don't set the DNS record for the outbound public ip

- only ip needed by azure
- exisitng clusters will get their dns removed, but not an issue
- keep ip name simple

cloud/services/publicips/publicips.go

@@ -31,11 +31,20 @@ func (s *Service) Reconcile(ctx context.Context) error {
 	for _, ip := range s.Scope.PublicIPSpecs() {
 		s.Scope.V(2).Info("creating public IP", "public ip", ip.Name)
 
+		// only set DNS properties if there is a DNS name specified
 		addressVersion := network.IPv4
 		if ip.IsIPv6 {
 			addressVersion = network.IPv6
 		}
 
+		var dnsSettings *network.PublicIPAddressDNSSettings
+		if ip.DNSName != "" {
+			dnsSettings = &network.PublicIPAddressDNSSettings{
+				DomainNameLabel: to.StringPtr(strings.ToLower(ip.Name)),
+				Fqdn:            to.StringPtr(ip.DNSName),
+			}
+		}
+
 		err := s.Client.CreateOrUpdate(
 			ctx,
 			s.Scope.ResourceGroup(),
@@ -47,10 +56,7 @@ func (s *Service) Reconcile(ctx context.Context) error {
 				PublicIPAddressPropertiesFormat: &network.PublicIPAddressPropertiesFormat{
 					PublicIPAddressVersion:   addressVersion,
 					PublicIPAllocationMethod: network.Static,
-					DNSSettings: &network.PublicIPAddressDNSSettings{
-						DomainNameLabel: to.StringPtr(strings.ToLower(ip.Name)),
-						Fqdn:            to.StringPtr(ip.DNSName),
-					},
+					DNSSettings:              dnsSettings,
 				},
 			},
 		)

cloud/services/publicips/publicips_test.go

@@ -19,9 +19,10 @@ package publicips
 import (
 	"context"
 	"net/http"
-	gomockinternal "sigs.k8s.io/cluster-api-provider-azure/internal/test/matchers/gomock"
 	"testing"
 
+	gomockinternal "sigs.k8s.io/cluster-api-provider-azure/internal/test/matchers/gomock"
+
 	azure "sigs.k8s.io/cluster-api-provider-azure/cloud"
 
 	. "github.com/onsi/gomega"
@@ -106,10 +107,6 @@ func TestReconcilePublicIP(t *testing.T) {
 						PublicIPAddressPropertiesFormat: &network.PublicIPAddressPropertiesFormat{
 							PublicIPAddressVersion:   network.IPv4,
 							PublicIPAllocationMethod: network.Static,
-							DNSSettings: &network.PublicIPAddressDNSSettings{
-								DomainNameLabel: to.StringPtr("my-publicip-3"),
-								Fqdn:            to.StringPtr(""),
-							},
 						},
 					})).Times(1),
 					m.CreateOrUpdate(context.TODO(), "my-rg", "my-publicip-ipv6", gomockinternal.DiffEq(network.PublicIPAddress{