A blockchain developer is auditing a Bitcoin transaction and notices that one of the inputs references a previous transaction output (UTXO) that has already been spent. What does this indicate about the transaction?

The transaction is valid if the signature is correct, regardless of the UTXO state.

The transaction is valid but will be placed in a queue until the previous output is confirmed.

The transaction is invalid and will be rejected by nodes during validation.

The transaction is valid and will be mined, but the previous output will be marked as spent again.

A company is building a decentralized identity system on a blockchain. They need to store personal data (e.g., name, address) but want to comply with data privacy regulations that require the ability to delete data. What is the best approach?

Encrypt personal data and store it on-chain.

Store personal data in the mempool and retrieve it when needed.

Store personal data off-chain and store only a hash on-chain.

Store personal data on-chain and rely on the blockchain's immutability.

In a typical blockchain transaction lifecycle, which sequence correctly describes the order of events from creation to finality?

Creation, validation, signing, broadcast, inclusion in a block, confirmation, finality

Creation, signing, broadcast, validation, inclusion in a block, confirmation, finality

Creation, broadcast, signing, validation, inclusion in a block, finality, confirmation

Creation, signing, broadcast, inclusion in a block, validation, confirmation, finality

What is the primary purpose of the digital signature in a blockchain transaction?

To create a new address for the recipient

To increase the transaction fee

To prove ownership and authorize the transfer of funds

To encrypt the transaction data for privacy

A blockchain stores the Merkle root of all transactions in the block header. A light client wants to verify that a specific transaction is included in a block without downloading the entire block. What must the light client obtain from a full node?

The full list of transactions in the block

The digital signature of the block producer

The transaction itself and the Merkle proof (the sibling hashes along the path to the root)

The block header and the previous block's header

EC-CouncilBlockchain Developer Certification

Domain 1Objective 4

Data and Transaction Flow in Blockchain BDC Practice Questions (Page 7)

Part of the Blockchain Fundamentals and Architecture domain, which makes up ~14% of our current practice bank.

51questions here

11free pages

10concepts

Questions 31–35

31application · medium
A blockchain developer is auditing a Bitcoin transaction and notices that one of the inputs references a previous transaction output (UTXO) that has already been spent. What does this indicate about the transaction?
Select an answer first
32expert · hard
A company is building a decentralized identity system on a blockchain. They need to store personal data (e.g., name, address) but want to comply with data privacy regulations that require the ability to delete data. What is the best approach?
Select an answer first
33foundation · easy
In a typical blockchain transaction lifecycle, which sequence correctly describes the order of events from creation to finality?
Select an answer first
34foundation · easy
What is the primary purpose of the digital signature in a blockchain transaction?
Select an answer first
35expert · medium
A blockchain stores the Merkle root of all transactions in the block header. A light client wants to verify that a specific transaction is included in a block without downloading the entire block. What must the light client obtain from a full node?
Select an answer first

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