PCDOE Practice Question: Applying site reliability engineering practices
A DevOps engineer receives an alert that the error budget for a critical service has been exhausted. The service runs on Compute Engine behind an HTTP(S) load balancer. The team wants to reduce the impact on users while investigating. What should the engineer do first?
⚠ Common exam trap
Google Cloud often tests the misconception that scaling out (increasing instances) is the correct response to any degradation, but here the error budget exhaustion indicates a functional defect, not a capacity issue, so scaling would not fix the root cause.
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
✓
Roll back the most recent deployment
Rolling back the most recent deployment is the correct first action because it immediately restores the service to a known stable state, stopping further consumption of the error budget. This aligns with the incident management principle of 'mitigate first, investigate later' — reducing user impact takes priority over root cause analysis. The HTTP(S) load balancer will automatically route traffic to the previous healthy version once the rollback is complete.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Roll back the most recent deployment
Why this is correct
Rolling back quickly restores the previous stable version.
- ✗
Begin a detailed postmortem analysis
Why it's wrong here
Postmortem should happen after mitigation, not before.
- ✗
Disable the alerting policy to reduce noise
Why it's wrong here
Ignoring alerts does not resolve the incident.
- ✗
Increase the number of instances in the managed instance group
Why it's wrong here
Scaling out may not address the root cause and could increase costs.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCDOE 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 PCDOE exam.