How Blockchain Works Quiz

Which of the following best describes the output of a SHA-256 hash function?

• A fixed 64-bit output

• A fixed 256-bit output

• A variable-length string

• An encrypted message

What is the key characteristic of SHA-256 that makes it useful in blockchain?

• Fast encryption

• Reversible function

• Deterministic and collision-resistant

• Variable output length

What does it mean when we say the blockchain is "immutable"?

• It can be easily updated

• Data once written cannot be changed

• It is temporary

• It is centralized

In blockchain, immutability is primarily ensured through:

• Centralized servers

• Regular backups

• Cryptographic hashing and linking of blocks

• Permissioned access

Which of the following is a key benefit of a distributed peer-to-peer (P2P) network in blockchain?

• Faster central processing

• Single point of failure

• Increased transparency and fault tolerance

• More control by one authority

In a P2P network, each node typically:

• Acts as a client only

• Acts as a server only

• Acts as both client and server

• Is dependent on a central authority

In blockchain mining, what is a “nonce”?

• A random string used to secure a wallet

• A fixed key to decrypt transactions

• A number miners change to find a valid hash

• A block identifier

The goal of mining in proof-of-work is to:

• Encrypt transactions

• Decrease block size

• Solve a mathematical puzzle to validate a block

• Create new cryptocurrencies at will

Byzantine Fault Tolerance refers to a system’s ability to:

• Work offline

• Tolerate failed hard drives

• Reach consensus despite malicious actors

• Encrypt messages

Which problem does Byzantine Fault Tolerance address in distributed systems?

• Power outage

• Honest majority assumption

• Miscommunication or malicious nodes

• Insufficient memory