The answer is performing a WHOIS lookup, because it is the most appropriate technique for passive reconnaissance that generates no traffic to the target’s network. WHOIS queries public databases maintained by regional internet registries like ARIN or RIPE, pulling domain registration details such as registrant contact information, name servers, and expiration dates entirely from external, third-party sources. This means no packets are sent to the target organization’s infrastructure, making it a true zero-traffic method. On the Certified Ethical Hacker CEH exam, this question tests your ability to distinguish passive from active reconnaissance—a common trap is confusing WHOIS with tools like Nmap or traceroute, which do generate traffic. Remember that passive reconnaissance relies on publicly available data that already exists elsewhere, so if you are not touching the target’s systems, you are staying passive. A simple memory tip: “WHOIS waits—no packets, no pings.”
CEH Footprinting, Reconnaissance and Scanning Practice Question
This CEH practice question tests your understanding of footprinting, reconnaissance and scanning. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. 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 wants to perform passive reconnaissance on a target organization without generating any traffic to the target's network. Which of the following techniques would be MOST appropriate?
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
WHOIS lookup is a passive reconnaissance technique that queries public databases (e.g., whois.arin.net) for domain registration details without sending any packets to the target's network. It relies on external, publicly available data, thus generating zero traffic to the target organization's infrastructure.
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.
✗
Running Nmap SYN scan
Why it's wrong here
Nmap SYN scan actively sends packets to the target, generating network traffic.
✗
Executing hping3 to probe ports
Why it's wrong here
hping3 sends custom packets to the target, actively probing the network.
✗
Using Netcat to connect to a service
Why it's wrong here
Netcat actively establishes a TCP connection to the target, generating traffic.
✓
Performing a WHOIS lookup
Why this is correct
WHOIS lookups query public databases and do not contact the target's servers, making them passive.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse active scanning tools (Nmap, hping3, Netcat) with passive information gathering, failing to recognize that any direct packet transmission to the target constitutes active reconnaissance.
Detailed technical explanation
How to think about this question
WHOIS queries use the WHOIS protocol (RFC 3912) over TCP port 43 to retrieve registration data from RIRs (e.g., ARIN, RIPE) or domain registrars. This data includes registrar info, name servers, and creation/expiration dates, which can reveal organizational structure or hosting providers. In a real-world engagement, passive reconnaissance like WHOIS is often combined with DNS record analysis (e.g., using `dig` or `nslookup` for passive DNS) to build a footprint without alerting IDS/IPS systems.
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 — WHOIS lookup is a passive reconnaissance technique that queries public databases (e.g., whois.arin.net) for domain registration details without sending any packets to the target's network. It relies on external, publicly available data, thus generating zero traffic to the target organization's infrastructure.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. During a security assessment, a tester uses Maltego to gather information about a target organization. Which type of reconnaissance is being performed?
easy
✓ A.Passive reconnaissance
B.Active reconnaissance
C.Vulnerability scanning
D.Social engineering
Why A: Maltego is a tool that collects publicly available information from sources like DNS records, WHOIS databases, and social media without directly interacting with the target's systems. This aligns with passive reconnaissance, which relies on open-source intelligence (OSINT) and does not send any packets to the target's network. The CEH defines passive reconnaissance as gathering information without engaging the target, making option A correct.
Last reviewed: Jun 24, 2026
Question Discussion
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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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