- A
The security VPC's network ACLs are blocking return traffic from the firewall appliance back to the Transit Gateway.
Why wrong: The issue is with traffic from the new VPC to other VPCs, not return traffic. The security VPC firewall rules are verified to allow the traffic. Network ACLs would affect both directions, but the stem states firewall rules are correct.
- B
The new VPC's route table does not have a default route pointing to the Transit Gateway attachment.
Why wrong: The new VPC's route table should have a route to the Transit Gateway for traffic to other VPCs. If missing, traffic would not reach the Transit Gateway at all. However, the stem indicates that some traffic is being dropped, implying connectivity exists but is blackholed.
- C
The Transit Gateway route table propagates the new VPC's CIDR, overriding the static blackhole route.
Why wrong: If propagation is enabled, the new VPC's CIDR would be propagated and appear as a route directly to the new VPC attachment, bypassing the security VPC. But the stem states there is a blackhole route for the new VPC's CIDR, which would override propagation if static routes have higher precedence.
- D
The Transit Gateway route table does not have a static route pointing to the security VPC attachment for the new VPC's CIDR.
The Transit Gateway route table must have a route for the new VPC's CIDR pointing to the security VPC attachment so that traffic from the new VPC is forwarded to the firewall for inspection. Without this route, traffic is blackholed.
ANS-C01 Network Security, Compliance and Governance Practice Question
This ANS-C01 practice question tests your understanding of network security, compliance and governance. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 hybrid network with an AWS Transit Gateway connecting multiple VPCs and an on-premises data center via AWS Direct Connect. The security team requires that all traffic between VPCs must be inspected by a centralized firewall appliance deployed in a security VPC. They have configured a Transit Gateway with a route table that has blackhole routes for all VPC CIDRs except the security VPC, and the security VPC appliance performs inspection and returns traffic to the Transit Gateway. Recently, they added a new VPC for a critical application. After configuration, some traffic from the new VPC to other VPCs is being dropped. The network engineer verifies that the Transit Gateway route table includes a blackhole route for the new VPC's CIDR and that the security VPC's firewall rules allow the traffic. What is the most likely cause of the dropped traffic?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
The Transit Gateway route table does not have a static route pointing to the security VPC attachment for the new VPC's CIDR.
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.
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.
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 security VPC's network ACLs are blocking return traffic from the firewall appliance back to the Transit Gateway.
Why it's wrong here
The issue is with traffic from the new VPC to other VPCs, not return traffic. The security VPC firewall rules are verified to allow the traffic. Network ACLs would affect both directions, but the stem states firewall rules are correct.
- ✗
The new VPC's route table does not have a default route pointing to the Transit Gateway attachment.
Why it's wrong here
The new VPC's route table should have a route to the Transit Gateway for traffic to other VPCs. If missing, traffic would not reach the Transit Gateway at all. However, the stem indicates that some traffic is being dropped, implying connectivity exists but is blackholed.
- ✗
The Transit Gateway route table propagates the new VPC's CIDR, overriding the static blackhole route.
Why it's wrong here
If propagation is enabled, the new VPC's CIDR would be propagated and appear as a route directly to the new VPC attachment, bypassing the security VPC. But the stem states there is a blackhole route for the new VPC's CIDR, which would override propagation if static routes have higher precedence.
- ✓
The Transit Gateway route table does not have a static route pointing to the security VPC attachment for the new VPC's CIDR.
Why this is correct
The Transit Gateway route table must have a route for the new VPC's CIDR pointing to the security VPC attachment so that traffic from the new VPC is forwarded to the firewall for inspection. Without this route, traffic is blackholed.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
CIDR notation defines the prefix length.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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 Security, Compliance and Governance — study guide chapter
Learn the concepts, then practise the questions
- →
Network Security, Compliance and Governance practice questions
Targeted practice on this topic area only
- →
All ANS-C01 questions
1,705 questions across all exam domains
- →
AWS Certified Advanced Networking Specialty ANS-C01 study guide
Full concept coverage aligned to exam objectives
- →
ANS-C01 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related ANS-C01 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Network Management and Operations practice questions
Practise ANS-C01 questions linked to Network Management and Operations.
Network Security, Compliance and Governance practice questions
Practise ANS-C01 questions linked to Network Security, Compliance and Governance.
Network Design practice questions
Practise ANS-C01 questions linked to Network Design.
Network Implementation practice questions
Practise ANS-C01 questions linked to Network Implementation.
ANS-C01 fundamentals practice questions
Practise ANS-C01 questions linked to ANS-C01 fundamentals.
ANS-C01 scenario practice questions
Practise ANS-C01 questions linked to ANS-C01 scenario.
ANS-C01 troubleshooting practice questions
Practise ANS-C01 questions linked to ANS-C01 troubleshooting.
Practice this exam
Start a free ANS-C01 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Security, Compliance and Governance — This question tests Network Security, Compliance and Governance — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The Transit Gateway route table does not have a static route pointing to the security VPC attachment for the new VPC's CIDR.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 →
Last reviewed: Jun 20, 2026
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.