The best defense against brute-force attacks on a login form is rate limiting on the login endpoint, because it directly restricts the number of requests an attacker can send within a given time window, making brute-force attacks impractical at the network or application layer. Unlike reactive measures such as account lockout after 5 failed attempts, rate limiting proactively throttles traffic and remains effective even against distributed attacks where attackers rotate IP addresses to bypass lockout policies. On the Certified Ethical Hacker CEH exam, this question tests your understanding of proactive versus reactive controls—a common trap is choosing account lockout, but remember that lockout only triggers after failures, whereas rate limiting prevents the volume of attempts altogether. For a memory tip, think “throttle before you lock”—rate limiting stops the flood at the gate, not just the door.
CEH Web Application and Injection Attacks Practice Question
This CEH practice question tests your understanding of web application and injection attacks. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which of the following is the BEST defense against brute-force attacks on a login form?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Rate limiting on the login endpoint
Rate limiting on the login endpoint is the best defense because it directly restricts the number of requests an attacker can send over a given time window, making brute-force attacks impractical. Unlike reactive measures like account lockout, rate limiting proactively throttles traffic at the network or application layer, preventing the attacker from even attempting many guesses. This approach is effective against distributed brute-force attacks where lockout policies can be bypassed by rotating IP addresses.
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.
✓
Rate limiting on the login endpoint
Why this is correct
Rate limiting reduces the speed of brute-force attempts, but account lockout is a more specific defense.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✓
CAPTCHA
Why this is correct
CAPTCHA can deter automated attacks but can be bypassed; lockout is more reliable.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Complex password policy
Why it's wrong here
Complex passwords make brute-force harder but do not prevent automated attempts; lockout is more effective.
✓
Account lockout after 5 failed attempts
Why this is correct
Account lockout directly prevents further attempts after a threshold, effectively stopping brute-force.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
EC-Council often tests the misconception that account lockout is the strongest defense, but the trap here is that lockout can be circumvented by distributed attacks or cause denial of service, whereas rate limiting is a proactive, scalable control that works at the protocol level.
Detailed technical explanation
How to think about this question
Rate limiting is typically implemented using token bucket or leaky bucket algorithms at the web server or reverse proxy (e.g., Nginx's `limit_req_zone` or Apache's `mod_evasive`). In a real-world scenario, an attacker using a botnet with thousands of IPs can bypass account lockout, but rate limiting per IP or per session still caps the overall attempt rate, making the attack take years to complete. The OWASP recommendation for brute-force prevention emphasizes rate limiting as a primary control because it works regardless of the number of accounts targeted.
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 practitioner preparing for the CEH exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Web Application and Injection Attacks — This question tests Web Application and Injection Attacks — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Rate limiting on the login endpoint — Rate limiting on the login endpoint is the best defense because it directly restricts the number of requests an attacker can send over a given time window, making brute-force attacks impractical. Unlike reactive measures like account lockout, rate limiting proactively throttles traffic at the network or application layer, preventing the attacker from even attempting many guesses. This approach is effective against distributed brute-force attacks where lockout policies can be bypassed by rotating IP addresses.
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". 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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Question Discussion
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