Blockchain Architecture and Its Core Components BBLC Practice Questions (Page 2)

Questions 6–10

1. 6application · medium

   In a public blockchain, a user submits a transaction. How does the transaction reach the miners or validators who will include it in a block?

   • AThe transaction is broadcast to the peer-to-peer network and propagated node-to-node until it reaches all nodes, including validators.
   • BThe transaction is sent directly to a central server that distributes it to miners.
   • CThe transaction is emailed to a list of known miners.
   • DThe transaction is stored in a cloud queue that miners poll periodically.
   Reveal Solution Discussion Select an answer first
2. 7foundation · easy

   In a blockchain block, what is the primary content of the block body?

   • AThe list of validated transactions
   • BThe hash of the previous block
   • CThe network's consensus rules
   • DThe public keys of all nodes
   Reveal Solution Discussion Select an answer first
4. 8application · medium

   A user submits a transaction to a public blockchain. The transaction is broadcast to the network and enters the mempool. Which sequence of events correctly describes the transaction lifecycle from this point?

   • AThe transaction is sent directly to every node, and each node independently adds it to its own ledger without a shared block.
   • BThe transaction is immediately finalized and written to the ledger without further validation.
   • CThe transaction is first validated by a central authority, then broadcast to the network for inclusion in the next block.
   • DA miner selects the transaction, includes it in a candidate block, solves the consensus puzzle, broadcasts the block, and the transaction is confirmed after the block is accepted.
   Reveal Solution Discussion Select an answer first
5. 9expert · hard

   A developer deploys a smart contract that transfers funds from a buyer to a seller when a shipment is delivered. The contract relies on an oracle to report delivery. The oracle is compromised and reports delivery before the shipment actually arrives. What is the most effective way to mitigate this risk?

   • AStore the delivery data directly on-chain without an oracle.
   • BUse a single reputable oracle to ensure accuracy.
   • CUse multiple independent oracles and require a threshold agreement (e.g., 3 out of 5) before triggering the payment.
   • DRemove the oracle and have the seller manually confirm delivery in the smart contract.
   Reveal Solution Discussion Select an answer first
6. 10application · medium

   A logistics company is implementing a private blockchain to track shipments. A shipping partner submits a transaction updating the status of a package. The transaction is broadcast to the network. What must happen before the update is considered final and part of the permanent ledger?

   • AThe transaction is immediately written to every node's local copy of the ledger without further validation.
   • BThe transaction is hashed and stored in the mempool until the next block is created, at which point it is automatically added without further checks.
   • CThe transaction is sent to a central authority that updates the ledger and broadcasts the new state to all nodes.
   • DThe transaction is added to a block, the block is validated by the consensus mechanism, and the block is cryptographically linked to the previous block.
   Reveal Solution Discussion Select an answer first