CAS-004 Security Operations Practice Question
A security analyst is reviewing a packet capture of suspicious traffic that uses a custom protocol over TCP. The analyst needs to determine the application-layer payload and session flow to identify potential data exfiltration. Which tool is MOST appropriate for this task?
⚠ Common exam trap
The trap here is assuming that any packet capture tool can perform deep application-layer analysis, when only Wireshark provides the necessary dissectors and stream reassembly.
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
✓
Wireshark
Wireshark is the correct choice because it enables deep packet inspection, protocol dissection, and TCP stream reassembly, which are essential for analyzing custom protocols and identifying data exfiltration. The other tools lack the granular payload analysis and session reconstruction capabilities required for this task.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Nmap
Why it's wrong here
Nmap is a port scanner and network mapping tool used for host discovery and service enumeration. It does not capture or analyze packet payloads or session flows, making it unsuitable for examining application-layer data in a packet capture.
- ✗
tcpdump
Why it's wrong here
tcpdump is a command-line packet analyzer that captures and displays packet headers and some payload data, but it lacks a graphical interface and advanced session reassembly features needed for deep inspection of custom protocols. It is useful for quick captures but not ideal for analyzing complex application-layer payloads and session flows in detail.
- ✓
Wireshark
Why this is correct
Wireshark provides deep packet inspection with protocol dissectors, allowing the analyst to view application-layer payloads, reassemble TCP streams, and analyze session flow. It supports custom protocol analysis through user-defined dissectors and is the most appropriate tool for this scenario.
- ✗
NetFlow
Why it's wrong here
NetFlow collects metadata about IP flows, such as source/destination and byte counts, but does not capture payload content. It cannot provide application-layer payload details or session reassembly, so it fails to meet the analyst's need for deep packet inspection.
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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 CompTIA exam blueprint
This CAS-005 practice question is part of Courseiva's free CompTIA 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 CAS-005 exam.