- A
Immediately restart all database servers to stop any malicious processes.
Why wrong: Restarting destroys volatile evidence and may not stop sophisticated malware.
- B
Isolate the database servers from the network and perform forensic analysis on system logs and memory dumps.
Containment and forensic analysis are the appropriate first steps to identify and remove the threat.
- C
Add a firewall rule to deny outbound traffic from the database tier to the unknown IP.
Why wrong: This is a reactive measure; it does not investigate the root cause or confirm compromise.
- D
Block the external IP that is attempting to log in to the web servers and continue monitoring.
Why wrong: This addresses only the brute-force attempt, not the likely data exfiltration from the databases.
Quick Answer
The answer is to isolate the database servers from the network and perform forensic analysis on system logs and memory dumps. This is correct because suspicious outbound traffic from database servers on port 443, when they normally only use port 3306 for internal MySQL communication, is a classic indicator of data exfiltration—likely a compromised server sending stolen data to a command-and-control server. Isolating the servers preserves volatile evidence like memory dumps, which can reveal running malware or active network connections, while forensic log analysis identifies the root cause of the breach. On the CISSP exam, this scenario tests your ability to prioritize containment and evidence preservation over reactive measures like blocking IPs or restarting servers, which destroy forensic artifacts. A common trap is focusing on the failed login alerts to the web tier, but the real threat is the active outbound traffic from the database tier. Memory tip: "Isolate and Investigate, don't Block and Reboot" — always contain the compromised asset first to stop data loss and preserve evidence.
CISSP Security Assessment and Testing Practice Question
This CISSP practice question tests your understanding of security assessment and testing. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 large e-commerce company operates a multi-tier application in a public cloud. The environment includes a web tier, application tier, and database tier. The security team recently deployed a host-based intrusion detection system (HIDS) on all servers. During a routine review, the HIDS alerts show repeated failed login attempts from a single external IP address to several web servers, but no successful logins from that IP. The team also notices that the database servers have been sending outbound traffic to an unknown IP address on port 443, which is unusual because the database servers typically communicate only with the application servers on port 3306 (MySQL). The application team confirms no changes were made recently. The CISO wants an immediate investigation. What should the security team do first?
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.
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
Isolate the database servers from the network and perform forensic analysis on system logs and memory dumps.
Option D is correct because the suspicious outbound traffic from database servers indicates potential data exfiltration. Isolating the affected servers and analyzing their logs and memory will help confirm compromise and contain the incident. Option A is wrong because focusing on the failed logins may miss the active exfiltration. Option B is wrong because restarting servers can destroy forensic evidence. Option C is wrong because blocking the IP on the firewall does not address the potential malware on the database servers.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Immediately restart all database servers to stop any malicious processes.
Why it's wrong here
Restarting destroys volatile evidence and may not stop sophisticated malware.
- ✓
Isolate the database servers from the network and perform forensic analysis on system logs and memory dumps.
Why this is correct
Containment and forensic analysis are the appropriate first steps to identify and remove the threat.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Standard ACLs match source addresses.
- ✗
Add a firewall rule to deny outbound traffic from the database tier to the unknown IP.
Why it's wrong here
This is a reactive measure; it does not investigate the root cause or confirm compromise.
- ✗
Block the external IP that is attempting to log in to the web servers and continue monitoring.
Why it's wrong here
This addresses only the brute-force attempt, not the likely data exfiltration from the databases.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
- Standard ACLs match source addresses.
- Extended ACLs can match source, destination, protocol and ports.
- The first matching ACL entry is used.
- There is usually an implicit deny at the end.
TExam Day Tips
- Check inbound versus outbound direction.
- Read the ACL from top to bottom.
- Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
A SOC analyst notices unusual lateral movement in the network at 2 AM. The IR playbook dictates: identify and contain (isolate the affected machine), then eradicate (remove the malware), then recover (restore from backup), then document. Skipping containment before eradication risks the attacker regaining access. Questions like this test the sequence and rationale of incident response phases.
What to study next
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related CISSP ACL questions on filtering logic and placement.
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Security Assessment and Testing — study guide chapter
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FAQ
Questions learners often ask
What does this CISSP question test?
Security Assessment and Testing — This question tests Security Assessment and Testing — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Isolate the database servers from the network and perform forensic analysis on system logs and memory dumps. — Option D is correct because the suspicious outbound traffic from database servers indicates potential data exfiltration. Isolating the affected servers and analyzing their logs and memory will help confirm compromise and contain the incident. Option A is wrong because focusing on the failed logins may miss the active exfiltration. Option B is wrong because restarting servers can destroy forensic evidence. Option C is wrong because blocking the IP on the firewall does not address the potential malware on the database servers.
What should I do if I get this CISSP question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related CISSP ACL questions on filtering logic and placement.
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?
Standard ACLs match source addresses.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
2 more ways this is tested on CISSP
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 is reviewing logs and notices multiple failed login attempts from a single IP address followed by a successful login. What should the analyst do next?
easy- A.Disable the account immediately
- B.Ignore, as failed logins are normal
- ✓ C.Investigate the successful login
- D.Block the IP address
Why C: The correct answer is C because a successful login immediately following multiple failed attempts from the same IP address is a classic indicator of a brute-force or password-spraying attack that succeeded. The analyst must investigate the successful login to determine if it was legitimate or an account compromise, checking for anomalous behavior, time of access, and any subsequent actions. Ignoring or prematurely blocking the IP could destroy forensic evidence or lock out a legitimate user, while disabling the account without investigation may be premature if the login was authorized.
Variation 2. A security team is analyzing logs from multiple sources and notices anomalous outbound traffic to a known command-and-control server. What is the most likely conclusion?
medium- A.A misconfigured firewall is causing traffic
- ✓ B.A host is compromised and is beaconing
- C.An employee is streaming video to a personal server
- D.The network is under a DDoS attack
Why B: Anomalous outbound traffic to a known command-and-control (C2) server is a classic indicator of compromise (IoC). Compromised hosts often beacon outbound to C2 infrastructure using HTTP, HTTPS, or DNS tunnels to receive instructions or exfiltrate data. This pattern is distinct from normal traffic and is a primary focus of network security monitoring and intrusion detection systems (IDS).
Last reviewed: Jun 24, 2026
This CISSP 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 CISSP exam.
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