Some ISPs require changes ever 24 hours and will disconnect you if needed. Also, if you set DNS to cache such a short amount of time that you can react to that in 5 minutes, you will incur way more DNS traffic which can become a problem when your site is busier. Also, even if your DNS TTL is set to a super short value, a web search suggests to me in practice there will likely be downstream clients and networks that ignore it and won’t really update in such a short time frame.

Even in an ideal DNS setup, you’re probably going to have downtimes whenever your dynamic IP changes. If only because some ISPs even force-disconnect you after a while to change your address.

No german ISP that i know of does this, it’s awful. One doesn’t even offer reverse IP ptr entries whatsoever, even if you had a static IP.

You know, what’s kind of encouraging is that I posted something similar to this complaint on reddit, and 100% of the responses were corporate apologia how it would apparently be so much work and so much more expensive to provide a static instead of a dynamic IP, or how routing through VPSes is so much better anyway. I hadn’t realized the reddit to lemmy brain drain was so bad, which seems good for decentralized morally good hosting.

Personally, I find it hard to believe that just not changing somebody’s prefix all the time would possibly cause so much technical extra effort that any additional fee is justified.