Xip.io - a magic domain name that provides wildcard DNS for any IP address

What is the use case that requires http://test.10.0.0.3.xip.io/test-page rather than http://10.0.0.3/test-page ? I've been using the latter on iphones and ipads with no problem. Honest question.

I found its internal working quite interesting: $ dig 127.0.0.1.xip.io ;; ANSWER SECTION: 127.0.0.1.xip.io. 403 IN CNAME 9zlhb.xip.io. 9zlhb.xip.io. 405 IN A 127.0.0.1 Returning CNAME pointing to some record? Apparently, 9zlhb is a base 36 of integer of 1.0.0.127. ip: 1.0.0.127 dec: 16777343 base 36: 9zlhb I guess they decided to reverse the IP address to make generated CNAME scale better (in number of characters): base 36 reverse base 36 1.0.0.0 9ZLDS 1 10.0.0.1 2RVXTT 9ZLE2 127.0.0.1 Z8KFLT 9ZLHB

Just a heads up that services like these won't work behind security-aware DNS recursive resolvers (like OpenDNS) or routers (like Google Wifi) that block DNS rebinding attacks. https://en.wikipedia.org/wiki/DNS_rebinding https://support.google.com/wifi/answer/9144137?hl=en

curl: (6) Could not resolve host: xip.io curl: (7) Failed to connect to www.xip.io port 80: Connection timed out but the front page is cached at http://webcache.googleusercontent.com/search?q=cache:o8L_uDk... with google site:xip.io you can see that this is mostly used to point at super-dodgy looking content (using an alternate "base36" representation of IP addresses) so that's awful example.9zlhb.xip.io has address 127.0.0.1