Quick Answer
The answer is a NAT Gateway in a public subnet and an Internet Gateway (IGW). This combination works because the IGW provides the VPC’s route tables with a target for all internet-bound traffic, while the NAT Gateway, placed in a public subnet, performs source network address translation on outbound traffic from private instances, mapping their private IPs to the NAT Gateway’s public IP. This allows private subnet instances to initiate outbound connections to the internet but blocks any unsolicited inbound traffic, maintaining security. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this question tests your understanding of VPC routing and NAT architecture, often appearing as a foundational scenario for hybrid networking. A common trap is forgetting that the IGW is required even though private instances don’t use it directly—the NAT Gateway itself needs a route to the IGW. Memory tip: think “Private outbound, NAT in public; IGW is the highway, NAT is the toll booth.”
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.
A company is designing a VPC with public and private subnets. The company needs to provide internet access to instances in the private subnets. Which TWO components are required? (Choose TWO.)
Internet Gateway attached to the VPC
IGW is needed for public subnet and NAT.
Transit Gateway
Why wrong: Not needed for this simple design.
NAT Gateway in a public subnet
NAT enables outbound internet for private instances.
VPC Gateway Endpoint for S3
Why wrong: Provides private access to S3, not general internet.
Virtual Private Gateway
Why wrong: Used for VPN, not internet.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Internet Gateway attached to the VPC
An Internet Gateway (IGW) is required to provide a target in the VPC route tables for internet-bound traffic. For instances in private subnets, a NAT Gateway placed in a public subnet translates their private IP addresses to the public IP of the NAT Gateway, allowing outbound internet access while preventing unsolicited inbound connections. The private subnet's route table must point 0.0.0.0/0 to the NAT Gateway, and the public subnet's route table must point 0.0.0.0/0 to the IGW.
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.
Internet Gateway attached to the VPC
Why this is correct
IGW is needed for public subnet and NAT.
Related concept
Read the scenario before looking for a memorised answer.
Transit Gateway
Why it's wrong here
Not needed for this simple design.
NAT Gateway in a public subnet
Why this is correct
NAT enables outbound internet for private instances.
Related concept
Read the scenario before looking for a memorised answer.
VPC Gateway Endpoint for S3
Why it's wrong here
Provides private access to S3, not general internet.
Virtual Private Gateway
Why it's wrong here
Used for VPN, not internet.
Common exam traps
The trap here is that candidates often think a NAT Gateway alone is sufficient, forgetting that an Internet Gateway must be attached to the VPC and the public subnet's route table must point to it for the NAT Gateway to reach the internet.
Detailed technical explanation
The NAT Gateway performs source network address translation (SNAT) by replacing the private source IP with its own Elastic IP address for outbound traffic, and then reverse-maps the response. It is highly available within an Availability Zone and supports up to 45 Gbps of bandwidth. A common real-world scenario is a web application where private instances need to download patches or access external APIs without being directly reachable from the internet.
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: Internet Gateway attached to the VPC — An Internet Gateway (IGW) is required to provide a target in the VPC route tables for internet-bound traffic. For instances in private subnets, a NAT Gateway placed in a public subnet translates their private IP addresses to the public IP of the NAT Gateway, allowing outbound internet access while preventing unsolicited inbound connections. The private subnet's route table must point 0.0.0.0/0 to the NAT Gateway, and the public subnet's route table must point 0.0.0.0/0 to the IGW.
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 24, 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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