For high availability, Amazon ElastiCache for Redis supports Multi-AZ with automatic failover, which provides primary and replica nodes in different Availability Zones. If the primary node fails, Redis automatically promotes a replica to primary.
From AWS Documentation:
“When you enable Multi-AZ with automatic failover, Amazon ElastiCache automatically detects failures and promotes a read replica to primary with minimal downtime.”
(Source: Amazon ElastiCache for Redis User Guide)
Why B is correct:
Multi-AZ provides automatic failover and data replication.
Ensures continuous availability and protects against node or AZ failures.
Fully managed with no manual intervention needed.
Why others are incorrect:
A: Manual promotion is not automatic.
C & D: Restoring from backup is slow and meant for disaster recovery, not failover.
[References:, Amazon ElastiCache for Redis User Guide – “High Availability with Multi-AZ”, AWS Well-Architected Framework – Reliability Pillar, , , , , ]
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