400-007 Exam Dumps : Cisco Certified Design Expert (CCDE v3.1)

The primary goal of resilient modular network design is to minimize the operational impact of failures by automating recovery and isolating fault domains.

C: Reducing failures that require manual intervention improves availability, reduces downtime, and ensures stability even under fault conditions.

Why other options are incorrect:

A: This is a limitation to avoid, not a design driver.

B: Minimizing app downtime is an outcome, not the operational driver itself.

D: Development time is not related to operational network resiliency.

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The SDN architecture separates the control plane from the data plane. In this model, the SDN controller is the central element responsible for:

Receiving application intent via northbound APIs

Translating intent into traffic policies

Communicating with infrastructure devices using southbound APIs

The SDN controller enforces policies such as path selection, QoS, and access control rules across the network fabric, ensuring traffic flows align with administrator-defined logic. Neither northbound nor southbound APIs enforce policy themselves; they serve as communication interfaces.

The packet forwarding engine (Option A) simply performs data-plane functions based on instructions, but does not interpret or apply policies.

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The scenario prioritizes:

In-house management (not managed services)

Scalability (exponential branch growth)

OPEX reduction (low operational cost)

SD-WAN over L3VPN offers a balance of:

Mid-level ISP cost (leveraging L3VPN as transport)

Centralized management and automation (ZTP, templates)

Support for segmentation, application-aware routing, and path control

Lower OPEX due to simplified configuration and monitoring

Managed SD-WAN has higher ISP and OPEX cost, and DMVPN is more manual and complex to scale. SD-WAN over L2VPN might reduce ISP cost but is less common and not optimal for rapid scalability.