PT0-002 A SYN scan sends only a TCP SYN packet. 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. A key principle to apply: a SYN scan sends only a TCP SYN packet.. 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 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?
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
✓
To perform a SYN scan and determine if port 80 is open
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.
Key principle: A SYN scan sends only a TCP SYN packet.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
To perform a TCP connect scan by completing the three-way handshake
Why it's wrong here
A TCP connect scan uses a full handshake. This script only sends a SYN and does not complete the handshake; it only checks for a SYN-ACK.
✓
To perform a SYN scan and determine if port 80 is open
Why this is correct
The script sends a SYN packet to port 80 and analyzes the response flags; a SYN-ACK indicates the port is open.
Clue confirmation
The clue word "primary" in the question point toward this answer.
To send an HTTP GET request and capture the web page
Why it's wrong here
HTTP requests require application-layer payload and proper handshake; this script only sends a raw SYN packet at the transport layer.
✗
To perform a UDP scan on port 80
Why it's wrong here
UDP scans use UDP packets, not TCP. This script explicitly uses TCP with SYN flag.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse a SYN scan with a full connect scan (Option A) because both involve sending a SYN, but the key difference is that a SYN scan never sends the final ACK, making it stealthier and not a full handshake.
Detailed technical explanation
How to think about this question
A SYN scan (stealth scan) exploits the TCP three-way handshake: an open port responds with SYN-ACK, a closed port with RST. The scanner never completes the handshake, so the target may not log the connection. Scapy's sr1() function sends a packet at layer 3 and waits for a response; the script checks for a TCP layer in the reply to distinguish between a SYN-ACK (open) and RST (closed), but does not handle the case where no response is received (filtered port).
KKey Concepts to Remember
A SYN scan sends only a TCP SYN packet.
An open port responds to a SYN with a SYN-ACK.
A SYN scan does not complete the TCP three-way handshake.
Scapy's `sr1` function sends a packet and waits for one response.
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
A SYN scan sends only a TCP SYN packet.
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 — A SYN scan sends only a TCP SYN packet..
What is the correct answer to this question?
The correct answer is: To perform a SYN scan and determine if port 80 is open — 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.
What should I do if I get this PT0-002 question wrong?
Review a SYN scan sends only a TCP SYN packet., then practise related PT0-002 questions on the same topic to reinforce the concept.
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?
A SYN scan sends only a TCP SYN packet.
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