The answer is to create a NAT gateway in each Availability Zone. This configuration provides a highly available, managed solution for outbound internet access from private subnets because a NAT gateway is a fully managed AWS service that automatically scales and handles failover within a single Availability Zone, but it is not resilient to zone-level failures. By deploying one NAT gateway per Availability Zone and routing each private subnet’s 0.0.0.0/0 traffic to the gateway in its own zone, you eliminate a single point of failure and ensure patch downloads continue even if an entire Availability Zone goes down. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of designing resilient network architectures while avoiding common traps like using a single NAT gateway or a NAT instance, which is not managed. A key memory tip is “one zone, one gateway” — if your workload spans multiple Availability Zones, each zone needs its own NAT gateway for true high availability.
SCS-C02 Infrastructure Security Practice Question
This SCS-C02 practice question tests your understanding of infrastructure security. 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. 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 has a VPC with public and private subnets. An EC2 instance in a private subnet needs to download patches from the internet. Which combination of components provides a highly available, managed solution? (Select TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a route to the private subnet's route table pointing 0.0.0.0/0 to the NAT gateway.
Option A is correct because a NATgateway enables outbound internet access for instances in a private subnet while preventing inbound connections from the internet. It is a managed AWS service that automatically scales and is highly available within a single Availability Zone. By adding a route for 0.0.0.0/0 to the NAT gateway in the private subnet's route table, traffic destined for the internet is forwarded to the NAT gateway, which then uses an internet gateway to reach the internet.
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 a route to the private subnet's route table pointing 0.0.0.0/0 to the NAT gateway.
VPC endpoint only provides access to S3, not general internet.
✓
Create a NAT gateway in each Availability Zone.
Why this is correct
NATgateway is managed and provides high availability across AZs.
Related concept
Read the scenario before looking for a memorised answer.
✗
Attach an internet gateway to the VPC.
Why it's wrong here
Internet gateway alone does not allow private instances to access internet.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think a single NATgateway is sufficient for high availability, but AWS requires one NAT gateway per Availability Zone to survive an AZ failure, and they may also confuse a VPC endpoint for S3 as a general internet access solution.
Detailed technical explanation
How to think about this question
A NATgateway uses source network address translation (SNAT) to replace the private IP of the EC2 instance with the NAT gateway's elastic IP when sending traffic to the internet. For high availability across multiple Availability Zones, you must create a NAT gateway in each AZ and add corresponding routes in each private subnet's route table; a single NAT gateway is an Availability Zone-level resource and will fail if that AZ goes down. AWS manages the NAT gateway's scaling and patching, unlike a NAT instance which requires you to handle failover with scripts or an auto scaling group.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
Infrastructure Security — This question tests Infrastructure Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a route to the private subnet's route table pointing 0.0.0.0/0 to the NAT gateway. — Option A is correct because a NAT gateway enables outbound internet access for instances in a private subnet while preventing inbound connections from the internet. It is a managed AWS service that automatically scales and is highly available within a single Availability Zone. By adding a route for 0.0.0.0/0 to the NAT gateway in the private subnet's route table, traffic destined for the internet is forwarded to the NAT gateway, which then uses an internet gateway to reach the internet.
What should I do if I get this SCS-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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