hardMultiple ChoiceObjective-mapped
PDE Practice Question: A data pipeline ingests sensor data from IoT…
A data pipeline ingests sensor data from IoT devices via Cloud Pub/Sub, processes it with Cloud Dataflow, and writes to BigQuery. The pipeline is failing with high latency and data loss. Which troubleshooting step should be taken first?
⚠ Common exam trap
Google Cloud often tests the principle of 'diagnose before you optimize' — the trap here is that candidates jump to scaling or switching technologies (options C and D) without first checking logs, which is the fundamental first step in any troubleshooting workflow.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check Stackdriver logging for error messages.
Stackdriver (now Cloud Logging) is the first place to investigate when a Dataflow pipeline experiences high latency and data loss. Dataflow automatically logs errors, worker failures, and system messages to Cloud Logging, which can reveal root causes such as insufficient resources, stuck steps, or Pub/Sub subscription issues. Checking logs first avoids premature scaling or configuration changes that may not address the actual problem.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Check Stackdriver logging for error messages.
Why this is correct
Identifies root cause.
- ✗
Disable exactly-once processing in Dataflow.
Why it's wrong here
Can cause data loss.
- ✗
Increase the number of Dataflow workers.
Why it's wrong here
May mask underlying issue.
- ✗
Switch to BigQuery streaming inserts.
Why it's wrong here
Design change, not troubleshooting.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PDE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PDE exam.