This CS0-003 practice question tests your understanding of security operations. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: impossible travel is a strong indicator of account compromise.. 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 UEBA rule flags a user authenticating from London and Singapore within 12 minutes, followed by a mailbox forwarding rule creation. What should the analyst investigate first? In the detection engineering phase, Which detection or tuning approach would reduce noise without losing the signal?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Why wrong: DHCP logs cannot explain the remote sign-in or mailbox change.
B
The organisation's public DNS zone file
Why wrong: DNS zone data is unrelated to mailbox-forwarding abuse.
C
Only the user's browser cache
Why wrong: Browser cache is not the authoritative source for sign-in and mailbox-rule activity.
D
Sign-in logs, MFA result, device details, and mailbox audit events
Impossible travel plus forwarding rule creation is a strong account-compromise pattern; identity and mailbox audit data confirm whether the activity is malicious.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Sign-in logs, MFA result, device details, and mailbox audit events
Option D is correct because the scenario describes a potential account takeover or lateral movement, where an impossible travel event (logins from London and Singapore within 12 minutes) is followed by a suspicious mailbox forwarding rule. The analyst must first verify the sign-in logs for authentication details, MFA results to check if the MFA was bypassed or prompted, device details to identify if a known or managed device was used, and mailbox audit events to confirm the forwarding rule creation and its origin. These combined data sources provide the most direct evidence to determine if the activity is malicious or a false positive.
Key principle: Impossible travel is a strong indicator of account compromise.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Only DHCP logs from the London office
Why it's wrong here
DHCP logs cannot explain the remote sign-in or mailbox change.
✗
The organisation's public DNS zone file
Why it's wrong here
DNS zone data is unrelated to mailbox-forwarding abuse.
✗
Only the user's browser cache
Why it's wrong here
Browser cache is not the authoritative source for sign-in and mailbox-rule activity.
✓
Sign-in logs, MFA result, device details, and mailbox audit events
Why this is correct
Impossible travel plus forwarding rule creation is a strong account-compromise pattern; identity and mailbox audit data confirm whether the activity is malicious.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Impossible travel is a strong indicator of account compromise.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that network-level logs (like DHCP or DNS) are sufficient for investigating user account anomalies, but the correct approach requires focusing on authentication and audit logs that directly capture user identity and actions.
Detailed technical explanation
How to think about this question
Under the hood, UEBA (User and Entity Behavior Analytics) uses machine learning models to establish baseline behavior and detect anomalies like impossible travel by comparing geolocation data from sign-in logs against known travel times. The mailbox forwarding rule creation is a common post-compromise action for data exfiltration, and investigating sign-in logs with MFA results (e.g., whether MFA was completed or skipped) can reveal if the attacker used a stolen session token or bypassed MFA via legacy authentication protocols. In real-world scenarios, attackers often use VPNs or proxy chains to fake geolocation, so device details (e.g., device ID, OS, browser fingerprint) help correlate the session with known corporate devices.
KKey Concepts to Remember
Impossible travel is a strong indicator of account compromise.
Mailbox audit logs track changes like forwarding rule creation.
MFA results indicate authentication strength and potential bypasses.
Device details help identify unfamiliar or compromised endpoints.
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
Impossible travel is a strong indicator of account compromise.
Real-world example
How this comes up in practice
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. Impossible travel is a strong indicator of account compromise. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CS0-003 question in full detail.
Review impossible travel is a strong indicator of account compromise., then practise related CS0-003 questions on the same topic to reinforce the concept.
Security Operations — This question tests Security Operations — Impossible travel is a strong indicator of account compromise..
What is the correct answer to this question?
The correct answer is: Sign-in logs, MFA result, device details, and mailbox audit events — Option D is correct because the scenario describes a potential account takeover or lateral movement, where an impossible travel event (logins from London and Singapore within 12 minutes) is followed by a suspicious mailbox forwarding rule. The analyst must first verify the sign-in logs for authentication details, MFA results to check if the MFA was bypassed or prompted, device details to identify if a known or managed device was used, and mailbox audit events to confirm the forwarding rule creation and its origin. These combined data sources provide the most direct evidence to determine if the activity is malicious or a false positive.
What should I do if I get this CS0-003 question wrong?
Review impossible travel is a strong indicator of account compromise., then practise related CS0-003 questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Impossible travel is a strong indicator of account compromise.
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Question Discussion
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