This ANS-C01 practice question tests your understanding of network design. 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.
An application running on EC2 instances in a private subnet needs to download patches from the internet. The VPC has an internet gateway and public subnets. Which resource should be used to provide outbound internet access to the instances?
VPC gateway endpoint for S3
Why wrong: Only for S3 and DynamoDB, not general internet access.
NAT gateway in a public subnet
Provides outbound internet access for private instances.
AWS Site-to-Site VPN connection
Why wrong: For connecting on-premises networks, not internet access.
Internet gateway in the private subnet
Why wrong: Would expose instances to inbound internet traffic.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
NAT gateway in a public subnet
A NAT gateway in a public subnet provides outbound-only internet access to instances in private subnets by translating their private IP addresses to the NAT gateway's Elastic IP address. This allows the EC2 instances to download patches from the internet while preventing any unsolicited inbound connections from the internet, which is the standard design for secure outbound internet access in a VPC.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
VPC gateway endpoint for S3
Why it's wrong here
Only for S3 and DynamoDB, not general internet access.
NAT gateway in a public subnet
Why this is correct
Provides outbound internet access for private instances.
Related concept
Read the scenario before looking for a memorised answer.
AWS Site-to-Site VPN connection
Why it's wrong here
For connecting on-premises networks, not internet access.
Internet gateway in the private subnet
Why it's wrong here
Would expose instances to inbound internet traffic.
Common exam traps
AWS often tests the misconception that an internet gateway can be placed in a private subnet or that a VPC endpoint can provide general internet access, but the key trap here is confusing a VPC gateway endpoint (which only works for specific AWS services like S3 and DynamoDB) with a NAT gateway that provides full outbound internet connectivity.
Detailed technical explanation
Under the hood, the NAT gateway performs source network address translation (SNAT) using port address translation (PAT), mapping each private IP and ephemeral port to the NAT gateway's Elastic IP and a unique source port. This allows multiple instances to share a single Elastic IP while maintaining session state. A real-world scenario is when an auto-scaling group of instances in private subnets needs to access software repositories or OS update servers; the NAT gateway handles the translation and connection tracking, and you must ensure the NAT gateway's route table has a default route (0.0.0.0/0) pointing to the internet gateway.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
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FAQ
Network Design — This question tests Network Design — Read the scenario before looking for a memorised answer..
The correct answer is: NAT gateway in a public subnet — A NAT gateway in a public subnet provides outbound-only internet access to instances in private subnets by translating their private IP addresses to the NAT gateway's Elastic IP address. This allows the EC2 instances to download patches from the internet while preventing any unsolicited inbound connections from the internet, which is the standard design for secure outbound internet access in a VPC.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This ANS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the ANS-C01 exam.
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