HI Sleepyhead,

I am the owner, developer and maintainer of the ircbl.org. The public dns server you can use for your RBL requests is rbl.ircbl.org.

I have now updated the ircbl.org website with an 'about' page, which has more information about the ircbl RBL and who can use it.
Spoiler alert: anybody.
There's no restrictions in place, unless you have to do dozens requests/second, then I may need to whitelist your server's ip on my dns server.

Visit https://ircbl.org/about for more info.

Let me know if you have any questions.

Undernet and DALnet admin
Quakenet irc operator
ircbl.org owner