Data and Transaction Flow in Blockchain BDC Practice Questions (Page 1)

Questions 1–5

1. 1expert · hard

   A developer is troubleshooting a transaction that has been pending for hours. The transaction has a low gas price, and the network is congested. The user wants to ensure the transaction is eventually included without waiting indefinitely. What is the most effective action?

   • ASubmit a new transaction with the same nonce and a higher gas price to replace the pending one.
   • BIncrease the gas limit of the pending transaction by modifying the transaction data.
   • CWait for the network congestion to clear, as the transaction will eventually be mined.
   • DCancel the transaction by sending a new transaction with a higher nonce and zero value.
   Reveal Solution Discussion Select an answer first
2. 2expert · hard

   A node operator is configuring a new node on a private blockchain. They want to ensure that only transactions with a valid signature and a minimum fee are accepted into the mempool. Which configuration is most appropriate?

   • AConfigure the node to only accept transactions from whitelisted addresses.
   • BSet a high block gas limit to allow more transactions to be included.
   • CDisable signature verification to speed up transaction processing and rely on the network's consensus.
   • DEnable strict signature verification and set a minimum gas price in the node's configuration.
   Reveal Solution Discussion Select an answer first
4. 3expert · hard

   A blockchain developer is implementing a lightweight client that needs to verify that a specific transaction is included in a block without downloading the entire block. Which data structure should the client use?

   • ABinary search tree
   • BLinked list
   • CHash table
   • DMerkle tree
   Reveal Solution Discussion Select an answer first
5. 4foundation · easy

   What is the final step in the lifecycle of a blockchain transaction?

   • AInclusion in a block
   • BValidation by the receiving node
   • CBroadcasting the transaction to the peer-to-peer network
   • DAchieving finality, where the transaction is considered irreversible
   Reveal Solution Discussion Select an answer first
6. 5application · medium

   A user submits two transactions from the same wallet: Transaction A with a gas price of 50 gwei and Transaction B with a gas price of 10 gwei. Both are valid and have sequential nonces (A has nonce 1, B has nonce 2). The mempool is congested. What will happen?

   • ATransaction B will be mined first because it has a lower fee, which is more attractive to miners.
   • BTransaction A will be mined first, and Transaction B will be mined after it because of the nonce ordering.
   • CBoth transactions will be mined in the same block regardless of nonce order.
   • DTransaction B will be rejected because its fee is too low for the current network conditions.
   Reveal Solution Discussion Select an answer first