The primary purpose of the command `hping3 -S -p 80 --flood 192.168.1.100` is to execute a denial-of-service (DoS) attack against the target’s web server. This is correct because the `-S` flag sends TCP SYN packets, `-p 80` targets the HTTP port, and the `--flood` flag disables packet rate limiting, causing a rapid stream of half-open connections that exhaust the server’s backlog queue and prevent legitimate handshakes. On the Certified Ethical Hacker CEH exam, this scenario tests your ability to identify a classic SYN flood attack using hping3, a common tool in the DoS and DDoS domain. A frequent trap is confusing `--flood` with a simple ping flood or mistaking the `-S` flag for a full three-way handshake; remember that the attack never completes the handshake. Memory tip: “SYN flood with hping3: ‘S’ for SYN, ‘flood’ for no mercy, ‘80’ for the web server’s door.”
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.
During a penetration test, you run the following command: hping3 -S -p 80 --flood 192.168.1.100. What is the PRIMARY purpose of this command?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Execute a denial-of-service (DoS) attack against the target's web server
The command `hping3 -S -p 80 --flood 192.168.1.100` sends a high volume of TCP SYN packets to port 80 of the target without completing the three-way handshake. The `--flood` flag disables packet rate limiting, causing a rapid stream of SYN packets that exhausts the target's connection queue, effectively performing a SYN flood denial-of-service (DoS) attack against the web server.
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.
✗
Banner grab the HTTP service on port 80
Why it's wrong here
Banner grabbing requires a full connection or specific payload, not a flood of SYN packets.
✗
Fingerprint the operating system of the target
Why it's wrong here
OS fingerprinting requires analyzing responses, but flood mode does not wait for replies.
✗
Perform a TCP connect scan to identify open ports
Why it's wrong here
hping3 can scan, but --flood is for DoS, not scanning. -S is SYN flag, but flood mode overwhelms the target.
✓
Execute a denial-of-service (DoS) attack against the target's web server
Why this is correct
--flood sends packets rapidly, and -S sets SYN flag, causing a SYN flood DoS attack.
Clue confirmation
The clue word "primary" in the question point toward this answer.
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 a SYN flood DoS attack with a SYN scan (port scanning), but the `--flood` flag explicitly indicates a denial-of-service intent, not reconnaissance.
Detailed technical explanation
How to think about this question
The SYN flood exploits the TCP three-way handshake by sending a barrage of SYN packets with spoofed or non-existent source IPs, causing the target to allocate memory for half-open connections until its backlog queue overflows. In real-world scenarios, modern operating systems use SYN cookies (RFC 4987) to mitigate this, but older or misconfigured servers remain vulnerable. The `--flood` flag in hping3 bypasses any inter-packet delay, saturating the target's network interface or CPU.
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: Execute a denial-of-service (DoS) attack against the target's web server — The command `hping3 -S -p 80 --flood 192.168.1.100` sends a high volume of TCP SYN packets to port 80 of the target without completing the three-way handshake. The `--flood` flag disables packet rate limiting, causing a rapid stream of SYN packets that exhausts the target's connection queue, effectively performing a SYN flood denial-of-service (DoS) attack against the web server.
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.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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