Blockchain Technology Core Concepts 2

Question 1

What property ensures that once a block is added to a blockchain, its data cannot be altered without changing all subsequent blocks?

Accepted Answer

Immutability

Answer

Immutability is the property that makes blockchain data tamper-resistant, since each block's hash depends on the previous block's data.

Question 2

In a Merkle tree structure used in blockchain, what does the root hash represent?

Accepted Answer

A single fingerprint of all transactions in a block

Answer

The Merkle root is a single hash derived from hashing all transactions in pairs recursively, summarizing the entire transaction set.

Question 3

Which type of blockchain network restricts participation to pre-approved entities?

Accepted Answer

Permissioned blockchain

Answer

Permissioned (or private) blockchains require participants to be authorized before joining the network.

Question 4

What is a 'genesis block' in blockchain terminology?

Accepted Answer

The first block in a blockchain

Answer

The genesis block is the very first block in a blockchain, hard-coded with no previous block reference.

Question 5

What does the nonce field in a block header primarily serve in Proof of Work?

Accepted Answer

It is a number miners adjust to find a valid hash below the difficulty target

Answer

Miners increment the nonce repeatedly until the resulting block hash meets the required difficulty target.

Blockchain Practice Test