You have been tasked to create a Layer 2 network design that uses vPC to provide resiliency and avoid loops. vPC removes Layer 2 loops while providing redundancy through which mechanism?

Dual-active detection is a keepalive mechanism used to identify a split-brain condition when the peer link fails while both switches remain active, and does not itself prevent forwarding loops.

Address synchronization keeps MAC address and ARP tables consistent between vPC peers to optimize forwarding decisions, but it is not the mechanism that prevents loop formation.

vPC's strict forwarding rules specify that any frame arriving on the vPC peer link must not be forwarded out a vPC member port, which breaks the potential loop path that would otherwise exist between the two vPC peer switches and their downstream device. This rule allows the peer link to remain active for orphan-port traffic and control-plane communication while preventing the loop that Spanning Tree would normally block, enabling loop-free Layer 2 redundancy without relying on STP to block active links.

Bridge Assurance is a Spanning Tree Protocol feature that detects unidirectional link failures on point-to-point links and is not part of the vPC loop-prevention design.