What it is: High availability setup: a primary DB and a synchronous standby in another AZ.

What it’s for:

• Automatic failover during an AZ outage.
• Keep the same DB endpoint for the application.

Key ideas:

• Replication is synchronous (data written to standby at the same time).
• Standby is not used for reads (in classic RDS Multi-AZ; it’s for failover).
• Failover is automatic (managed by RDS).

Exam cues:

• “AZ failure, no manual intervention, same endpoint” → Multi-AZ.

Hard words:

• *synchronous* /ˈsɪŋkrənəs/: đồng bộ (ghi cùng lúc)
• *standby* /ˈstændbaɪ/: máy dự phòng
• *intervention* /ˌɪntərˈvenʃn/: can thiệp