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ANS-C01 Network Implementation Practice Question

A company has a VPC with a CIDR of 10.0.0.0/16. They need to create subnets for a three-tier application. Which THREE subnet CIDR blocks are valid within this VPC?

⚠ Common exam trap

The ANS-C01 exam often tests the misconception that any private IP range can be used as a subnet as long as it starts with 10.x.x.x, but the subnet must be a strict subset of the VPC CIDR, not just any overlapping range.

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

10.0.1.0/24

(10.0.1.0/24) is a valid subnet within the VPC CIDR 10.0.0.0/16 because its entire address range (10.0.1.0–10.0.1.255) falls within the VPC's address space. The /24 subnet mask is smaller than the VPC's /16, so it is a proper subset. AWS VPCs allow any RFC 1918 private IP range as long as the subnet CIDR is fully contained within the VPC CIDR.

Answer analysis

Option-by-option breakdown

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

  • 10.0.1.0/24

    Why this is correct

    Within 10.0.0.0/16.

  • 10.0.3.0/24

    Why this is correct

    Within VPC CIDR.

  • 10.0.5.0/24

    Why this is correct

    Within VPC CIDR.

  • 10.1.0.0/24

    Why it's wrong here

    Outside VPC CIDR.

  • 10.0.0.0/8

    Why it's wrong here

    Not a subnet; overlaps but not valid as a subnet within /16.

Visual reference

192.168.1.0 /24 256 addresses (254 usable) 192.168.1.0 /25 Subnet A 128 addr (126 usable) 192.168.1.128 /25 Subnet B 128 addr (126 usable) Borrowing 1 bit from host portion creates 2 subnets (/25)

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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.