Update period (hours): (Default: 576) The time between periodic updates to the dynamic DNS, if your dynamic IP address has not changed. The timeout period is entered in hours so valid values are from 1 to 8760.
Override External IP: The external IP is usually configured automatically during connection. However, in situations where the unit is within a private network behind a firewall or router, the network's external IP address will have to be manually configured in this field.
You may find out what your external IP address is by going to http://myip.dnsomatic.com/ in a web browser.