SOA-C02 Networking and Content Delivery Practice Question
This SOA-C02 practice question tests your understanding of networking and content delivery. 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.
Network Topology
Refer to the exhibit. A SysOps administrator is troubleshooting connectivity issues for a web application that uses an ALB. The ALB sends health check requests to targets on port 443. The network ACL shown is associated with the target subnet. Based on the exhibit, what is causing the health checks to fail?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The network ACL allows inbound HTTPS (443) from 0.0.0.0/0, which includes the ALB, so this should work. The issue is likely elsewhere.
Option A is correct because the network ACL has an inbound rule (Rule 120) that denies all traffic (protocol -1) after allowing specific ports. However, health checks originate from the ALB's private IP addresses, which are not 0.0.0.0/0? Actually, the ALB's health check traffic comes from the ALB's subnet IPs, which might be in the same VPC or different? The NACL rule 100 allows TCP 443 from 0.0.0.0/0, which should include the ALB's IPs. But the deny rule 120 will block traffic not matching the allow rules. However, health check traffic on port 443 should be allowed by rule 100. The issue might be that the NACL is stateless, and the ephemeral ports for response are not allowed. But the question is about health checks failing. Option B is wrong because the ALB does not send health checks on port 80 unless configured. Option C is wrong because health checks originate from ALB, not internet. Option D is wrong because the NACL allows inbound 443 from 0.0.0.0/0.
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 network ACL allows inbound HTTPS (443) from 0.0.0.0/0, which includes the ALB, so this should work. The issue is likely elsewhere.
Why this is correct
The NACL rules seem to allow health checks, so the problem might be elsewhere.
The network ACL does not allow inbound traffic from the ALB on ephemeral ports.
Why it's wrong here
Health checks are on port 443, not ephemeral.
✗
The network ACL is blocking inbound traffic from the internet, but health checks come from the ALB.
Why it's wrong here
Health checks come from ALB, not internet.
✗
The network ACL does not allow inbound HTTP (port 80) from the ALB.
Why it's wrong here
Health checks are on port 443, not 80.
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 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 SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Networking and Content Delivery — This question tests Networking and Content Delivery — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The network ACL allows inbound HTTPS (443) from 0.0.0.0/0, which includes the ALB, so this should work. The issue is likely elsewhere. — Option A is correct because the network ACL has an inbound rule (Rule 120) that denies all traffic (protocol -1) after allowing specific ports. However, health checks originate from the ALB's private IP addresses, which are not 0.0.0.0/0? Actually, the ALB's health check traffic comes from the ALB's subnet IPs, which might be in the same VPC or different? The NACL rule 100 allows TCP 443 from 0.0.0.0/0, which should include the ALB's IPs. But the deny rule 120 will block traffic not matching the allow rules. However, health check traffic on port 443 should be allowed by rule 100. The issue might be that the NACL is stateless, and the ephemeral ports for response are not allowed. But the question is about health checks failing. Option B is wrong because the ALB does not send health checks on port 80 unless configured. Option C is wrong because health checks originate from ALB, not internet. Option D is wrong because the NACL allows inbound 443 from 0.0.0.0/0.
What should I do if I get this SOA-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 SOA-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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