private String lastIp() {
   return _propertyStore.get(LAST_IP_KEY);
 }
 private Object lastHost() {
   return _propertyStore.get(LAST_HOST_KEY);
 }
 private void recordLastSuccess(String ip, String host) {
   _propertyStore.set(LAST_IP_KEY, ip);
   _propertyStore.set(LAST_HOST_KEY, host);
 }