- A
Replacing every NAT gateway with an internet gateway attached to private subnets
Why wrong: Private subnets cannot use an internet gateway directly without public IP routing.
- B
Whether one NAT gateway per AZ is sufficient for the required private subnets
NAT gateways are normally deployed per AZ for resilience; duplicate NAT gateways in the same AZ may be unnecessary.
- C
Disabling route tables
Why wrong: Route tables are required for subnet routing.
- D
Moving all workloads to public subnets
Why wrong: This weakens security posture and is not a cost-first best practice.
Question 925 of 1,040
Optimizing NAT Gateway Count: How to Reduce Costs
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 provide outbound internet access for private subnets.. 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?
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 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
✓
Whether one NAT gateway per AZ is sufficient for the required private subnets
Option B is correct because the question asks what the architect should review first. Using two NAT gateways per Availability Zone (AZ) when only one private subnet per AZ needs outbound internet access is likely over-provisioned and costly. The architect should first verify if a single NAT gateway per AZ can handle the traffic load, as NAT gateways are highly available within an AZ and can support up to 45 Gbps of bandwidth. This review directly addresses cost optimization without sacrificing functionality.
Key principle: NAT Gateways provide outbound internet access for private subnets.
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
- ✗
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 always improve reliability, but the question emphasizes cost optimization, so the first review should be whether the existing number of gateways is necessary rather than immediately adding or removing resources.
Detailed technical explanation
How to think about this question
NAT gateways are managed AWS services that scale automatically up to 45 Gbps, and each AZ can have multiple NAT gateways for redundancy, but a single NAT gateway per AZ is often sufficient for moderate traffic. The route table in the private subnet must have a default route (0.0.0.0/0) pointing to the NAT gateway in the same AZ to avoid cross-AZ data transfer charges. In real-world scenarios, using two NAT gateways per AZ is only justified when the single gateway's bandwidth is consistently exceeded or when strict high-availability requirements mandate active-active failover within the same AZ.
KKey Concepts to Remember
- NAT Gateways provide outbound internet access for private subnets.
- A best practice is to deploy one NAT Gateway per Availability Zone for high availability.
- Multiple NAT Gateways in the same AZ for the same subnets are usually redundant.
- NAT Gateways incur hourly charges and data processing charges.
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 provide outbound internet access for private subnets.
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.
Visual reference
What to study next
Got this wrong? Here's your next step.
Review nAT Gateways provide outbound internet access for private subnets., then practise related SAA-C03 questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this SAA-C03 question test?
Design Cost-Optimized Architectures — This question tests Design Cost-Optimized Architectures — NAT Gateways provide outbound internet access for private subnets..
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 question asks what the architect should review first. Using two NAT gateways per Availability Zone (AZ) when only one private subnet per AZ needs outbound internet access is likely over-provisioned and costly. The architect should first verify if a single NAT gateway per AZ can handle the traffic load, as NAT gateways are highly available within an AZ and can support up to 45 Gbps of bandwidth. This review directly addresses cost optimization without sacrificing functionality.
What should I do if I get this SAA-C03 question wrong?
Review nAT Gateways provide outbound internet access for private subnets., 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 provide outbound internet access for private subnets.
About these practice questions
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Same concept, more angles
2 more ways this is tested on SAA-C03
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. 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 architecture review board prefers a managed AWS-native control.
hard- A.Replacing every NAT gateway with an internet gateway attached to private subnets
- ✓ B.Whether one NAT gateway per AZ is sufficient for the required private subnets
- C.Disabling route tables
- D.Moving all workloads to public subnets
Why B: The architecture currently uses two NAT gateways per AZ, but only one private subnet per AZ requires outbound internet access. Since a single NAT gateway in an AZ can serve all private subnets in that AZ via the route table, the first step is to verify whether one NAT gateway per AZ is sufficient for the required throughput and availability. This aligns with cost optimization by eliminating unnecessary NAT gateway hourly charges and data processing fees.
Variation 2. 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.
hard- A.Replacing every NAT gateway with an internet gateway attached to private subnets
- ✓ B.Whether one NAT gateway per AZ is sufficient for the required private subnets
- C.Disabling route tables
- D.Moving all workloads to public subnets
Why B: 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.
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Last reviewed: Jun 11, 2026
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