CAS-004 Security Operations Practice Question
A security team is conducting a penetration test against a client's web application. During the reconnaissance phase, the tester discovers a subdomain that hosts a development version of the application with debug mode enabled. Which type of reconnaissance does this activity represent?
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
✓
Active reconnaissance because the tester is sending requests to the target network to identify subdomains
Active reconnaissance involves directly interacting with the target, such as probing subdomains or services. Discovering a subdomain by scanning or querying DNS is active, as it sends traffic to the target's infrastructure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Open-source intelligence (OSINT) gathering by examining the target's website source code
Why it's wrong here
While OSINT can be passive, enumerating subdomains via DNS queries is active.
- ✗
Social engineering because the tester tricked an employee into revealing the subdomain
Why it's wrong here
No social engineering involved; the subdomain was found through technical means.
- ✓
Active reconnaissance because the tester is sending requests to the target network to identify subdomains
Why this is correct
Active reconnaissance involves direct interaction with the target, such as DNS enumeration or port scanning.
- ✗
Passive reconnaissance because the tester is using publicly available information
Why it's wrong here
Using DNS scans or tools to enumerate subdomains is active because it involves direct requests to the target's servers.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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