Blockchain Developer FREE Blockchain Developer Blockchain Fundamentals and Cryptography Questions and Answers 2 — Questions and Answers
Question 1: What is the primary purpose of a Merkle tree in blockchain technology?
- To efficiently verify the integrity of large datasets (Correct answer)
- To encrypt transaction data for privacy
- To determine the order of block creation
- To manage peer-to-peer network connections
Correct answer: To efficiently verify the integrity of large datasets
Merkle trees allow efficient and secure verification of data integrity by organizing transaction hashes into a binary tree structure where any change propagates to the root.
Question 2: Which cryptographic property ensures that even a single-bit change in input produces a completely different hash output?
- Collision resistance
- Preimage resistance
- Avalanche effect (Correct answer)
- Determinism
Correct answer: Avalanche effect
The avalanche effect means that a small change in input causes a drastic change in the hash output, making it practically impossible to predict modifications.
Question 3: In a proof-of-work consensus mechanism, what does the nonce value represent?
- The block reward amount
- A variable miners adjust to find a valid block hash (Correct answer)
- The timestamp of the block
- The number of transactions in a block
Correct answer: A variable miners adjust to find a valid block hash
The nonce is an arbitrary number that miners repeatedly change to produce a block hash that meets the network's difficulty target.
Question 4: What type of cryptography does Bitcoin use for generating wallet addresses and signing transactions?
- RSA asymmetric encryption
- Elliptic Curve Digital Signature Algorithm (ECDSA) (Correct answer)
- Advanced Encryption Standard (AES)
- Diffie-Hellman key exchange
Correct answer: Elliptic Curve Digital Signature Algorithm (ECDSA)
Bitcoin uses ECDSA with the secp256k1 curve to create public-private key pairs and digitally sign transactions.
Question 5: What is a 51% attack in blockchain?
- When a single entity controls the majority of mining power and can manipulate the chain (Correct answer)
- When 51% of nodes go offline simultaneously
- When more than half of all tokens are held by one wallet
- When a smart contract contains a critical vulnerability
Correct answer: When a single entity controls the majority of mining power and can manipulate the chain
A 51% attack occurs when an attacker gains majority hash rate control, enabling them to reverse transactions and double-spend coins.
Question 6: Which data structure links blocks together to form an immutable chain?
- Doubly linked list with timestamps
- Each block containing the cryptographic hash of the previous block's header (Correct answer)
- A centralized index table mapping block numbers to data
- A directed acyclic graph with random connections
Correct answer: Each block containing the cryptographic hash of the previous block's header
Each block header includes the hash of the previous block's header, creating a tamper-evident chain where altering any block invalidates all subsequent blocks.
Blockchain Developer FREE Blockchain Developer Blockchain Fundamentals and Cryptography Questions and Answers 2
What is the primary purpose of a Merkle tree in blockchain technology?