N10-009 Networking Concepts Practice Question
At which layer of the OSI model does a device provide flow control, error detection, and recovery for end-to-end communication?
⚠ Common exam trap
The N10-009 exam often tests the distinction between hop-by-hop (Data Link) and end-to-end (Transport) responsibilities, tricking candidates into confusing link-layer error detection (e.g., Ethernet CRC) with end-to-end recovery, which is exclusively a Transport layer function.
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
✓
A: Transport layer
The Transport layer (Layer 4) is responsible for end-to-end communication between source and destination hosts. It provides flow control (e.g., TCP's sliding window mechanism), error detection (via checksums in TCP and UDP headers), and recovery (through TCP retransmission of lost segments). These functions ensure reliable data delivery across the network, distinguishing it from lower layers that handle hop-by-hop or link-local tasks.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
A: Transport layer
Why this is correct
The Transport layer, specifically through protocols like TCP, provides end-to-end flow control to manage the rate of data transmission between a sending and receiving application. It prevents a faster sender from overwhelming a slower receiver by using a sliding window mechanism, where the receiver advertises its available buffer space. This ensures that the sender only transmits data up to the receiver's advertised window size, dynamically adjusting the data flow to match the receiver's processing capabilities and preventing buffer overflows.
- ✗
B: Network layer
Why it's wrong here
The Network layer is primarily responsible for logical addressing (e.g., IP addresses) and routing packets across different networks from a source host to a destination host. Its main function is to determine the optimal path for data, ensuring inter-network communication and packet forwarding. This layer does not implement mechanisms for end-to-end flow control or reliable data delivery, as these functions are delegated to higher layers in the OSI model.
When this WOULD be correct
A question asking 'At which layer does a device provide logical addressing and routing between networks?' would have the Network layer as the correct answer.
- ✗
C: Data Link layer
Why it's wrong here
The Data Link layer implements local flow control, which manages data transmission between two directly connected devices on the same physical link. This prevents a single device from monopolizing the medium or overwhelming its immediate neighbor's buffer. However, it does not provide the end-to-end flow control necessary to manage data rates across an entire network path, which is a responsibility handled at the Transport layer.
When this WOULD be correct
A question asking: 'At which layer of the OSI model does a device provide flow control, error detection, and recovery for communication between two directly connected nodes?' would make the Data Link layer correct.
- ✗
D: Session layer
Why it's wrong here
The Session layer establishes, manages, and terminates communication sessions between applications, providing services like dialog control and synchronization. It determines whose turn it is to transmit data and can insert checkpoints into the data stream for recovery purposes. While it manages the structure and flow of the dialogue, it does not concern itself with the rate at which data is exchanged or the reliable, error-free delivery of that data, which are functions handled at lower layers.
When this WOULD be correct
A question asking: 'At which OSI layer does a device manage dialog control, session establishment, and checkpointing?' would make the Session layer 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.
✓A: Transport layerCorrect answer▾
Why this is correct
The Transport layer, specifically through protocols like TCP, provides end-to-end flow control to manage the rate of data transmission between a sending and receiving application. It prevents a faster sender from overwhelming a slower receiver by using a sliding window mechanism, where the receiver advertises its available buffer space. This ensures that the sender only transmits data up to the receiver's advertised window size, dynamically adjusting the data flow to match the receiver's processing capabilities and preventing buffer overflows.
✗B: Network layerWrong answer — click to see why▾
Why this is wrong here
The Network layer (Layer 3) handles routing and logical addressing, but flow control, error detection, and recovery for end-to-end communication are functions of the Transport layer (Layer 4).
★ When this WOULD be the correct answer
A question asking 'At which layer does a device provide logical addressing and routing between networks?' would have the Network layer as the correct answer.
Why candidates choose this
Candidates may confuse the Network layer's end-to-end delivery of packets with the Transport layer's end-to-end communication services, or they may associate error detection with IP checksums.
✗C: Data Link layerWrong answer — click to see why▾
Why this is wrong here
The Data Link layer provides flow control, error detection, and recovery only for direct node-to-node links, not for end-to-end communication across multiple network segments.
★ When this WOULD be the correct answer
A question asking: 'At which layer of the OSI model does a device provide flow control, error detection, and recovery for communication between two directly connected nodes?' would make the Data Link layer correct.
Why candidates choose this
Candidates may confuse the Data Link layer's local error control with the Transport layer's end-to-end responsibilities, especially since both layers perform similar functions but at different scopes.
✗D: Session layerWrong answer — click to see why▾
Why this is wrong here
The Session layer (Layer 5) manages sessions, dialog control, and synchronization, but does not provide flow control, error detection, or recovery for end-to-end communication; those functions belong to the Transport layer.
★ When this WOULD be the correct answer
A question asking: 'At which OSI layer does a device manage dialog control, session establishment, and checkpointing?' would make the Session layer the correct answer.
Why candidates choose this
Candidates may confuse session management with end-to-end communication services, or incorrectly associate 'recovery' with session checkpointing rather than transport-layer retransmission.
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?”
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
Learn chapter
Network Virtualization and VXLAN
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.
Key term
UDP
UDP (User Datagram Protocol) is a communication protocol that sends data quickly without first checking if the receiver is ready or if the data arrived correctly.
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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.