This article describes the purpose, benefits, and limitations of enabling a CNAME setup for a Cloudflare domain.

Overview

A CNAME setup allows a customer to maintain authoritative DNS outside of Cloudflare.  It allows individual subdomains to benefit from Cloudflare's services without requiring updates for a domain's registration to point to Cloudflare's nameservers for DNS resolution.  

The logical flow of a DNS lookup for a domain on a CNAME setup is shown in the diagram below:

Limitations

The CNAME setup has two limitations:

1. DDOS protection for attacks against DNS infrastructure is only available for the delegated subdomain records.
2. Only subdomains, not the root domain, can use Cloudflare's services. This limitation is imposed by Internet DNS specifications.

Related resources

Configuring a CNAME setup