The answer is to correlate DNS query logs with endpoint process and network connection telemetry. This is the correct choice because validating DGA beaconing requires linking the algorithmically generated domain queries to a specific process initiating outbound connections, which directly confirms whether the DNS activity is part of a malware’s command-and-control channel. A SOC analyst reviewing DNS telemetry will see hundreds of NXDOMAIN responses at fixed intervals, but without endpoint data, those queries could be from a misconfigured service; cross-referencing the parent process and its network connections provides the definitive evidence to validate C2 beaconing. On the CompTIA CySA+ CS0-003 exam, this tests your ability to combine multiple evidence sources rather than relying on DNS logs alone—a common trap is stopping at the DNS anomaly without verifying the process behind it. Remember the memory tip: “DNS shows the call, but endpoint shows the caller.”
CS0-003 Security Operations Practice Question
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. 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 SOC analyst reviews DNS telemetry and sees a workstation resolving hundreds of algorithmically generated domains at fixed intervals, with most responses returning NXDOMAIN. What evidence should the analyst prioritize to validate command-and-control beaconing? In the evidence source phase, Which evidence source best supports or refutes the detection?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Correlate DNS query logs with endpoint process and network connection telemetry
Correlating DNS query logs with endpoint process and network connection telemetry (Option D) provides direct evidence of command-and-control (C2) beaconing by linking the algorithmically generated domain (AGD) queries to a specific process initiating outbound connections. This cross-referencing validates whether the DNS activity is part of a malware's C2 channel, as legitimate applications rarely generate hundreds of NXDOMAIN responses at fixed intervals. The SOC analyst can confirm the detection by identifying the parent process (e.g., a suspicious executable) and matching its network connections to the queried domains.
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.
✗
Search only for successful HTTP 200 responses
Why it's wrong here
DGA activity may fail resolution frequently, so HTTP status codes alone miss the behaviour.
✗
Delete the host from the SIEM asset inventory
Why it's wrong here
Removing context makes investigation harder and does not contain the threat.
✗
Block all DNS traffic from the subnet
Why it's wrong here
Immediate blanket blocking may disrupt operations and does not validate the source process.
✓
Correlate DNS query logs with endpoint process and network connection telemetry
Why this is correct
The pattern is suspicious, but process and connection context shows whether a host process is repeatedly attempting outbound C2 communication.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often focus on the DNS NXDOMAIN responses alone and choose a reactive action like blocking traffic (Option C) or deleting the host (Option B), instead of recognizing that correlation with endpoint telemetry is required to validate the detection before any response.
Detailed technical explanation
How to think about this question
Under the hood, malware using domain generation algorithms (DGAs) queries a sequence of pseudo-random domains until one resolves to a C2 server, with NXDOMAIN responses indicating failed attempts. Correlating DNS logs with endpoint process creation events (e.g., via Sysmon Event ID 1) and network connection logs (e.g., NetFlow or Windows Event ID 5156) allows the analyst to identify the specific process (e.g., a suspicious .exe in %TEMP%) that initiated the DNS queries and subsequent outbound connections. In a real-world scenario, this correlation can reveal that the beaconing process is masquerading as a legitimate service (e.g., svchost.exe) but is actually a malware instance, as seen in Emotet or TrickBot infections.
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 CS0-003 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: Correlate DNS query logs with endpoint process and network connection telemetry — Correlating DNS query logs with endpoint process and network connection telemetry (Option D) provides direct evidence of command-and-control (C2) beaconing by linking the algorithmically generated domain (AGD) queries to a specific process initiating outbound connections. This cross-referencing validates whether the DNS activity is part of a malware's C2 channel, as legitimate applications rarely generate hundreds of NXDOMAIN responses at fixed intervals. The SOC analyst can confirm the detection by identifying the parent process (e.g., a suspicious executable) and matching its network connections to the queried domains.
What should I do if I get this CS0-003 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: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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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 SOC analyst reviews DNS telemetry and sees a workstation resolving hundreds of algorithmically generated domains at fixed intervals, with most responses returning NXDOMAIN. What evidence should the analyst prioritize to validate command-and-control beaconing? In the containment trade-off phase, Which response balances containment with evidence preservation?
medium
✓ A.Correlate DNS query logs with endpoint process and network connection telemetry
B.Search only for successful HTTP 200 responses
C.Block all DNS traffic from the subnet
D.Delete the host from the SIEM asset inventory
Why A: Option A is correct because correlating DNS query logs with endpoint process and network connection telemetry directly validates command-and-control (C2) beaconing. The algorithmically generated domains (AGDs) and NXDOMAIN responses are classic indicators of a domain generation algorithm (DGA) attempting to resolve a C2 server that may be offline or blocked. By linking the DNS queries to specific processes and network connections on the endpoint, the analyst can confirm whether the workstation is executing malicious code that generates these queries, rather than benign software or a false positive.
Variation 2. A SOC analyst reviews DNS telemetry and sees a workstation resolving hundreds of algorithmically generated domains at fixed intervals, with most responses returning NXDOMAIN. What evidence should the analyst prioritize to validate command-and-control beaconing? In the detection engineering phase, Which detection or tuning approach would reduce noise without losing the signal?
medium
A.Delete the host from the SIEM asset inventory
B.Search only for successful HTTP 200 responses
C.Block all DNS traffic from the subnet
✓ D.Correlate DNS query logs with endpoint process and network connection telemetry
Why D: Option D is correct because correlating DNS query logs with endpoint process and network connection telemetry provides direct evidence of command-and-control (C2) beaconing. The algorithmically generated domains (DGA) and NXDOMAIN responses are strong indicators of an infected host attempting to contact a C2 server that is currently offline or unreachable. By linking the DNS queries to the specific process generating them and the subsequent network connections, the analyst can confirm malicious activity rather than benign misconfiguration.
Variation 3. A SOC analyst reviews DNS telemetry and sees a workstation resolving hundreds of algorithmically generated domains at fixed intervals, with most responses returning NXDOMAIN. What evidence should the analyst prioritize to validate command-and-control beaconing? In the root-cause analysis phase, Which finding would most directly explain the activity?
medium
A.Block all DNS traffic from the subnet
B.Search only for successful HTTP 200 responses
✓ C.Correlate DNS query logs with endpoint process and network connection telemetry
D.Delete the host from the SIEM asset inventory
Why C: Option C is correct because correlating DNS query logs with endpoint process and network connection telemetry provides direct evidence of command-and-control (C2) beaconing. The algorithmically generated domains (DGA) and NXDOMAIN responses are characteristic of malware that generates many domains to evade static blocklists, but only a few are actually registered by the attacker. By mapping the DNS queries to the specific process that initiated them (via endpoint telemetry) and the subsequent network connections (e.g., to the resolved IP of a successful DGA domain), the analyst can confirm C2 activity rather than just anomalous DNS traffic.
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Question Discussion
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