Core Concepts Flashcards
7 cards from real Blockchain Technology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Core Concepts flashcards as text
What is the role of a cryptographic hash function's 'avalanche effect' in blockchain security?
Answer: A small change in input produces a drastically different output hash, preventing predictability
The avalanche effect ensures that even a single-bit change in input results in a completely different hash, making tampering immediately detectable.
In the context of blockchain, what does 'finality' mean?
Answer: The point at which a confirmed transaction cannot be reversed
Finality refers to the guarantee that a committed transaction is irreversible and permanently settled on the blockchain.
What is a 51% attack and what does it allow an attacker to do?
Answer: Controlling the majority of network hash power to double-spend transactions
An attacker with >50% of the network's hash rate can reorganize the chain and potentially reverse recent transactions to double-spend.
What is the purpose of transaction fees in a blockchain network?
Answer: To incentivize miners/validators to include transactions in blocks and prevent spam
Transaction fees reward miners or validators for processing transactions and also deter spam by making mass frivolous transactions costly.
How do SPV (Simplified Payment Verification) clients verify transactions without downloading the full blockchain?
Answer: By downloading only block headers and using Merkle proofs to verify inclusion
SPV clients download block headers and verify that a transaction is included in a block using its Merkle proof path.
What is the difference between a coin and a token in the blockchain ecosystem?
Answer: Coins have their own native blockchain; tokens are built on top of an existing blockchain
Coins (like BTC, ETH) operate on their own blockchain, while tokens (like ERC-20 tokens) are created and run on an existing blockchain platform.
What does 'trustless' mean in the context of blockchain systems?
Answer: Participants do not need to trust each other because the protocol enforces rules cryptographically
Trustless means the system's rules are enforced by math and code rather than requiring participants to trust each other or a central authority.