario?

Accepted Answer

Practical Byzantine Fault Tolerance (PBFT)

Answer

Proof of Work (PoW)

Answer

Proof of Stake (PoS)

Answer

Delegated Proof of Stake (DPoS)

Question 5

When comparing the vulnerability to a 51% attack, what is the fundamental difference between Proof of Work (PoW) and Proof of Stake (PoS) blockchains?

Accepted Answer

In PoW, an attacker needs 51% of the network's hash rate, while in PoS, an attacker needs 51% of the total staked cryptocurrency.

Answer

PoS is immune to 51% attacks, while PoW is not.

Answer

In PoW, an attacker needs 51% of the total cryptocurrency, while in PoS, an attacker needs 51% of the network's hash rate.

Answer

Both mechanisms require 51% of the total nodes to be controlled by an attacker.

Question 6

A key advantage of Proof of Stake (PoS) over Proof of Work (PoW) is its significantly lower energy consumption. What is the primary reason for this difference?

Accepted Answer

PoS eliminates the need for an energy-intensive competitive mining process to solve complex puzzles.

Answer

PoS networks process fewer transactions per second.

Answer

PoS validators use more efficient, specialized hardware.

Answer

PoS relies on a centralized server to validate transactions, reducing distributed energy use.