The answer is to associate an Amazon-provided IPv6 CIDR block with the VPC. This is the necessary first step because AWS does not allow you to bring your own IPv6 CIDR to a VPC unless you use BYOIP; for standard use, you must request an Amazon-provided IPv6 block, which is a globally unique /56 range allocated from Amazon’s pool. Once associated, you then assign IPv6 CIDRs to your subnets and launch EC2 instances with IPv6 addresses to enable dual-stack communication. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this concept tests your understanding of VPC networking fundamentals—specifically that IPv6 is not automatically enabled and requires explicit association at the VPC level. A common trap is thinking you can manually assign any IPv6 range or that adding an IPv4 CIDR is sufficient; remember, IPv6 is a separate address family requiring its own block. Memory tip: think “VPC first, subnet second, instance third” for the IPv6 enablement chain.
SOA-C02 Networking and Content Delivery Practice Question
This SOA-C02 practice question tests your understanding of networking and content delivery. 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 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 and ensure that EC2 instances can communicate over IPv6. Which step is necessary?
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.
To use IPv6, the VPC must be associated with an Amazon-provided IPv6 CIDR block, and subnets must have IPv6 CIDR blocks assigned. Instances must be launched with IPv6 addresses.
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.
✗
Attach an internet gateway that supports IPv6.
Why it's wrong here
IGWs support IPv6 by default, but the VPC must have an IPv6 CIDR block first.
✗
Create a new VPC with an IPv6 CIDR block and migrate resources.
Why it's wrong here
Unnecessary; existing VPC can be associated with IPv6.
✓
Associate an Amazon-provided IPv6 CIDR block with the VPC.
DNS64 is for translating IPv6 to IPv4; not required for native IPv6.
Common exam traps
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 SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Networking and Content Delivery — This question tests Networking and Content Delivery — 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. — To use IPv6, the VPC must be associated with an Amazon-provided IPv6 CIDR block, and subnets must have IPv6 CIDR blocks assigned. Instances must be launched with IPv6 addresses.
What should I do if I get this SOA-C02 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 SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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