The correct action is to update the AWS WAF IP set rule to block the specific IP address. AWS WAF operates at the application layer (Layer 7) and uses IP set rules—a collection of IP addresses and CIDR ranges—to allow or block traffic based on the source IP, making it the precise tool for this task. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of where each security control applies: security groups and NACLs manage network-layer traffic within a VPC and cannot inspect HTTP requests, while CloudFront alone lacks native IP blocking at the application layer. A common trap is confusing WAF’s IP sets with VPC-level controls, so remember that WAF is for web traffic, not network packets. Memory tip: “WAF watches web requests, NACLs and SGs see subnets and servers.”
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 uses AWS WAF to protect its web application from common exploits. The security team notices that a specific IP address is generating a high volume of requests and should be blocked immediately. Which action should be taken?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "immediately / without restart"
Why it matters: Time or reboot constraint — the correct answer must take effect right away without requiring a reboot or reload.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Update the AWS WAF IP set rule to block the IP address
AWS WAF allows creating IP set rules to block specific IPs. Option C is correct. Option A is wrong because security groups are for VPC traffic, not HTTP-level. Option B is wrong because NACLs are stateless and less flexible. Option D is wrong because CloudFront alone does not block IPs at the application layer.
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.
✓
Update the AWS WAF IP set rule to block the IP address
Why this is correct
WAF can block specific IPs at the application layer.
Clue confirmation
The clue word "immediately / without restart" in the question point toward this answer.
Add a rule to the security group to deny traffic from that IP
Why it's wrong here
Security groups do not filter at the HTTP level and are not integrated with WAF.
✗
Add a network ACL rule to deny traffic from that IP in the subnet
Why it's wrong here
NACLs are not application-aware and would block all traffic from that IP, not just HTTP.
✗
Use AWS CloudFront geo-restriction to block the IP
Why it's wrong here
Geo-restriction blocks by country, not individual 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 — 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: Update the AWS WAF IP set rule to block the IP address — AWS WAF allows creating IP set rules to block specific IPs. Option C is correct. Option A is wrong because security groups are for VPC traffic, not HTTP-level. Option B is wrong because NACLs are stateless and less flexible. Option D is wrong because CloudFront alone does not block IPs at the application layer.
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: "immediately / without restart". Time or reboot constraint — the correct answer must take effect right away without requiring a reboot or reload.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
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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 is using AWS WAF to protect a web application. They want to block requests that originate from known malicious IP addresses. Which WAF rule type should be used?
easy
A.String match condition
B.Regex match condition
C.SQL injection match condition
✓ D.IP set match condition
Why D: IP set match conditions are used to match the source IP address of a request against a list of IP addresses. Regex, string match, and SQL injection are for other attack types.
Last reviewed: Jun 20, 2026
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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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