Certified Blockchain Professional (CBCP) MCQ Flashcards

In Solidity, what is the difference between 'storage' and 'memory' variable locations in smart contract execution?

Answer: Storage persists permanently on-chain between calls; memory is temporary within a single call

In Solidity, 'storage' variables are written to the blockchain and persist across transactions, while 'memory' variables exist only during a function call and are discarded afterward.

What is the 'Oracle Problem' in smart contract design?

Answer: Blockchains cannot natively access external real-world data without a trusted intermediary

The Oracle Problem describes the challenge that blockchains are deterministic closed systems unable to access real-world data natively, requiring external oracles that introduce trust assumptions.

A DeFi protocol suffers a flash loan attack where an attacker borrows millions, manipulates an on-chain price oracle, and profits instantly. What is the root cause?

Answer: Reliance on a single on-chain DEX spot price as an oracle without time-weighting

Flash loan attacks typically exploit spot-price oracles drawn from a single DEX, which an attacker can manipulate within one transaction block; time-weighted average prices (TWAPs) mitigate this.

Which property ensures that a blockchain transaction, once confirmed in sufficient blocks, cannot be reversed by any single party?

Answer: Finality

Finality (probabilistic or absolute depending on consensus mechanism) is the property ensuring a confirmed transaction cannot be rolled back, providing settlement certainty to participants.

In enterprise blockchain governance, what is a 'permissioned' network's primary advantage over a public blockchain for regulated industries?

Answer: Permissioned networks allow known, vetted identities and regulatory compliance controls

Permissioned blockchains restrict participation to vetted entities, enabling KYC/AML compliance, auditability by regulators, and governance controls required in finance, healthcare, and supply chain.

What does the CAP theorem imply for distributed blockchain systems during a network partition?

Answer: Blockchains must choose between consistency and availability when partitioned

CAP theorem states a distributed system can only guarantee two of Consistency, Availability, and Partition Tolerance; during a partition, most blockchains prioritize consistency (refusing to fork) or availability (allowing temporary forks).

Which tokenization model represents fractional ownership of a real-world asset such as real estate on a blockchain?

Answer: Security Token (STO)

Security Tokens represent ownership stakes or financial rights in real-world assets and are subject to securities regulations, making them the appropriate model for tokenized real estate or equity.