Quick Answer
The correct answer is a password spraying attack. This is because the attacker deliberately avoids triggering the account lockout policy by using a small set of common passwords against many different usernames, rather than launching many attempts against a single account. When one account locks after five failed tries, the attacker simply moves to the next username, which perfectly matches the password spraying pattern. On the CISSP exam, this question tests your ability to distinguish between password spraying and brute force attacks—a common trap is confusing the two when you see repeated failures from one IP. Remember that brute force focuses many passwords on one account, while password spraying spreads few passwords across many accounts. A helpful memory tip: think of a garden sprinkler—spraying water (passwords) over many plants (accounts) rather than flooding one plant.
This CISSP practice question tests your understanding of security operations. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 security analyst observes repeated failed logon attempts from a single IP address against a domain controller. The account lockout policy is set to 5 attempts within 30 minutes. However, after the account is locked, the attack switches to a different username. Which type of attack is most likely occurring?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
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.
Password spraying attack
Password spraying tries common passwords across many accounts.
Brute-force attack
Why wrong: Brute-force would lock the target account.
Dictionary attack
Why wrong: Dictionary attack also targets a single account.
Rainbow table attack
Why wrong: Rainbow tables are used offline, not for login attempts.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Password spraying attack
This is a password spraying attack because the attacker attempts a small set of common passwords against many usernames, avoiding account lockout by not exceeding the threshold for any single account. The observed behavior—repeated failed attempts from one IP, then switching usernames after lockout—matches the pattern of password spraying, where the attacker tries one or a few passwords across many accounts rather than many passwords against one account.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Password spraying attack
Why this is correct
Password spraying tries common passwords across many accounts.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Brute-force attack
Why it's wrong here
Brute-force would lock the target account.
Dictionary attack
Why it's wrong here
Dictionary attack also targets a single account.
Rainbow table attack
Why it's wrong here
Rainbow tables are used offline, not for login attempts.
Common exam traps
The trap here is that candidates confuse password spraying with brute-force or dictionary attacks, failing to recognize that the key differentiator is the attacker's strategy of targeting multiple usernames with a few passwords to evade account lockout thresholds.
Detailed technical explanation
Password spraying exploits the fact that many organizations enforce account lockout policies (e.g., 5 attempts in 30 minutes) but fail to monitor for distributed login attempts across multiple accounts. In Active Directory, the lockout threshold is per user account, not per source IP, so an attacker can rotate through usernames (often harvested from email addresses or LDAP queries) using common passwords like 'Spring2024!' without triggering lockouts. Tools like Hydra or custom scripts automate this, and successful authentication logs show Event ID 4625 with a different TargetUserName each time.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
What to study next
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
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
The correct answer is: Password spraying attack — This is a password spraying attack because the attacker attempts a small set of common passwords against many usernames, avoiding account lockout by not exceeding the threshold for any single account. The observed behavior—repeated failed attempts from one IP, then switching usernames after lockout—matches the pattern of password spraying, where the attacker tries one or a few passwords across many accounts rather than many passwords against one account.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A security analyst notices repeated failed login attempts from an internal IP address on the domain controller. After enabling account lockout, the lockouts continue but the source IP changes. What is the best next step?
mediumWhy A: Option A is correct because the changing source IP indicates a distributed attack, likely a password spraying or brute-force attempt from multiple compromised hosts. Analyzing log events helps identify the attack pattern (e.g., timing, targeted accounts, source IP ranges) so you can implement additional controls like MFA, which mitigates credential-based attacks regardless of source IP changes. Account lockout alone is insufficient when attackers rotate IPs, as lockout policies are per-account and per-source, not adaptive to distributed sources.
Last reviewed: Jun 24, 2026
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