The answer is WHOIS queries, Google dork queries, and social media footprinting. These are correct because passive reconnaissance techniques involve gathering information from publicly available sources without directly interacting with the target’s systems—no packets are sent to their servers, and no network scans are performed. WHOIS queries retrieve domain registration data from third-party registries, Google dork queries expose indexed documents via search engine operators, and social media footprinting collects employee or organizational details from public profiles. On the Certified Ethical Hacker CEH exam, this question tests your ability to distinguish passive from active reconnaissance, a core concept in the information-gathering phase. A common trap is confusing DNS enumeration (which can be active if querying the target’s server) with WHOIS lookups (always passive). Remember the memory tip: “Passive means public—no packets, no probes.”
CEH Footprinting, Reconnaissance and Scanning Practice Question
This CEH practice question tests your understanding of footprinting, reconnaissance and scanning. 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 conducting passive reconnaissance on a target organization. Which THREE of the following are examples of passive reconnaissance techniques? (Select 3)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Performing a WHOIS lookup on the target's domain
WHOIS queries are a classic passive reconnaissance technique because they retrieve publicly registered domain ownership data from WHOIS databases (e.g., registrar, creation date, name servers) without sending any packets directly to the target's infrastructure. This information is stored by third-party registries and is accessible via standard WHOIS protocol (RFC 3912) or web-based lookup tools, making it completely non-intrusive.
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.
✓
Performing a WHOIS lookup on the target's domain
Why this is correct
WHOIS queries use public databases, no direct target interaction.
Related concept
Read the scenario before looking for a memorised answer.
✓
Querying a public DNS resolver cache for the target's mail server records
Why this is correct
DNS cache snooping uses public resolvers without contacting the target's DNS server directly.
Related concept
Read the scenario before looking for a memorised answer.
✗
Running an Nmap SYN scan against the target's web server
Why it's wrong here
SYN scan sends packets to the target; active reconnaissance.
✗
Banner grabbing with Netcat on port 80
Why it's wrong here
Banner grabbing connects to the target to retrieve a banner; active reconnaissance.
✓
Using Google dork queries to find exposed documents
Why this is correct
Google dorking uses search engine results, no direct target interaction.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
EC-Council often tests the distinction between passive and active reconnaissance by including techniques that appear passive (like banner grabbing) but actually involve direct interaction with the target's services, leading candidates to mistakenly classify them as passive.
Detailed technical explanation
How to think about this question
Passive reconnaissance relies solely on publicly available information from third-party sources (e.g., WHOIS databases, DNS resolvers, search engine caches) and does not involve any direct interaction with the target's systems. For example, querying a public DNS resolver (like 8.8.8.8) for MX records is passive because the query is sent to a third-party server, not the target's own DNS server, and the resolver's cache may already contain the records from previous legitimate queries. Google dorking uses search engine indexes to find exposed documents without ever touching the target's servers.
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 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Footprinting, Reconnaissance and Scanning — This question tests Footprinting, Reconnaissance and Scanning — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Performing a WHOIS lookup on the target's domain — WHOIS queries are a classic passive reconnaissance technique because they retrieve publicly registered domain ownership data from WHOIS databases (e.g., registrar, creation date, name servers) without sending any packets directly to the target's infrastructure. This information is stored by third-party registries and is accessible via standard WHOIS protocol (RFC 3912) or web-based lookup tools, making it completely non-intrusive.
What should I do if I get this CEH question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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