SAA-C03 Design Secure Architectures Practice Question
This SAA-C03 practice question tests your understanding of design secure architectures. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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
{
"cloudfront_log_sample": [
"2026-04-27T09:14:01Z c-ip=203.0.113.44 uri=/api/search 1",
"2026-04-27T09:14:02Z c-ip=203.0.113.44 uri=/api/search 1",
"2026-04-27T09:14:02Z c-ip=203.0.113.44 uri=/api/search 1"
],
"origin_metrics": {
"5xxErrorRate": "spiking",
"ALBRequestCount": "high",
"single_source_ip_percentage": "82%"
},
"waf_status": "No Web ACL associated with the CloudFront distribution"
}
Based on the exhibit, a public API is behind CloudFront. A single client IP is sending bursts of requests that are overwhelming the origin, and the team wants AWS to automatically mitigate the abuse at the edge without changing the application code. What should the team do?
{
"cloudfront_log_sample": [
"2026-04-27T09:14:01Z c-ip=203.0.113.44 uri=/api/search 1",
"2026-04-27T09:14:02Z c-ip=203.0.113.44 uri=/api/search 1",
"2026-04-27T09:14:02Z c-ip=203.0.113.44 uri=/api/search 1"
],
"origin_metrics": {
"5xxErrorRate": "spiking",
"ALBRequestCount": "high",
"single_source_ip_percentage": "82%"
},
"waf_status": "No Web ACL associated with the CloudFront distribution"
}
A
Associate an AWS WAF web ACL with CloudFront and add a rate-based rule for the offending IP behavior.
AWS WAF is the right control at the CloudFront edge because it can inspect requests before they reach the origin and enforce a rate-based rule on abusive traffic patterns. A rate-based rule can automatically count requests by source IP and block or challenge requests that exceed the configured threshold, which directly addresses the burst traffic shown in the logs. This meets the requirement to mitigate at the edge without any application changes.
B
Increase the ALB idle timeout to allow the origin to absorb more concurrent requests.
Why wrong: ALB idle timeout affects how long an existing connection can remain open, not how many requests a hostile client can generate. Increasing it may actually increase resource consumption at the origin instead of stopping the abuse.
C
Add an Amazon Route 53 health check to fail over traffic to another DNS name.
Why wrong: Route 53 health checks and failover are used for endpoint availability and regional failover, not for filtering or rate-limiting abusive requests from a single client IP. This would not stop the malicious traffic from reaching the origin.
D
Enable AWS Shield Advanced and rely on automatic DDoS protection for all request bursts.
Why wrong: AWS Shield Advanced is useful for broader DDoS resiliency, especially for large-scale network and transport layer attacks, but the precise control for this HTTP request pattern is AWS WAF with a rate-based rule. The scenario calls for request-level edge filtering, not only infrastructure-level DDoS protection.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Associate an AWS WAF web ACL with CloudFront and add a rate-based rule for the offending IP behavior.
AWS WAF rate-based rules automatically block or rate-limit requests from a client IP when the request rate exceeds a threshold you define. By associating the web ACL with CloudFront, the rule is enforced at the edge before traffic reaches the origin, mitigating abuse without modifying application code.
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.
✓
Associate an AWS WAF web ACL with CloudFront and add a rate-based rule for the offending IP behavior.
Why this is correct
AWS WAF is the right control at the CloudFront edge because it can inspect requests before they reach the origin and enforce a rate-based rule on abusive traffic patterns. A rate-based rule can automatically count requests by source IP and block or challenge requests that exceed the configured threshold, which directly addresses the burst traffic shown in the logs. This meets the requirement to mitigate at the edge without any application changes.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the ALB idle timeout to allow the origin to absorb more concurrent requests.
Why it's wrong here
ALB idle timeout affects how long an existing connection can remain open, not how many requests a hostile client can generate. Increasing it may actually increase resource consumption at the origin instead of stopping the abuse.
✗
Add an Amazon Route 53 health check to fail over traffic to another DNS name.
Why it's wrong here
Route 53 health checks and failover are used for endpoint availability and regional failover, not for filtering or rate-limiting abusive requests from a single client IP. This would not stop the malicious traffic from reaching the origin.
✗
Enable AWS Shield Advanced and rely on automatic DDoS protection for all request bursts.
Why it's wrong here
AWS Shield Advanced is useful for broader DDoS resiliency, especially for large-scale network and transport layer attacks, but the precise control for this HTTP request pattern is AWS WAF with a rate-based rule. The scenario calls for request-level edge filtering, not only infrastructure-level DDoS protection.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse AWS Shield Advanced's automatic DDoS mitigation (which handles network/transport layer floods) with the need for a WAF rate-based rule to stop application-layer request bursts from a single IP.
Trap categories for this question
Scenario analysis trap
AWS Shield Advanced is useful for broader DDoS resiliency, especially for large-scale network and transport layer attacks, but the precise control for this HTTP request pattern is AWS WAF with a rate-based rule. The scenario calls for request-level edge filtering, not only infrastructure-level DDoS protection.
Detailed technical explanation
How to think about this question
A rate-based rule in AWS WAF counts requests from a source IP over a sliding window (e.g., 5 minutes) and triggers a block action when the count exceeds the threshold (e.g., 2000 requests). This is implemented at the CloudFront edge location, so abusive traffic is dropped before consuming origin capacity. In practice, you can also combine this with a 'scope-down statement' to match only specific URI paths or headers, reducing false positives on legitimate high-traffic clients.
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 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Design Secure Architectures — This question tests Design Secure Architectures — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Associate an AWS WAF web ACL with CloudFront and add a rate-based rule for the offending IP behavior. — AWS WAF rate-based rules automatically block or rate-limit requests from a client IP when the request rate exceeds a threshold you define. By associating the web ACL with CloudFront, the rule is enforced at the edge before traffic reaches the origin, mitigating abuse without modifying application code.
What should I do if I get this SAA-C03 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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