Use Ubuntu NTP servers
diff --git a/files/openstack.cfg b/files/openstack.cfg
index bbbbad7..7180ccc 100644
--- a/files/openstack.cfg
+++ b/files/openstack.cfg
@@ -15,6 +15,7 @@
    disable-neutron-security-groups: "True"
    openstack-origin: "cloud:trusty-kilo"
 ntp:
+   source: "0.ubuntu.pool.ntp.org 1.ubuntu.pool.ntp.org 2.ubuntu.pool.ntp.org 3.ubuntu.pool.ntp.org"
 openstack-dashboard:
    openstack-origin: "cloud:trusty-kilo"
 neutron-gateway: