The hierarchical model provides:
* A: Fault isolation by limiting failures to specific layers.
* D: Modularity and flexibility, making it easier to implement changes without affecting the entire network.
Why other options are incorrect:
* B: Design typically starts at the access layer upwards.
* C: Server access is handled at the distribution or access layer, not the core.
* E: Security is handled at access/distribution layers, not primarily at core layer.

Cisco FabricPath is a Layer 2 multipath technology that blends traditional Layer 2 Ethernet with routing technologies to enable loop-free forwarding and scalability. Two critical mechanisms used to mitigate loops:
* C. RPF (Reverse Path Forwarding) Check: FabricPath applies a reverse path forwarding check, similar to multicast, to verify the source of a frame and discard duplicates arriving on unexpected paths.
* D. TTL Header: FabricPath adds a Time-To-Live (TTL) field to Layer 2 frames, which is not present in traditional Ethernet. This prevents indefinite circulation of frames by limiting their lifetime in the network-much like in IP.
These elements allow FabricPath to prevent broadcast storms and loops in multipath Layer 2 topologies, addressing legacy STP limitations with efficient loop-avoidance methods.

* TOGAF (The Open Group Architecture Framework) provides a full enterprise architecture methodology including:
* Business requirements gathering
* Gap analysis
* Architecture modeling
* Comprehensive design documentation
* TOGAF is widely referenced in CCDE v3.1 for high-level architecture development.
Why other options are incorrect:
* B (ITIL): Focuses on service management, not architecture design.
* C (FCAPS): Defines network management functional areas.
* D (COBIT): Focuses on governance and compliance, not design frameworks.
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