200-901 Application Deployment and Security Practice Question
This 200-901 practice question tests your understanding of application deployment and security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
A company uses a blue/green deployment strategy for their web application. The current live version is blue, and a new version green is ready. The load balancer currently routes all traffic to blue. What is the correct next step to switch traffic to green with minimal downtime?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Update the load balancer to route all traffic to green
In a blue/green deployment, the entire new version (green) is deployed alongside the current live version (blue). The correct next step to switch traffic with minimal downtime is to update the load balancer to route all traffic to green. This instant switch avoids the incremental risk of rolling updates and ensures a clean cutover that can be quickly reverted if issues arise.
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.
✗
Scale down blue pods and scale up green
Why it's wrong here
This could cause partial downtime and is not the standard blue/green approach.
✗
Perform a rolling update from blue to green
Why it's wrong here
Rolling update is a different strategy, not blue/green.
✗
Delete the blue deployment and create green
Why it's wrong here
This would cause downtime during deletion.
✓
Update the load balancer to route all traffic to green
Why this is correct
This switches traffic instantly with minimal downtime.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between deployment strategies, and the trap here is confusing a rolling update (which gradually replaces pods) with a blue/green deployment (which switches traffic at the load balancer level), leading candidates to incorrectly select Option B.
Detailed technical explanation
How to think about this question
Under the hood, the load balancer (e.g., AWS ALB, NGINX, or HAProxy) uses a target group or upstream block that can be atomically updated via API or config reload to point to the green environment's instance pool. In Kubernetes, this is often achieved by updating the Service selector to point to the green Deployment's labels, which takes effect immediately without dropping existing connections if session affinity is configured. A real-world scenario where this matters is when a critical security patch must be rolled out and instantly rolled back if a regression is detected, making the blue/green switch the safest approach.
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: Update the load balancer to route all traffic to green — In a blue/green deployment, the entire new version (green) is deployed alongside the current live version (blue). The correct next step to switch traffic with minimal downtime is to update the load balancer to route all traffic to green. This instant switch avoids the incremental risk of rolling updates and ensures a clean cutover that can be quickly reverted if issues arise.
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.
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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