The correct answer is port scanning, specifically a TCP SYN scan. This is because the script uses Scapy to craft and send TCP SYN packets to a target IP across a range of ports, then monitors for SYN-ACK responses—a SYN-ACK reply indicates the port is open and listening, while no response or an RST packet indicates a closed or filtered port. On the CompTIA PenTest+ PT0-002 exam, this scenario tests your ability to recognize common reconnaissance techniques from code snippets; a common trap is confusing SYN scans with denial-of-service attacks, but the key distinction is the targeted port range and the expectation of a handshake response rather than flooding. Remember that a SYN scan is often called a “half-open” scan because it never completes the three-way handshake. A helpful memory tip: SYN sent, SYN-ACK received equals open port—think “SYN-ACK means crack in the stack.”
PT0-002 Tools and Code Analysis Practice Question
This PT0-002 practice question tests your understanding of tools and code analysis. 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.
A penetration tester is analyzing a Python script that imports the 'scapy' library. The script defines a function that sends a series of TCP SYN packets to a target IP and port range, and then waits for SYN-ACK responses. Which attack is the script performing?
Why wrong: A SYN flood is a Denial of Service attack that sends many SYN packets without completing the handshake to overwhelm the target, not to enumerate open ports.
B
Port scanning
The script performs a SYN scan to identify open ports by observing SYN-ACK responses, which is a form of port scanning.
C
ARP poisoning
Why wrong: ARP poisoning involves manipulating ARP tables on a local network, not sending TCP packets to a remote target.
D
DNS spoofing
Why wrong: DNS spoofing corrupts DNS responses, not related to TCP SYN packets.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Port scanning
The script sends TCP SYN packets to a range of ports and waits for SYN-ACK responses. This is the classic behavior of a SYN scan, a type of port scanning that identifies open ports by observing which ports respond with a SYN-ACK. The use of Scapy to craft and send these packets confirms the script is performing port scanning, not a denial-of-service attack.
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.
✗
TCP SYN flood
Why it's wrong here
A SYN flood is a Denial of Service attack that sends many SYN packets without completing the handshake to overwhelm the target, not to enumerate open ports.
✓
Port scanning
Why this is correct
The script performs a SYN scan to identify open ports by observing SYN-ACK responses, which is a form of port scanning.
Related concept
Read the scenario before looking for a memorised answer.
✗
ARP poisoning
Why it's wrong here
ARP poisoning involves manipulating ARP tables on a local network, not sending TCP packets to a remote target.
✗
DNS spoofing
Why it's wrong here
DNS spoofing corrupts DNS responses, not related to TCP SYN packets.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing a TCP SYN flood (a denial-of-service attack that sends many SYN packets without completing handshakes) with a SYN scan (a reconnaissance technique that sends SYN packets and analyzes responses to identify open ports).
Detailed technical explanation
How to think about this question
In a SYN scan, the attacker sends a SYN packet to each target port; if the port is open, the target responds with a SYN-ACK, and the attacker can then send an RST to tear down the half-open connection, avoiding a full TCP handshake. This technique is often called 'stealth scanning' because it may evade some logging mechanisms that only record completed connections. Scapy's low-level packet manipulation allows precise control over TCP flags, making it ideal for crafting these probes without relying on the host OS's TCP stack.
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 security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this PT0-002 question in full detail.
Tools and Code Analysis — This question tests Tools and Code Analysis — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Port scanning — The script sends TCP SYN packets to a range of ports and waits for SYN-ACK responses. This is the classic behavior of a SYN scan, a type of port scanning that identifies open ports by observing which ports respond with a SYN-ACK. The use of Scapy to craft and send these packets confirms the script is performing port scanning, not a denial-of-service attack.
What should I do if I get this PT0-002 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
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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. A penetration tester is analyzing a Python script that uses the 'scapy' library. The script contains the line: `packet = IP(dst='10.0.0.1')/TCP(dport=80, flags='S')`. The tester then uses `sr1(packet, timeout=2)`. What is the primary purpose of this code?
medium
✓ A.Perform a TCP SYN scan to determine if port 80 is open
B.Perform a DNS resolution for the target IP
C.Send a TCP ACK packet to test firewall rules
D.Complete a full TCP three-way handshake
Why A: The code constructs an IP packet with destination 10.0.0.1 and a TCP segment with destination port 80 and the SYN flag set (flags='S'). The sr1() function sends this packet and waits for a response (up to 2 seconds). This is the classic technique for a TCP SYN scan: if a SYN-ACK is received, the port is open; if an RST is received, the port is closed. The primary purpose is therefore to probe whether port 80 on the target is open.
Variation 2. A penetration tester is analyzing a Python script that uses the 'scapy' library to craft custom network packets. The relevant code is: ```python from scapy.all import * packet = IP(dst="192.168.1.1")/TCP(dport=80, flags="S") response = sr1(packet, timeout=2) if response.haslayer(TCP): print(response.getlayer(TCP).flags) ``` What is the primary goal of this script?
medium
A.To perform a TCP connect scan by completing the three-way handshake
✓ B.To perform a SYN scan and determine if port 80 is open
C.To send an HTTP GET request and capture the web page
D.To perform a UDP scan on port 80
Why B: The script uses Scapy to craft a TCP SYN packet (flags='S') to port 80 and sends it with sr1(), which waits for a single response. If a TCP layer is present in the reply, it prints the flags. This is the classic behavior of a SYN scan (half-open scan): it sends a SYN and analyzes the response to determine if the port is open (SYN-ACK) or closed (RST), without completing the handshake. Option B correctly identifies this as a SYN scan to check if port 80 is open.
Variation 3. A penetration tester is analyzing a Python script that uses the 'scapy' library to craft and send packets. The script contains the following code snippet: 'send(IP(dst=target)/TCP(dport=port, flags='S'))'. The script then listens for responses and looks for packets with flags 'SA'. Which type of scan is this script performing?
medium
A.TCP Connect scan
✓ B.TCP SYN scan (half-open scan)
C.TCP FIN scan
D.TCP Xmas scan
Why B: The script sends a TCP SYN packet (flags='S') and listens for a SYN-ACK response (flags='SA'), which is the defining behavior of a TCP SYN scan (also known as a half-open scan). This scan never completes the three-way handshake, making it stealthier than a full TCP Connect scan. The use of Scapy's `send()` function (Layer 3) rather than `sr()` or a socket-level connect confirms it is crafting raw packets, not relying on the OS's TCP stack.
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