This CEH practice question tests your understanding of footprinting and reconnaissance. 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 security analyst is tasked with performing passive reconnaissance on a target organization. Which of the following is the BEST approach to gather information about the target's technology stack without directly interacting with the target's systems?
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.
Engage in social engineering via phone calls
Why wrong: Social engineering is active and risky.
Use Shodan to search for target infrastructure
Shodan indexes public data passively.
Initiate a DNS zone transfer request
Why wrong: Zone transfer is active and often blocked.
Perform a port scan with Nmap
Why wrong: Active scanning generates traffic.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Use Shodan to search for target infrastructure
Shodan is a search engine that indexes banners from internet-connected devices, allowing an analyst to discover a target's exposed services, open ports, and technology stack (e.g., web servers, SSH versions, IoT devices) without sending any packets to the target's systems. This makes it a purely passive reconnaissance technique, as it relies on Shodan's pre-collected data rather than direct interaction.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Engage in social engineering via phone calls
Why it's wrong here
Social engineering is active and risky.
Use Shodan to search for target infrastructure
Why this is correct
Shodan indexes public data passively.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Initiate a DNS zone transfer request
Why it's wrong here
Zone transfer is active and often blocked.
Perform a port scan with Nmap
Why it's wrong here
Active scanning generates traffic.
Common exam traps
EC-Council often tests the distinction between passive and active reconnaissance, and the trap here is that candidates confuse Shodan (a passive, third-party data source) with active tools like Nmap or DNS zone transfers, which require direct interaction with the target's systems.
Detailed technical explanation
Shodan works by continuously scanning the entire IPv4 address space and storing service banners (e.g., HTTP Server headers, SSH version strings) from responses to connection attempts. A subtle behavior is that Shodan's data may be hours or days old, so the analyst must consider that the target's technology stack could have changed since the last scan. In a real-world scenario, an analyst might combine Shodan with Censys or Google dorks to cross-reference passive data without ever touching the target's network.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the CEH exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Footprinting and Reconnaissance — This question tests Footprinting and Reconnaissance — Read the scenario before looking for a memorised answer..
The correct answer is: Use Shodan to search for target infrastructure — Shodan is a search engine that indexes banners from internet-connected devices, allowing an analyst to discover a target's exposed services, open ports, and technology stack (e.g., web servers, SSH versions, IoT devices) without sending any packets to the target's systems. This makes it a purely passive reconnaissance technique, as it relies on Shodan's pre-collected data rather than direct interaction.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This CEH practice question is part of Courseiva's free EC-Council 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 CEH exam.
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