PCDOE Implementing service monitoring strategies Practice Question
A team is monitoring a production service on Google Kubernetes Engine (GKE) and notices that a deployment is occasionally returning HTTP 503 errors. The team has set up a ServiceMonitor in Prometheus to scrape metrics from the pods. What is the most likely cause of the intermittent 503 errors?
⚠ Common exam trap
Google Cloud often tests the distinction between liveness probes (which restart pods) and readiness probes (which control traffic routing), and candidates mistakenly attribute 503 errors to pod crashes or resource limits rather than the readiness probe's role in endpoint management.
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
✓
The readiness probes are failing, causing the pods to be removed from the service endpoints.
Intermittent HTTP 503 errors in a GKE deployment typically indicate that the service's endpoints are temporarily unavailable. When a readiness probe fails, Kubernetes removes the pod from the Service's endpoints, causing traffic to be routed to remaining healthy pods. If multiple pods fail their readiness probes simultaneously or in quick succession, the Service may have no available endpoints, resulting in 503 errors for incoming requests.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The pods are crashing and restarting frequently.
Why it's wrong here
Restarts would cause 503s but less likely than readiness probe failures.
- ✗
The Prometheus scrape interval is too long, causing missed metrics.
Why it's wrong here
Prometheus scraping does not affect pod availability.
- ✓
The readiness probes are failing, causing the pods to be removed from the service endpoints.
Why this is correct
Readiness probe failures remove pods from service endpoints, causing 503s if all replicas fail.
- ✗
The container resource limits are set too low, causing out-of-memory errors.
Why it's wrong here
OOM errors cause restarts, not directly 503s.
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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.