This CCSP practice question tests your understanding of cloud application security. 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.
A cloud application uses a RESTful API that handles payment transactions. The security team identifies that the API is vulnerable to brute-force attacks on the authentication endpoint. Which control should be implemented to mitigate this?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement rate limiting on the authentication endpoint
Rate limiting restricts the number of authentication requests from a single source within a given time window, directly mitigating brute-force attacks by making it infeasible to guess credentials at high speed. This control is specifically designed for authentication endpoints where repeated failed attempts are the primary attack vector, and it is a standard recommendation in OWASP and NIST guidelines for API security.
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 authentication endpoint
Why this is correct
Rate limiting reduces the number of allowed attempts, blocking brute-force attacks.
Related concept
Read the scenario before looking for a memorised answer.
✗
Require API keys for all requests
Why it's wrong here
API keys allow access but do not prevent repeated attempts.
✗
Use TLS to encrypt the communication channel
Why it's wrong here
Encryption prevents eavesdropping but not brute-force.
✗
Add input validation for all parameters
Why it's wrong here
Input validation prevents injection but not brute-force.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the distinction between authentication-specific controls (rate limiting) and general security measures (encryption, input validation), leading candidates to choose TLS or API keys because they are commonly associated with API security but do not address brute-force frequency.
Detailed technical explanation
How to think about this question
Rate limiting can be implemented using token bucket or leaky bucket algorithms, often enforced at the API gateway or reverse proxy (e.g., NGINX, AWS API Gateway) with configurable thresholds like 5 requests per minute per IP. In a real-world scenario, an attacker might rotate IP addresses via a botnet to bypass simple IP-based rate limiting, so advanced implementations use sliding window counters, CAPTCHA challenges after a threshold, or account lockout policies (e.g., after 10 failed attempts) as complementary controls.
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 developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach 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.
Cloud Application Security — This question tests Cloud Application Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement rate limiting on the authentication endpoint — Rate limiting restricts the number of authentication requests from a single source within a given time window, directly mitigating brute-force attacks by making it infeasible to guess credentials at high speed. This control is specifically designed for authentication endpoints where repeated failed attempts are the primary attack vector, and it is a standard recommendation in OWASP and NIST guidelines for API security.
What should I do if I get this CCSP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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