Cisco 400-007 Based on Real Exam Environment

Graphical user interface Description automatically generated with medium confidence

B (OTV — Overlay Transport Virtualization): Allows Layer 2 extension across data centers while maintaining fault isolation by not extending STP across the WAN. Control plane handles MAC learning, which provides stability and loop avoidance between data centers.

Why other options are incorrect:

A: FabricPath is mainly for intra-data center Layer 2 fabric.

C: Advanced VPLS extends Layer 2 but carries STP across the WAN.

D: LISP operates at Layer 3, not for Layer 2 extension.

E: TRILL also focuses on intra-DC Layer 2 but not DCI fault isolation.

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B (OSPF Type 1 external):Type 1 external routes include both the external cost (from redistribution) and the internal OSPF cost to the ASBR. This ensures accurate end-to-end metric calculation across domains.

Other options explained:

A: Type 2 external ignores internal OSPF cost, potentially creating suboptimal routing.

C/D: EIGRP doesn’t use OSPF metric types; redistribution into EIGRP uses EIGRP metrics.