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Question 244 of 1,010

Network and Web Application Attacks →easyMultiple ChoiceObjective-mapped

Quick Answer

The answer is to block the IP address of the attacker at the firewall. This is correct because the scenario describes a classic application-layer DoS attack, where a single source sends repeated requests to a database-backed endpoint like /product?id=1, /product?id=2, causing resource exhaustion through expensive ORM queries that spike CPU usage to 100%. Blocking the IP at the firewall stops the malicious traffic at the network perimeter with minimal overhead, preserving server resources for legitimate users without requiring complex application changes. On the Certified Ethical Hacker CEH exam, this question tests your ability to distinguish application-layer DoS from network-layer floods and to prioritize immediate containment over forensic analysis—a common trap is to suggest rate-limiting or patching the ORM first, which are slower responses. Remember the memory tip: “One IP, one endpoint, one firewall block” to instantly recall the best first step in a single-source application-layer DoS attack.

CEH Network and Web Application Attacks Practice Question

This CEH practice question tests your understanding of network and web application attacks. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 a security analyst for a medium-sized e-commerce company. The company hosts its web application on a single server running Apache on Ubuntu. Recently, the operations team noticed that the server's CPU usage spikes to 100% every few minutes, causing the website to become unresponsive. They have ruled out hardware issues. The web server logs show repeated requests to the same URL with varying parameters, such as /product?id=1, /product?id=2, etc., all originating from a single IP address. Each request returns a 200 OK response, but the server takes several seconds to generate the page. The application uses a relational database backend with an ORM. You suspect an attack is occurring. What is the most likely attack and the best immediate course of action?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1easymultiple choice

Read the full NAT/PAT explanation →

A
Implement rate limiting on the /product endpoint
Why wrong: Rate limiting would reduce the impact but does not stop the attack immediately; the attacker could still exhaust resources at a lower rate.
B
Block the IP address of the attacker at the firewall
Blocking the single source IP immediately stops the attack; further analysis can be done later.
C
Install a web application firewall (WAF) to detect and block malicious requests
Why wrong: Installing a WAF is a good long-term solution but not immediate; it requires configuration and may not stop the current attack in time.
D
Apply input validation to ensure product IDs are positive integers
Why wrong: Input validation is a preventive measure but does not stop the current attack; the attacker can still send valid IDs.

Full breakdown with real-world context →

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

✓

Block the IP address of the attacker at the firewall

The attack is a resource exhaustion or application-layer DoS attack, where repeated requests to a database-backed endpoint (e.g., /product?id=1, /product?id=2) cause high CPU usage due to expensive ORM queries. The immediate best course is to block the single attacking IP at the firewall, as it stops the malicious traffic at the network perimeter with minimal overhead, preserving server resources for legitimate users.

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.

✗
Implement rate limiting on the /product endpoint
Why it's wrong here
Rate limiting would reduce the impact but does not stop the attack immediately; the attacker could still exhaust resources at a lower rate.
✓
Block the IP address of the attacker at the firewall
Why this is correct
Blocking the single source IP immediately stops the attack; further analysis can be done later.
Clue confirmation
The clue words "best", "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Install a web application firewall (WAF) to detect and block malicious requests
Why it's wrong here
Installing a WAF is a good long-term solution but not immediate; it requires configuration and may not stop the current attack in time.
✗
Apply input validation to ensure product IDs are positive integers
Why it's wrong here
Input validation is a preventive measure but does not stop the current attack; the attacker can still send valid IDs.

Common exam traps

Common exam trap: answer the scenario, not the keyword

EC-Council often tests the distinction between immediate containment (blocking the IP) and long-term hardening (WAF, rate limiting, input validation), and the trap here is that candidates choose a more 'secure' but slower solution like a WAF or input validation, missing the urgency of stopping the active attack first.

Detailed technical explanation

How to think about this question

This attack exploits the fact that each request triggers a full ORM-to-database query cycle, often involving lazy loading or unoptimized joins, which can consume significant CPU and database connections. In Apache, each request spawns a child process or thread, and with 100% CPU, the server's MPM (e.g., prefork or worker) can become saturated, leading to connection timeouts. A real-world scenario is the 'Slowloris' variant or 'HTTP flood' where a single IP sends many legitimate-looking requests to a resource-intensive endpoint, bypassing simple rate limits if the endpoint is not cached.

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.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this CEH question test?

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: Block the IP address of the attacker at the firewall — The attack is a resource exhaustion or application-layer DoS attack, where repeated requests to a database-backed endpoint (e.g., /product?id=1, /product?id=2) cause high CPU usage due to expensive ORM queries. The immediate best course is to block the single attacking IP at the firewall, as it stops the malicious traffic at the network perimeter with minimal overhead, preserving server resources for legitimate users.

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: "best", "most likely". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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This CEH practice question is part of Courseiva's free EC-Council 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 CEH exam.