Blockchain 101 Certification Blockchain 101 Certification Consensus Mechanisms & Protocols 3

Question 1

What distinguishes a 'soft fork' from a 'hard fork' in blockchain protocol upgrades?

Accepted Answer

Soft forks are backward-compatible; hard forks are not

Answer

Soft forks require all nodes to upgrade; hard forks do not

Answer

Soft forks change block size; hard forks change consensus rules

Answer

Soft forks are temporary; hard forks are permanent

Question 2

What is Intel's Proof of Elapsed Time (PoET) consensus designed for?

Accepted Answer

Permissioned blockchains using trusted execution environments

Answer

Public blockchains with anonymous miners

Answer

Mobile blockchain applications

Answer

IoT device networks

Question 3

In blockchain consensus, what is 'liveness'?

Accepted Answer

The ability of a network to always add new valid blocks

Answer

The speed of transaction finality

Answer

The number of active nodes

Answer

The latency between nodes

Question 4

What does the term 'uncle block' (ommer block) refer to in Ethereum?

Accepted Answer

A valid block that was mined simultaneously but not included in the main chain

Answer

An invalid block rejected by all nodes

Answer

The block preceding the genesis block

Answer

A duplicate transaction block

Question 5

Which property ensures that consensus nodes agree on the same blockchain state?

Accepted Answer

Safety

Answer

Liveness

Answer

Throughput

Answer

Scalability

Question 6

What is 'Proof of Burn' consensus?

Accepted Answer

Sending cryptocurrency to an unspendable address to earn mining rights

Answer

Destroying computing hardware to prove work

Answer

Burning gas fees for priority

Answer

Destroying tokens to reduce supply