Quick Answer
The answer is to perform a WHOIS lookup against the domain. This is the most appropriate technique because a WHOIS query returns the registered network range—often listed as NetRange or CIDR—and the ISP, typically found in the OrgName or descr fields, directly from the regional internet registry database. On the Certified Ethical Hacker CEH exam, this question tests your understanding of footprinting and reconnaissance, specifically how to map a target’s IP address block and upstream provider without active scanning. A common trap is confusing WHOIS with DNS tools like nslookup, which reveal IP addresses but not the owning ISP or network range. Remember the memory tip: “WHOIS gives the who, where, and which ISP—DNS only gives the IP.”
This CEH practice question tests your understanding of footprinting and reconnaissance. 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 penetration tester is performing a footprinting exercise on a target company. The tester wants to identify the network range and ISP of the target. Which of the following tools or techniques is MOST appropriate for this purpose?
Query the Netcraft site for the domain
Why wrong: Netcraft gives technology stack, not ISP.
Perform a WHOIS lookup against the domain
WHOIS provides IP range and ISP info.
Use nslookup to query the authoritative name servers
Why wrong: nslookup only resolves DNS records.
Run a traceroute to the target web server
Why wrong: Shows path, not ISP ownership.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Perform a WHOIS lookup against the domain
A WHOIS lookup against the target domain returns registration details that include the organization's network range (via the 'NetRange' or 'CIDR' fields) and the ISP (via the 'OrgName' or 'descr' fields). This directly maps to the footprinting goal of identifying the target's IP address block and upstream provider, as defined in RFC 3912 and common WHOIS database schemas.
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.
Query the Netcraft site for the domain
Why it's wrong here
Netcraft gives technology stack, not ISP.
Perform a WHOIS lookup against the domain
Why this is correct
WHOIS provides IP range and ISP info.
Related concept
Read the scenario before looking for a memorised answer.
Use nslookup to query the authoritative name servers
Why it's wrong here
nslookup only resolves DNS records.
Run a traceroute to the target web server
Why it's wrong here
Shows path, not ISP ownership.
Common exam traps
The trap here is that candidates confuse DNS resolution (nslookup) or path tracing (traceroute) with ownership data, but only WHOIS provides the authoritative registration records for network blocks and ISPs.
Trap categories for this question
Command / output trap
Shows path, not ISP ownership.
Detailed technical explanation
WHOIS data is stored in distributed registries (RIRs like ARIN, RIPE, APNIC) and queried via port 43 (whois protocol) or web interfaces. The returned 'NetRange' field contains the exact CIDR block assigned to the organization, while 'OrgName' identifies the ISP or entity. In real-world engagements, a tester might combine WHOIS with BGP looking glass queries to verify the ISP's ASN, but WHOIS remains the direct source for network range and ISP identification.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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: Perform a WHOIS lookup against the domain — A WHOIS lookup against the target domain returns registration details that include the organization's network range (via the 'NetRange' or 'CIDR' fields) and the ISP (via the 'OrgName' or 'descr' fields). This directly maps to the footprinting goal of identifying the target's IP address block and upstream provider, as defined in RFC 3912 and common WHOIS database schemas.
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 11, 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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