CCA Transactions & Verification 3

Question 1

What does the Merkle root in a Bitcoin block header represent?

Accepted Answer

A single hash summarizing all transactions in the block

Answer

The Merkle root is the top hash of a binary Merkle tree built from all transaction hashes in the block, enabling efficient transaction verification.

Question 2

An auditor identifies that two blockchain transactions share identical TXIDs. What does this most likely indicate?

Accepted Answer

Transaction malleability or a deliberate hash collision attack

Answer

Duplicate TXIDs indicate transaction malleability (pre-SegWit) or a serious protocol-level attack, either of which requires immediate investigation.

Question 3

What is a Child-Pays-for-Parent (CPFP) transaction, and how does it affect audit trail completeness?

Accepted Answer

A transaction where the recipient creates a high-fee child to accelerate the parent's confirmation

Answer

CPFP lets a recipient spend an unconfirmed output with a high-fee transaction, incentivizing miners to confirm both; auditors must link parent and child transactions.

Question 4

In Ethereum, what is the purpose of the 'gasLimit' field set by a transaction sender?

Accepted Answer

It sets the maximum amount of gas the sender authorizes to be consumed

Answer

The gasLimit is the maximum units of gas the sender permits the transaction to consume, protecting against runaway computation costs.

Question 5

Which verification method allows a lightweight (SPV) client to confirm a transaction without downloading the full blockchain?

Accepted Answer

Merkle proofs linking the transaction to a block header

Answer

SPV clients use Merkle branch proofs to verify that a transaction is included in a block without needing all block data.

(CCA) Certified Cryptocurrency Auditor Practice Test

(CCA) Certified Cryptocurrency Auditor Practice Test

CCA Transactions & Verification 3