Craig - Thanks for posting your question on the forum!
First, I want to mention that AOS's dynamic DNS client currently only works with Dynamic Networking Services, Inc. (www.dyndns.org). The AOS client will automatically notify DynDNS when the router's interface changes IP address. DynDNS will then propagate the change through its network of DNS servers. The scheduled update you see is in case there is no change to the IP address within 35 days. The reason this update is scheduled is that if you are using Dynamic DNS service with DynDNS, then the entry will be deleted if there is no update received within 35 days, even if the IP address did not change.
The document below goes into further details on how to configure Dynamic DNS within AOS and the services that Dynamic Networking Services offer that interop with AOS.
Let us know if you have any further questions.
That is precisely what I needed to know. I was just worried that it would only update every 35 days, so thank you for clarifying. We are using DynDNS.org, but using their Managed DynECT service (Managed DNS | Outsourced DNS | Anycast DNS) using dyndns-custom. All of the updates have worked thus far