DNS resolution in partial zones
When you have a 1, Cloudflare handles DNS records a bit differently from full zones in order to internally resolve the origin server where proxied HTTP requests are sent to.
Records within the same zone
For example, Cloudflare would show a warning if you had the following records in your partial zone:
sub1.partialzone.com CNAME sub2.partialzone.comsub2.partialzone.com A 192.0.2.1
Since Cloudflare contains both the
CNAME and its target, our DNS resolution will send incoming HTTP requests to
sub1.partialzone.com to the origin
This can cause issues if you already have DNS records for
sub2.partialzone.com at your authoritative DNS provider. These records may point to
192.0.2.4, another IP address, or another domain but - because Cloudflare contains the initial record and the target - it never queries your authoritative DNS provider for the record for
When you avoid this situation - meaning you do not have the target of the
CNAME record within your partial zone - this DNS resolution would happen differently.
Records pointing to a partial zone within the same account
In this case, Cloudflare will always resolve the
CNAME target based on the value at your authoritative DNS provider of the partial target zone.
A partial (
CNAME) setup allows you to use Cloudflare’s reverse proxy while maintaining your primary and authoritative DNS provider.
Use this option to proxy only individual subdomains through Cloudflare’s global network when you cannot change your authoritative DNS provider.↩︎