Quick Answer
The answer is TCP, the Transmission Control Protocol, because it is the Transport layer protocol specifically designed for reliable, connection-oriented delivery. TCP achieves this by segmenting data, assigning sequence numbers to each segment, and requiring acknowledgments from the receiver, ensuring that data is delivered error-free and in the correct order. On the CompTIA Network+ N10-009 exam, this concept tests your ability to distinguish TCP from UDP at Layer 4; a common trap is confusing TCP’s reliability with UDP’s speed, so remember that TCP is the “guaranteed delivery” protocol. The exam often presents scenarios involving file transfers or web traffic where data integrity is critical, and TCP is the correct choice. A simple memory tip: TCP stands for “Trustworthy, Confirmed Packets” — if you need to confirm every piece arrived, think TCP.
This N10-009 practice question tests your understanding of networking concepts. 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 network technician is explaining the OSI model to a junior technician. The technician mentions that the Transport layer is responsible for end-to-end communication and data segmentation. Which protocol operates at the Transport layer?
IP
Why wrong: IP operates at the Network layer (Layer 3), not the Transport layer.
TCP
Correct. TCP operates at the Transport layer (Layer 4) and provides reliable, connection-oriented communication with segmentation and reassembly.
Ethernet
Why wrong: Ethernet operates at the Data Link layer (Layer 2) and Physical layer.
HTTP
Why wrong: HTTP operates at the Application layer (Layer 7).
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
TCP
TCP (Transmission Control Protocol) operates at Layer 4 (Transport) of the OSI model, providing reliable, connection-oriented end-to-end communication and data segmentation with sequencing and acknowledgment. It ensures data is delivered error-free and in order, directly fulfilling the described responsibilities.
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.
IP
Why it's wrong here
IP operates at the Network layer (Layer 3), not the Transport layer.
TCP
Why this is correct
Correct. TCP operates at the Transport layer (Layer 4) and provides reliable, connection-oriented communication with segmentation and reassembly.
Related concept
Read the scenario before looking for a memorised answer.
Ethernet
Why it's wrong here
Ethernet operates at the Data Link layer (Layer 2) and Physical layer.
HTTP
Why it's wrong here
HTTP operates at the Application layer (Layer 7).
Common exam traps
CompTIA often tests the distinction between TCP and UDP at the Transport layer, but here the trap is that candidates confuse IP (Layer 3) with Transport layer protocols because IP is fundamental to networking, yet it does not perform end-to-end communication or segmentation.
Detailed technical explanation
TCP segments data by breaking it into units called segments, each with a header containing source and destination port numbers (16-bit fields), sequence numbers, and acknowledgment numbers to manage reliable delivery. The Transport layer also provides flow control via TCP's sliding window mechanism and error recovery through retransmission of lost segments, as defined in RFC 793. In contrast, UDP (also at Layer 4) offers a simpler, connectionless service without segmentation guarantees, highlighting that not all Transport protocols handle segmentation identically.
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 N10-009 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
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
Networking Concepts — This question tests Networking Concepts — Read the scenario before looking for a memorised answer..
The correct answer is: TCP — TCP (Transmission Control Protocol) operates at Layer 4 (Transport) of the OSI model, providing reliable, connection-oriented end-to-end communication and data segmentation with sequencing and acknowledgment. It ensures data is delivered error-free and in order, directly fulfilling the described responsibilities.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
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. Which of the following network protocols operates at the Transport layer of the OSI model and provides connection-oriented, reliable data delivery?
easyWhy B: TCP (Transmission Control Protocol) operates at the Transport layer (Layer 4) of the OSI model and provides connection-oriented, reliable data delivery through mechanisms such as three-way handshake, sequence numbers, acknowledgments, and retransmission of lost segments. This ensures that data is delivered in order and without errors, making TCP the correct choice for the question.
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Last reviewed: Jun 30, 2026
This N10-009 practice question is part of Courseiva's free CompTIA 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 N10-009 exam.
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