200-901 Application Deployment and Security Practice Question
This 200-901 practice question tests your understanding of application deployment and security. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 application running on Kubernetes is experiencing intermittent 503 errors. The logs show 'upstream timed out'. The application is behind a Cisco Application Policy Infrastructure Controller (APIC) load balancer. 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 Readiness probe is not defined
The 'upstream timed out' error in a Kubernetes environment behind a Cisco APIC load balancer indicates that the load balancer is attempting to forward traffic to a pod that is not ready to accept connections. Without a Readiness probe, Kubernetes assumes the pod is ready as soon as it starts, but the application may still be initializing or unable to handle requests. The APIC load balancer then sends traffic to an unready pod, causing timeouts and 503 errors.
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 service port is misconfigured
Why it's wrong here
Service port misconfiguration would cause persistent failure, not intermittent.
✓
The Readiness probe is not defined
Why this is correct
Without Readiness probe, the service may send traffic to unready pods causing timeouts.
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 Liveness probe timeout is too low
Why it's wrong here
Liveness probe affects whether pod is restarted, not load balancer routing.
✗
The pod is not ready
Why it's wrong here
Pod not ready is a symptom, not the root cause.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between Readiness and Liveness probes, where candidates mistakenly associate 'upstream timed out' with Liveness probe failures, but the correct focus is on traffic routing via Readiness probes.
Detailed technical explanation
How to think about this question
Kubernetes Readiness probes (e.g., HTTP GET, TCP socket, or exec) are checked periodically, and if they fail, the pod is removed from the Endpoints object that the Service uses to route traffic. The Cisco APIC load balancer integrates with Kubernetes via the ACI CNI plugin, which watches these Endpoints; without a Readiness probe, the pod is added to the Endpoints immediately upon starting, even if the application's worker threads or database connections are not yet established. This mismatch between pod state and actual readiness is a common cause of intermittent failures in production.
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 200-901 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.
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.
Application Deployment and Security — This question tests Application Deployment and Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Readiness probe is not defined — The 'upstream timed out' error in a Kubernetes environment behind a Cisco APIC load balancer indicates that the load balancer is attempting to forward traffic to a pod that is not ready to accept connections. Without a Readiness probe, Kubernetes assumes the pod is ready as soon as it starts, but the application may still be initializing or unable to handle requests. The APIC load balancer then sends traffic to an unready pod, causing timeouts and 503 errors.
What should I do if I get this 200-901 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.
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Question Discussion
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