CCE Blockchain Fundamentals & Architecture 3

Question 1

What distinguishes a permissioned blockchain from a permissionless blockchain?

Accepted Answer

Permissioned blockchains restrict participation to approved entities, while permissionless allow anyone

Answer

Permissioned blockchains (e.g., Hyperledger Fabric) require identity verification and approval before participation, enabling enterprise use cases with privacy and compliance requirements.

Question 2

What is the role of a 'full node' in a blockchain network?

Accepted Answer

It downloads, validates, and stores the entire blockchain and enforces consensus rules

Answer

Full nodes independently download every block and transaction, verify all consensus rules, and maintain a complete copy of the blockchain, making them the backbone of network security.

Question 3

In blockchain terminology, what is 'block finality'?

Accepted Answer

The point at which a block is considered irreversible and cannot be reorganized out of the chain

Answer

Finality refers to the guarantee that a confirmed block will not be reversed; PoW chains have probabilistic finality while PoS chains like Ethereum can achieve economic finality through slashing.

Question 4

What is the 'mempool' (memory pool) in a blockchain node?

Accepted Answer

A holding area for valid but unconfirmed transactions waiting to be included in a block

Answer

The mempool is an in-memory buffer on each node storing valid transactions that have been broadcast but not yet included in a confirmed block.

Question 5

What is a 'soft fork' in the context of blockchain protocol upgrades?

Accepted Answer

A backward-compatible upgrade where old nodes still accept new blocks but may not understand new rules

Answer

A soft fork tightens consensus rules so new blocks remain valid under old rules, making the upgrade backward-compatible — old nodes don't update but continue accepting the chain.

(CCE) Certified Cryptocurrency Expert Practice Test

(CCE) Certified Cryptocurrency Expert Practice Test

CCE Blockchain Fundamentals & Architecture 3