CKAD Application Observability and Maintenance Practice Question
This CKAD practice question tests your understanding of application observability and maintenance. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
You have a Deployment that uses an httpGet liveness probe on port 8080 with path /healthz. The probe fails after the container starts, but you can successfully curl http://localhost:8080/healthz from within the container. 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.
Why wrong: The probe is configured on port 8080, and curl works from within the container, so the port is correct.
B
The container is not running
Why wrong: The container is running because curl works inside it.
C
The liveness probe path is incorrect
Why wrong: The path /healthz works from within the container, so it is correct.
D
The container is listening on localhost (127.0.0.1) instead of 0.0.0.0
The liveness probe runs from the node and cannot reach localhost inside the container. The container must listen on all interfaces (0.0.0.0) for the probe to succeed.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The container is listening on localhost (127.0.0.1) instead of 0.0.0.0
The liveness probe is executed by the kubelet from the node's network namespace, not from within the container. If the application binds only to 127.0.0.1 (localhost), it will only accept connections from within the container itself. The kubelet's HTTP GET request to the pod's IP on port 8080 will be refused because the socket is not listening on 0.0.0.0, causing the probe to fail even though a local curl succeeds.
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 liveness probe port is incorrect
Why it's wrong here
The probe is configured on port 8080, and curl works from within the container, so the port is correct.
✗
The container is not running
Why it's wrong here
The container is running because curl works inside it.
✗
The liveness probe path is incorrect
Why it's wrong here
The path /healthz works from within the container, so it is correct.
✓
The container is listening on localhost (127.0.0.1) instead of 0.0.0.0
Why this is correct
The liveness probe runs from the node and cannot reach localhost inside the container. The container must listen on all interfaces (0.0.0.0) for the probe to succeed.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates see a successful curl from inside the container and assume the probe should work, failing to realize that the kubelet probes from outside the container's network namespace and cannot reach a service bound only to 127.0.0.1.
Detailed technical explanation
How to think about this question
By default, many application frameworks (e.g., Node.js, Python Flask, Go net/http) bind to localhost unless explicitly configured to bind to 0.0.0.0. The kubelet performs liveness probes by sending HTTP requests to the pod's IP address (which is a virtual IP on the node's network), not to 127.0.0.1. This is a common pitfall when containerizing applications that were originally designed for local development, where binding to localhost is sufficient.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKAD question in full detail.
Application Observability and Maintenance — This question tests Application Observability and Maintenance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The container is listening on localhost (127.0.0.1) instead of 0.0.0.0 — The liveness probe is executed by the kubelet from the node's network namespace, not from within the container. If the application binds only to 127.0.0.1 (localhost), it will only accept connections from within the container itself. The kubelet's HTTP GET request to the pod's IP on port 8080 will be refused because the socket is not listening on 0.0.0.0, causing the probe to fail even though a local curl succeeds.
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.