Google PCA Design and plan a cloud solution architecture Practice Question
Network Topology
Refer to the exhibit. All five nginx pods are scheduled on the same node (default-pool-1). What is the most likely reason?
⚠ Common exam trap
This question tests the distinction between taints/tolerations and nodeSelector/affinity in Kubernetes on Google Cloud. Candidates often overlook that taints can silently exclude pods from all but one node, and assume only nodeSelector restricts pod placement.
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 other nodes have taints that the pods do not tolerate.
Taints on nodes prevent pods from being scheduled unless the pods have corresponding tolerations. If the other nodes have taints that the nginx pods do not tolerate, the scheduler will only place them on nodes without those taints, which in this case is default-pool-1. This is a common scenario when nodes are dedicated to specific workloads or have special hardware.
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 node auto-scaler has not created additional nodes yet, but the other nodes are present.
Why it's wrong here
Autoscaler lag would delay new nodes, yet the stem states other nodes already exist, so scheduling could spread pods across them. That rules out capacity as the cause; an affinity or selector constraint pinning pods to default-pool-1 explains the concentration.
- ✗
The pods have a nodeSelector that matches only default-pool-1.
Why it's wrong here
A nodeSelector matching only default-pool-1 would indeed pin pods there, but the exhibit shows other nodes present and schedulable, so the constraint is not the observed cause. Node selectors are correct when workloads must target specific hardware or labelled pools deliberately.
- ✓
The other nodes have taints that the pods do not tolerate.
Why this is correct
Taints on other nodes repel pods lacking matching tolerations, so the scheduler cannot place them there. With no tolerations defined in the pod spec, every other node rejects the nginx pods, leaving default-pool-1 as the only viable target and concentrating all five replicas on it.
- ✗
The resource requests are too high, so the scheduler packed pods onto one node due to resource constraints on the others.
Why it's wrong here
Incorrect: The total requests for 5 pods are 2500m CPU and 5Gi memory, which would easily fit on one e2-standard-2 node (2 vCPU, 8GB RAM), but the other nodes also have capacity. The scheduler would spread by default.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCA 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 PCA exam.