Default VPC Demo

In this guide, we explore AWS Default VPCs, the network environment AWS provisions by default in each region. You’ll learn how to inspect the default VPC, examine its subnets and resources, and launch a test EC2 instance with internet connectivity—all without manual network configuration.

Table of Contents

1. Inspecting the Default VPC
2. Default VPC Across Regions
3. Subnets by Availability Zone
4. Resource Map Visualization
5. Internet Gateway & Default Route
6. Launching a Test EC2 Instance
7. Connecting via SSH & Testing Connectivity
8. Links and References

Inspecting the Default VPC

1. Sign in to the AWS Management Console.
2. Navigate to VPC (search “VPC” or select from recently visited services).
3. Click VPCs in the sidebar and locate the one marked Default VPC.

You should see:

• State: available
• CIDR block: 172.31.0.0/16
• Default VPC: Yes

Default VPC Across Regions

AWS creates an identical default VPC in each region. To verify:

1. Switch your region (e.g., from US East (N. Virginia) to US East (Ohio)).
2. Open VPCs—you’ll again see one default VPC with the same settings and CIDR block.

Subnets by Availability Zone

Within a default VPC, AWS provisions one subnet per Availability Zone (AZ). In us-east-1 there are six AZs, so you get six subnets.

Resource Map Visualization

Use the Resource Map view to see the relationships between subnets, route tables, and the Internet Gateway.

Internet Gateway & Default Route

• A Default Internet Gateway is attached to your default VPC.
• The main route table includes an 0.0.0.0/0 route targeting the Internet Gateway.
• Each default subnet has Auto-assign Public IPv4 enabled.

As a result, any EC2 instance launched into a default subnet receives a public IP and immediate internet access.

Launching a Test EC2 Instance

Let’s launch a Linux instance into the default VPC to validate internet connectivity.

1. Go to the EC2 console and click Launch Instance.
2. Select Amazon Linux 2 AMI and t2.micro.
3. Click Next until Key Pair—create a new key named aws-demo and download the .pem file.

4. In Configure Security Group, allow SSH (port 22) from your IP.
5. Under Configure Instance, ensure:
   • Network: Default VPC (172.31.0.0/16)
   • Subnet: e.g., us-east-1b
   • Auto-assign Public IP: Enabled
6. Review and Launch.

Connecting via SSH & Testing Connectivity

Once the instance state is running, copy its public IP and connect:

ssh -i aws-demo.pem ec2-user@<PUBLIC_IP_ADDRESS>

Test internet connectivity:

ping -c 4 8.8.8.8

Example output:

64 bytes from 8.8.8.8: icmp_seq=1 ttl=110 time=0.965 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=110 time=1.01 ms
--- 8.8.8.8 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss

This confirms that instances in the default VPC automatically receive a public IP and internet access.

Links and References

• Amazon VPC User Guide
• Launching an Instance (EC2)
• AWS Regions and AZs