This CKAD practice question tests your understanding of application deployment. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
Exhibit
Refer to the exhibit.
```
apiVersion: apps/v1
kind: Deployment
metadata:
name: web
spec:
replicas: 3
selector:
matchLabels:
app: web
template:
metadata:
labels:
app: web
spec:
containers:
- name: nginx
image: nginx:1.21
ports:
- containerPort: 80
livenessProbe:
httpGet:
path: /healthz
port: 8080
initialDelaySeconds: 3
periodSeconds: 3
```
The exhibit shows a Deployment manifest. When applied, the pods are created but show 'CrashLoopBackOff'. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The liveness probe targets port 8080, but the container only listens on port 80
The liveness probe is configured to check port 8080, but the container (nginx) only listens on port 80 by default. Since the probe never receives a successful HTTP response, Kubernetes restarts the container repeatedly, causing the CrashLoopBackOff state. The probe must target the same port the application is serving on.
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.
✗
The selector does not match the pod labels
Why it's wrong here
The selector matchLabels matches the template labels, so this is correct.
✓
The liveness probe targets port 8080, but the container only listens on port 80
Why this is correct
The probe will fail because there is no service on port 8080.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The initialDelaySeconds is too short, starting probes before the app is ready
Why it's wrong here
initialDelaySeconds=3 is reasonable, and failure would cause restarts but not necessarily crash loop if the app eventually starts.
✗
The container image nginx:1.21 does not exist
Why it's wrong here
The image exists and is valid.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between probe misconfiguration (wrong port/path) and other failure modes like image errors or selector mismatches, tempting candidates to overthink with options like initialDelaySeconds.
Detailed technical explanation
How to think about this question
Kubernetes liveness probes use HTTP GET requests to the specified port and path; if the probe fails, kubelet restarts the container based on the failureThreshold and periodSeconds. The default nginx image listens on port 80, not 8080, so the probe will always fail unless the container is reconfigured. This is a common misconfiguration when copying probe settings from a different application without adjusting the port.
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 practitioner preparing for the CKAD exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKAD question in full detail.
Application Deployment — This question tests Application Deployment — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The liveness probe targets port 8080, but the container only listens on port 80 — The liveness probe is configured to check port 8080, but the container (nginx) only listens on port 80 by default. Since the probe never receives a successful HTTP response, Kubernetes restarts the container repeatedly, causing the CrashLoopBackOff state. The probe must target the same port the application is serving on.
What should I do if I get this CKAD question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This CKAD 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 CKAD exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.