Internet Gateway (IGW)

What it is: A VPC component that enables internet connectivity for resources in public subnets.

What it’s for:

• Allow inbound/outbound internet traffic for resources that are designed to be public.

Key ideas:

• IGW is attached to a VPC.
• Subnet must route `0.0.0.0/0` to IGW to be public.

Exam cues:

• “public subnet requires internet gateway” → IGW.
• “route to the internet” → IGW + route table.

Hard words:

• *gateway* /ˈɡeɪtweɪ/: cổng
• *connectivity* /ˌkɑːnekˈtɪvəti/: khả năng kết nối