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Chapter 9: Domain Names, DNS and Subdomains

9.4 Before you point a domain: prepare the server

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  1. A working website on EC2, tested with curl -I http://localhost and http://<PUBLIC_IP> (Chapters 7 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. 13.233.10.25. 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 section 14.1.) 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).