====== RDS Multi-AZ ======

**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