The correct solution is to implement Amazon RDS Proxy to manage database connections. This directly resolves the connection exhaustion and CPU saturation because RDS Proxy sits between the application and the MySQL RDS instance, pooling and reusing connections from the EC2 instances efficiently. Even though the application already uses fixed-size connection pooling on the EC2 side, RDS Proxy prevents the database from being overwhelmed during traffic spikes by reducing the total number of open connections to the RDS instance, which eliminates the 503 errors and latency. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of how RDS Proxy decouples application connection bursts from database limits—a common trap is assuming that EC2-side pooling alone is sufficient, but without a proxy, each instance’s fixed pool can still collectively exhaust the database’s max connections. Memory tip: think of RDS Proxy as a bouncer at a club—it limits how many people (connections) actually enter the database, even if a crowd (spike) shows up outside.
SAP-C02 Design for New Solutions Practice Question
This SAP-C02 practice question tests your understanding of design for new 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 production web application on AWS using an Application Load Balancer (ALB) in front of an Auto Scaling group of EC2 instances. The application uses a MySQL database hosted on Amazon RDS with Multi-AZ enabled. Recently, during a traffic spike, some users experienced increased latency and occasional 503 errors. The operations team noticed that the database CPU utilization reached 100% and the number of database connections peaked at the maximum limit. The application team confirmed that the application uses connection pooling on the EC2 instances but the pool size is fixed. Which solution should the solutions architect recommend to prevent recurrence?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement Amazon RDS Proxy to manage database connections.
Option C is correct because the issue stems from database connections hitting the maximum limit, causing CPU saturation and 503 errors. Amazon RDS Proxy sits between the application and the database, efficiently managing and pooling connections from the EC2 instances, reducing the number of open connections to the RDS instance and preventing connection exhaustion. This allows the existing connection pooling on the EC2 side to scale without overwhelming the database, directly addressing the root cause.
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.
✗
Add read replicas to offload read queries.
Why it's wrong here
Read replicas do not help if the issue is connection exhaustion or write-heavy workload.
✗
Increase the DB instance class to a larger size.
Why it's wrong here
Vertical scaling may not be cost-effective and still has connection limits.
✓
Implement Amazon RDS Proxy to manage database connections.
Why this is correct
RDS Proxy pools connections, reducing the load on the database and preventing connection exhaustion.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the maximum number of EC2 instances in the Auto Scaling group.
Why it's wrong here
More EC2 instances will increase database connections, worsening the problem.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse connection exhaustion with CPU or memory bottlenecks and choose vertical scaling (Option B) or read replicas (Option A), missing that the core issue is the fixed connection pool size and the database's max connections limit, which RDS Proxy directly addresses by pooling and reusing connections.
Detailed technical explanation
How to think about this question
RDS Proxy uses a connection multiplexing technique where it maintains a persistent pool of connections to the RDS instance and transparently multiplexes many client-side connections from the application over a smaller number of database connections. This reduces the overhead of establishing new connections (TCP handshake, SSL negotiation, authentication) and keeps the database connection count stable even during traffic spikes. In real-world scenarios, this is critical for serverless or containerized applications that create many short-lived connections, as it also improves failover times by preserving connections during Multi-AZ failover.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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 for New Solutions — This question tests Design for New Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement Amazon RDS Proxy to manage database connections. — Option C is correct because the issue stems from database connections hitting the maximum limit, causing CPU saturation and 503 errors. Amazon RDS Proxy sits between the application and the database, efficiently managing and pooling connections from the EC2 instances, reducing the number of open connections to the RDS instance and preventing connection exhaustion. This allows the existing connection pooling on the EC2 side to scale without overwhelming the database, directly addressing the root cause.
What should I do if I get this SAP-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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Question Discussion
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