NAT Gateway vs Internet Gateway: Who Gets to Talk to the Internet

Mon, 03 Aug 2026 06:27:51 +0900

Overview

Both connect a VPC to the internet, but they serve opposite purposes: an Internet Gateway lets public-facing resources send and receive traffic directly, while a NAT Gateway lets private resources reach out without ever being reachable from outside. Picking the wrong one either exposes resources you meant to keep private or silently blocks the outbound access your servers need.

Comparison Diagram

Comparison Table

Aspect	Internet Gateway	NAT Gateway
Primary purpose	Enables communication between a VPC and the internet in both directions	Enables outbound-only internet access for resources without public IPs
Traffic direction	Bidirectional — accepts inbound connections and sends outbound	Outbound only — inbound traffic allowed only as replies to established connections
Placement	Attaches directly to the VPC as a whole	Deployed inside a specific public subnet
IP address handling	1:1 NAT between a private IP and an Elastic/public IP	Many-to-one PAT — many private IPs share the gateway’s public IP
Which resources use it	Instances with a public/Elastic IP routed via a public subnet route table	Instances with only private IPs routed via a private subnet route table
Scaling and availability	Managed, horizontally scaled, highly available with no bandwidth cap	Bandwidth-bounded per gateway; needs one per AZ for high availability
Cost model	No hourly charge and no data processing fee	Hourly charge plus per-GB data processing fee
Failure impact	Loss cuts off all direct internet reachability for the public subnet	Loss cuts off outbound internet access for the private subnet only

Key Differences

Internet Gateway provides bidirectional access; NAT Gateway only permits outbound connections.
Internet Gateway attaches to the whole VPC; NAT Gateway lives inside a specific subnet.
Internet Gateway does 1:1 Elastic IP mapping; NAT Gateway does many-to-one PAT.
NAT Gateway bills per GB processed; Internet Gateway is free.

When to Use Each

Internet Gateway

Vpc on IT Comparison

NAT Gateway vs Internet Gateway: Who Gets to Talk to the Internet

Overview

Comparison Diagram

Comparison Table

Key Differences

When to Use Each