CBP - Certified Bitcoin Professional Blockchain and Transaction Mechanics Questions and Answers 1 — Questions and Answers
Question 1: In the Bitcoin network, what is the primary role of the mempool?
- A permanent storage ledger for all confirmed transactions.
- A waiting area for unconfirmed transactions before they are included in a block. (Correct answer)
- A database of all active public and private keys on the network.
- A system for converting fiat currency into Bitcoin.
Correct answer: A waiting area for unconfirmed transactions before they are included in a block.
The mempool (memory pool) is a node's holding area for transactions that have been broadcast to the network but have not yet been included in a block. Miners select transactions from their mempool to build a new block.
Question 2: A user sends 1 BTC from an address that holds a single UTXO of 3 BTC. The transaction has one output of 1 BTC to the recipient. Which of the following accurately describes the outputs of this transaction?
- One output of 1 BTC to the recipient.
- Two outputs: one of 1 BTC to the recipient and one of 2 BTC back to the sender as a new UTXO. (Correct answer)
- One output of 3 BTC that is now co-owned by the sender and recipient.
- The transaction is invalid because the entire UTXO must be spent.
Correct answer: Two outputs: one of 1 BTC to the recipient and one of 2 BTC back to the sender as a new UTXO.
Bitcoin's Unspent Transaction Output (UTXO) model requires that an entire UTXO be consumed in a transaction. The outputs will consist of the payment to the recipient and the 'change' which is sent back to the sender in the form of a new UTXO. In this case, 1 BTC goes to the recipient, and the remaining 2 BTC (minus any transaction fee) goes back to the sender.
Question 3: What is the primary factor miners use to prioritize transactions for inclusion in a new block?
- The age of the transaction.
- The monetary value of the transaction.
- The transaction fee rate (satoshis per virtual byte). (Correct answer)
- The physical location of the originating node.
Correct answer: The transaction fee rate (satoshis per virtual byte).
Miners are economically incentivized to maximize their revenue. They do this by selecting transactions that offer the highest fee relative to their size in the block. This is measured in satoshis per virtual byte (sat/vB). A higher fee rate makes a transaction more attractive to a miner.
Question 4: Which of the following represents the first confirmation of a Bitcoin transaction?
- When the transaction is successfully broadcast to the network's nodes.
- When the transaction is included in a valid block that is added to the blockchain. (Correct answer)
- After six additional blocks have been added to the blockchain following the transaction's block.
- When the recipient's wallet acknowledges receipt of the transaction broadcast.
Correct answer: When the transaction is included in a valid block that is added to the blockchain.
A Bitcoin transaction receives its first confirmation when it is included by a miner into a newly mined, valid block that is accepted by the network and added to the blockchain. Subsequent blocks added on top increase the number of confirmations.
Question 5: A user is trying to send a Bitcoin transaction, but it remains unconfirmed for an unusually long time during a period of high network activity. What is the most likely reason for this delay?
- The recipient's wallet is offline.
- The transaction fee included was too low compared to other competing transactions. (Correct answer)
- The user's internet connection is too slow.
- The Bitcoin network's difficulty has just increased significantly.
Correct answer: The transaction fee included was too low compared to other competing transactions.
During periods of high network congestion, many transactions compete for limited space in each block. Miners prioritize transactions with higher fee rates. If a transaction has a fee that is too low, it will be consistently outbid by others and will have to wait in the mempool until fees come down or it is dropped.
Question 6: What problem in distributed systems does Bitcoin's proof-of-work consensus mechanism and blockchain structure effectively solve, preventing the same digital money from being spent more than once?
- The Byzantine Generals' Problem.
- The Double-Spending Problem. (Correct answer)
- The Halting Problem.
- The Traveling Salesman Problem.
Correct answer: The Double-Spending Problem.
The double-spending problem is the risk that a digital currency can be spent twice. Bitcoin solves this by using a public ledger (the blockchain) and a proof-of-work consensus mechanism. Once a transaction is confirmed in a block, it is extremely difficult to reverse, thus preventing the same UTXOs from being spent again.
CBP - Certified Bitcoin Professional Blockchain and Transaction Mechanics Questions and Answers 1
In the Bitcoin network, what is the primary role of the mempool?