High Availability in RDS

Multi-AZ (Disaster Recovery):

• Creates a synchronous standby in a different AZ.
• AWS automatically fails over to the standby if the primary fails.
• Same DNS endpoint is used.

Read Replicas (Performance):

• Creates asynchronous copies for read-only traffic.
• Offloads work from the primary DB.
• Can be promoted to its own standalone DB.
• Used for scaling reads, not for DR.