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200-901 Practice Question: A company uses a blue/green deployment strategy…
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?
⚠ Common exam trap
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.
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
✓
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.
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
Scaling down blue removes the live version before green serves any traffic, so requests fail during the gap. Blue/green switching requires repointing the load balancer's target group to green, then decommissioning blue. Scaling is used for capacity changes within one environment, not for cutover.
- ✗
Perform a rolling update from blue to green
Why it's wrong here
A rolling update replaces instances incrementally within one environment, so blue and green versions serve traffic simultaneously — the opposite of blue/green's atomic switch. Repointing the load balancer to green achieves the cutover. Rolling updates suit in-place upgrades where two full environments do not exist.
- ✗
Delete the blue deployment and create green
Why it's wrong here
Deleting blue first destroys the rollback target and causes an outage until green is created and healthy. Blue/green keeps both environments running and flips the load balancer's target group to green, preserving instant rollback. Recreate-style deployment is used when no zero-downtime requirement exists.
- ✓
Update the load balancer to route all traffic to green
Why this is correct
Updating the load balancer to route all traffic to green switches the live environment in a single atomic change, satisfying the minimal-downtime constraint. Because green is already deployed and healthy, no rebuild or restart is needed; the load balancer's routing rule is the only cutover point, so blue remains available for instant rollback.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 practice question is part of Courseiva's free Cisco 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 200-901 exam.