Add CNAME flattening example

Author: RebeccaTamachiro

src/content/docs/dns/internal-dns/internal-zones/internal-dns-records.mdx

@@ -6,6 +6,8 @@ sidebar:
   label: Internal DNS records
 ---
 
+import { Details, Example } from "~/components";
+
 Internal zones can contain the same [DNS record types](/dns/manage-dns-records/reference/dns-record-types/) that Cloudflare supports for public zones.
 
 You can manage internal DNS records in the same way as you would manage public DNS records, with the difference that [proxy status](/dns/proxy-status/) does not apply to internal DNS records.
@@ -18,6 +20,36 @@ With CNAME flattening, Cloudflare finds the IP address that a CNAME points to an
 
 Cloudflare will try to flatten the CNAME record considering both the specified [DNS view](/dns/internal-dns/dns-views/) and any existing [reference zones](/dns/internal-dns/internal-zones/reference-zones/). If the reference zone then has another CNAME, the record will again be considered from the perspective of the original view.
 
+<Details header="Example">
+
+- Query for `abc.example.local` with view ID 111.
+- Zone 600 references zone 700, which does not belong to any view.
+
+```mermaid
+flowchart LR
+        accTitle: Internal DNS zones and CNAME flattening example
+        accDescr: Diagram exemplifying Internal DNS zones and containing CNAME and A records
+        subgraph Internal DNS
+				subgraph Zone 700 - net
+				A[@ A 192.0.2.10]
+				B[xyz CNAME def.example.local]
+				end
+				subgraph View 111 - London
+        subgraph Zone 600 - example.local
+				X[@ A 192.0.2.1]
+				Y[abc CNAME xyz.net]
+				Z[def A 192.0.2.9]
+				end
+				end
+				end
+```
+
+After finding the CNAME record that points to `xyz.net`, Cloudflare cannot resolve it within zone 600. However, since this zone is referencing zone 700, this will be considered in the resolution.
+
+The record in zone 700 then points to `def.example.local`, which Cloudflare will then try to resolve in the original view. As an `A` record can be found for `def.example.local`, Cloudflare will return the IP address `192.0.2.9`.
+
+</Details>
+
 If it is not possible to flatten the CNAME record, the following will happen:
 
 1. The CNAME record is returned to Gateway resolver as-is.