- A
Review the security group rules for the database to ensure the application can connect.
Why wrong: Security group rules are static and unlikely to cause periodic outages.
- B
Review the ALB target group health checks and ensure the EC2 instances are passing the health check.
Why wrong: Health checks would fail if instances are unhealthy, but the issue is likely database-related, not instance-level.
- C
Increase the EC2 instance size to handle more concurrent connections.
Why wrong: The symptoms indicate a database bottleneck; scaling EC2 instances does not resolve database issues.
- D
Check the RDS Enhanced Monitoring metrics for the database instance to identify resource bottlenecks such as high memory pressure or disk I/O.
Enhanced Monitoring provides detailed OS-level metrics to pinpoint the root cause of the database spike.
Quick Answer
The answer is to check the RDS Enhanced Monitoring metrics for the database instance to identify resource bottlenecks such as high memory pressure or disk I/O. This is correct because the hourly 30-second HTTP 504 errors from the ALB, paired with a spike in RDS CPU and active connections, strongly indicate a database-side bottleneck rather than a web server or load balancer issue. Enhanced Monitoring provides OS-level visibility into memory swap usage, disk queue depth, and IOPS exhaustion—metrics that standard CloudWatch cannot capture—allowing you to pinpoint the exact resource contention causing the ALB to time out. On the AWS Certified SAP on AWS Specialty PAS-C01 exam, this scenario tests your ability to differentiate between application-layer and database-layer root causes when troubleshooting HTTP 504 errors from an ALB with an RDS bottleneck. A common trap is to focus on scaling the ALB or EC2 instances, but the hourly recurrence and correlated RDS spike point directly to database resource saturation. Memory tip: “Enhanced Monitoring sees what CloudWatch misses—swap, I/O, and queue depths.”
PAS-C01 Technology Practice Question
This PAS-C01 practice question tests your understanding of technology. 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 runs a critical web application on Amazon EC2 instances behind an Application Load Balancer (ALB). The application uses an Amazon RDS for PostgreSQL database. The operations team reports that the application becomes unresponsive for about 30 seconds every hour at the same time. The team checks the ALB access logs and notices that during the outage, the ALB returns HTTP 504 errors. The RDS monitoring shows a spike in CPU usage and active connections during the same period. The application team confirms there are no scheduled jobs during that time. What should the team do to diagnose the root cause?
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
Check the RDS Enhanced Monitoring metrics for the database instance to identify resource bottlenecks such as high memory pressure or disk I/O.
Option D is correct because the symptoms—hourly 30-second unresponsiveness, HTTP 504 errors from the ALB, and a correlated spike in RDS CPU and active connections—point to a database-side bottleneck. RDS Enhanced Monitoring provides OS-level metrics (memory, disk I/O, CPU) that can reveal resource contention or throttling events (e.g., swap usage, IOPS exhaustion) not visible in standard CloudWatch metrics, enabling precise root cause identification.
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.
- ✗
Review the security group rules for the database to ensure the application can connect.
Why it's wrong here
Security group rules are static and unlikely to cause periodic outages.
- ✗
Review the ALB target group health checks and ensure the EC2 instances are passing the health check.
Why it's wrong here
Health checks would fail if instances are unhealthy, but the issue is likely database-related, not instance-level.
- ✗
Increase the EC2 instance size to handle more concurrent connections.
Why it's wrong here
The symptoms indicate a database bottleneck; scaling EC2 instances does not resolve database issues.
- ✓
Check the RDS Enhanced Monitoring metrics for the database instance to identify resource bottlenecks such as high memory pressure or disk I/O.
Why this is correct
Enhanced Monitoring provides detailed OS-level metrics to pinpoint the root cause of the database spike.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse HTTP 504 errors with ALB or EC2 health check failures, but 504 specifically indicates the ALB received no response from the target (often due to database timeout), not that the target is unhealthy.
Detailed technical explanation
How to think about this question
RDS Enhanced Monitoring collects metrics from the hypervisor and OS using an agent, providing granular data such as memory usage (including swap), file system I/O, and process-level CPU consumption. In contrast, standard CloudWatch metrics aggregate at 1-minute intervals and may miss short-lived spikes. A common real-world scenario is a cron job or application heartbeat that triggers an expensive query or connection storm, causing RDS to throttle or queue requests, which manifests as ALB 504 errors when the database cannot respond within the ALB idle timeout (default 60 seconds).
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.
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FAQ
Questions learners often ask
What does this PAS-C01 question test?
Technology — This question tests Technology — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Check the RDS Enhanced Monitoring metrics for the database instance to identify resource bottlenecks such as high memory pressure or disk I/O. — Option D is correct because the symptoms—hourly 30-second unresponsiveness, HTTP 504 errors from the ALB, and a correlated spike in RDS CPU and active connections—point to a database-side bottleneck. RDS Enhanced Monitoring provides OS-level metrics (memory, disk I/O, CPU) that can reveal resource contention or throttling events (e.g., swap usage, IOPS exhaustion) not visible in standard CloudWatch metrics, enabling precise root cause identification.
What should I do if I get this PAS-C01 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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Last reviewed: Jun 11, 2026
This PAS-C01 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 PAS-C01 exam.
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