GCIH Network and Log Investigations Practice Question
An incident handler is triaging a suspected beaconing implant on a Windows workstation. NetFlow records show a repeating outbound connection to the same external IP address every 60 seconds, but the packets are only 200 bytes each, so no payload is captured. The handler wants to confirm the beacon's timing jitter and any command-and-control content without deploying a new agent to the endpoint. Which investigative approach BEST accomplishes this?
⚠ Common exam trap
The trap here is assuming that flow records contain enough detail to characterize beaconing, when they actually omit payload and sub-second precision.
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
✓
Enable full packet capture on the perimeter sensor and filter the traffic by the destination IP address, then analyze inter-arrival times and payload content.
Perimeter full packet capture retains both timing and payload, which are exactly the two data points needed to characterize the beacon. Flow records and host logs provide timing or authentication context but never the command-and-control content. Scanning the adversary infrastructure is intrusive and yields no information about the local implant's behavior, so it does not meet the investigative requirement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Export the NetFlow records to a collector and generate a histogram of flow start times to measure the beacon interval precisely.
Why it's wrong here
NetFlow records include flow start and end timestamps and byte counts, so a histogram can reveal the approximate interval, but flow records carry no payload. The handler cannot confirm jitter to sub-second precision or inspect command-and-control content from flow metadata alone. This approach answers only half the requirement and leaves the content question unresolved.
- ✗
Pull Windows Security event logs for logon type 3 events and correlate their timestamps with the observed outbound connections.
Why it's wrong here
Logon type 3 events describe network logons on the Windows host and are unrelated to outbound TCP session timing. Correlating them with the observed connections would produce coincidental matches at best and would never expose the command-and-control payload. This approach also depends on host logs that may not record outbound connections at all, so it cannot answer the question.
- ✓
Enable full packet capture on the perimeter sensor and filter the traffic by the destination IP address, then analyze inter-arrival times and payload content.
Why this is correct
Full packet capture at the perimeter preserves both the timing of each connection and the payload bytes, allowing the handler to calculate beacon jitter and inspect command-and-control content. Filtering by the known destination IP keeps the capture volume manageable. Because no endpoint agent is installed, this satisfies the requirement without touching the host.
- ✗
Run a port scan against the external IP address from the workstation to identify the listening service and infer the implant family.
Why it's wrong here
Scanning the external command-and-control address is both operationally risky and analytically weak. It may alert the adversary, and an open port reveals nothing about the local implant's jitter or its command-and-control payloads. It also fails to produce any evidence about the workstation's outbound behavior, so it cannot confirm beacon timing or content for the investigation.
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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 GIAC exam blueprint
This GCIH practice question is part of Courseiva's free GIAC 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 GCIH exam.