Can't you just look up the IP in rDNS? You definitely can, I just tried, but it's not 100% clear to me if you can keep a name out of there if you try. I don't

Can't you just look up the IP in rDNS? You definitely can, I just tried, but it's not 100% clear to me if you can keep a name out of there if you try. I don't think you can, I mean DNS is public.