N10-009 Networking Concepts Practice Question
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?
⚠ Common exam trap
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.
Answer choices
Why each option matters
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.
Answer analysis
Option-by-option breakdown
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 (Internet Protocol) functions at the Network layer (Layer 3) of the OSI model, primarily responsible for logical addressing and routing packets across different networks. Unlike TCP, IP provides a connectionless, best-effort delivery service, meaning it does not guarantee delivery, order, or error-free transmission. Its main role is to enable end-to-end communication by determining the optimal path for data packets, making it distinct from the Transport layer's focus on reliable host-to-host communication.
When this WOULD be correct
A question asking 'Which protocol is responsible for logical addressing and routing between networks?' would make IP the correct answer, as it operates at the Network layer.
- ✓
TCP
Why this is correct
TCP (Transmission Control Protocol) is a core protocol of the Transport layer (Layer 4) of the OSI model. It provides reliable, connection-oriented communication by establishing a three-way handshake before data transfer. TCP ensures data integrity through sequence numbers, acknowledgments, and retransmission of lost segments, also managing flow control and congestion control to optimize data delivery. This makes it suitable for applications requiring guaranteed delivery, such as web browsing and email.
- ✗
Ethernet
Why it's wrong here
Ethernet is a suite of protocols and standards that primarily operates at the Data Link layer (Layer 2) and the Physical layer (Layer 1) of the OSI model. At Layer 2, Ethernet defines how data is formatted into frames, uses MAC addresses for local device identification, and manages access to the physical medium, often employing CSMA/CD or CSMA/CA. It handles error detection within a single network segment but does not provide end-to-end reliability or routing across multiple networks.
When this WOULD be correct
A question asking 'Which protocol operates at the Data Link layer of the OSI model?' would make Ethernet the correct answer, as it defines framing, MAC addressing, and media access control.
- ✗
HTTP
Why it's wrong here
HTTP (Hypertext Transfer Protocol) operates at the Application layer (Layer 7) of the OSI model, serving as the foundation for data communication on the World Wide Web. It defines the methods for clients to request and servers to respond with resources, such as web pages or images. As an application-layer protocol, HTTP focuses on the specific services and data formats required by end-user applications, relying on lower-layer protocols like TCP/IP to handle the actual data transmission.
When this WOULD be correct
If the question asked 'Which protocol operates at the Application layer of the OSI model?' or 'Which protocol is used for web traffic?', then HTTP would be the correct answer.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓TCPCorrect answer▾
Why this is correct
TCP (Transmission Control Protocol) is a core protocol of the Transport layer (Layer 4) of the OSI model. It provides reliable, connection-oriented communication by establishing a three-way handshake before data transfer. TCP ensures data integrity through sequence numbers, acknowledgments, and retransmission of lost segments, also managing flow control and congestion control to optimize data delivery. This makes it suitable for applications requiring guaranteed delivery, such as web browsing and email.
✗IPWrong answer — click to see why▾
Why this is wrong here
IP operates at the Network layer (Layer 3), not the Transport layer. It handles routing and addressing, not end-to-end communication and data segmentation.
★ When this WOULD be the correct answer
A question asking 'Which protocol is responsible for logical addressing and routing between networks?' would make IP the correct answer, as it operates at the Network layer.
Why candidates choose this
Candidates often confuse IP with TCP because they are commonly paired (TCP/IP), leading them to mistakenly associate IP with Transport layer functions.
✗EthernetWrong answer — click to see why▾
Why this is wrong here
Ethernet operates at the Data Link layer (Layer 2) and the Physical layer (Layer 1), not the Transport layer (Layer 4). It handles local network framing and media access, not end-to-end communication or segmentation.
★ When this WOULD be the correct answer
A question asking 'Which protocol operates at the Data Link layer of the OSI model?' would make Ethernet the correct answer, as it defines framing, MAC addressing, and media access control.
Why candidates choose this
Candidates may confuse Ethernet with TCP/IP because both are fundamental to networking, or they might think Ethernet handles data delivery across networks, not realizing it is limited to local segments.
✗HTTPWrong answer — click to see why▾
Why this is wrong here
HTTP operates at the Application layer (Layer 7) of the OSI model, not the Transport layer. The Transport layer is responsible for end-to-end communication and segmentation, which is handled by protocols like TCP and UDP.
★ When this WOULD be the correct answer
If the question asked 'Which protocol operates at the Application layer of the OSI model?' or 'Which protocol is used for web traffic?', then HTTP would be the correct answer.
Why candidates choose this
Candidates may confuse HTTP with TCP because HTTP relies on TCP for reliable transport, or they might mistakenly think HTTP is a transport protocol due to its common association with network communication.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
Go deeper
Related to this question
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Key term
OSI model
The OSI model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven distinct layers, from physical hardware to application software.
Key term
TCP
TCP is a connection-oriented transport layer protocol that ensures reliable, ordered, and error-checked delivery of data between applications over IP networks.
About these practice questions
One of 464 original N10-009 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on N10-009
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?
easy- A.UDP
- ✓ B.TCP
- C.IP
- D.ARP
Why 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.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.