DNS over IRC
IRC carries hostname and IP mappings that a local cache and libc Name Service Switch use to resolve names without publishing them through DNS.
This design exchanges hostname and IP mappings over IRC. A local cache and libc Name Service Switch make those mappings available to local applications as name-resolution results.
It is unusual because it uses a chat network for name resolution without sending DNS update requests or publishing the mappings in normal DNS.
Primary source: https://purpleidea.com/blog/2020/09/01/inexpensive-dns-over-irc/