For a customer with 12 Nutanix blocks distributed across three racks and an additional datacenter 400 kilometers away, achieving the highest level of resiliency involves ensuring both local and remote data protection.
Option B, "Async DR to a remote site," is essential for protecting against site failures by asynchronously replicating data to a branch office. This method is suitable for long-distance replication where latency and bandwidth are concerns.
Option C, "Rack awareness," is crucial in a multi-rack setup to ensure that data is distributed in such a way that a failure of a single rack does not lead to data loss or significant downtime. Rack awareness configures the placement of data replicas across different racks, improving fault tolerance within the primary datacenter.
References:Nutanix documentation on disaster recovery and data resilience strategies, such as those found in the Nutanix Bible and official Nutanix training materials, supports these recommendations, emphasizing the importance of both remote site replication and local redundancy configurations.