- A
Security Groups: Acts as a virtual firewall for an EC2 instance at the instance level, controlling inbound and outbound traffic.
Security Groups are stateful firewalls that operate at the instance level.
- B
Network ACLs: Acts as a firewall for a VPC subnet, controlling inbound and outbound traffic at the subnet level.
Network ACLs are stateless firewalls operating at the subnet level.
- C
AWS WAF: A web application firewall that helps protect web applications from common web exploits.
AWS WAF filters and monitors HTTP/HTTPS requests to protect web apps.
- D
AWS Shield: A managed DDoS protection service that safeguards applications running on AWS.
AWS Shield provides automatic DDoS mitigation for AWS resources.
- E
Security Groups: Acts as a firewall at the subnet level.
Why wrong: Incorrect — Security Groups operate at the instance level, not subnet. This describes Network ACLs.
- F
Network ACLs: Acts as a virtual firewall for an EC2 instance.
Why wrong: Incorrect — Network ACLs operate at the subnet level, not instance. This describes Security Groups.
ANS-C01 Network Implementation Practice Question
This ANS-C01 practice question tests your understanding of network implementation. 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.
Match each AWS security feature to its description.
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
Security Groups: Acts as a virtual firewall for an EC2 instance at the instance level, controlling inbound and outbound traffic.
These are core security services for network protection. Security Groups are instance-level, NACLs are subnet-level, WAF protects web apps, and Shield provides DDoS protection.
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.
- ✓
Security Groups: Acts as a virtual firewall for an EC2 instance at the instance level, controlling inbound and outbound traffic.
Why this is correct
Security Groups are stateful firewalls that operate at the instance level.
Related concept
CIDR notation defines the prefix length.
- ✓
Network ACLs: Acts as a firewall for a VPC subnet, controlling inbound and outbound traffic at the subnet level.
Why this is correct
Network ACLs are stateless firewalls operating at the subnet level.
Related concept
CIDR notation defines the prefix length.
- ✓
AWS WAF: A web application firewall that helps protect web applications from common web exploits.
- ✓
AWS Shield: A managed DDoS protection service that safeguards applications running on AWS.
Why this is correct
AWS Shield provides automatic DDoS mitigation for AWS resources.
Related concept
CIDR notation defines the prefix length.
- ✗
Security Groups: Acts as a firewall at the subnet level.
Why it's wrong here
Incorrect — Security Groups operate at the instance level, not subnet. This describes Network ACLs.
- ✗
Network ACLs: Acts as a virtual firewall for an EC2 instance.
Why it's wrong here
Incorrect — Network ACLs operate at the subnet level, not instance. This describes Security Groups.
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.
Visual reference
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.
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FAQ
Questions learners often ask
What does this ANS-C01 question test?
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: Security Groups: Acts as a virtual firewall for an EC2 instance at the instance level, controlling inbound and outbound traffic. — These are core security services for network protection. Security Groups are instance-level, NACLs are subnet-level, WAF protects web apps, and Shield provides DDoS protection.
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.
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Last reviewed: Jun 11, 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.
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