Quick Answer
The answer is WHOIS lookup and Google dorking. Both are passive reconnaissance techniques because they gather publicly available information without directly interacting with the target’s systems. WHOIS queries access domain registration databases to reveal owner details, email addresses, and name servers, while Google dorking uses advanced search operators to find indexed files or exposed directories on search engines—neither sends packets to the target’s infrastructure. On the Certified Ethical Hacker CEH exam, this distinction tests your understanding of the reconnaissance phase, where passive techniques are defined by zero direct contact; a common trap is confusing active tools like Nmap or netcat with passive methods. Remember the memory tip: if you’re not touching the target’s network, it’s passive—think “search and query, never ping and probe.”
This CEH practice question tests your understanding of footprinting, reconnaissance and scanning. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
Which TWO of the following are passive reconnaissance techniques?
Ping sweep
Why wrong: Ping sweep sends ICMP echo requests, which is active.
Google hacking (dorking)
Google dorking uses search engines to find information passively.
Nmap SYN scan
Why wrong: Nmap sends packets to the target, making it active.
Banner grabbing with Netcat
Why wrong: Banner grabbing requires connecting to the target service, which is active.
WHOIS lookup
WHOIS is a passive query to public databases.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Google hacking (dorking)
Google hacking (dorking) is a passive reconnaissance technique because it involves using advanced search operators in Google to discover publicly indexed information about a target, such as exposed configuration files or login pages, without sending any packets directly to the target's systems. It relies entirely on the search engine's pre-existing index, making it undetectable and non-intrusive. This aligns with the CEH definition of passive reconnaissance, where no direct interaction with the target occurs.
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.
Ping sweep
Why it's wrong here
Ping sweep sends ICMP echo requests, which is active.
Google hacking (dorking)
Why this is correct
Google dorking uses search engines to find information passively.
Related concept
Read the scenario before looking for a memorised answer.
Nmap SYN scan
Why it's wrong here
Nmap sends packets to the target, making it active.
Banner grabbing with Netcat
Why it's wrong here
Banner grabbing requires connecting to the target service, which is active.
WHOIS lookup
Why this is correct
WHOIS is a passive query to public databases.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse 'passive' with 'stealthy' and incorrectly classify techniques like banner grabbing or SYN scans as passive because they can be performed with minimal noise, but CEH strictly defines passive reconnaissance as having zero direct interaction with the target's systems.
Detailed technical explanation
WHOIS lookups query public databases maintained by regional internet registries (RIRs) like ARIN, RIPE, or APNIC via port 43 (WHOIS protocol) or web-based interfaces, retrieving registration details such as domain ownership, nameservers, and administrative contacts. This data is publicly available and does not involve any packets sent to the target's own infrastructure, making it purely passive. In real-world engagements, combining WHOIS with Google dorking can reveal forgotten subdomains or exposed internal documents without alerting the target.
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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Footprinting, Reconnaissance and Scanning — study guide chapter
Learn the concepts, then practise the questions
Footprinting, Reconnaissance and Scanning practice questions
Targeted practice on this topic area only
All CEH questions
1,010 questions across all exam domains
Certified Ethical Hacker CEH study guide
Full concept coverage aligned to exam objectives
CEH practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise CEH questions linked to Footprinting, Reconnaissance and Scanning.
Practise CEH questions linked to Enumeration and System Hacking.
Practise CEH questions linked to Malware, Social Engineering and Network Attacks.
Practise CEH questions linked to Web Application and Injection Attacks.
Practise CEH questions linked to Introduction to Ethical Hacking.
Practise CEH questions linked to Scanning Networks and Enumeration.
Practise CEH questions linked to Vulnerability Analysis and System Hacking.
Practise CEH questions linked to Advanced Topics: Wireless, Cloud, IoT, Cryptography.
Practise CEH questions linked to Footprinting and Reconnaissance.
Practise CEH questions linked to Network and Web Application Attacks.
Practise CEH questions linked to Wireless, IoT and Cloud Security.
Practise CEH questions linked to Cryptography and Malware Analysis.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Footprinting, Reconnaissance and Scanning — This question tests Footprinting, Reconnaissance and Scanning — Read the scenario before looking for a memorised answer..
The correct answer is: Google hacking (dorking) — Google hacking (dorking) is a passive reconnaissance technique because it involves using advanced search operators in Google to discover publicly indexed information about a target, such as exposed configuration files or login pages, without sending any packets directly to the target's systems. It relies entirely on the search engine's pre-existing index, making it undetectable and non-intrusive. This aligns with the CEH definition of passive reconnaissance, where no direct interaction with the target occurs.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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 →
Same concept, more angles
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. Which TWO of the following are passive reconnaissance techniques? (Select 2)
easyWhy A: A WHOIS lookup queries public databases (e.g., ARIN, RIPE) to retrieve domain registration details such as registrar, creation date, and name server records. This is passive because it relies on publicly available information without sending any packets to the target network or interacting with its live systems.
Variation 2. Which TWO of the following are passive reconnaissance techniques? (Select 2)
mediumWhy A: A WHOIS lookup queries public databases (e.g., whois.arin.net) to retrieve registration details for domains or IP blocks, such as registrar, creation date, and administrative contacts. This is passive because it relies on publicly available information without sending any packets directly to the target system. The CEH defines passive reconnaissance as gathering data without interacting with the target's network or services.
Last reviewed: Jun 24, 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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.