Fix wildcard behavior described for advaced nameservers

Author: RebeccaTamachiro

src/content/docs/dns/foundation-dns/setup.mdx

@@ -27,7 +27,25 @@ Before opting in for advanced nameservers, consider the following:
 
 Some behaviors are different from standard Cloudflare nameservers:
 
-- Wildcard records: if moving from standard Cloudflare nameservers to Foundation DNS advanced nameservers, make sure to explicitly create records for subdomains currently covered by wildcard records (`*.example.com`).
+- Wildcard records: with advanced nameservers, a wildcard record (`*.example.com`) will not apply to a subdomain that is an empty non-terminal (ENT) [^1].
+
+<Details header="Example">
+
+<Example>
+
+DNS management for **example.com**
+
+| **Type** | **Name** | **Content** |
+| -------- | -------- | ------------------------- |
+| A | * | `192.0.2.1` |
+| A | a.b | `192.0.2.5` |
+
+</Example>
+
+In this example, although no records exist for `b.example.com`, the wildcard record defined for `*.example.com` will not apply to `b.example.com`.
+
+</Details>
+
 - Subdomain delegation: once a subdomain is delegated via NS records, Cloudflare will not serve any other records (such as A, TXT, or CNAME) on that subdomain from the parent zone, even if those records exist.
 
 <Details header="Example">
@@ -85,3 +103,5 @@ To enable advanced nameservers on an existing zone:
 
      Make sure the values for your assigned nameservers are copied exactly.
      :::
+
+[^1]: A node in the DNS tree that has no records associated with it but has descendants that do.