KCNA RollingUpdate Practice Question
A developer creates a Deployment with replicas: 3 and strategy type: RollingUpdate with maxSurge: 1 and maxUnavailable: 1. During a rolling update, the Deployment controller creates a new ReplicaSet. After the new ReplicaSet has 2 pods ready, the node running one of the original ReplicaSet's pods fails. What is the MOST likely number of total pods running after the node failure, assuming no other actions?
⚠ Common exam trap
Candidates may mistakenly think that the failed pod is immediately replaced by the Deployment controller to maintain the desired replica count, leading to 3 pods (2 new + 1 replacement). They might also overlook that the failed pod is no longer running, incorrectly counting 3 pods (2 new + 1 old). In reality, right after the node failure, only the 2 new pods are running, and the controller has not yet reacted.
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
✓
2 pods running
Initially, the Deployment has 3 old pods. The rolling update starts: with maxSurge=1, the controller creates a new pod. Once it's ready, it terminates one old pod to keep desired replicas at 3. Then it creates another new pod. After the second new pod is ready, it terminates a second old pod. At this point, the new ReplicaSet has 2 ready pods, and the old ReplicaSet has only 1 pod remaining. The node running that last old pod fails, killing it. Thus, only the 2 new pods are running, giving a total of 2 pods.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
2 pods running
Why this is correct
Before node failure: old ReplicaSet scaled down to 1, new up to 2 (total 3). Node failure kills the old pod, leaving 2 new pods running.
- ✗
4 pods running
Why it's wrong here
4 would be the maximum allowed by maxSurge=1, but the controller would not keep both old and new at full count simultaneously during update.
- ✗
3 pods running
Why it's wrong here
3 would be the initial count; after update and failure, only 2 remain.
- ✗
1 pod running
Why it's wrong here
The new ReplicaSet has 2 pods; the old had 1 left before failure, but after failure, only the 2 new pods remain.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This KCNA practice question is part of Courseiva's free CNCF 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 KCNA exam.