In this guide, we will provide a brief overview of CNAME Flattening, discuss whether or not your domain provider supports it, and explain what to do if it does not.
In summary, some providers now offer the ability to add a CNAME to your root domain (e.g. example.com) rather than just a subdomain (e.g. www.example.com or blog.example.com). This feature was not offered by some traditional domain providers, till today.
Cloudflare has an in-depth article introducing CNAME Flattening:
Different providers implement CNAME Flattening in various ways, and they may refer to it by different names, such as CNAME flattening, ANAME, or ALIAS.
To determine if your domain provider supports ALIAS or ANAME records, simply check if they offer the option in the DNS records management interface. If you encounter an error when attempting to add a CNAME to your root domain, it's possible that your provider does not support it.
Confirmed Supported ✓
Confirmed Not Supported ✕