Ravindra BagaleCourses & study guides

12. Domains and DNS: GoDaddy, Elastic IP, A/CNAME and Subdomains

12.2 Preparing the Server: Elastic IP and Security Group

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  1. A working website on EC2, tested with curl -I http://localhost and http://<PUBLIC_IP> (Chapter 8 and 8).

  2. An Elastic IP, so the address never changes after stop/start. Quick steps:

    • EC2 console → Network & Security → Elastic IPs → Allocate Elastic IP address → Allocate.
    • Select it → Actions → Associate Elastic IP address → choose your instance → Associate.
    • Note the address, e.g. 203.0.113.10. SSH now uses this IP too.

    (Charges, the default limit of 5 per region, moving an EIP to a replacement server and releasing it safely are covered in detail in Chapter 12.) 3. Security group: inbound HTTP 80 and HTTPS 443 from 0.0.0.0/0 (and ::/0 for IPv6).

Never point DNS to the auto-assigned public IP

It changes on every stop/start. Your domain would then point to an IP that may soon belong to someone else's instance. Always use an Elastic IP (or a load balancer).

Elastic IP charges

Public IPv4 addresses, including Elastic IPs, are charged by AWS. Release Elastic IPs you no longer need (Disassociate, then Release). Check the AWS pricing page for current details – the UI and pricing may change.

Ravindra Bagale's Tip

You pointed the domain at the auto-assigned public IP and then stopped and started the instance – now the domain may point at someone else's server! Many students have made this mistake. First the Elastic IP, then DNS – never break this order.

Practice task

Allocate an Elastic IP, associate it with your web server, and SSH to the server using the new address.