200-901 Question #498: Real Exam Question with Answer & Explanation

Question

Drag and Drop Question Drag and drop the protocols from the left onto the management technologies on the right that expose the protocols to network engineers. Answer:

Explanation

The correct solution categorizes network protocols based on whether they are primarily used for direct device-based management or for controller-based (Software-Defined Networking) management.

Approach. The correct interaction is to drag 'OpenFlow' and 'REST' into the 'Controller-based management' section, and 'NETCONF' and 'RESTCONF' into the 'Device-based management' section. This is correct because:

• OpenFlow: This is a foundational protocol for Software-Defined Networking (SDN). It enables an SDN controller to directly program the forwarding plane of network devices (switches, routers), making it central to controller-based management architectures.
• REST: Representational State Transfer (REST) is an architectural style for networked applications. In the context of controller-based management, RESTful APIs are frequently used as northbound interfaces by SDN controllers to expose network services and capabilities to applications, orchestration platforms, or other controllers. While general, its typical role in modern network automation often involves interacting with controllers.
• NETCONF: The Network Configuration Protocol (NETCONF) is an IETF standard protocol designed for configuring network devices. It provides a programmatic and robust way to manage configuration and retrieve operational data directly from a network device, making it a key protocol for device-based management.
• RESTCONF: RESTCONF is an HTTP-based protocol that provides a programmatic interface for accessing configuration and operational data on network devices using REST principles and often leveraging YANG data models. Like NETCONF, it is used for direct interaction with network devices for management and configuration, fitting into the device-based management category.

Common mistakes.

• common_mistake. A common mistake would be confusing the roles of REST and RESTCONF, or misplacing OpenFlow. For instance, putting RESTCONF under 'Controller-based management' is incorrect because RESTCONF is specifically designed for direct configuration interaction with network devices, not as a controller's northbound API. Similarly, placing NETCONF under 'Controller-based management' would be wrong as NETCONF is for direct device configuration. Placing OpenFlow under 'Device-based management' is incorrect because OpenFlow's primary role is to facilitate the programming of devices by a centralized controller, not for direct device management by an engineer in a traditional sense. Misplacing REST to 'Device-based management' would also be incorrect because while a device might expose a REST API, 'RESTCONF' is the more specific and standardized RESTful approach for device configuration, and 'REST' is more commonly associated with northbound interfaces of SDN controllers.

Concept tested. The core concept being tested is the understanding of different network management paradigms- specifically distinguishing between controller-based (Software-Defined Networking) and device-based management- and knowing the primary role and context of key network management protocols and APIs like NETCONF, OpenFlow, RESTCONF, and REST.

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