Blockchain Fundamental Flashcards
7 cards from real CBCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Blockchain Fundamental flashcards as text
In blockchain, what is a 'mempool' (memory pool)?
Answer: A holding area where unconfirmed transactions wait to be included in a block
The mempool is each node's local buffer of broadcast transactions awaiting confirmation; miners select transactions from it to fill new blocks.
What property ensures that a blockchain transaction cannot be denied or reversed by the sender after it is confirmed?
Answer: Non-repudiation
Non-repudiation, enforced by digital signatures and immutable ledger records, means a sender cannot later claim they did not authorize a transaction.
What is a '51% attack' and why does it threaten blockchain security?
Answer: When a single entity controls more than half of the network's consensus power, enabling double-spends
Controlling >50% of hash rate (PoW) or stake (PoS) lets an attacker rewrite recent history and double-spend coins on that chain.
Which component of asymmetric cryptography is used to verify a blockchain transaction's digital signature?
Answer: The sender's public key
Anyone can use the sender's public key to verify that the signature was created by the corresponding private key, confirming authenticity without exposing the private key.
What does 'finality' mean in the context of blockchain consensus?
Answer: The guarantee that a confirmed transaction cannot be reversed
Finality describes the point at which a transaction is considered irreversibly settled; different consensus mechanisms offer probabilistic or absolute finality.
In blockchain architecture, what is the purpose of a 'sidechain'?
Answer: To run transactions off the main chain while remaining pegged to it, enabling scalability and experimentation
Sidechains operate independently but are linked to the main chain via a two-way peg, allowing assets to move between chains and offloading traffic from the mainchain.
What is the 'blockchain trilemma' as described by Ethereum co-founder Vitalik Buterin?
Answer: The difficulty of simultaneously achieving decentralization, security, and scalability
The blockchain trilemma states that a network can typically optimize for only two of three properties — decentralization, security, and scalability — at any given design point.