hardMultiple Choice
How to Respond to Suspicious Outbound Traffic from Database Servers
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?
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.
⚠ Common exam trap
CISSP often tests the containment-before-eradication principle — the trap is choosing 'restart' or 'block the IP' because they feel decisive, when the correct first action is to isolate and preserve evidence.
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.
The outbound port 443 traffic from database servers to an unknown IP is a strong indicator of active compromise (e.g., C2 beaconing or data exfiltration), so the first priority is containment via network isolation to stop further damage while preserving volatile evidence. Forensic analysis of logs and memory dumps must follow immediately to determine scope, persistence, and lateral movement before any remediation.
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 the database servers terminates running processes and clears memory-resident artefacts, erasing the evidence needed to determine how the outbound port 443 channel was established. Restarts are a valid containment step for a confirmed, understood infection, but here the investigation has not yet established what is happening.
- ✓
Isolate the database servers from the network and perform forensic analysis on system logs and memory dumps.
Why this is correct
Outbound port 443 traffic from database servers that should only speak MySQL on 3306 signals likely exfiltration or compromise. Isolating preserves volatile evidence such as memory-resident malware while containing the threat, satisfying the CISO's demand for immediate investigation before the attacker exfiltrates further data.
- ✗
Add a firewall rule to deny outbound traffic from the database tier to the unknown IP.
Why it's wrong here
Blocking the outbound flow destroys volatile evidence of the likely database compromise before forensic capture, and the HIDS alerts already identified the anomaly. Firewall egress rules are the right control for enforcing long-term segmentation once the incident is contained and scoped, not as the first investigative action.
- ✗
Block the external IP that is attempting to log in to the web servers and continue monitoring.
Why it's wrong here
Blocking the external IP that attempted logins addresses the failed login attempts, but the more critical issue is the outbound traffic from the database servers. This could be a distraction technique; the focus should be on the database tier.
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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: 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).
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 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.