- A
Data plane
Why wrong: The data plane forwards packets based on rules from the control plane.
- B
Application plane
Why wrong: The application plane interacts with the controller via northbound APIs.
- C
Management plane
Why wrong: The management plane handles administrative tasks.
- D
Control plane
The control plane decides how traffic should be routed.
Question 646 of 1,000
200-901 Network Fundamentals Practice Question
This 200-901 practice question tests your understanding of network fundamentals. 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.
In an SDN architecture, which layer is responsible for making decisions about where traffic should be forwarded?
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
✓
Control plane
In SDN architecture, the control plane is responsible for making forwarding decisions by maintaining the network topology and computing paths for traffic flows. It communicates these decisions to the data plane via southbound protocols like OpenFlow or NETCONF, ensuring that packets are forwarded according to the desired policies.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Data plane
Why it's wrong here
The data plane forwards packets based on rules from the control plane.
- ✗
Application plane
Why it's wrong here
The application plane interacts with the controller via northbound APIs.
- ✗
Management plane
Why it's wrong here
The management plane handles administrative tasks.
- ✓
Control plane
Why this is correct
The control plane decides how traffic should be routed.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between the control plane and management plane, where candidates mistakenly think that configuration (management plane) is the same as making forwarding decisions, but the control plane is the one that dynamically determines traffic paths.
Detailed technical explanation
How to think about this question
Under the hood, the control plane in SDN typically runs as a logically centralized controller (e.g., OpenDaylight, ONOS) that uses a network-wide view to compute optimal paths using algorithms like Dijkstra's shortest path or traffic engineering constraints. The controller installs flow entries into switches' flow tables via OpenFlow, where each entry contains match fields, actions, and counters; the data plane then processes packets at wire speed using TCAM-based lookups. In a real-world scenario, if a link fails, the control plane recalculates paths and updates flow tables, while the data plane simply follows the new rules without any local decision-making.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 200-901 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
Got this wrong? Here's your next step.
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
Questions learners often ask
What does this 200-901 question test?
Network Fundamentals — This question tests Network Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Control plane — In SDN architecture, the control plane is responsible for making forwarding decisions by maintaining the network topology and computing paths for traffic flows. It communicates these decisions to the data plane via southbound protocols like OpenFlow or NETCONF, ensuring that packets are forwarded according to the desired policies.
What should I do if I get this 200-901 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jul 4, 2026
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.
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