diff --git a/README.md b/README.md
index 38d4dd2..b4cbf77 100644
--- a/README.md
+++ b/README.md
@@ -4,3 +4,9 @@ Because any other "Whats my IP?"-tool sucks.
 Try it here: https://ip.clerie.de
 
 It's just one nginx site config. Feel free to host it yourself. It's open-source.
+
+ip.clerie.de is the HTML page with some JavaScript. This page needs an A and AAAA record in DNS.
+
+ip4.clerie.de and ip6.clerie.de just returns the remote addr.
+
+ip4.clerie.de has only an A record. ip6.clerie.de has only an AAAA record.