The answer is that the Deny statement overrides the Allow statement for the specific CIDR. This occurs because AWS IAM policy evaluation logic is explicit deny by default—any Deny statement, regardless of where it appears in the policy, will supersede any Allow for the same action. In this scenario, the first statement broadly allows ec2:CreateVpc, but the second statement explicitly denies that action when the condition key aws:RequestedRegion or a CIDR-specific condition matches 10.0.0.0/16, causing the engineer’s attempt to fail. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this tests your understanding of IAM policy precedence and condition keys, often appearing as a trap where candidates assume the Allow alone is sufficient. A common memory tip is “Deny always wins”—think of it as a veto power that cannot be overridden by any Allow, even if the Allow is more general.
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 network engineer is assigned an IAM policy to manage VPC resources. The engineer attempts to create a VPC with CIDR 10.0.0.0/16 and fails. What is the reason?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Deny statement overrides the Allow statement for the specific CIDR.
Option C is correct because the second statement explicitly denies creating a VPC with CIDR 10.0.0.0/16. Option A is incorrect because the first statement allows VPC creation in general. Option B is incorrect because the resource ARN matches all VPCs. Option D is incorrect because the condition is on the CIDR, not region.
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.
✗
The resource ARN in the Deny statement does not match the VPC being created.
Why it's wrong here
The ARN uses a wildcard for VPC ID, so it matches.
✓
The Deny statement overrides the Allow statement for the specific CIDR.
The condition in the Deny statement is not evaluated correctly.
Why it's wrong here
Condition is evaluated correctly.
✗
The first statement allows only specific actions, not CreateVpc.
Why it's wrong here
CreateVpc is included in the first statement.
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 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: The Deny statement overrides the Allow statement for the specific CIDR. — Option C is correct because the second statement explicitly denies creating a VPC with CIDR 10.0.0.0/16. Option A is incorrect because the first statement allows VPC creation in general. Option B is incorrect because the resource ARN matches all VPCs. Option D is incorrect because the condition is on the CIDR, not region.
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.