NAT Gateway

What it is: A managed Network Address Translation service that lets instances in private subnets access the internet outbound.

What it’s for:

• Allow private instances to download updates, call external APIs, etc.
• Prevent inbound internet connections to those private instances.

Key ideas:

• NAT Gateway is placed in a public subnet.
• It uses an Elastic IP.
• Private subnet route table: `0.0.0.0/0 → NAT Gateway`.

Exam cues:

• “private subnet needs outbound internet only” → NAT Gateway.
• “managed NAT” → NAT Gateway (not NAT instance).

Hard words:

• *translation* /trænzˈleɪʃn/: dịch/chuyển đổi (ở đây là đổi địa chỉ)
• *outbound* /ˈaʊtbaʊnd/: đi ra
• *Elastic IP* /ɪˈlæstɪk aɪ piː/: IP tĩnh public của AWS