Multiple host updates was actually in an abandoned https://github.com/home-assistant/core/pull/28607 4 years ago that WOULD have done this in addition to being able to verify the IP update frequency (something the documentation for the CURRENT integration doesn’t even discuss).
In case you are curious I looked at the code in the system integration and it seems to check every 5 mins,
Unfortunately, while an engineer for years, I don’t know Python, and just don’t have the time at present for all that would be required to learn all the beuqacratic & process requirements to get an integration qualified while at the same time trying to learn HA design and process internals. I am trying to pick up more knowledge in may spare time (what little there is) but don’t believe I can do more on this than point out what was started previously and hoped someone will pick up the mantle and perhaps move the code along (think it will need a number of things added to even start a chance of being qualified for HA today including config flow, UI support, etc).
So your choices either wildcard the domain entries as suggested earlier (not what I wanted), fork the code and fix it (probably not that hard if you are doing this for your own use and actually understand how internals of HA work, and GitHub process), or use @galaxy_explorer kindly donated code above. You could also manually tweak the integration with I suspect is the easiest solution but It will get replaced with the “production/HA” system integration everytime HA updates so not really a long term solution. The final idea would be to create a HACS integration which would eliminate MOST of the qualification hurtles (as you could even just host it on GitHub, and not have it published/qualified for HACS discovery).
In the end I actually discovered this system integration when looking at the Analytics report of top deployed integrations so it seems there are quite a few people who use this if that helps anyone justify looking into this further
Personally I’m going to test adding multiple hosts by adding multiple instances of the integration in YAML to see if it will update multiple hosts as I have yet to see anyone conclusively answer that question and it ALSO is not addressed in the system integration doc, and as a parting gift I will open a PR to update the doc for the integration to so that at the very least that answer and the update frequency will get pushed to the integration doc and HOPEFULLY save someone else a whole lot of time searching threads and source code.
*** Update- Unfortunately adding multiple instances of the integration in the configuration YAML dosen’t work so ultimately this integration in it’s current public form only supports a SINGLE host entry (be it a single ACTUAL single host host entry or the wildcard ‘*’ entry for ALL hosts). There is no way to update n > 1 DNS records. When I get some time (perhaps over the wknd I’ll try to type this up in a short sweet Documentation PR request in the hops that thee powers that be will push it into th HA docs.
I my case I think I’m going to go with the next most straightforward solution and leverage the script/automation I refereed to above as it should work at least as well as this integration even if it is a bit more complicated (requires additional DNS integration as well as config of automation/script/REST cmd), but is MUCH more versatile in that it can be easily adapted to support ANY DDNS service (that offers a REST api) by simply revising the command script.
Perhaps THIS should be the starting point for a standard integration for a generic DDNS updates pushed from your HA server as we could eliminate the need for ANY provider specific integration (just the config would vary). This would mean that it would be MUCH more widely adopted and ideally that means more broadly supported by the community… Any thoughts/anyone want to take up a general DDNS integration (yes that’s even more work than just adding support for multiple DNS entries… Anyone interested in taking up the mantel?