What it is: Deploying across multiple Availability Zones.

What it’s for:

• Survive an AZ failure with minimal downtime.
• Enable *failover* /ˈfeɪlˌoʊvər/ (chuyển dự phòng).

How it’s used (examples):

• RDS Multi-AZ: primary in one AZ, standby in another AZ; automatic failover.
• Load balancer + EC2: instances in 2+ AZs behind an ALB/NLB.

Exam cues:

• “same endpoint, automatic failover” → often points to RDS Multi-AZ.
• “strict HA requirement” → Multi-AZ design.

Hard words:

• *failover* /ˈfeɪlˌoʊvər/: chuyển dự phòng
• *standby* /ˈstændbaɪ/: chờ sẵn
• *downtime* /ˈdaʊntaɪm/: thời gian gián đoạn