Blockchain Architecture, Node Infrastructure, and Types BDC Practice Questions (Page 7)

Questions 31–35

1. 31foundation · easy

   In a blockchain system, which component is responsible for validating and ordering transactions before they are grouped into a block?

   • AThe consensus mechanism
   • BThe cryptographic hash function
   • CThe peer-to-peer network layer
   • DThe smart contract runtime
   Reveal Solution Discussion Select an answer first
2. 32expert · hard

   A developer is explaining to a client why a blockchain is considered 'immutable'. The client asks: 'If I have the private key of a node, can I change a past transaction?' What is the correct response?

   • AYes, because the node's private key can sign a new block
   • BNo, because the blockchain is stored on a single server that cannot be modified
   • CNo, because each block is cryptographically linked to the previous block, and changing one would invalidate all subsequent blocks
   • DYes, if you control a majority of the network's hash power
   Reveal Solution Discussion Select an answer first
4. 33expert · hard

   A government agency is evaluating blockchain options for a national land registry. They need to ensure that the system is resilient to a single point of failure, but they also need to comply with data residency laws that require data to remain within the country. Which architecture best meets these constraints?

   • AA public blockchain with all nodes hosted in the country
   • BA consortium blockchain with nodes distributed across multiple data centers within the country
   • CA private blockchain with all nodes hosted in a single data center within the country
   • DA public blockchain with nodes distributed globally
   Reveal Solution Discussion Select an answer first
5. 34application · medium

   A developer is setting up a monitoring tool for a public blockchain. The tool needs to track the current state of all accounts and smart contracts without storing the entire transaction history. Which node type should the tool connect to?

   • AA light node
   • BA full node with pruning enabled
   • CA full node
   • DAn archive node
   Reveal Solution Discussion Select an answer first
6. 35expert · hard

   A blockchain developer is troubleshooting why a transaction that was included in a block is no longer visible in the canonical chain. The network uses a proof-of-work consensus. What is the most likely cause?

   • AThe transaction was double-spent and automatically reversed
   • BThe block containing the transaction was orphaned due to a chain reorganisation
   • CThe transaction was invalid and was removed by a later block
   • DThe transaction was pruned from the node's local storage
   Reveal Solution Discussion Select an answer first