[wesamco]

I guess the accuracy really depends on your location or ISP.

I believe my ISP rarely or never rotates IP addresses, and on top of that I think my ISP provided router is assigned an IPv6 address and it prioritizes using it, because when I visit whatismyipaddress.com with JS disabled, it can only show my IPv6 address, but if I enable JS it can show an IPv4 address too (I assume through the WebRTC IP leak method, which requires JS)

[xp84]

When I built the thing I mentioned, and even if i did so now, I'd just not make an AAAA record for it, because it's still safe to assume ipv4 connectivity exists (and not just via some remote proxy or something), and I think at least the database I had access to was for ipv4.

I don't think they need any hackery to get your IPv4, they just need a separate hostname configured that they can fetch from, which only has an ipv4 (A) record.