The answer is to check the ALB access logs and health check settings for the target group, verify the ECS service is running with healthy tasks, and confirm the service’s desired count matches the number of running tasks. When you diagnose ALB 503 error on ECS Fargate, the root cause is almost always that the load balancer cannot route traffic to healthy targets, either because the health checks are misconfigured, the tasks are failing to start, or the service’s desired count is out of sync with actual running tasks. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of how ALB health checks interact with ECS service auto-recovery and task lifecycle. A common trap is to jump to changing the load balancer type or enabling stickiness, but those do not address the underlying connectivity failure. Memory tip: think “H-D-S” — Health checks, Desired count, Service status — the three pillars of Fargate target group troubleshooting.
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. 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.
A company is running a critical microservices application on Amazon ECS with Fargate launch type. The application uses an Application Load Balancer (ALB) to distribute traffic. Recently, the team noticed that the ALB's 5xx error rate has increased. The error is HTTP 503. The team suspects the target group is unhealthy. Which THREE steps should the team take to diagnose and resolve the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Verify the ECS service's desired count and compare with the number of healthy tasks in the target group.
Option A, Option C, and Option E are correct. Option A checks health check settings and logs. Option C checks if the service is running and tasks are healthy. Option E checks if the service's desired count matches running tasks. Option B (Check target group stickiness) is not directly related to 503 errors. Option D (Switch to Network Load Balancer) is a major change and not diagnostic.
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.
✓
Verify the ECS service's desired count and compare with the number of healthy tasks in the target group.
Why this is correct
A mismatch may indicate scaling issues.
Related concept
Read the scenario before looking for a memorised answer.
✗
Replace the ALB with a Network Load Balancer (NLB) to bypass health checks.
Why it's wrong here
NLB does not solve the underlying issue; it just hides it.
✓
Check the ECS service events and task status to ensure tasks are running and passing health checks.
Why this is correct
Unhealthy tasks cause 503 errors.
Related concept
Read the scenario before looking for a memorised answer.
✗
Verify that sticky sessions (session affinity) are enabled on the target group.
Why it's wrong here
Stickiness affects session persistence, not health.
✓
Check the ALB access logs and health check settings for the target group.
Why this is correct
Access logs show 503 responses; health check settings may be misconfigured.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Identify which SAP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Verify the ECS service's desired count and compare with the number of healthy tasks in the target group. — Option A, Option C, and Option E are correct. Option A checks health check settings and logs. Option C checks if the service is running and tasks are healthy. Option E checks if the service's desired count matches running tasks. Option B (Check target group stickiness) is not directly related to 503 errors. Option D (Switch to Network Load Balancer) is a major change and not diagnostic.
What should I do if I get this SAP-C02 question wrong?
Identify which SAP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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