Ethereum Architecture and Transaction Lifecycle BBLC Practice Questions (Page 7)

Questions 31–35

1. 31expert · hard

   A company is evaluating whether to run a full node or a light node for their dApp. They need to verify transaction receipts and event logs without storing the entire blockchain. Which option is most appropriate?

   • ARun an archive node, which stores all historical states and is needed for event logs.
   • BRun a light node, which downloads block headers and requests state data on demand.
   • CRun a mining node, which validates transactions and creates blocks.
   • DRun a full node, which stores all state and is required for any verification.
   Reveal Solution Discussion Select an answer first
2. 32application · medium

   A dApp needs to display a notification when a specific smart contract event is emitted. The frontend uses a library to listen for events. Which component of the transaction receipt is used to detect this event?

   • AThe `status` field, which indicates success or failure.
   • BThe `contractAddress` field, which shows the contract's address.
   • CThe `logs` field, which contains the event's topics and data.
   • DThe `gasUsed` field, which shows the gas consumed.
   Reveal Solution Discussion Select an answer first
4. 33application · medium

   A developer is building a tool to monitor pending transactions from a specific wallet. They need to identify the order in which the wallet's transactions were created. Which transaction field should they use?

   • Ablock number
   • Bnonce
   • Cvalue
   • Dgas price
   Reveal Solution Discussion Select an answer first
5. 34expert · hard

   A developer is debugging a failed transaction. The receipt shows status 0x0 and gasUsed equals the gas limit. The transaction was a call to a contract function that transfers tokens. What is the most likely cause?

   • AThe transaction ran out of gas because the function required more gas than the limit.
   • BThe contract function threw an exception that was caught and handled.
   • CThe transaction was rejected by the node because the nonce was too low.
   • DThe transaction was included in a block but the block was reorged.
   Reveal Solution Discussion Select an answer first
6. 35foundation · easy

   What is the fundamental difference between a transaction and a message in Ethereum?

   • AA transaction can only be sent to a contract, while a message can be sent to any account
   • BA message is signed by the sender, while a transaction is not signed
   • CA transaction is free, while a message requires gas
   • DA transaction is signed and originates from an EOA, while a message is an internal call between contracts
   Reveal Solution Discussion Select an answer first