Which solution will meet these requirements?
Use Multi-AZ Redis replication groups with shards that contain multiple nodes.
Use Redis shards that contain multiple nodes with Redis append only files (AOF) turned on.
Use a Multi-AZ Redis cluster with more than one read replica in the replication group.
Use Redis shards that contain multiple nodes with Auto Scaling turned on.
Explanations:
Multi-AZ Redis replication groups with shards containing multiple nodes provide high availability and durability by replicating data across multiple Availability Zones (AZs) and allow failover without data loss.
While Redis append only files (AOF) help with durability by logging operations, this does not provide high availability across AZs or Regions. Redis AOF alone is insufficient for regional failover or HA at the node level.
Adding read replicas improves read performance but does not provide high availability across multiple AZs at the primary node level. Read replicas alone do not offer regional redundancy.
Auto Scaling does not provide high availability at the node or Region level, as it primarily adjusts capacity based on traffic without adding fault tolerance or cross-AZ resilience.
I reckon the answer is:
Use Multi-AZ Redis replication groups with shards that contain multiple nodes.