The correct action is to associate an Amazon-provided IPv6 CIDR block with the VPC. AWS automatically assigns a global unicast address (GUA) from its pool of IPv6 addresses, specifically a /56 block, when you request an Amazon-provided IPv6 CIDR for your VPC. This is necessary because you cannot bring your own IPv6 GUA range to a VPC, nor can you manually specify a /56 prefix—AWS handles the allocation. On the ANS-C01 exam, this concept tests your understanding of VPC IPv6 addressing constraints and the distinction between IPv4 and IPv6 CIDR association workflows. A common trap is assuming you can directly assign a /56 or that IPv6 CIDRs are added at the subnet level first; in reality, the VPC must have an IPv6 block before subnets can be associated. Memory tip: think “VPC first, then subnet”—the IPv6 CIDR must be attached to the VPC before any subnet gets its own /64.
ANS-C01 Network Implementation Practice Question
This ANS-C01 practice question tests your understanding of network implementation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 an IPv4 CIDR block of 10.0.0.0/16. They need to add an IPv6 CIDR block to the VPC. Which action should they take?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Associate an Amazon-provided IPv6 CIDR block with the VPC.
Option C is correct because AWS provides an Amazon-provided IPv6 CIDR block that is automatically assigned. Option A is wrong because you cannot bring your own IPv6 GUA. Option B is wrong because you cannot directly assign a /56; AWS gives a /56 block. Option D is wrong because you must associate an IPv6 CIDR with the VPC, not just subnets.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Request an IPv6 CIDR block from your regional internet registry and associate it with the VPC.
Why it's wrong here
AWS does not support BYOIPv6 for VPC; you use Amazon-provided block.
✗
Enable IPv6 on the subnets directly without associating a VPC CIDR.
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
Network Implementation — This question tests Network Implementation — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Associate an Amazon-provided IPv6 CIDR block with the VPC. — Option C is correct because AWS provides an Amazon-provided IPv6 CIDR block that is automatically assigned. Option A is wrong because you cannot bring your own IPv6 GUA. Option B is wrong because you cannot directly assign a /56; AWS gives a /56 block. Option D is wrong because you must associate an IPv6 CIDR with the VPC, not just subnets.
What should I do if I get this ANS-C01 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.