🌐 AWS 103: Mapping Your Cloud Neighborhood - Creating Your First Subnet

Source: Dev.to

🗺️ AWS Subnets: The Foundation of Your Cloud Network

Hey Cloud Geeks and Network Enthusiasts! 👋

Welcome to Day 3 of the #100DaysOfCloud Challenge: Create Subnet! We’re marching forward in our journey of breaking down massive cloud migration tasks into simple, systematic steps, following the plan from the awesome folks at KodeKloud Engineer.

We’ve secured our access (Key Pair) and set up our virtual firewall (Security Group). Now, it’s time to define the actual location where our future servers will reside: the Subnet!

1. Introduction: Understanding Subnets 💡

Think of your VPC (Virtual Private Cloud) as your own private house in the cloud. A Subnet is a room inside that house.

• What it is: A Subnet is a contiguous range of IP addresses within your VPC, dedicated to a single Availability Zone (AZ).
• Availability Zone: An AZ is one or more discrete data centers in a region, designed to be isolated from failures in other AZs. A Subnet can never span multiple AZs.
• Why it matters: Subnets let you logically segment your network. For example, you can put web servers in a “Public Subnet” and database servers in a “Private Subnet” for enhanced security and control.

For this task, we will create a single Subnet named nautilus-subnet under the default VPC. AWS automatically assigns an available IP range when you create a Subnet in the default VPC, simplifying the process for us!

2. Step-by-Step Guide: Creating the Nautilus Subnet via AWS Console

Step 2.1: Navigate to the VPC Dashboard

• Log in to the AWS Console.
• In the search bar, type VPC and click the first result to open the VPC Dashboard.

• In the left‑hand navigation menu, scroll down and click “Subnets”.

Step 2.2: Initiate Subnet Creation

• Click the orange “Create subnet” button.

Step 2.3: Configure VPC and Subnet Details

• VPC ID: Select your Default VPC (provisioned automatically by AWS).
• Add new subnet: Click if the section isn’t expanded.
• Availability Zone: Choose any AZ in your region (e.g., us-east-1a). Remember, a Subnet lives in only one AZ.
• Subnet name: Enter nautilus-subnet.
• IPv4 CIDR block: In the Default VPC, AWS will suggest an available CIDR. If you must specify one, a typical range is 172.31.32.0/20.

Step 2.4: Finalize and Create

• Review the settings, ensuring the correct VPC and the name nautilus-subnet.
• Click the “Create subnet” button at the bottom.

You have now successfully defined a dedicated network space for your application servers within a specific Availability Zone! 🎉

3. Key Takeaways 📝

• 1:1 AZ Mapping: A Subnet must belong to exactly one Availability Zone.
• Networking Blocks: Subnets define the IP address range available for the servers you launch inside them.
• Default VPC Simplicity: Using the Default VPC simplifies CIDR block allocation, as the primary range is already defined.

4. Common Mistakes to Avoid 🚫

• Wrong VPC: Creating the Subnet in the wrong VPC (especially if you have multiple custom VPCs). Always double‑check the VPC ID!
• Naming Confusion: Use clear naming conventions that reflect purpose and AZ (e.g., app-tier-public-us-east-1a).
• Running out of IPs: Small CIDR blocks like /28 provide only 16 IPs, with AWS reserving the first four and the last one, leaving just 11 usable addresses.

5. Conclusion + Call to Action! 🌟

You’ve successfully mapped out the infrastructure location for the Nautilus team! By creating this Subnet, you’ve set the stage for launching the actual computing resources. Keep the momentum going!

• Connect on LinkedIn: Hritik Raj
• Support the #100DaysOfCloud journey on GitHub: Follow the repository and star the project.