CKAD Application Deployment Practice Question
You have a Deployment with the following strategy: rollingUpdate: maxSurge: 25%, maxUnavailable: 25%. The Deployment has 4 replicas. During an update, what is the minimum number of pods guaranteed to be available?
⚠ Common exam trap
The trap here is that candidates often misinterpret the percentage calculation, incorrectly rounding up maxUnavailable (e.g., 25% of 4 = 1, but some might think it's 2 due to rounding up or misapplying the surge logic), leading them to choose 2 or 1 instead of the correct 3.
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
✓
3
With 4 replicas and a rolling update strategy of maxSurge: 25% and maxUnavailable: 25%, the maximum number of pods that can be unavailable during the update is 25% of 4, which is 1. Therefore, the minimum number of pods guaranteed to be available is 4 - 1 = 3. This is calculated by rounding down the maxUnavailable value (1) and ensuring the desired replica count minus unavailable pods equals the minimum available.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
3
Why this is correct
With a Deployment of 4 replicas and the default rolling update strategy, maxUnavailable is 25% of 4, which equals 1 (Kubernetes rounds up for maxUnavailable). This means at any point during the rollout, at most one Pod can be taken down or become unhealthy, so at least 3 replicas remain available to serve traffic. Thus the minimum guaranteed availability is 3, not 2 or 4.
- ✗
2
Why it's wrong here
Choosing 2 available incorrectly assumes that half the replicas can be temporarily down. A maxUnavailable of 25% permits only one unavailable Pod (since 25% of 4 rounds up to 1). With 2 unavailable, you'd be at 50%, violating the Deployment's availability guarantee and potentially causing a service disruption.
- ✗
4
Why it's wrong here
Selecting 4 assumes no Pod ever goes down during the update. While the desired end state is 4 available, the rolling update process intentionally cycles one Pod at a time; during that cycle a replacement may not be ready immediately. The standard guarantees only 3 available at any instant, and 4 is the upper bound, not the minimum.
- ✗
1
Why it's wrong here
Having just 1 available means 3 Pods are unavailable, which is 75% of the Deployment. This wildly exceeds the 25% maxUnavailable threshold (rounded up to 1). Even during a rollout, a healthy Deployment never drops below 3 available replicas, so 1 is far too low.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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