DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. 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 web application running on Amazon EC2 instances behind an Application Load Balancer (ALB) is experiencing intermittent 503 errors. Which TWO steps should be taken to diagnose the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check the CPU utilization of the EC2 instances.
Option B is correct because high CPU utilization on EC2 instances can cause them to become unresponsive or fail to respond to health checks within the ALB's configured timeout, leading to 503 errors. The ALB routes traffic only to healthy targets; if instances are overwhelmed, they may fail health checks or drop requests, resulting in a 503 response to clients.
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.
High CPU can cause instances to fail health checks and return 503.
Related concept
Read the scenario before looking for a memorised answer.
✓
Check the target group health check settings and instance health status.
Why this is correct
Unhealthy targets cause 503 errors.
Related concept
Read the scenario before looking for a memorised answer.
✗
Check the security group rules for the ALB.
Why it's wrong here
Security groups cause connection timeouts, not 503s.
✗
Check the EBS volume type of the EC2 instances.
Why it's wrong here
EBS volume type does not cause 503 errors.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse Route 53 health checks (DNS-level) with ALB target group health checks (application-level), or assume that security groups or EBS volumes are the root cause of HTTP 503 errors when they are not directly related to load balancer routing failures.
Detailed technical explanation
How to think about this question
The ALB's target group health checks are performed at the application layer (HTTP/HTTPS) using a configured path (e.g., /health). If an EC2 instance's CPU is saturated, the web server may not respond within the health check interval (default 30 seconds) or unhealthy threshold (default 2 consecutive failures), causing the ALB to mark it unhealthy and stop routing traffic. Intermittent 503 errors often occur when only some instances are unhealthy due to resource exhaustion, while others remain healthy, leading to partial capacity.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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.
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Check the CPU utilization of the EC2 instances. — Option B is correct because high CPU utilization on EC2 instances can cause them to become unresponsive or fail to respond to health checks within the ALB's configured timeout, leading to 503 errors. The ALB routes traffic only to healthy targets; if instances are overwhelmed, they may fail health checks or drop requests, resulting in a 503 response to clients.
What should I do if I get this DVA-C02 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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This DVA-C02 practice question is part of Courseiva's free Amazon Web Services 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 DVA-C02 exam.
Question Discussion
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