Question 149 of 505

Application Deployment and Security →mediumMultiple ChoiceObjective-mapped

200-901 Application Deployment and Security Practice Question

This 200-901 practice question tests your understanding of application deployment and security. 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

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
      maxSurge: 1
  selector:
    matchLabels:
      app: webapp
  template:
    metadata:
      labels:
        app: webapp
    spec:
      containers:
      - name: web
        image: nginx:1.21
        ports:
        - containerPort: 80
        readinessProbe:
          httpGet:
            path: /health
            port: 80
          initialDelaySeconds: 5
          periodSeconds: 10

Refer to the exhibit. During a rolling update, a developer notices that the new pods are not passing the readiness probe and the update stalls. What is the most likely reason?

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.

Question 1mediummultiple choice

Full question →

Exhibit

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
      maxSurge: 1
  selector:
    matchLabels:
      app: webapp
  template:
    metadata:
      labels:
        app: webapp
    spec:
      containers:
      - name: web
        image: nginx:1.21
        ports:
        - containerPort: 80
        readinessProbe:
          httpGet:
            path: /health
            port: 80
          initialDelaySeconds: 5
          periodSeconds: 10

A
The rolling update strategy is configured incorrectly with maxUnavailable and maxSurge.
Why wrong: The configuration is standard and should work.
B
The readiness probe path /health is not implemented in the new image.
If the endpoint is missing, the probe fails and pods remain not ready.
C
The image tag is incorrect.
Why wrong: The tag nginx:1.21 exists; incorrect tag would cause image pull failure, not probe failure.
D
The selector does not match the new pods' labels.
Why wrong: The selector matches the template labels, so new pods have the correct labels.

Full breakdown with real-world context →

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

✓

The readiness probe path /health is not implemented in the new image.

The rolling update stalls because the new pods fail the readiness probe. The readiness probe is configured to check the /health endpoint, and if that endpoint is not implemented in the new image, the probe never returns a success status. Kubernetes will not route traffic to pods that fail the readiness probe, and the rolling update will not proceed to replace old pods until the new ones are ready.

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 rolling update strategy is configured incorrectly with maxUnavailable and maxSurge.
Why it's wrong here
The configuration is standard and should work.
✓
The readiness probe path /health is not implemented in the new image.
Why this is correct
If the endpoint is missing, the probe fails and pods remain not ready.
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 image tag is incorrect.
Why it's wrong here
The tag nginx:1.21 exists; incorrect tag would cause image pull failure, not probe failure.
✗
The selector does not match the new pods' labels.
Why it's wrong here
The selector matches the template labels, so new pods have the correct labels.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the distinction between readiness and liveness probes, and the trap here is that candidates may confuse a readiness probe failure with a liveness probe failure or assume the issue is with the rolling update strategy configuration rather than the application endpoint not being implemented.

Detailed technical explanation

How to think about this question

The readiness probe is a Kubernetes mechanism that determines whether a pod is ready to serve traffic. It is defined in the pod spec under `spec.containers.readinessProbe` and can use HTTP GET, TCP socket, or exec commands. If the probe fails, the pod is removed from the Service's endpoints, but the pod continues running. In a rolling update, the Deployment controller waits for the new ReplicaSet's pods to become ready before scaling down the old ReplicaSet; if readiness never succeeds, the update is effectively paused. This behavior is governed by the `minReadySeconds` and `progressDeadlineSeconds` settings, but the root cause here is the missing /health endpoint.

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.

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.

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FAQ

Questions learners often ask

What does this 200-901 question test?

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 path /health is not implemented in the new image. — The rolling update stalls because the new pods fail the readiness probe. The readiness probe is configured to check the /health endpoint, and if that endpoint is not implemented in the new image, the probe never returns a success status. Kubernetes will not route traffic to pods that fail the readiness probe, and the rolling update will not proceed to replace old pods until the new ones are ready.

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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Last reviewed: Jun 24, 2026

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