The correct first action is to analyze the incoming request patterns in the reverse proxy logs to identify if there is a high volume of requests to a specific API endpoint. This is because the symptoms—HTTP 503 errors, high CPU but normal memory, and no bandwidth saturation—are classic indicators of a Layer 7 DDoS attack, where the attack targets application logic rather than network capacity. By examining the reverse proxy logs for a surge in requests to a single resource-intensive endpoint, you can confirm an HTTP flood attack, such as a GET or POST flood, which exhausts server processing power. On the CEH exam, this scenario tests your ability to distinguish Layer 7 attacks from network-layer DDoS or application bugs; a common trap is jumping to rate-limiting or blocking IPs before verifying the attack vector through log analysis. Remember the mnemonic “CPU high, memory fine, check the endpoint line” to recall that Layer 7 attacks strain CPU without saturating bandwidth or memory.
CEH Network and Web Application Attacks Practice Question
This CEH practice question tests your understanding of network and web application attacks. 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.
You are the lead security engineer for a financial technology company that hosts a critical web application on three load-balanced servers behind a reverse proxy. The application uses a REST API to process transactions. Recently, the company has experienced intermittent service outages during peak hours. Upon reviewing logs, you find that the reverse proxy is returning HTTP 503 errors for legitimate API requests, and the application servers show high CPU usage but normal memory. The network team reports no bandwidth issues. The application team claims no code changes were made. You suspect a specific type of attack is causing the outages. Which action should you take first to confirm the attack type?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Analyze the incoming request patterns in the reverse proxy logs to identify if there is a high volume of requests to a specific API endpoint.
Option B is correct because the symptoms—HTTP 503 errors, high CPU usage on application servers, normal memory, and no bandwidth issues—strongly suggest a Layer 7 DDoS attack, specifically an HTTP flood targeting a resource-intensive API endpoint. By analyzing reverse proxy logs for a high volume of requests to a specific endpoint, you can confirm the attack type (e.g., a slow loris or GET flood) before taking mitigation steps. This aligns with the CEH methodology of first identifying the attack vector through log analysis.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 firewall to block all incoming traffic from the IPs that appear most frequently in logs.
Why it's wrong here
This is a reactive measure and does not confirm the attack type.
✓
Analyze the incoming request patterns in the reverse proxy logs to identify if there is a high volume of requests to a specific API endpoint.
Why this is correct
This can confirm a Layer 7 DDoS attack targeting a specific endpoint.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the number of application servers to handle the load.
Why it's wrong here
This may alleviate symptoms but does not confirm the attack type.
✗
Run a SQL injection scanner on the application.
Why it's wrong here
SQL injection does not typically cause high CPU and 503 errors.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often jump to blocking IPs (Option A) or scaling horizontally (Option C) as immediate fixes, but the CEH exam emphasizes first confirming the attack vector through log analysis rather than taking reactive or misdirected actions.
Detailed technical explanation
How to think about this question
HTTP 503 errors from a reverse proxy (e.g., Nginx, HAProxy) typically indicate upstream server timeouts or resource exhaustion, often due to a Layer 7 DDoS like an HTTP flood targeting a slow API endpoint (e.g., /api/transactions). Under the hood, the reverse proxy queues requests until backend workers are saturated, causing CPU spikes on app servers while memory remains normal—a hallmark of CPU-bound attacks. In real-world scenarios, attackers use botnets to send thousands of legitimate-looking GET/POST requests to a single endpoint, bypassing traditional DDoS mitigation that focuses on bandwidth.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Network and Web Application Attacks — This question tests Network and Web Application Attacks — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Analyze the incoming request patterns in the reverse proxy logs to identify if there is a high volume of requests to a specific API endpoint. — Option B is correct because the symptoms—HTTP 503 errors, high CPU usage on application servers, normal memory, and no bandwidth issues—strongly suggest a Layer 7 DDoS attack, specifically an HTTP flood targeting a resource-intensive API endpoint. By analyzing reverse proxy logs for a high volume of requests to a specific endpoint, you can confirm the attack type (e.g., a slow loris or GET flood) before taking mitigation steps. This aligns with the CEH methodology of first identifying the attack vector through log analysis.
What should I do if I get this CEH question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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