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.
Which TWO of the following are examples of active reconnaissance techniques? (Select two)
Querying Shodan for open ports on a target
Why wrong: Shodan uses previously collected data, passive.
Running an Nmap SYN scan against a target
Nmap sends packets to the target.
Searching for sensitive files using Google dorks
Why wrong: Google dorking is passive.
Performing a WHOIS lookup
Why wrong: WHOIS is passive.
Using Netcat to grab banners from a web server
Netcat connects to the server, making it active.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Running an Nmap SYN scan against a target
Option B is correct because an Nmap SYN scan (also known as a half-open scan) sends a TCP SYN packet to a target port and analyzes the response. If a SYN/ACK is received, the port is open; if an RST is received, the port is closed. This scan actively interacts with the target system by sending network traffic, making it an active reconnaissance technique.
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.
Querying Shodan for open ports on a target
Why it's wrong here
Shodan uses previously collected data, passive.
Running an Nmap SYN scan against a target
Why this is correct
Nmap sends packets to the target.
Related concept
Read the scenario before looking for a memorised answer.
Searching for sensitive files using Google dorks
Why it's wrong here
Google dorking is passive.
Performing a WHOIS lookup
Why it's wrong here
WHOIS is passive.
Using Netcat to grab banners from a web server
Why this is correct
Netcat connects to the server, making it active.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse passive information-gathering tools (like Shodan, Google dorks, or WHOIS) with active techniques, because they involve querying external databases rather than directly engaging the target's systems.
Detailed technical explanation
Active reconnaissance techniques involve direct interaction with the target, such as sending probes, packets, or connection requests. For example, an Nmap SYN scan sends a TCP SYN packet and waits for a SYN/ACK (open) or RST (closed) response, but never completes the three-way handshake, making it stealthier than a full connect scan. In contrast, passive techniques like Shodan queries or Google dorks rely on third-party data and leave no trace on 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, Reconnaissance and Scanning — This question tests Footprinting, Reconnaissance and Scanning — Read the scenario before looking for a memorised answer..
The correct answer is: Running an Nmap SYN scan against a target — Option B is correct because an Nmap SYN scan (also known as a half-open scan) sends a TCP SYN packet to a target port and analyzes the response. If a SYN/ACK is received, the port is open; if an RST is received, the port is closed. This scan actively interacts with the target system by sending network traffic, making it an active reconnaissance technique.
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.
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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.
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