Backport of docs: admin partition and DNS clarification into release/…

…1.15.x (#18632)

* backport of commit bd136d1

* backport of commit cb770fa

---------

Co-authored-by: Jared Kirschner <85913323+jkirschner-hashicorp@users.noreply.github.com>

website/content/docs/enterprise/admin-partitions.mdx

@@ -53,7 +53,12 @@ Only resources in the `default` admin partition will be replicated to secondary
 
 ### DNS Queries
 
-Client agents will be configured to operate within a specific admin partition. The DNS interface will only return results for the admin partition within the scope of the client.
+When queried, the DNS interface returns results for a single admin partition.
+The query may explicitly specify the admin partition to use in the lookup.
+If you do not specify an admin partition in the query,
+the lookup uses the admin partition of the Consul agent that received the query.
+Server agents always exist within the `default` admin partition.
+Client agents are configured to operate within a specific admin partition.
 
 ### Service Mesh Configurations