By default, how does VRRP function on a Huawei AR router?

The correct understanding of how VRRP (Virtual Router Redundancy Protocol) operates by default on a Huawei AR router points to its preemption mode. When configured in preemption mode, the router that has the highest priority within the VRRP group will take over as the master router. This allows for dynamic changes in the master role as routers come online or go offline based on their priority settings.

In the context of VRRP, preemption ensures that if a router with a higher priority becomes available after a backup router has assumed the master role, it will assert itself as the master. This capability is significant for maintaining the best possible packet forwarding performance and ensures continuity in service by always prioritizing routers that are capable of providing the best service.

The other options do not accurately describe the default configuration of VRRP on Huawei AR routers. Since the emphasis is on preemption in these scenarios, that mode is critical for promoting an efficient routing environment and optimal redundancy.