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Network DesigneasyMultiple ChoiceObjective-mapped

ANS-C01 Network Design Practice Question

A company has a VPC with a public subnet and a private subnet. The private subnet instances need to access an S3 bucket. Which configuration provides the most secure and efficient access without traversing the internet?

⚠ Common exam trap

AWS often tests the misconception that a NAT Gateway is required for private subnet internet access, but the trap here is that S3 can be accessed privately via a Gateway Endpoint without any internet gateway or NAT, making options like B and D seem plausible but incorrect.

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

Create a VPC Gateway Endpoint for Amazon S3 and associate it with the private subnet route table.

A VPC Gateway Endpoint for Amazon S3 allows instances in a private subnet to access S3 directly over the AWS network without traversing the internet, using a route table entry that targets the endpoint's prefix list. This provides the most secure and efficient access by keeping traffic within the AWS backbone, avoiding NAT Gateway costs and internet exposure.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Establish a VPN connection to on-premises and route to S3 from there.

    Why it's wrong here

    Unnecessary and inefficient.

  • Use a NAT Gateway in the public subnet to route traffic to S3.

    Why it's wrong here

    Traffic goes through the internet, which is less secure and adds latency.

  • Create a VPC Gateway Endpoint for Amazon S3 and associate it with the private subnet route table.

    Why this is correct

    Gateway Endpoint provides private, secure access to S3 without internet.

  • Configure a proxy server in the public subnet.

    Why it's wrong here

    Proxy adds complexity and maintenance overhead.

Visual reference

Inside (Private) PC-A 10.0.0.1 PC-B 10.0.0.2 NAT Router Outside (Public) 203.0.113.1 Inside Global Server PAT: many private IPs share one public IP via unique port numbers

Quick reference

AWS S3 Storage Class Comparison

Storage ClassMin DurationRetrievalUse Case
S3 StandardNoneImmediateFrequently accessed data
S3 Standard-IA30 daysImmediateInfrequent access, rapid retrieval
S3 One Zone-IA30 daysImmediateNon-critical infrequent data
S3 Intelligent-TieringNoneImmediate–hoursUnknown or changing access patterns
S3 Glacier Instant90 daysMillisecondsArchive with instant retrieval
S3 Glacier Flexible90 daysMinutes–hoursArchive, flexible retrieval
S3 Glacier Deep Archive180 daysHoursLong-term compliance archive

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JA

Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

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.