diff --git a/nova/network/neutron.py b/nova/network/neutron.py
index 3160846a3b77..33ad71306a51 100644
--- a/nova/network/neutron.py
+++ b/nova/network/neutron.py
@@ -710,7 +710,7 @@ class API:
             # dns_domain), or if we cannot retrieve network info, we use the
             # admin client to reset dns_name.
             if (
-                self.has_dns_extension(client=port_client) and
+                detach and self.has_dns_extension(client=port_client) and
                 not network.get('dns_domain')
             ):
                 port_req_body['port']['dns_name'] = ''
@@ -726,7 +726,8 @@ class API:
             # NOTE: For external DNS integration, we use the neutron client
             # with user's context to reset the dns_name since the recordset is
             # under user's zone.
-            self._reset_port_dns_name(network, port_id, neutron)
+            if detach:
+                self._reset_port_dns_name(network, port_id, neutron)
 
     def _validate_requested_port_ids(self, context, instance, neutron,
                                      requested_networks):
diff --git a/nova/tests/functional/test_servers.py b/nova/tests/functional/test_servers.py
index 705c1f3cda18..cf8df5bb761a 100644
--- a/nova/tests/functional/test_servers.py
+++ b/nova/tests/functional/test_servers.py
@@ -37,6 +37,7 @@ from nova.compute import manager as compute_manager
 from nova.compute import rpcapi as compute_rpcapi
 from nova import context
 from nova import exception
+from nova.network import constants as neutron_constants
 from nova.network import neutron as neutronapi
 from nova import objects
 from nova.objects import block_device as block_device_obj
@@ -6784,6 +6785,21 @@ class PortBindingShelvedServerTest(integrated_helpers._IntegratedTestBase):
         super(PortBindingShelvedServerTest, self).setUp()
         self.flavor_id = self._create_flavor(
             disk=10, ephemeral=20, swap=5 * 1024)
+        self.neutron.list_extensions = self.list_extensions
+
+    def list_extensions(self, *args, **kwargs):
+        return {
+            'extensions': [
+                {
+                    # Copied from neutron-lib dns.py
+                    "updated": "2015-08-15T18:00:00-00:00",
+                    "name": neutron_constants.DNS_INTEGRATION,
+                    "links": [],
+                    "alias": "dns-integration",
+                    "description": "Provides integration with DNS."
+                }
+            ]
+        }
 
     def test_shelve_offload_with_port(self):
         # Do not wait before offloading
@@ -6811,3 +6827,27 @@ class PortBindingShelvedServerTest(integrated_helpers._IntegratedTestBase):
         self.assertEqual(port['device_id'], server['id'])
         self.assertIsNone(port['binding:host_id'])
         self.assertNotIn('binding:status', port)
+
+    def test_shelve_offload_with_port_preserve_dns(self):
+        # Do not wait before offloading
+        self.flags(shelved_offload_time=0)
+
+        server_name = 'dns-name-test'
+        server = self._create_server(
+            name=server_name,
+            flavor_id=self.flavor_id,
+            networks=[{'port': self.neutron.port_1['id']}])
+
+        port = self.neutron.show_port(self.neutron.port_1['id'])['port']
+
+        # Assert that the port uses a DNS name matching the server name
+        self.assertEqual(port['dns_name'], server_name)
+
+        # Do shelve
+        server = self._shelve_server(server, 'SHELVED_OFFLOADED')
+
+        # Retrieve the updated port
+        port = self.neutron.show_port(self.neutron.port_1['id'])['port']
+
+        # Assert that the port still uses the same DNS name
+        self.assertEqual(port['dns_name'], server_name)
diff --git a/nova/tests/unit/network/test_neutron.py b/nova/tests/unit/network/test_neutron.py
index fa794cb012bc..935cc6e71f39 100644
--- a/nova/tests/unit/network/test_neutron.py
+++ b/nova/tests/unit/network/test_neutron.py
@@ -6223,8 +6223,36 @@ class TestAPI(TestAPIBase):
 
     @mock.patch('nova.network.neutron.API.has_dns_extension',
                 new=mock.Mock(return_value=True))
+    @mock.patch('nova.network.neutron.API._reset_port_dns_name')
     @mock.patch('nova.network.neutron.API._show_port')
-    def test_unbind_ports_reset_dns_name_by_admin(self, mock_show):
+    def test_unbind_ports_keep_dns_name_no_detach(self,
+            mock_show,
+            mock_reset_dns):
+        neutron = mock.Mock()
+        neutron.show_network.return_value = {
+            'network': {
+                'id': 'net1',
+                'dns_domain': None
+            }
+        }
+        port_client = mock.Mock()
+        ports = [uuids.port_id]
+        mock_show.return_value = {'id': uuids.port}
+        self.api._reset_port_dns_name = mock.Mock()
+        self.api._unbind_ports(self.context, ports, neutron, port_client,
+                               detach=False)
+        port_req_body = {'port': {'binding:host_id': None,
+                                  'binding:profile': {}}}
+        port_client.update_port.assert_called_once_with(
+            uuids.port_id, port_req_body)
+        mock_reset_dns.assert_not_called()
+
+    @mock.patch('nova.network.neutron.API.has_dns_extension',
+                new=mock.Mock(return_value=True))
+    @mock.patch('nova.network.neutron.API._reset_port_dns_name')
+    @mock.patch('nova.network.neutron.API._show_port')
+    def test_unbind_ports_reset_dns_name_by_admin(self, mock_show,
+                                                  mock_reset_dns):
         neutron = mock.Mock()
         neutron.show_network.return_value = {
             'network': {
@@ -6244,6 +6272,9 @@ class TestAPI(TestAPIBase):
         port_client.update_port.assert_called_once_with(
             uuids.port_id, port_req_body)
         neutron.update_port.assert_not_called()
+        mock_reset_dns.assert_called_once_with(
+            neutron.show_network.return_value['network'],
+            uuids.port_id, neutron)
 
     @mock.patch('nova.network.neutron.API.has_dns_extension',
                 new=mock.Mock(return_value=True))