diff --git a/nova/network/neutronv2/api.py b/nova/network/neutronv2/api.py
index 4163abcf26..1cbf1d412c 100644
--- a/nova/network/neutronv2/api.py
+++ b/nova/network/neutronv2/api.py
@@ -315,11 +315,12 @@ class API(base_api.NetworkAPI):
             # in case the caller forgot to filter the list.
             if port_id is None:
                 continue
-            port_req_body = {'port': {'device_id': '', 'device_owner': '',
-                                      'dns_name': ''}}
+            port_req_body = {'port': {'device_id': '', 'device_owner': ''}}
             if port_binding:
                 port_req_body['port']['binding:host_id'] = None
                 port_req_body['port']['binding:profile'] = {}
+            if constants.DNS_INTEGRATION in self.extensions:
+                port_req_body['port']['dns_name'] = ''
             try:
                 port_client.update_port(port_id, port_req_body)
             except Exception:
diff --git a/nova/tests/unit/network/test_neutronv2.py b/nova/tests/unit/network/test_neutronv2.py
index 5a53f82e32..e36d62c25a 100644
--- a/nova/tests/unit/network/test_neutronv2.py
+++ b/nova/tests/unit/network/test_neutronv2.py
@@ -3548,7 +3548,7 @@ class TestNeutronv2WithMock(test.TestCase):
         api = neutronapi.API()
         api._unbind_ports(mock_ctx, ports, mock_client)
 
-        body = {'port': {'device_id': '', 'device_owner': '', 'dns_name': ''}}
+        body = {'port': {'device_id': '', 'device_owner': ''}}
         if has_ext:
             body['port']['binding:host_id'] = None
             body['port']['binding:profile'] = {}
@@ -3828,6 +3828,20 @@ class TestNeutronv2WithMock(test.TestCase):
                           self.api.get_floating_ips_by_project,
                           self.context)
 
+    def test_unbind_ports_reset_dns_name(self):
+        neutron = mock.Mock()
+        port_client = mock.Mock()
+        with mock.patch.object(self.api, '_has_port_binding_extension',
+                               return_value=False):
+            self.api.extensions = [constants.DNS_INTEGRATION]
+            ports = [uuids.port_id]
+            self.api._unbind_ports(self.context, ports, neutron, port_client)
+            port_req_body = {'port': {'device_id': '',
+                                      'device_owner': '',
+                                      'dns_name': ''}}
+            port_client.update_port.assert_called_once_with(
+                uuids.port_id, port_req_body)
+
 
 class TestNeutronv2ModuleMethods(test.NoDBTestCase):