Blockchain Deployment and Monitoring Tools BDC Practice Questions (Page 4)

Questions 16–20

1. 16application · medium

   A monitoring system for a Proof-of-Authority (PoA) Ethereum network sends an alert: 'Validator node 3 has not produced a block in 2 hours.' The node process is running and the machine is responsive. What is the most likely cause and the first troubleshooting step?

   • AThe node's keystore file is corrupted; re-import the validator's private key.
   • BThe node is under a denial-of-service attack; immediately block all inbound traffic to the node.
   • CThe node's clock is skewed; synchronize the system time with an NTP server.
   • DThe node's peer count is too low; add more peers to the node's enode list.
   Reveal Solution Discussion Select an answer first
2. 17foundation · easy

   What does the 'peer count' metric indicate in a blockchain network?

   • AThe number of other nodes a node is connected to
   • BThe number of blocks in the blockchain
   • CThe node's CPU utilization
   • DThe total number of transactions in the mempool
   Reveal Solution Discussion Select an answer first
4. 18foundation · easy

   Which tool is specifically designed to query and display blockchain data such as blocks, transactions, and addresses in a web interface?

   • AGrafana
   • BBlock explorer
   • CPrometheus
   • DDocker
   Reveal Solution Discussion Select an answer first
5. 19application · medium

   A Grafana dashboard for a Hyperledger Fabric peer shows that the peer's container is using 90% of its allocated 4GB memory. The peer is still responding, but the team wants to prevent OOM kills. The peer's workload is expected to grow. What is the most appropriate action?

   • AReduce the peer's cache size in the core.yaml configuration.
   • BSet up an alert to notify the team when memory usage exceeds 95%.
   • CAdd a memory swap limit to the container.
   • DIncrease the container's memory limit to 8GB and restart the peer.
   Reveal Solution Discussion Select an answer first
6. 20expert · medium

   A Grafana dashboard for a Kubernetes-based blockchain network shows that the 'container_cpu_usage_seconds_total' metric is increasing linearly for a validator node, but the 'container_memory_working_set_bytes' is stable. The node is still producing blocks. What is the most likely explanation?

   • AThe metric is a counter, and its increase is expected as the node processes more transactions.
   • BThe node is experiencing a disk I/O bottleneck.
   • CThe node is experiencing a memory leak.
   • DThe node is under a CPU throttling condition.
   Reveal Solution Discussion Select an answer first