* B (Strategic planning): Long-term business-aligned decisions that shape future infrastructure needs.
* D (Tactical planning): Short-to-mid-term activities that adjust design based on evolving operational realities, constraints, and priorities.
Why other options are incorrect:
* A & E: While cost and business optimization are goals, they are not defined planning approaches.
* C: Modular is a design methodology, not a planning approach.
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Explanation:
Graphical user interface Description automatically generated with medium confidence

* PIM-SSM (Source-Specific Multicast) is optimized for multicast delivery directly via Shortest Path Tree (SPT) only.
* SSM eliminates the need for shared trees (RPs), simplifies the control plane, and avoids rendezvous points altogether.
* This design is highly scalable in multidomain and IPv6 environments, fully aligned with CCDE v3.1 best practices for modern multicast deployments.
Why other options are incorrect:
* A: PIM-DM floods traffic initially, not SPT-based.
* B: PIM-SM uses shared trees first and may switch to SPT later.
* D: Bidir-PIM uses shared trees exclusively, not SPT.
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#Explanation:
* D: PIM Sparse Mode with RP advertisement via BSR (Bootstrap Router) is more standards-based and interoperable across vendors compared to Auto-RP, which is Cisco-proprietary. Using BSR minimizes manual RP configuration and supports multi-vendor environments.
Incorrect options:
* A and C: Dense mode is inefficient and doesn't scale well, especially on WANs.
* B: Auto-RP is Cisco-proprietary and may not work across mixed vendor routers.