Invalid reverse DNS detected.

[snarked]

"hello.world.ipv6" is not valid for 2001:470:912e::7f.  Whoever has this needs to fix it.

[tufinhas]

loool
ok

where you found that message?

[snarked]

In my web server logs - when the person to whom this is allocated tried to access my avatar (personalized picture) while reading a forum posting I had made.  I supply the image by a link back to my server.

I use a custom format that logs the IP address and related hostname of the requestor.  (It also denies access via a 403 error to those that have invalid DNS entries - and this was likewise denied.)