Bitcoin Network and Its Transactions BDC Practice Questions (Page 4)

Questions 16–20

1. 16application · medium

   A developer is designing a Bitcoin transaction that sends 0.5 BTC to a recipient. The developer has a UTXO of 1.0 BTC. What must the transaction include to avoid losing the excess value?

   • AA higher fee to consume the excess value.
   • BA second input that spends another UTXO to make the total exactly 0.5 BTC.
   • CA second output that sends the remaining 0.5 BTC back to the sender as change.
   • DA locktime that delays the transaction until the excess is returned.
   Reveal Solution Discussion Select an answer first
2. 17expert · hard

   A company runs a Bitcoin full node for internal auditing. They want to ensure that the node always has the most up-to-date blockchain and can validate transactions independently. The node is behind a firewall that only allows outbound connections. What is the impact on the node's ability to sync and validate?

   • AThe node can sync and validate normally because it can initiate outbound connections to peers.
   • BThe node will only receive blocks that are relayed by miners, not from other nodes.
   • CThe node will have a higher risk of accepting invalid blocks because it cannot connect to enough peers.
   • DThe node cannot sync because it cannot accept inbound connections from peers.
   Reveal Solution Discussion Select an answer first
4. 18expert · hard

   A user broadcasts a Bitcoin transaction with a fee of 5 sat/vB. The network is congested, and the mempool is full of transactions with fees above 20 sat/vB. The user wants the transaction to confirm soon. What is the best course of action?

   • ABroadcast the transaction multiple times to increase its priority.
   • BWait for the mempool to clear, as the transaction will eventually be confirmed.
   • CUse Replace-By-Fee (RBF) to resubmit the transaction with a higher fee.
   • DCancel the transaction and create a new one with a higher fee, but only if the original transaction is not confirmed.
   Reveal Solution Discussion Select an answer first
5. 19application · medium

   A company wants to run a Bitcoin node to validate transactions and blocks without participating in mining. They plan to connect to the Bitcoin network. What is the primary function of this node?

   • ATo provide a centralized authority for transaction approval.
   • BTo maintain a copy of the blockchain and enforce consensus rules by validating transactions and blocks.
   • CTo create new blocks and earn block rewards.
   • DTo store private keys for users and sign transactions on their behalf.
   Reveal Solution Discussion Select an answer first
6. 20expert · hard

   A merchant accepts a Bitcoin payment and waits for 1 confirmation before releasing goods. An attacker attempts a double-spend by broadcasting a conflicting transaction with a higher fee. What is the most effective defense for the merchant?

   • AAccept the payment only if the transaction is broadcast from a known IP address.
   • BWait for more confirmations, such as 6, before releasing goods.
   • CUse a service that monitors the mempool for conflicting transactions and alerts the merchant.
   • DRequire the customer to pay a higher fee to make the transaction more attractive to miners.
   Reveal Solution Discussion Select an answer first