SAA-C03 Design Cost-Optimized Architectures Practice Question
This SAA-C03 practice question tests your understanding of design cost-optimized 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. A key principle to apply: nAT Gateways enable instances in private subnets to initiate outbound internet connections.. 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 batch analytics job currently uses two NAT gateways in each of three Availability Zones, but only one private subnet per AZ needs outbound internet access. What should the architect review first? The design must avoid adding custom operational scripts.
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Whether one NAT gateway per AZ is sufficient for the required private subnets
Option B is correct because the current setup uses two NAT gateways per AZ, which is likely over-provisioned and incurs unnecessary costs. Since only one private subnet per AZ requires outbound internet access, a single NAT gateway per AZ is typically sufficient to handle the traffic, and this is the first cost-optimization step to review before making other changes.
Key principle: NAT Gateways enable instances in private subnets to initiate outbound internet connections.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Replacing every NAT gateway with an internet gateway attached to private subnets
Why it's wrong here
Private subnets cannot use an internet gateway directly without public IP routing.
✓
Whether one NAT gateway per AZ is sufficient for the required private subnets
Why this is correct
NAT gateways are normally deployed per AZ for resilience; duplicate NAT gateways in the same AZ may be unnecessary.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
NAT Gateways enable instances in private subnets to initiate outbound internet connections.
✗
Disabling route tables
Why it's wrong here
Route tables are required for subnet routing.
✗
Moving all workloads to public subnets
Why it's wrong here
This weakens security posture and is not a cost-first best practice.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may assume more NAT gateways are always better for high availability, but the question explicitly states only one private subnet per AZ needs outbound access, making a single NAT gateway per AZ the cost-optimized starting point.
Detailed technical explanation
How to think about this question
NAT gateways are managed by AWS and automatically scale up to 45 Gbps per AZ, so a single NAT gateway per AZ can handle significant traffic from multiple private subnets. The cost is $0.045 per hour per NAT gateway plus data processing charges, so reducing from two to one per AZ can cut costs by half for that AZ. In real-world scenarios, architects should also consider using a single NAT gateway across all AZs for even greater savings, but that introduces a single point of failure and cross-AZ data transfer costs.
KKey Concepts to Remember
NAT Gateways enable instances in private subnets to initiate outbound internet connections.
AWS best practice recommends one NAT Gateway per Availability Zone for high availability.
A single NAT Gateway in an AZ can serve multiple private subnets within that same AZ.
NAT Gateway costs are based on hourly usage and data processing, making over-provisioning expensive.
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
NAT Gateways enable instances in private subnets to initiate outbound internet connections.
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 nAT Gateways enable instances in private subnets to initiate outbound internet connections., then practise related SAA-C03 questions on the same topic to reinforce the concept.
Design Cost-Optimized Architectures — This question tests Design Cost-Optimized Architectures — NAT Gateways enable instances in private subnets to initiate outbound internet connections..
What is the correct answer to this question?
The correct answer is: Whether one NAT gateway per AZ is sufficient for the required private subnets — Option B is correct because the current setup uses two NAT gateways per AZ, which is likely over-provisioned and incurs unnecessary costs. Since only one private subnet per AZ requires outbound internet access, a single NAT gateway per AZ is typically sufficient to handle the traffic, and this is the first cost-optimization step to review before making other changes.
What should I do if I get this SAA-C03 question wrong?
Review nAT Gateways enable instances in private subnets to initiate outbound internet connections., then practise related SAA-C03 questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
NAT Gateways enable instances in private subnets to initiate outbound internet connections.
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Question Discussion
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