SAA-C03 Design High-Performing Architectures Practice Question
This SAA-C03 practice question tests your understanding of design high-performing architectures. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: memory-optimized instances (R-family) are ideal for memory-intensive applications.. 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
CloudWatch summary for app servers:
- Average CPUUtilization: 24%
- Average MemoryUtilization: 91%
- Average NetworkIn/Out: low
- Current instance type: m6i.large
- User reports: application slows when more sessions are active
Based on the exhibit, the team wants to improve application performance without changing the code. Which EC2 instance family should they choose next?
CloudWatch summary for app servers:
- Average CPUUtilization: 24%
- Average MemoryUtilization: 91%
- Average NetworkIn/Out: low
- Current instance type: m6i.large
- User reports: application slows when more sessions are active
A
Choose a compute-optimized instance family such as C6i to increase CPU performance.
Why wrong: Compute-optimized instances help when CPU is the bottleneck, but this workload shows low CPU usage and high memory usage.
B
Choose a memory-optimized instance family such as R6i to provide more RAM.
Memory-optimized instances are the best fit when memory pressure is causing slowdowns. The exhibit shows CPU is low while memory is consistently near saturation, which strongly suggests the application needs more RAM rather than more compute. Moving to an R6i family should reduce paging and improve response times without changing the application design.
C
Choose a storage-optimized instance family such as I4i to improve block storage throughput.
Why wrong: Storage-optimized instances are useful for high I/O workloads, but the exhibit does not show storage latency or throughput as the issue.
D
Choose a burstable instance family such as T3 to reduce cost and improve performance.
Why wrong: Burstable instances are not a good fix for sustained memory pressure. They are intended for variable, low-average CPU workloads, not memory shortages.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Choose a memory-optimized instance family such as R6i to provide more RAM.
The exhibit shows that the application is experiencing high memory utilization (e.g., memory pressure or swapping), which degrades performance. Choosing a memory-optimized instance family such as R6i provides more RAM per vCPU, directly addressing the bottleneck without requiring code changes. This improves application performance by reducing or eliminating swap usage and allowing more data to be cached in memory.
Key principle: Memory-optimized instances (R-family) are ideal for memory-intensive applications.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Choose a compute-optimized instance family such as C6i to increase CPU performance.
Why it's wrong here
Compute-optimized instances help when CPU is the bottleneck, but this workload shows low CPU usage and high memory usage.
✓
Choose a memory-optimized instance family such as R6i to provide more RAM.
Why this is correct
Memory-optimized instances are the best fit when memory pressure is causing slowdowns. The exhibit shows CPU is low while memory is consistently near saturation, which strongly suggests the application needs more RAM rather than more compute. Moving to an R6i family should reduce paging and improve response times without changing the application design.
Related concept
Memory-optimized instances (R-family) are ideal for memory-intensive applications.
✗
Choose a storage-optimized instance family such as I4i to improve block storage throughput.
Why it's wrong here
Storage-optimized instances are useful for high I/O workloads, but the exhibit does not show storage latency or throughput as the issue.
✗
Choose a burstable instance family such as T3 to reduce cost and improve performance.
Why it's wrong here
Burstable instances are not a good fix for sustained memory pressure. They are intended for variable, low-average CPU workloads, not memory shortages.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume 'improving performance' always means faster CPU or storage, but the exhibit’s memory utilization metric directly points to a memory bottleneck, making the memory-optimized family the correct choice despite the lack of explicit code changes.
Trap categories for this question
Command / output trap
Compute-optimized instances help when CPU is the bottleneck, but this workload shows low CPU usage and high memory usage.
Detailed technical explanation
How to think about this question
Memory-optimized instances like R6i use DDR5 memory and support up to 768 GiB of RAM, enabling larger in-memory caches and reducing page faults. Under the hood, the operating system’s memory management relies on the page cache and swap; when RAM is insufficient, the kernel swaps pages to disk (e.g., via the swap partition or file), causing latency spikes. In a real-world scenario, an in-memory database (e.g., Redis or Memcached) or a large Java heap application would see immediate performance gains from an R6i instance because it reduces garbage collection frequency and avoids disk-backed paging.
KKey Concepts to Remember
Memory-optimized instances (R-family) are ideal for memory-intensive applications.
High memory utilization with low CPU often indicates a memory bottleneck.
Increasing RAM can reduce paging and improve application response times.
EC2 instance families are specialized for different workload requirements.
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
Memory-optimized instances (R-family) are ideal for memory-intensive applications.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Review memory-optimized instances (R-family) are ideal for memory-intensive applications., then practise related SAA-C03 questions on the same topic to reinforce the concept.
Design High-Performing Architectures — This question tests Design High-Performing Architectures — Memory-optimized instances (R-family) are ideal for memory-intensive applications..
What is the correct answer to this question?
The correct answer is: Choose a memory-optimized instance family such as R6i to provide more RAM. — The exhibit shows that the application is experiencing high memory utilization (e.g., memory pressure or swapping), which degrades performance. Choosing a memory-optimized instance family such as R6i provides more RAM per vCPU, directly addressing the bottleneck without requiring code changes. This improves application performance by reducing or eliminating swap usage and allowing more data to be cached in memory.
What should I do if I get this SAA-C03 question wrong?
Review memory-optimized instances (R-family) are ideal for memory-intensive applications., then practise related SAA-C03 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Memory-optimized instances (R-family) are ideal for memory-intensive applications.
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Question Discussion
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