What it is: The process where Auto Scaling removes unhealthy instances and adds replacements to keep desired capacity.

What it’s for:

• Self-healing: keep the fleet healthy automatically.

Default behavior (exam detail):

• ASG creates a scaling activity to terminate the unhealthy instance first.
• Then (while/after termination), another scaling activity launches a new instance to replace it. :contentReference[oaicite:6]{index=6}

Note:

• You can change “launch sooner” behavior using an instance maintenance policy. :contentReference[oaicite:7]{index=7}

Hard words:

• *terminate* /ˈtɝːmɪneɪt/: chấm dứt (tắt/huỷ instance)
• *replace* /rɪˈpleɪs/: thay thế
• *maintenance policy* /ˈmeɪntənəns ˈpɑːləsi/: chính sách bảo trì