This CC 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. 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 company's security operations center (SOC) receives an alert about suspicious outbound traffic from a server in the DMZ to an external IP address known for command-and-control activity. The SOC analyst reviews the logs and sees that the source port is 443 and the destination port is 8080. Which of the following actions should the analyst take 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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Isolate the server from the network and investigate further
The SOC analyst should first isolate the server from the network because the outbound traffic from a DMZ server to a known C2 IP address, using source port 443 (HTTPS) to destination port 8080 (HTTP alternate), indicates a potential compromise. Isolating the server stops the data exfiltration and prevents further C2 communication, allowing for a controlled forensic investigation without alerting the attacker. This aligns with the NIST SP 800-61 incident response process, where containment is prioritized before eradication or recovery.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Notify the incident response team and management immediately
Why it's wrong here
Notification is important but should come after taking immediate containment actions.
✓
Isolate the server from the network and investigate further
Why this is correct
Isolation contains the threat and allows forensic analysis without risk of further damage.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Block the external IP address at the firewall
Why it's wrong here
Blocking the IP is reactive and may not address the root cause; the server could still be compromised.
✗
Modify the firewall rule to deny all outbound traffic from the DMZ
Why it's wrong here
This could affect other legitimate services in the DMZ and should be done after analysis.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the candidate's ability to prioritize containment over notification or broad blocking, trapping those who confuse 'first action' with 'escalation' or who apply overly aggressive firewall changes without considering service impact.
Detailed technical explanation
How to think about this question
In a DMZ, servers typically use source port 443 for HTTPS traffic to external clients, but here the destination port 8080 (often used for HTTP proxies or alternate web services) combined with a known C2 IP suggests the server is acting as a client to an external C2 server, possibly using HTTPS encapsulation over port 8080 to evade detection. Isolating the server at the network level (e.g., via ACL or disabling the switch port) preserves volatile evidence like memory and active connections for forensic analysis, which is critical for identifying the root cause and scope of compromise. Real-world scenarios, such as the SolarWinds attack, highlight that immediate containment prevents lateral movement and data exfiltration while preserving forensic integrity.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC question in full detail.
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Isolate the server from the network and investigate further — The SOC analyst should first isolate the server from the network because the outbound traffic from a DMZ server to a known C2 IP address, using source port 443 (HTTPS) to destination port 8080 (HTTP alternate), indicates a potential compromise. Isolating the server stops the data exfiltration and prevents further C2 communication, allowing for a controlled forensic investigation without alerting the attacker. This aligns with the NIST SP 800-61 incident response process, where containment is prioritized before eradication or recovery.
What should I do if I get this CC question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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?
Read the scenario before looking for a memorised answer.
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