Internet Gateway — Complete Guide
Internet Gateway — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of AWS Cloud Tutorial on Toolliyo Academy.
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AWS Cloud Tutorial · Lesson 17 of 100
Internet Gateway
Core services → Projects
Core services · 1 — AWS basics · ~6 min · AWS — Networking & Security
What is this?
An Internet Gateway attaches to a VPC and enables bidirectional internet routing for public subnets when instances have public IPs or EIPs.
Why should you care?
AwsVerse public ALB and CloudFront origins need IGW-backed subnets for internet-facing endpoints.
See it live — copy this example
Run in AWS CloudShell / local AWS CLI v2, or follow the matching steps in the AWS Console (Free Tier).
aws ec2 attach-internet-gateway \
--internet-gateway-id igw-0a1b2c3d \
--vpc-id vpc-0abc123What happened?
- Attaches IGW to VPC.
- Without this and a 0.0.0.0/0 route on a public route table, instances cannot reach the internet.
Practice next
- Create IGW; attach to VPC.
- Add route 0.0.0.0/0 → IGW on public route table.
- Launch EC2 with public IP; curl ifconfig.me to verify.
- Detach IGW in lab and observe lost connectivity.
- Use aws ec2 describe-internet-gateways.
Remember
IGW = VPC internet doorway. Works with public IPs/EIPs. One IGW per VPC.
AwsVerse public edge
Customer HTTPS hits ALB in public subnet.
Outcome: IGW plus public RT delivers traffic to load balancer only.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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