The correct answer is to modify the WAF rule to allow traffic from the corporate IP range on the admin path and allow all traffic on the main application path. This is because AWS WAF path-based rules allow you to apply different conditions to different URI paths within a single web ACL, using string match or regex patterns on the request URI. The original mistake was creating a blanket block rule that applied to all traffic, which prevented external users from reaching the main application. On the SCS-C02 exam, this scenario tests your understanding of WAF rule priority and how to combine IP set conditions with path-based string matching to enforce granular access control. A common trap is assuming a single allow rule for corporate IPs will automatically let other traffic through—it won’t, because WAF rules are evaluated in order and a default block will catch everything else. Memory tip: think “path first, then IP”—always define the path scope before applying the IP condition, and remember to include an explicit allow-all rule for non-admin paths.
SCS-C02 Infrastructure Security Practice Question
This SCS-C02 practice question tests your understanding of infrastructure security. 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 company is running a critical web application on EC2 instances behind an Application Load Balancer (ALB) in a VPC. The application serves traffic on port 443. The security team has implemented a security group for the ALB that allows inbound HTTPS from 0.0.0.0/0. The EC2 instances are in a private subnet with a security group that allows inbound traffic from the ALB security group on port 8080. The application works correctly. However, the security team wants to add an additional layer of defense by implementing a web application firewall (WAF) to block common web exploits. The team also wants to ensure that only traffic from the company's corporate IP range (203.0.113.0/24) can access the application for administrative purposes on a separate path. The team has enabled AWS WAF on the ALB and associated a web ACL. They have also created a rule to allow traffic from the corporate IP range and block all other traffic. After deploying these changes, external users (not from corporate IP) cannot access the application at all. The company wants external users to be able to access the main application, but only corporate IPs should access the admin path. What should the security engineer do to fix the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Modify the WAF rule to allow traffic from the corporate IP range on the admin path and allow all traffic on the main application path.
The correct action is to create a WAF rule that allows traffic from corporate IPs on the admin path and allows all other traffic on the main path, instead of blocking all non-corporate traffic. Option A is correct. Option B would allow all traffic, defeating the purpose. Option C is too permissive. Option D doesn't address the WAF issue.
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.
✗
Configure the security group of the ALB to allow only corporate IPs.
Why it's wrong here
Would block all external users.
✗
Create two separate ALBs, one for admin traffic and one for main traffic.
Why it's wrong here
Overly complex and not necessary.
✗
Remove the WAF rule that blocks all non-corporate traffic and rely on security groups.
Why it's wrong here
Removing rule would allow all traffic, not restrict admin path.
✓
Modify the WAF rule to allow traffic from the corporate IP range on the admin path and allow all traffic on the main application path.
Why this is correct
This allows external users on main path and restricts admin path.
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 SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Infrastructure Security — This question tests Infrastructure Security — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Modify the WAF rule to allow traffic from the corporate IP range on the admin path and allow all traffic on the main application path. — The correct action is to create a WAF rule that allows traffic from corporate IPs on the admin path and allows all other traffic on the main path, instead of blocking all non-corporate traffic. Option A is correct. Option B would allow all traffic, defeating the purpose. Option C is too permissive. Option D doesn't address the WAF issue.
What should I do if I get this SCS-C02 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 SCS-C02 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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