Network Communication and Protocol Layers BDC Practice Questions (Page 4)

Questions 16–20

1. 16expert · hard

   A blockchain network is facing a Sybil attack where an attacker creates many nodes to influence consensus. The network uses a proof-of-stake consensus. Which mitigation is most appropriate?

   • AUse a proof-of-work algorithm instead.
   • BReduce the block time to increase transaction throughput.
   • CIncrease the block reward to attract more honest nodes.
   • DIncrease the minimum stake required to become a validator.
   Reveal Solution Discussion Select an answer first
2. 17foundation · easy

   What is the role of the 'gossip protocol' in a peer-to-peer blockchain network?

   • AIt coordinates the order in which nodes validate transactions.
   • BIt ensures that all nodes have the same view of the network topology.
   • CIt provides a secure channel for nodes to encrypt their communications.
   • DIt allows nodes to exchange messages about transactions and blocks with a subset of peers, who then relay them.
   Reveal Solution Discussion Select an answer first
4. 18application · medium

   A developer is troubleshooting why a newly deployed blockchain node is not receiving the latest blocks. The node has a public IP and is reachable from the internet. Which step should the developer take first?

   • AModify the node's genesis block to match the network's chain ID.
   • BIncrease the node's disk space to accommodate more blockchain data.
   • CEnable the node's JSON-RPC API to allow external queries.
   • DCheck the node's peer list to ensure it has active outbound and inbound connections.
   Reveal Solution Discussion Select an answer first
5. 19application · medium

   A blockchain developer is configuring a node to connect to a public blockchain network. The node is behind a NAT that does not support port forwarding. Which approach will allow the node to participate in the network?

   • AUse a static IP address assigned by the local ISP.
   • BDisable the node's networking and use a manual block import.
   • CUse outbound connections to known peers and rely on the network's relay or discovery mechanisms.
   • DSet the node's listening port to a high number to bypass NAT restrictions.
   Reveal Solution Discussion Select an answer first
6. 20application · medium

   A developer is building a blockchain-based supply chain tracking system. They need to ensure that transaction data is propagated quickly to all nodes while minimizing redundant network traffic. Which approach should they use?

   • AUse a flooding protocol that sends every transaction to every node multiple times.
   • BUse a centralized server to broadcast transactions to all nodes.
   • CHave each node send transactions only to its direct neighbors without any deduplication.
   • DImplement a gossip protocol where each node forwards new transactions to a subset of peers and uses a seen-set to avoid re-broadcasting.
   Reveal Solution Discussion Select an answer first