200-901 Network Fundamentals Practice Question
A developer is writing a script that uses a REST API to configure network devices via NETCONF. Which layer of the SDN architecture does NETCONF belong to?
⚠ Common exam trap
Cisco often tests the distinction between the protocol itself (NETCONF) and the architectural layer it belongs to, leading candidates to mistakenly select 'Control layer' because they associate NETCONF with the controller, rather than recognizing it as a southbound interface protocol.
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
✓
Southbound interface
NETCONF is a network management protocol used to install, manipulate, and delete the configuration of network devices. In the SDN architecture, the southbound interface is the layer that connects the control plane to the data plane, and NETCONF operates as a southbound protocol by carrying configuration data from a controller or management system down to network devices.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Northbound interface
Why it's wrong here
NETCONF sits between the SDN controller and managed devices, so it is a southbound protocol; the northbound interface instead exposes controller capabilities to applications via REST APIs. It is tempting because the developer's script calls a REST API, which is itself a northbound construct, but that describes the script, not NETCONF.
- ✓
Southbound interface
Why this is correct
NETCONF carries configuration and state data between the SDN controller and managed network devices, sitting below the controller. This places it in the southbound interface layer, distinct from northbound APIs that expose controller capabilities to applications.
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Application layer
Why it's wrong here
The application layer hosts the orchestrating scripts and business logic that call the controller; NETCONF operates below the controller, carrying configuration to devices. It is tempting because the developer writes an application, yet the question asks which layer the protocol itself occupies, not where the script runs.
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Control layer
Why it's wrong here
The control layer contains the SDN controller's decision logic and maintains network state; NETCONF is the southbound protocol the controller uses to push configuration to devices, not the control layer itself. It is tempting because NETCONF traffic terminates at the controller, blurring the boundary between protocol and controller function.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 practice question is part of Courseiva's free Cisco 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 200-901 exam.