When you have a [partial zone](https://developers.cloudflare.com/dns/zone-setups/partial-setup/), 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

When you [create a new DNS record](https://developers.cloudflare.com/dns/manage-dns-records/how-to/create-dns-records/#create-dns-records) in a partial zone, Cloudflare automatically checks whether any of your CNAME records point to existing A, AAAA, or CNAME records within the same zone.

For example, Cloudflare would show a warning if you had the following records in your partial zone:

```txt
sub1.partialzone.com   CNAME   sub2.partialzone.com
sub2.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 `192.0.2.1`.

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 `sub2.partialzone.com`.

```mermaid
    flowchart TD
      accTitle: DNS resolution flow with CNAME target in same partial zone
      A[Request to <code>sub1.partialzone.com</code>] --> B[<code>CNAME</code> record for <code>sub1.partialzone.com</code> to <code>sub2.partialzone.com</code>]
      subgraph Cloudflare
        B --> C[<code>A</code> record for <code>sub2.partialzone.com</code> to <code>192.0.2.1</code>]
      end
      C --> D[<code>192.0.2.1</code>]
      subgraph Authoritative DNS
      E[<code>A</code> record for <code>sub2.partialzone.com</code> to <code>192.0.2.4</code>]
      end
```



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.

```mermaid
    flowchart TD
      accTitle: DNS resolution flow with CNAME target not in partial zone
      A[Request to <code>sub1.partialzone.com</code>] --> B[<code>CNAME</code> record for <code>sub1.partialzone.com</code> to <code>sub2.partialzone.com</code>]
      B --> C[<code>A</code> record for <code>sub2.partialzone.com</code> to <code>192.0.2.4</code>]
      C --> D[<code>192.0.2.4</code>]
      subgraph Cloudflare
        B
      end
      subgraph Authoritative DNS
        C
      end
```

***

## Records pointing to a partial zone within the same account

You could also [create a CNAME record](https://developers.cloudflare.com/dns/manage-dns-records/how-to/create-dns-records/#create-dns-records) in a zone (partial or full setup) that points to a record in another partial zone within your 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.

```mermaid
    flowchart TD
      accTitle: DNS resolution flow with CNAME target in a zone within the same account
      A[Request to <code>www\.alice.com</code>] --> B[<code>CNAME</code> record for <code>www\.alice.com</code> to <code>www\.partialzone.com</code>]
      B --> C[<code>A</code> record for <code>www\.partialzone.com</code> to <code>192.0.2.4</code>]
      C --> D[<code>192.0.2.4</code>]
      subgraph Cloudflare account
        subgraph Cloudflare zone 1
          B
        end
        subgraph Cloudflare zone 2
        E[<code>A</code> record for <code>www\.partialzone.com</code> to <code>203.0.113.1</code>]
        end
      end
      subgraph Authoritative DNS
      C
      end
```
