ISC2 CC Access Controls Concepts Practice Question
An organisation implements an account lockout policy that locks an account after 5 failed login attempts within 15 minutes. This control is designed to prevent:
⚠ Common exam trap
It's easy for candidates to confuse brute-force mitigation (lockout) with DoS prevention, when lockout can actually facilitate DoS rather than prevent it.
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
✓
Brute-force attacks
Account lockout after a small number of failed attempts within a short window is a classic brute-force mitigation: it throttles automated password-guessing by making repeated attempts impractical. Brute-force attacks rely on trying many passwords rapidly, so lockout thresholds and time windows directly disrupt that pattern. The control does not address DoS, MITM, or phishing, which operate through different mechanisms.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Denial-of-service attacks
Why it's wrong here
Lockout counters brute-force password guessing by capping repeated authentication attempts; a denial-of-service attack floods resources or bandwidth, and lockout can itself be abused to cause one. Lockout is tempting here because it does throttle repeated requests, but that throttling targets credential guessing, not service availability.
- ✓
Brute-force attacks
Why this is correct
Locking an account after five failed attempts within fifteen minutes throttles repeated authentication guesses, directly disrupting automated brute-force attacks. The threshold and time window constrain the rate at which an attacker can try passwords, satisfying the stem's stated control design.
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Man-in-the-middle attacks
Why it's wrong here
Man-in-the-middle attacks intercept traffic between two parties; lockout thresholds never inspect session integrity or certificates, so they cannot detect or stop interception. Lockout is tempting because it is an authentication control, but it would be correct against online password guessing, where repeated failed logins signal an attack.
- ✗
Phishing attacks
Why it's wrong here
Phishing harvests credentials through deceptive messages; lockout only reacts after failed authentication attempts, and a phished password succeeds on the first try, so no threshold triggers. Lockout is tempting because it is authentication-related, but it would be correct against brute-force or password-spraying attempts, not social-engineering credential theft.
Go deeper
Related to this question
Learn chapter
Access Control Fundamentals
Key term
Phishing
Phishing is a type of cyber attack where criminals impersonate legitimate organizations or individuals to trick victims into revealing sensitive information such as passwords, credit card numbers, or personal data.
Key term
DoS
A cyberattack that floods a target with traffic or requests to exhaust its resources, making it unavailable to legitimate users.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISC2 exam blueprint
This CC practice question is part of Courseiva's free ISC2 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 CC exam.