diff --git a/config/v1/types_dns.go b/config/v1/types_dns.go
index 44fa6e4d27d..c371895471b 100644
--- a/config/v1/types_dns.go
+++ b/config/v1/types_dns.go
@@ -20,6 +20,12 @@ type DNS struct {
 }
 
 type DNSSpec struct {
+	// baseDomain is the base domain of the cluster. All managed DNS records will
+	// be sub-domains of this base.
+	//
+	// For example, given the base domain `openshift.example.com`, an API server
+	// DNS record may be created for `cluster-api.openshift.example.com`.
+	BaseDomain string `json:"baseDomain"`
 }
 
 type DNSStatus struct {