Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
In a controller-based design, which statement best describes a northbound API?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
An application-facing API used by external software to communicate with the controller
This is correct because northbound APIs are intended for communication from applications and orchestration systems into the controller.
B
Distractor review
A cable type used between controller clusters
This is wrong because northbound and southbound refer to logical API direction, not physical cabling.
C
Distractor review
The link-state protocol the controller uses to reach switches
This is wrong because northbound APIs are not routing protocols.
D
Distractor review
A mechanism that removes the need for authentication
This is wrong because APIs often still require authentication and authorization.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is mistaking the northbound API for a physical cable or a routing protocol. Some candidates incorrectly associate 'northbound' with physical connections between controllers or with link-state protocols, which is incorrect. Northbound APIs are purely logical interfaces used by applications to communicate with the controller, not hardware or routing mechanisms. Another trap is assuming northbound APIs bypass security controls; in reality, these APIs require proper authentication and authorization. Misunderstanding these points can lead to selecting incorrect answers that describe physical or protocol-related concepts rather than software interfaces.
Technical deep dive
How to think about this question
A northbound API in a controller-based network architecture is the interface that allows external applications, orchestration platforms, and management tools to communicate with the network controller. This API exposes the controller's capabilities such as retrieving network state information, pushing configuration changes, and automating policy enforcement. It acts as the upward-facing interface, enabling software above the controller layer to interact programmatically with the network infrastructure. The decision to use a northbound API is based on the architectural separation between the controller and the applications that consume its services. While the controller manages the underlying network devices via southbound protocols (like OpenFlow or NETCONF), the northbound API provides a standardized and abstracted method for applications to request data or trigger network changes without dealing with device-specific details. This abstraction is critical in automation and programmability, as it simplifies integration and orchestration. A common exam trap is confusing northbound APIs with physical cabling or routing protocols. Northbound APIs are purely logical software interfaces and do not represent physical connections or routing mechanisms. In practical Cisco environments, northbound APIs often use RESTful web services or other programmatic interfaces secured by authentication and authorization, contrary to the misconception that they remove security requirements. Understanding this distinction helps avoid misinterpretation of controller roles and API directions in exam scenarios.
KKey Concepts to Remember
- A northbound API exposes the controller's functions to external applications and orchestration systems for network automation and management.
- Controllers use southbound APIs to communicate with network devices, while northbound APIs serve as the interface for software above the controller.
- Northbound APIs enable programmability by abstracting device-specific details and providing a standardized method to query or configure the network.
- Northbound APIs typically use RESTful or similar web-based protocols secured by authentication and authorization mechanisms.
- The northbound interface does not represent physical cabling or routing protocols but is a logical software interface in the network architecture.
- Automation tools rely on northbound APIs to integrate with controllers and implement policy changes or gather telemetry data.
- Understanding the directionality of northbound versus southbound APIs is essential to correctly interpret controller-based network designs.
- Northbound APIs facilitate scalability and flexibility by decoupling application logic from the underlying network infrastructure.
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.
Related practice questions
Related 200-301 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
A northbound API exposes the controller's functions to external applications and orchestration systems for network automation and management.
What is the correct answer to this question?
The correct answer is: An application-facing API used by external software to communicate with the controller — A northbound API is the interface exposed by the controller to external applications, orchestration systems, dashboards, or automation tools. In plain language, it is the way software above the controller communicates with the controller so that it can request data, apply policy, or trigger changes. This is different from the southbound side, where the controller interacts with the underlying infrastructure devices. This concept appears often in automation topics because it helps define where the controller sits in the larger architecture. A northbound API is not a physical cable, and it does not replace security controls. It is an application-facing software interface, which is exactly what the correct answer should capture.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
Discussion
Loading comments…
Sign in to join the discussion.