- A
The instance is routing traffic through a NAT Gateway that has a route to the internet
The security group allows outbound HTTPS to certain IPs, but if the traffic goes through a NAT Gateway, the destination IP seen by the security group is the NAT Gateway's IP, not the final destination.
- B
The instance is using a VPC Endpoint to connect to the external IP
Why wrong: VPC Endpoints only connect to AWS services, not external IPs.
- C
The security group outbound rules are being overridden by a Network ACL
Why wrong: Network ACLs can override, but they are stateless and would affect both inbound/outbound; security groups are still evaluated.
- D
The instance has a public IP address and is using an Internet Gateway directly
Why wrong: The instance is in a private subnet, so it cannot have a public IP.
Quick Answer
The answer is a NAT Gateway with a route to the internet, because when an EC2 instance in a private subnet sends outbound traffic, its security group rules are evaluated against the destination IP of the first hop, not the final external IP. If the security group allows outbound HTTPS to the NAT Gateway’s private IP, the traffic is permitted, and the NAT Gateway then forwards the packets to any external destination, effectively bypassing the intended IP restrictions. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of how security groups interact with routing—a common trap is assuming security groups filter traffic at the final destination, when in fact they only filter based on the immediate next hop. Remember the key insight: security groups are stateful and apply to the instance’s network interface, so if the instance can reach the NAT Gateway, the NAT Gateway’s own rules (or lack thereof) govern onward routing. Memory tip: “First hop, final stop”—the security group only cares about the first hop’s IP, not where the NAT Gateway ultimately sends the traffic.
ANS-C01 Network Security, Compliance and Governance Practice Question
This ANS-C01 practice question tests your understanding of network security, compliance and governance. 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's security team is investigating a potential data exfiltration incident. They notice that an EC2 instance in a private subnet is making HTTPS connections to an unknown external IP address. The instance's security group only allows outbound HTTPS to a specific set of IPs. What is the MOST likely cause of the 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 instance is routing traffic through a NAT Gateway that has a route to the internet
Option A is correct because a NAT Gateway in a public subnet can allow outbound traffic to any destination, bypassing security group restrictions if the security group allows traffic to the NAT Gateway. Option B is wrong because security groups are stateful; outbound rules apply regardless. Option C is wrong because an Internet Gateway is not in a private subnet. Option D is wrong because a VPC Endpoint is for AWS services, not external IPs.
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 instance is routing traffic through a NAT Gateway that has a route to the internet
Why this is correct
The security group allows outbound HTTPS to certain IPs, but if the traffic goes through a NAT Gateway, the destination IP seen by the security group is the NAT Gateway's IP, not the final destination.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
CIDR notation defines the prefix length.
- ✗
The instance is using a VPC Endpoint to connect to the external IP
Why it's wrong here
VPC Endpoints only connect to AWS services, not external IPs.
- ✗
The security group outbound rules are being overridden by a Network ACL
Why it's wrong here
Network ACLs can override, but they are stateless and would affect both inbound/outbound; security groups are still evaluated.
- ✗
The instance has a public IP address and is using an Internet Gateway directly
Why it's wrong here
The instance is in a private subnet, so it cannot have a public IP.
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 instance is routing traffic through a NAT Gateway that has a route to the internet — Option A is correct because a NAT Gateway in a public subnet can allow outbound traffic to any destination, bypassing security group restrictions if the security group allows traffic to the NAT Gateway. Option B is wrong because security groups are stateful; outbound rules apply regardless. Option C is wrong because an Internet Gateway is not in a private subnet. Option D is wrong because a VPC Endpoint is for AWS services, not external IPs.
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 →
Same concept, more angles
1 more ways this is tested on ANS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company has a VPC with a public subnet containing a NAT gateway and a private subnet containing EC2 instances. The EC2 instances need to download patches from the internet. The security team wants to ensure that the EC2 instances cannot initiate outbound connections to any other internet destinations. What should the network engineer do?
easy- A.Remove the NAT gateway and attach an Internet Gateway to the private subnet route table.
- B.Attach an egress-only Internet Gateway to the VPC and route private subnet traffic to it.
- C.Configure a network ACL on the private subnet to allow outbound traffic only to the patch server's IP address.
- ✓ D.Assign a security group to the EC2 instances that allows outbound HTTPS traffic only to the patch server's IP address.
Why D: Option D is correct because an egress-only Internet Gateway is for IPv6, not IPv4. For IPv4, the solution is to use a NAT gateway with a security group that denies all outbound traffic except to the patch server. However, the best approach is to configure the security group to allow only HTTPS outbound to the patch server's IP and deny all else. Option A is wrong because it would allow all outbound traffic. Option B is wrong because egress-only IGW is for IPv6. Option C is wrong because NACLs are stateless and not ideal for this granular control.
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.