PCDOE Implementing service monitoring strategies Practice Question
An SRE team needs to define an SLI for a web service's availability SLO of 99.9%. Which metric should they use?
⚠ Common exam trap
Google Cloud often tests the distinction between availability (binary up/down) and performance (latency/error rate), so candidates mistakenly choose latency metrics like p99 for availability SLOs, conflating responsiveness with uptime.
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
✓
Uptime check success rate
An uptime check success rate directly measures the proportion of time the service is reachable and responding, which aligns with the definition of availability for a 99.9% SLO. This metric is typically derived from synthetic probes or health check endpoints (e.g., HTTP 200 responses) and reflects the binary state of the service being up or down, making it the appropriate SLI for availability.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Error budget
Why it's wrong here
Error budget is derived from SLO, not an SLI metric.
- ✗
CPU utilization
Why it's wrong here
CPU utilization is a system metric, not service availability.
- ✗
Request latency (p99)
Why it's wrong here
Latency measures speed, not availability.
- ✓
Uptime check success rate
Why this is correct
Uptime checks measure the fraction of successful probes, directly reflecting availability.
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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.