What it is: Rules that tell an ASG when to scale out/in.

What it’s for:

• Automatically match capacity to load.

Common types:

• Target tracking: keep a metric near a target (e.g., CPU ~ 50%).
• Step scaling: scale by steps when thresholds are crossed.
• Scheduled scaling: scale at specific times.

Exam cues:

• “keep average CPU at 40%” → target tracking.
• “scale every day at 9am” → scheduled scaling.

Hard words:

• *threshold* /ˈθreʃhoʊld/: ngưỡng
• *scheduled* /ˈskedʒuːld/: theo lịch