With the zone redundancy feature for Azure Cache for Redis in the Premium tier, you can deploy your caches across multiple availability zones and obtain increased availability. You can also improve redundancy by adding more replica nodes. A zone-enabled cache automatically distributes its replicating nodes over the zones that you have selected. It is more resilient to datacenter-level issues and outages.
To get started, review the documentation on Enable zone redundancy and Add more replicas. The high availability documentation will help you learn about the different options that Azure Cache for Redis supports.