SAA-C03 Design High-Performing Architectures Practice Question
This SAA-C03 practice question tests your understanding of design high-performing architectures. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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
Aurora cluster summary:
- 1 writer instance: db.r6g.large
- 2 reader instances: db.r6g.large
- Writer CPU avg: 82% / p95 91%
- Reader CPU avg: 18% / p95 26%
- Database connections: 480 total, all established to the cluster writer endpoint
- Query sample: 72% SELECT, 22% INSERT/UPDATE, 6% administrative queries
Based on the exhibit, an application runs on Amazon Aurora MySQL. The writer instance is frequently near 85% CPU while the reader instance is under 20% CPU. Application traces show that most of the database traffic is read-only SELECT queries, but the code currently sends all queries to the writer endpoint. What should the solutions architect recommend to improve performance with the smallest functional change?
Exhibit
Aurora cluster summary:
- 1 writer instance: db.r6g.large
- 2 reader instances: db.r6g.large
- Writer CPU avg: 82% / p95 91%
- Reader CPU avg: 18% / p95 26%
- Database connections: 480 total, all established to the cluster writer endpoint
- Query sample: 72% SELECT, 22% INSERT/UPDATE, 6% administrative queries
A
Increase the writer instance size and keep all traffic on the writer endpoint.
Why wrong: A larger writer can postpone saturation, but it wastes available read capacity and does not fix the traffic split problem.
B
Point read-only database traffic to the Aurora reader endpoint and keep writes on the writer endpoint.
This directly uses the cluster’s read scale-out capability. The reader endpoint distributes read traffic across replicas, reducing load on the writer and increasing read throughput without changing schema or database engine.
C
Convert the cluster to a Multi-AZ RDS PostgreSQL deployment to get automatic failover and better read performance.
Why wrong: This changes both the engine and architecture, and it is not the lowest-impact way to improve read throughput for Aurora MySQL.
D
Enable cross-Region read replicas so SELECT queries are routed to a remote Region for improved performance.
Why wrong: Cross-Region replication helps disaster recovery and regional locality, but it adds latency and operational complexity rather than solving local writer saturation.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Point read-only database traffic to the Aurora reader endpoint and keep writes on the writer endpoint.
Option B is correct because the Aurora reader endpoint distributes read-only traffic across all available reader instances, offloading the writer instance and reducing its CPU utilization. Since the application traces show most traffic is read-only SELECT queries, this change requires only modifying the connection string for reads while keeping writes on the writer endpoint, making it the smallest functional change.
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.
✗
Increase the writer instance size and keep all traffic on the writer endpoint.
Why it's wrong here
A larger writer can postpone saturation, but it wastes available read capacity and does not fix the traffic split problem.
✓
Point read-only database traffic to the Aurora reader endpoint and keep writes on the writer endpoint.
Why this is correct
This directly uses the cluster’s read scale-out capability. The reader endpoint distributes read traffic across replicas, reducing load on the writer and increasing read throughput without changing schema or database engine.
Related concept
Read the scenario before looking for a memorised answer.
✗
Convert the cluster to a Multi-AZ RDS PostgreSQL deployment to get automatic failover and better read performance.
Why it's wrong here
This changes both the engine and architecture, and it is not the lowest-impact way to improve read throughput for Aurora MySQL.
✗
Enable cross-Region read replicas so SELECT queries are routed to a remote Region for improved performance.
Why it's wrong here
Cross-Region replication helps disaster recovery and regional locality, but it adds latency and operational complexity rather than solving local writer saturation.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think increasing instance size (Option A) is the simplest fix, but they overlook the fact that Aurora's architecture is designed to offload reads to reader instances, which is a more cost-effective and scalable solution with minimal code change.
Detailed technical explanation
How to think about this question
Aurora's reader endpoint uses a load-balanced DNS name that automatically distributes connections across all available reader instances in the cluster, with no application-side changes beyond using a different endpoint for reads. Under the hood, Aurora uses a shared storage volume, so reader instances have near-zero replication lag, making them ideal for offloading SELECT queries without stale data concerns. In real-world scenarios, this pattern is often implemented using a separate connection pool or ORM configuration that routes read queries to the reader endpoint and write queries to the writer endpoint.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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 High-Performing Architectures — This question tests Design High-Performing Architectures — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Point read-only database traffic to the Aurora reader endpoint and keep writes on the writer endpoint. — Option B is correct because the Aurora reader endpoint distributes read-only traffic across all available reader instances, offloading the writer instance and reducing its CPU utilization. Since the application traces show most traffic is read-only SELECT queries, this change requires only modifying the connection string for reads while keeping writes on the writer endpoint, making it the smallest functional change.
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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