The answer is a StatefulSet with a PersistentVolumeClaim template. This is correct because StatefulSets are specifically designed for stateful applications on GKE, providing stable, unique network identities and ordered deployment, while the PersistentVolumeClaim template ensures each Pod gets its own dedicated PersistentVolume that survives rolling updates and rescheduling, preventing data disruption. On the Google Professional Cloud Developer exam, this tests your understanding of the fundamental difference between Deployments and StatefulSets—a common trap is choosing a Deployment with a shared PersistentVolume, which would cause data corruption when Pods are replaced. Remember the memory tip: "StatefulSet for sticky storage" — if your app needs each Pod to keep its own data through updates, you need the PVC template inside the StatefulSet spec, not a separate volume claim.
PCD Deploying applications Practice Question
This PCD practice question tests your understanding of deploying applications. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An organization runs a stateful application on GKE that uses PersistentVolumes. They want to perform a rolling update of the application without disrupting the underlying persistent data. What should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A StatefulSet with a PersistentVolumeClaim template.
A StatefulSet is the correct choice because it is designed for stateful applications that require stable, unique network identifiers and persistent storage. By including a PersistentVolumeClaim template in the StatefulSet spec, each Pod gets its own dedicated PersistentVolume that persists across rescheduling and rolling updates, ensuring data is not disrupted.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
A ReplicaSet with a headless service.
Why it's wrong here
ReplicaSet does not preserve pod identity; headless service is for DNS.
✓
A StatefulSet with a PersistentVolumeClaim template.
Why this is correct
StatefulSet ensures each pod gets its own PVC and updates gracefully, preserving data.
Related concept
Read the scenario before looking for a memorised answer.
✗
A DaemonSet with a PodDisruptionBudget.
Why it's wrong here
DaemonSet runs one pod per node, not suitable for stateful apps with unique volumes.
✗
A Deployment with a PersistentVolumeClaim template.
Why it's wrong here
Deployment does not guarantee pod identity and can cause data loss on updates.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that a Deployment with a PersistentVolumeClaim template can handle stateful workloads, but the trap is that Deployments treat all Pods as interchangeable and would force all Pods to share the same PVC, causing data loss or corruption during updates.
Detailed technical explanation
How to think about this question
Under the hood, StatefulSet uses a PersistentVolumeClaim template to dynamically provision a unique PersistentVolume for each Pod, with the volume name derived from the Pod's ordinal index (e.g., `pvc-<statefulset-name>-<ordinal>`). During a rolling update, StatefulSet deletes and recreates Pods one at a time in reverse ordinal order, and the existing PersistentVolume is reattached to the new Pod because the PVC is not deleted. This behavior is governed by the `podManagementPolicy` (default `OrderedReady`) and ensures data persistence even if the Pod is rescheduled to a different node.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Deploying applications — This question tests Deploying applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A StatefulSet with a PersistentVolumeClaim template. — A StatefulSet is the correct choice because it is designed for stateful applications that require stable, unique network identifiers and persistent storage. By including a PersistentVolumeClaim template in the StatefulSet spec, each Pod gets its own dedicated PersistentVolume that persists across rescheduling and rolling updates, ensuring data is not disrupted.
What should I do if I get this PCD question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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