diff --git a/smoketest/scripts/cli/test_service_dns_dynamic.py b/smoketest/scripts/cli/test_service_dns_dynamic.py
index b2b425d80..044d053b4 100755
--- a/smoketest/scripts/cli/test_service_dns_dynamic.py
+++ b/smoketest/scripts/cli/test_service_dns_dynamic.py
@@ -1,170 +1,175 @@
 #!/usr/bin/env python3
 #
 # Copyright (C) 2019-2020 VyOS maintainers and contributors
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 2 or later as
 # published by the Free Software Foundation.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import re
 import os
 import unittest
+import tempfile
 
 from base_vyostest_shim import VyOSUnitTestSHIM
 
 from vyos.configsession import ConfigSessionError
 from vyos.util import cmd
 from vyos.util import process_running
 
 DDCLIENT_CONF = '/run/ddclient/ddclient.conf'
 DDCLIENT_PID = '/run/ddclient/ddclient.pid'
 
 base_path = ['service', 'dns', 'dynamic']
 hostname = 'test.ddns.vyos.io'
 interface = 'eth0'
 
 def get_config_value(key):
     tmp = cmd(f'sudo cat {DDCLIENT_CONF}')
     tmp = re.findall(r'\n?{}=+(.*)'.format(key), tmp)
     tmp = tmp[0].rstrip(', \\')
     return tmp
 
 class TestServiceDDNS(VyOSUnitTestSHIM.TestCase):
     def tearDown(self):
         # Check for running process
         self.assertTrue(process_running(DDCLIENT_PID))
 
         # Delete DDNS configuration
         self.cli_delete(base_path)
         self.cli_commit()
 
         # PID file must no londer exist after process exited
         self.assertFalse(os.path.exists(DDCLIENT_PID))
 
     def test_dyndns_service(self):
         ddns = ['address', interface, 'service']
         services = {'cloudflare': {'protocol': 'cloudflare', 'zone': 'vyos.io'},
                     'freedns': {'protocol': 'freedns', 'username': 'vyos_user'},
                     'zoneedit': {'protocol': 'zoneedit1', 'username': 'vyos_user'}}
         password = 'vyos_pass'
         zone = 'vyos.io'
 
         for svc, details in services.items():
             self.cli_delete(base_path)
             self.cli_set(base_path + ddns + [svc, 'host-name', hostname])
             for opt, value in details.items():
                 self.cli_set(base_path + ddns + [svc, opt, value])
             self.cli_set(base_path + ddns + [svc, 'password', password])
             self.cli_set(base_path + ddns + [svc, 'zone', zone])
 
             # commit changes
             if details['protocol'] == 'cloudflare':
                 self.cli_commit()
             else:
                 # zone option does not work on all protocols, an exception is
                 # raised for all others
                 with self.assertRaises(ConfigSessionError):
                     self.cli_commit()
                 self.cli_delete(base_path + ddns + [svc, 'zone', zone])
                 # commit changes again - now it should work
                 self.cli_commit()
 
             for opt in details.keys():
                 if opt == 'username':
                     self.assertTrue(get_config_value('login') == details[opt])
                 else:
                     self.assertTrue(get_config_value(opt) == details[opt])
 
             self.assertTrue(get_config_value('use') == 'if')
             self.assertTrue(get_config_value('if') == interface)
 
     def test_dyndns_rfc2136(self):
         # Check if DDNS service can be configured and runs
         ddns = ['address', interface, 'rfc2136', 'vyos']
-        ddns_key_file = '/config/auth/my.key'
+        srv = 'ns1.vyos.io'
+        zone = 'vyos.io'
+        ttl = '300'
 
-        with open(ddns_key_file, 'w') as f:
-            f.write('S3cretKey')
+        with tempfile.NamedTemporaryFile(prefix='/config/auth/') as key_file:
+            key_file.write(b'S3cretKey')
 
-        self.cli_set(base_path + ddns + ['key', ddns_key_file])
-        self.cli_set(base_path + ddns + ['host-name', 'test.ddns.vyos.io'])
-        self.cli_set(base_path + ddns + ['server', 'ns1.vyos.io'])
-        self.cli_set(base_path + ddns + ['ttl', '300'])
-        self.cli_set(base_path + ddns + ['zone', 'vyos.io'])
+            self.cli_set(base_path + ddns + ['key', key_file.name])
+            self.cli_set(base_path + ddns + ['host-name', hostname])
+            self.cli_set(base_path + ddns + ['server', srv])
+            self.cli_set(base_path + ddns + ['ttl', ttl])
+            self.cli_set(base_path + ddns + ['zone', zone])
 
-        # commit changes
-        self.cli_commit()
+            # commit changes
+            self.cli_commit()
 
-        # TODO: inspect generated configuration file
+            # Check some generating config parameters
+            self.assertEqual(get_config_value('protocol'), 'nsupdate')
+            self.assertTrue(get_config_value('password') == key_file.name)
+            self.assertTrue(get_config_value('server') == srv)
+            self.assertTrue(get_config_value('zone') == zone)
+            self.assertTrue(get_config_value('ttl') == ttl)
+            self.assertEqual(get_config_value('use'), 'if')
+            self.assertEqual(get_config_value('if'), interface)
 
     def test_dyndns_dual(self):
         ddns = ['address', interface, 'service']
         services = {'cloudflare': {'protocol': 'cloudflare', 'zone': 'vyos.io'},
                     'freedns': {'protocol': 'freedns', 'username': 'vyos_user'}}
         password = 'vyos_pass'
         ip_version = 'both'
 
         for svc, details in services.items():
             self.cli_delete(base_path)
             self.cli_set(base_path + ddns + [svc, 'host-name', hostname])
             for opt, value in details.items():
                 self.cli_set(base_path + ddns + [svc, opt, value])
             self.cli_set(base_path + ddns + [svc, 'password', password])
             self.cli_set(base_path + ddns + [svc, 'ip-version', ip_version])
 
             # commit changes
             self.cli_commit()
 
+            # Check some generating config parameters
             for opt in details.keys():
                 if opt == 'username':
                     self.assertTrue(get_config_value('login') == details[opt])
                 else:
                     self.assertTrue(get_config_value(opt) == details[opt])
 
             self.assertTrue(get_config_value('usev4') == 'ifv4')
             self.assertTrue(get_config_value('usev6') == 'ifv6')
             self.assertTrue(get_config_value('ifv4') == interface)
             self.assertTrue(get_config_value('ifv6') == interface)
 
     def test_dyndns_ipv6(self):
         ddns = ['address', interface, 'service', 'dynv6']
         proto = 'dyndns2'
         user = 'none'
         password = 'paSS_4ord'
         srv = 'ddns.vyos.io'
         ip_version = 'ipv6'
 
         self.cli_set(base_path + ddns + ['host-name', hostname])
         self.cli_set(base_path + ddns + ['username', user])
         self.cli_set(base_path + ddns + ['password', password])
         self.cli_set(base_path + ddns + ['protocol', proto])
         self.cli_set(base_path + ddns + ['server', srv])
         self.cli_set(base_path + ddns + ['ip-version', ip_version])
 
         # commit changes
         self.cli_commit()
 
-        protocol = get_config_value('protocol')
-        login = get_config_value('login')
-        pwd = get_config_value('password')
-        server = get_config_value('server')
-        usev6 = get_config_value('usev6')
-
         # Check some generating config parameters
-        self.assertEqual(protocol, proto)
-        self.assertEqual(login, user)
-        self.assertEqual(pwd, password)
-        self.assertEqual(server, srv)
-        self.assertEqual(usev6, 'ifv6')
+        self.assertEqual(get_config_value('protocol'), proto)
+        self.assertEqual(get_config_value('login'), user)
+        self.assertEqual(get_config_value('password'), password)
+        self.assertEqual(get_config_value('server'), srv)
+        self.assertEqual(get_config_value('usev6'), 'ifv6')
         self.assertEqual(get_config_value('ifv6'), interface)
 
 if __name__ == '__main__':
     unittest.main(verbosity=2)